Replacing my 230sl differential...

[waqas]

Note: this thread has been transformed into a rear axle/differential assembly replacement thread.

Greetings:
On changing the manual transmission and differential fluids in my recently acquired 230SL ('65), I found metal slivers floating around (and mocking me with their oily gleams). I've been dreading this, but what is the best way to approach this?  Replace the manual transmission and differential with good used ones? Try to rebuild? Run it until something gives? (of course, the transmission is already complaining with a nice warm hum, typical of warn gears; however, shifting is still extremely smooth).
If replacement/rebuilding is inevitable, I was considering using this opportunity to replace the 4-speed with a 5-speed. How easy is it to find a ZF? Which other MB 5-speed manuals fit? I also read about someone changing out the differential with another having a different ratio. Is this advisable if also changing to a 5-sp? What kind of expenditure am I looking at here? (DIY or not)
So many questions, so little time...

waqas
--
1965 230 SL Euro, 4sp. man, dark green

[ja17]

Hello Waqas,
Don't count your old units down and out yet. Transmission noise will often times is caused by damaged or worn main ball bearings or a loose spanner nut on the gear cluster. The five speeds are very rare and very expensive if you can find one. In any case a transmission removal is in your future if you are experiencing noise from the unit.

The standard transmissions are not that difficult to repair. Many sedan era standard transmissions will bolt right up to your W113 but the first gear ratio is real granny on the sedans.

Change the differential oil and don't worry about it unless it gets noisy also.
Good luck, keep us up to date.


Joe Alexander
Blacklick, Ohio

[waqas]

Thanks for the re-assurance. Having changed the transmission fluid, I can attest to the fact that the previously apparent gear hum is noticably lower, although still quite prominent. Would it be helpful if I flush out the transmission a few times to clear as many particles as possible? Will I be ruining any refurbishable parts by continuing to drive it this way? Is there such a thing as a re-build kit available, and what does it typically comprise?

Lastly, perhaps it would be best if I leave the rebuild to the experts (the most I've done in the past is swap out transmissions on my old Honda). Would you recommend anyone in particular?

Thanks for all your kind advice!

waqas
--
1965 230 SL Euro, 4sp. man, dark green

[waqas]

In the interest of thread non-proliferation, it's time to resurrect this old thread. It seems my differential finally gave out (gave up?): as I was heading out of the house, I heard a thunk, and the car slowed to a stop (engine running). No gears worked. I peered underneath, and my drive-shaft was still turning (car was in first). As you can probably guess from my earlier posts, it seems that lack of oil over the years with the previous owner finally caught up to me.

My question is this: is there a differential rebuild kit available? I'll probably take the diff. and kit to an expert (I'm in Austin, TX), as I've little experience with such things.  If not, what are my options for a replacement? Which other MB differentials can I use?

Also, what other maintenance tasks would you recommend while the differential is out?

waqas
--
1965 230 SL Euro, 4sp. manual

[ja17]

Hello Waqas,
Sorry to hear about the bad luck.  It sounds like the splinned univeral in the differential sheared. These can be changed out, but the differential will need to be opened up and removal is probably best.


Download Attachment: SUDDEN DIFFERENTIAL FAILURE.JPG
34.61 KB

The new part is very expensive. A good used differential is a good option. Good used univeral units can also be had. Most W111, W112, W108 sedans and coupes of the era had this type of differential. The 3.75 ratio of the 230-SL may be a little more difficult to find. However 4.08, 3.96, 3.69 and 3.27 are a lot more common. These will also have disc brakes on the rear also.
Locating a good used differential unit or the part is not difficult or expensive, let us know which way you wish to proceed.



Joe Alexander
Blacklick, Ohio

[waqas]

Hi Joe,
Thanks for the information. A preliminary search on the web has yielded little on where to get a used replacement. It seems the alternatives you mention might be my only option. Judging by John Livingston's recent experience --nicely documented in these pages, I might gratefully add-- I've a 'fun' time waiting ahead for me :-)

Regarding my current differential ratio, I'm not sure what exactly I have. It appears the rear axel/assembly may not be original (my drums have lug nuts and not lug bolts, and 113's had lug bolts on all four wheels, including the 230sl drums, as pointed out by Ray Paul of SL Classics on the phone a few months back).

Correlating the behavior in 1st gear with other 113 owners, I've a hunch it is higher than 3.27, and indeed, it may still be the original 3.75-- which begs the question: how can I tell? (lettering on the casing?)  I'm not necessarily in favor of changing to a 3.27 (I'm not a 'cruiser'; I do a lot of backroad driving; besides, I love that load roar). I suppose a reasonable alternative would be the 3.69 ratio. Which models were these fitted in?  

Lastly, would you be able to recommend any junkyard/dealers in your 'rust-prone' north who might have a reasonable donor waiting to lose it's rear end?

Thanks again and kind regards,

waqas
--
1965 230 SL Euro, 4sp. manual

[Naj ✝︎]

A pity that MB chose not to use a little magnet on the drain plugs to catch these floating slivers  :evil:
naj

65 230SL
68 280SL

[rwmastel]

quote:Originally posted by naj

A pity that MB chose not to use a little magnet on the drain plugs to catch these floating slivers

I've got a motor oil drain plug with a magnet.  I got it from Will Samples at S&S Imports (see our vendors list).  I never thought of getting one for transmission or differential.  Are they available?

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[n/a]

When I bought my car the transmission made noises and when I changed the fluid it was filled with metal chips.  After taking it apart I found that the bearing between the input shaft and the output shaft had disintigrated.  This explained why the tranny was noisy in all gears exept 4th.  In 4th the two shafts rotate at the same rpm.  

This was about 9 years ago and the price for new shafts was ridiculous.  I guess now it would be ludricous.  I bought a used tranny and put it in.  I am curious if there are numbers on the transmission that are matched to the VIN.  DOes anyone know?

[Tom]

Kevin,

Yes, the transmission number is a part of the matching numbers of the car.  The transmission number is on the data card and on a metal plaque on the transmission.  If you switch out the transmission, the numbers will no longer match.  For some, this does not matter.  But I think matching numbers will generally bring a higher price at resale.

Best,

Tom


1971 280sl Tunis Beige Metallic (restored & enhanced)
1971 280sl Tobacco Brown (low mileage stock)
1970 280sl Deep Red (Project Car)

[waqas]

Anyone know if the axles are interchangable between the 113 and others of the same era? (108, 109, etc) i.e, will I need the entire rear assembly (diff/axles/struts/comp-spring, etc) as a complete unit from the donor vehicle?  Also, any propeller shaft modification needed? (length etc)

waqas
--
1965 230 SL Euro, 4sp. manual

[ja17]

Hello Waqas,
Yes sedans of the era had rear axle assemblies which will directly interchange. The W111, W108, & W110, sedans coupes and convertibles will change over easily. Do not use a W109 or W112 chasis air suspesion rear assembly they will not change over. The earliest sedans had drum brakes also. Most had rear disc brakes. The W113 compensator spring different from the sedan spring. The W113 spring will change over replacing the sedan spring or compensator. Driveshaft hook-up is the same. Use your W113 springs also.

Removal of the exhaust is normally chosen to make access better during the process. Ratios 4.08, 3.96, 3.75, 3.69 and 3.27 were some common ratios.

Joe Alexander
Blacklick, Ohio

[waqas]

My rear axle/differential assembly is enroute-- I managed to find an original 230sl axle with 3.75 differential ratio. In the mean time, I've started removing bits and pieces. This evening, as I removed the exhaust/header bolts, I realized that maneuvering the exhaust pipes out from under the car may not be as easy with jack-stands under only the rear half. How high do you think I need to raise the car before I can maneuver the entire exhaust out from underneath?   Also, I usually support the rear on the trailing arm mounts to the chassis. Since I need to remove the trailing arms for axle removal, is there any other relatively safe spot to place jackstands under the rear?

waqas
--
1965 230 SL Euro, 4sp. manual

[ja17]

Hello Waqas,
Try raising the car just on the right side to remove the exhaust!

After exhaust removal, jack up the car on all corners. You will need to block up the vehicle in the rear and leave access to the rear suspension for removal. Do not allow the right rear axle to hinge down hard against it's casting which can crack! Prevent this by removing the transverse compensator spring first.

Check your new unit by unclamping the larger boot clamp and inspecting the thin lip of the casting for cracks.


Yes you should closely inspect the axel boot. Replace it if at all questionalble.
Also if you split the axle to replace the axel boot you will have performed the work required to repair your original broken rear axle. Maybe you should practice on your original first to see what is involved. You can change the broken yoke assembly and have a spare rear axle assembly while your in there!




Joe Alexander
Blacklick, Ohio

[Benz Dr.]

Just did this job on a 220Sb sedan.  The replacement axel was cracked and a piece was broken out. I already had this axel ready to go in so we had to take it apart. Ricardo was here at the time and somehow I put it all back together yet managed to install the shaft backwards. We had to take it all apart and start over.
 The old one was so loud due to gear play that you couldn't have a normal converstation without shouting and all the windows were rolled up. It also had next to no brakes because the rear cylinders were leaking. This axel is a carbon copy of the 230SL.
 Oddly, it's a 4.08 ratio out of a 200 fin car. Excellent condidtion without any real wear.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org

[waqas]

Alright. I was able to remove the exhaust and rotate it to the right, without removing it entirely from the car. quite amusing actually. It seems my exhaust seals either disintegrated, or were never installed in the first place (at the exhaust manifold header). In any case, I shall install new ones. I disconnected the e-brake cables and brake hoses. I surveyed the damage, and it looks as if some seal exploded in there! From what I understand, here are the recommended steps in order (even though they somewhat differ from the Haynes and BBB instructions):
(1) remove springs first
(2) remove shocks (supporting axles from thereon)
(3) then remove compensating spring (according to ja17's instructions)
Sunday is national car repair day in Austin, Texas, and I shall attempt the above if no objections are raised.

Waqas

Download Attachment: exhaust.jpg
54.96 KB

[ja17]

Hello waqas,
 
I leave the rear shocks attached until until the right axle half is supported with a floor hjack or such. This will prevent the axle from hinging down hard against it's casting.  Let the rear axles hang down releaving pressure on the compensator spring. Remove the rear compensator spring next. Removal of the compensator spring should be done with a spring compressor (compressed springs are very dangerous).

You can support the axle halves easily with a floor jack and disconnect the trailing arms and remove the rear springs (no spring compressor needed for these).




Joe Alexander
Blacklick, Ohio

[waqas]

I was able to remove the springs and shocks yesterday (rear axles are supported). Having lowered the axles quite bit, I was still unable to get my spring compressor jaws into the compensating spring. I'm now considering making my own tool... but does anyone have a recommendation on a commercially available spring compressor that will fit?

Download Attachment: springs.jpg
55.05 KB

Download Attachment: axle_support.jpg
56.4 KB

waqas
--
1965 230 SL Euro, 4sp. manual

[waqas]

My new (to me at least) differential arrived this afternoon, and I just completed a photoshoot: I have a ton of questions (please bear with a newby like me).
Download Attachment: new_diff.jpg
52.1 KB

(1) First of all, my axle boot looks ok. Is there any conventional wisdom out there regarding replacement? It seems like a lot of work to replace.
Download Attachment: axle_boot.jpg
41.76 KB

(2) The differential hanger/mount is a big unknown to me. Any suggestions?
Download Attachment: diff_hanger.jpg
54.07 KB
Download Attachment: diff_hanger2.jpg
38.39 KB

(3) It seems that the e-brake cables and attachment points are still intact. How can I check to make sure they are usable and safe? (and thereby obviating the need to remove and replace them from the drum assembly)

(4) What in the world is this little pipe sticking up in the air? It has a little cap on top, which seems somewhat loosely attached. Anything to worry about?
Download Attachment: diff_pipe.jpg
48.4 KB

(5) Lastly, how can I tell if my differential is of the correct ratio? It has the following part number stamped on the case (driver's side):  110-357-0018  (I don't see any other numbers)

Thanks for any assistance.

Waqas in Austin, Texas

[rwmastel]

quote:(4) What in the world is this little pipe sticking up in the air? It has a little cap on top, which seems somewhat loosely attached. Anything to worry about?

Breather tube to release pressure build up (from heat?) in the differential.  It must be kept clean.  Rumor is that if this is plugged then fluid will come out the pinion seal.

quote:(5) Lastly, how can I tell if my differential is of the correct ratio? It has the following part number stamped on the case (driver's side):  110-357-0018  (I don't see any other numbers)

On the lower part of the rear of the differential there should be a small (2 inches) half-circle that is flat and has the ratio stamped into it.  It will say 3/75 or 4/08 or something like that.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[A Dalton]

The rear hanger is easy to check when the rear diff is out by checking the lateral play grabbing the hanger arm at top and rocking foward/backward..
 These are often over-looked  [ vs the often changed top support one in the trunk mount]..
 .if the front seal shows evidence of long time leak/seeage, then the rubber in the support is shot.
 The other reason to check these is cuz the first ones were a two piece rubber inset.  They were later changed/modified to a single, much better full length support. The ratio on yours may be found on a machined flat just in front of the lower/front, outer/left axle
tube mounting bolt.  The first series of #'s will be the serial and the last 3 will be the ratio.. they will use a comma on the ratio #, vs a colon as commonly used here in the USA.
 ie ... 3,75 rather than 3:75

[jlennon3]

If you've still got the "new" rear end out, you'll be way ahead of the game by doing some extra work now. Well actually a lot of extra work, but very satisfying work. You really should replace the rubber "boot", unless you know it's been replced prior. While you're at it you'll want to replace the axle shaft seals (since you have to remove the axles to replace the boot). There's a trick to pulling the axle shafts; not difficult but essential to ensure you don't break a snap ring (can't remember the details, but they're in the BBB). Also check the axle bearing and replace if necessary. Also replace the rubber seals and, if necessary, brass bearings at the axle pivot point. I didn't do anything with my pinion seal; didn't feel comfortable trying to set "pre-load" by myself (there's probably not many mechanics left that know how to do it). It's a couple days work, but you'll feel a lot better knowing you won't have leaks, bearing failure, etc and have to go to all the trouble of removing your "new" rear end after you've gone to all the trouble of installing it.....

[graphic66]

As for the compensating spring, if you havn't yet take out the fuel tank, it will be worth the extra work. I had to take a spring compressor and grind the ends until they fit into the spring. I could only get one compressor on it. Be carefull it's a real loaded gun waiting to go off.

[waqas]

I finally found the semi-circular machined surface with the ratio stamped "SL 3/75". Armed with the knowledge of where to look.. I found that my existing differential shows "B 4/10".. confirming that it was not original (and promising a noticable improvement when I'm done). My previous clue was the fact that my drums had studs instead of threaded sockets for the lug bolts. Another interesting note: the welded seams on each end of both axles are quite noticable! I saw them on my "new" rear end, and panicked... but then I found similar seams on my old axles at the same spots... was this standard MB practice? they seem awfully unfinished compared to all the fine joints and seams everywhere else...

I appreciate all your input... it appears that I shall have to break my vow of finishing this job before May 1st, and do it right. Feel free to continue providing guidance.

Waqas in Austin, Texas

[Benz Dr.]

You don't have to pull the axel if you use a split boot. If you split the axel in two you will find out just how much work that is and how tricky it is to do it. The slip coupling also has to be removed before you can take the hinged side off.
You can install the split boot without removing anything although is easier to do this with the cpmpensating spring removed.

We found a way to remove and install the spring that's really quite easy, but as in all things involving springs, you must be very carefull and have good tools to work with.
What we did was to install the right flange that holds the spring using only one screw. We left the outer one out and used a long piece of wood placed under a heavy floor jack with the other end under the flange. I locked the wheels of the jack in place but if you lift straight up it will be safer. As you raise the jack upwards the spring will compress and when it moves just far enough you carefully install the second screw. Install time is about 5 minutes.

You can remove the spring the same way by always taking the outer screw out first. This allows the flange to swing down out of the way with the jack placed under it. Always have the axels fully down to release as much tension as possible from the compensating spring.

This isn't advice for people without a hoist or a good floor jack. You need to understand how things can move and how to line things up. This is also a 2 man operation. Trying this by yourself could get you hurt.

We are able do this operation here, but then we often do things that can't be done ~)

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org

[ja17]

Hello Dan,
I also have a method for removing and installing compensator spring without a spring compressor. But the method could be dangerous in the hands of non professionals so I hesitate to recommend it.

Joe Alexander
Blacklick, Ohio

[Benz Dr.]

Uh, yeah. I suppose you have a point there Joe. I'm more than aware of how coil springs can hurt you because I've been a victim........

 After setting fire to my car once and other assorted screw ups I'm much more carefull as I age. Amazing that I've lived this long ( 50 )

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org

[waqas]

Well, I just finished cleaning up the mess I made. It seems my differential supplier decided not to drain the oil before shipping. That, coupled with my brilliant assumption that they had indeed done so, resulted in lots of cat-litter on my garage floor. And all I was trying to do was check the boot and differential housing for cracks (as per Joe Alexander's suggestion). It seems the boot may have been replaced in the past ten years or so-- the rubber appears to be fairly supple. That, and the fact that there was no apparent oil leak around the entire differential housing, lead me to believe I can probably spare myself the headache of messing with axle removal and boot replacement. If something happens later, I can always use the split boot (too many people have voiced their confidence in them for me to ignore).

My question of the hour: anyone know how to replace the tubular mount in the differential carrier/hangar, without removing or unhinging the right axle?  The bushings in the right axle hinge seem fine, but the tubular mount appears suspect.  I already tried to remove the wedge screw so I could partially slide out the long connecting bolt (until it reaches the right axle hinge portion), but the wedge screw wouldn't even budge!  Does it make sense to instead remove the differential front "cover with clamping eye" and slide off the carrier mount? (I'll need to remove the flange for pinion seal replacement anyhow)

Waqas in Austin, Texas

[A Dalton]

You can change the hanger lower mount either way.
If you remove the wedge lock bolt, you can push the pivot pin back without removing it from the axle casing enough to change the mount.
Careful with the wedge, they are very brittle.........
 The other way, [ which I do if doing a pinion seal at the same time],
  you will have to take the pinion nut off to remove the flange.
The trick here is to index this nut in relation to the pinion shaft
for re-assemby, as you do not want to overtighten the crush bushing
any further than spec torque. This will get you back to where you started , which is a safe way to do it.
 However , I prefer to set the torque preload on the pinion to Spec. , so i use the inch lb conversion of 24-26 in/lb to set the crush load.
 The reason this is a better way is that by indexing, you are only assuming the preload was correct before you removed the nut , whereas I find that most used units have some bearing wear and can use a little more load to come back to factory specs. This can only be done with touque readings and is a tricky little job [ until you have done one]
 Most I have done usually wind up requiring about a 1/16th to 1/8'
more turn, but do not use that info without taking torque readings and doing it the correct way.
 If you go the flange removal route, index the flange also and change the seal while you are there , for sure.
Most hanger mounts deterioration is caused by a long time leaking/seeping pinion seal, anyway.  [ aside from the inferior design of the early 2 piece ones]
 A word of caution:
 If you over -tightened the pinion nut and cause the crush bushing to be to tight, you can NOT loosen the pinion nut for correction... the crush , once crushed, will not return by loosening the pinion nut and MUST be replaced if this happens, so use care...
 Also remember, the torque of the pinion nut is a very high torque , whereas the torge spec for the bearing load measure is very low, so do not confuse the two.
 The load spec I talk of [ 24/26 in/lbs]is the force required to turn the pinion shaft with no load on the differential [ brakes,etc], whereas, the pinion nut torque is the actual tightening torque of the pinion nut with the flange locked.. [ pry bar ].. and the torque
on that nut determines the load on the crush/bearings, so it is not a specific torque, but rather, what ever it takes to get the load spec correct..
 A little long winded on this subject, but another important item to consider with the new hanger installed ... it is best to position the hanger before hanging the rear end. the important setting is to have the hanger at 90 degres in relation to the left/rear axle [ the fixed axle].. it is best to use the center line of the axle casing rather than the axle casing itself, as they have a slight taper.
 Other measures are lateral, but thay can be close enough by measuring the old one before removal. Once therse are established , you can tighten the cinch bolt.
 The last measure is axle centering after the whole axle has been installed . This is done with the cross link/strut adjuster nuts and I have a pictoral somewhere here on the site explaining that and a diagram for an easy to make diyer tool...
 

[Benz Dr.]

It's important to get the pin going up into the trunk at a 90 degree angle to the axels. I use a level and do it with the compensating spring removed.

 Place small pieces of wood or cardboard under the centre of the axel until it sits level on both sides. Place your level on the pin ( verticle ) and move it either way until the bubbles sit dead centre. Not 100% accurate but better than by eye or not at all. Never had a problem using  this method.



Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org

[waqas]

A quick update: still waiting for all parts; was able to completely remove old diff/axle assembly with ease on a wooden plank contraption thingy mounted on my floor jack; also, I made a simple little compressor with a single threaded bolt and a couple metal plates for the compensating spring that allows safe and easy spring removal without the petrol tank hindering in the least; one end mounts directly onto and through the differential portion of the spring mount; once the axle side of the spring mount has been removed, the spring can slowly be de-compressed while still mounted on the differential portion. I can post more details if anyone is interested.

For now, I've a few brain-dead questions about parts. Thanks in advance for any and all guidance.

(1) When I removed the differential mount (trunk), it looked ok to me. In fact, the new one looks a bit different than the original. I suspect the new one (on the right) will lower my riding height by a bit (seems minor). Should I worry about alignment issues if I use the new one, or should I just play it safe and keep the old one?
Download Attachment: 113-diff-mount-sidebyside-close.jpg
33.3 KB
Download Attachment: 113-diff-mount-top-close.jpg
44.55 KB

(2) The new muffler hanger rings seem different from the originals. For example, my old rings from the centre hanger look triangular (part # 113-492-0082), while the replacement rings are smaller and completely circular. Can these rings stretch so much?? Or did I get the wrong parts...?
Download Attachment: 113-muffler-ring-closup.jpg
56.76 KB
Download Attachment: 113-muffler-ring-sidebyside.jpg
50.08 KB

(3) My old rear muffler hangar rings were of two different kinds. What is the correct part number for these rings? #107-492-0082 (on the left) seems pretty soft, while #116-492-0182 (on the right) seems pretty hard... shouldn't they be the same??
Download Attachment: 113-muffler-ring-small.jpg
60.36 KB

(4) Regarding the upper rear spring mounts, I have read somewhere that replacing with the 30mm version is recommended, especially when the old springs are to be re-installed. My old pads look quite alright, except that one of them is about 23mm, and the other is about 18mm (both measured at the same thickest point, and where the centre-line of the spring coil wire sits). I never really noticed any difference in how level the car sat (5mm is pretty subtle). Should I just bite the bullet and order the 30mm pads? Or can I stick with my oldies?

Thanks again and kind regards,

Waqas in Austin, Texas

[A Dalton]

The triagular shape of the old hangers is just the results of long term position memory of the rubber.....

[George Davis]

Waqas,

Please post more information on your compensating spring removal method.  I want to replace the rubber pads on mine.

I don't know where you are on the rest of your work, but here are some thoughts:

Use the new diff mount, it will settle pretty quickly to a lower height anyway.  If it affects ride height at all, it will be by a very small amount.

On the rear spring pads, these are (or should be) select-fit to achieve proper rear camber (which also sets rear ride height).  If your current pads are the correct thicknesses, no need to replace them.  Unfortunately, this may involve reassembling, checking camber, and if you need taller pads then you get to do it again.

Rear camber should be positive 1.5 +/- 0.5 degrees, measured with hardtop installed, full fuel tank, and spare tire and tools on board.



George Davis
'69 280 SL Euro manual

[waqas]

George,
I'll post more details when I get home tonight. Regarding the whole project, I haven't been able to get one of the trailing arm bolts off, rounding it off in the process. I think I may need to weld a socket to it. But I've been too busy at work to pay any more attention.

Waqas in Austin, Texas

[waqas]

George,
In order to remove the compensating spring, I had to make my own crude little spring compressor. Having never removed the spring before, I had no idea of the fully extended length of the spring (mine turned out to be 11"), and hence the amount of energy stored therein. All the commercial spring compressors I found had grappling hooks too thick to fit comfortably between the coils, and I felt uncomfortable grinding them down. Compounding things further was the close proximity of the petrol tank, pump and hoses. I then noticed that the differential side (left side) of the spring mount was hollow (had a through-hole). This gave me an idea. I used a 15" long 0.5" diameter threaded bolt (Home Depot, about $3/ft), some washers and nuts, and a couple of home-made metal plates.

Download Attachment: pagoda-comp-spring-parts.jpg
52.8 KB

The plate holding the spring (on the right in the photograph) is about 5"x2"x0.25", with a 0.5" hole drilled through the centre. The plate on the left is about 3.5"x2"x0.25".

(0) As a prerequisite, relieve as much tension from the compensating spring as possible. An old post by Joe Alexander mentioned removing the shock absorbers, and slowly lowering the axles, always keeping them fully supported. Also, slightly loosen the two spring mount bolts on the right (axle) side.
(1) slide the threaded bolt through the spring from the differential side of the mount (left to right).
(2) slide the 5" long plate through the spring, a few coil turns from the end, and slide the bolt through the plate.
(3) carefully slide a nut through the spring, on the right side of the plate, and screw-in the bolt until it almost hits the mount on the right. This was the painful part, but a thin pair of clamping pliers holding the nut really helped.
(4) place the smaller plate on the left side, along with any washers, and tighten with a nut. Be sure to grease the bolt threads on this (the left) side before tightening, as this is where the spring will be decompressed from.

Download Attachment: pagoda-comp-spring-side.jpg
28.39 KB

(5) tighten the left nut until you hear the spring compress ever so slightly. now tighten a little more.
(6) carefully remove the two bolts (inner one first) holding the right mount, and remove the mount. The spring will now be compressed against the differential side mount.
(7) slowly loosen the left nut (remember the grease?) until the spring has completely decompressed (this is where the 15" bolt length comes in handy), and remove the spring.

Download Attachment: pagoda-comp-spring-rear.jpg
50.46 KB

Hope this helps,

Waqas in Austin, Texas

[A Dalton]

 << carefully slide a nut through the spring, on the right side of the plate, and screw-in the bolt until it almost hits the mount on the right. This was the painful part, but a thin pair of clamping pliers holding the nut really helped.
>>

 ..you may want to cut a slotted hole on this plate so you do not have the problem of starting the end nut. or you may just use a little thicker plate and tap the hole...

 ..Good job, either way.

[waqas]

Alright, I have a dumb question: when you turn the driveshaft flange on the differential, the wheels are supposed to turn, right? If I hold the wheel drum still, and then turn the flange, should it not also resist turning? My "new" differential flange keeps turning... regardless of whether I hold the drums still or not. When I received it, I turned the flange, and both wheels turned also. I never tested it like this-- by holding the wheel drums still (the lug bolts are in there). Now, while preparing to change the pinion seal, I stumbled upon this behavior. Am I nuts, or is my "new" differential messed up...??  (when I turn the flange, the grooved nut and centre drive bolt both turn with it, as I would expect)

A Dalton, did you mention the driveshaft/flange turning torque as 24-26 inch-lb? Where is this listed in the BBB? I can't seem to locate it in section 35-0.... or maybe I'm going blind AND nuts!

Waqas in Austin, Texas

[Naj ✝︎]

quote:If I hold the wheel drum still, and then turn the flange, should it not also resist turning?

No, you're not nuts  

It means your diff is working correctly. When on the car, power goes to the wheel with the least resistance (just as is happening here), so if one wheel is on say wet grass and the other on tarmac, the one on the grass would get the power and spin...
Now, if you had a limited slip diff,...

naj

65 230SL
68 280SL

[Douglas]

Naj,

Didn't you just describe the characteristics of a limited slip differential?

Douglas Kim
New York, NY
280 SL #016220

[A Dalton]

<<-- by holding the wheel drums still (the lug bolts are in there).>>

 If you have BOTH drums locked and both with the lugs in them, the flange has also got to lock...if not, you prob have a bad slip joint or broken axle.

 The turning torque is in the old Original BBB.. the new reprints have eliminated much of this info [ which is really too bad], so I suspect you have the later reprint version..
 If you ever see the old ones on ebay, grab it .. they are invaluable..

[Naj ✝︎]

Doug,
 

quote:Didn't you just describe the characteristics of a limited slip differential?

With the limited slip diff, power to the spinning wheel would be reduced and applied to the stationary wheel, allowing the vehicle to move on. This is acheived with two multi-disk clutch packs, one on either side in the diff casing.

In modern cars with electronic stability control, the abs sensors are used to apply brakes on the spinning wheel allowing transfer of power to the stationary wheel.

naj

65 230SL
68 280SL

[waqas]

Phew!  Talk about needless stress!  Having just taken Drivetrain 101 (they give you a new splined unversal as your completion certificate), I went back and re-attached the lug bolts, wedged both drums, and tried to turn the flange... voila!  resistance!  (wedging just one side produces motion on the other).

And here I was feeling all proud of my new trailing arm bolt (the final one to come off)

Download Attachment: pagoda-trailing-arm-bolts.jpg
42.99 KB

So how many points do you think I'll get docked for re-using this?  

Waqas in Austin, Texas

[A Dalton]

 Is that Gorrilla glue  (:

[waqas]

haha! I should've tried gorilla glue first. I call this technique "brazed and confused" (TM)

Waqas in Austin, Texas

[George Davis]

Waqas,

very clever method for removing the compensating spring, and thank you very much for posting pics and description!  I'll be trying it soon.

George Davis
'69 280 SL Euro manual

[waqas]

George, you're most welcome-- it's the least I can do to start repaying all the kind guidance I've received here.

Speaking of guidance, regarding the breather tube on the top side of the differential, how can I make sure it isn't clogged?  (while the diff. is still out and accessible). It looks a bit oily around the edges...

Also, any recommendations for 'sealing compound' for the new pinion seal?

Waqas in Austin, Texas

[ja17]

Hello Waqas,
The vent can be unscrewed and flushed clean with solvents or replaced.

I like to use Permatex #2 sealing compound.


Download Attachment: permatex2.JPG
57.79 KB

Joe Alexander
Blacklick, Ohio

[waqas]

My springs are slightly different sizes (~5mm difference). I've no plans to replace them any time soon. Any recommendations as to whether I can successfully adjust spring height using the spring retainer adjustment holes?

Here's a photo of the spring retainer after grinding off all the rust/crap before I apply POR-15. You can see faint numbers (1,2,3) for what I assume are height adjustment settings. Can I make up for the difference by setting these differently on each side...?
Download Attachment: pagoda-spring-retainer.jpg
41.15 KB

Waqas in Austin, Texas

[A Dalton]

Regardless of spring dimension, you want to take ride heigth from the floor on both sides of the car.. this will tell how the springs are setting.
 The plate adjusters will only slightly change the height [ each click only changes camber 0 degrees 10', whereas a 3 mm addition on the  rubber on the comp spring will change 30'.
 Most guys using old springs just get new 6mm comp spring rubbers
 [ one on each end] and start from there.
 if the camber is out from each side , you can then tweak it in with
individual notch positioning.. [whereas the comp spring dimension affects both sides]..#1 is the highest notch settimg.
 Most old suspensions have all they can do to go with full bottom plate notch #1, 6 mm comp spring pads and thick upper spring pads/mounts... and a new hanger mount [trunk] to get close to original
height/camber..............

[waqas]

My snail's pace continues with this job. Somehow the scope keeps expanding, and new parts must be awaited with patience. My question of the hour: when I first removed the differential carrier/mount from the long connecting bolt, the bolt was covered in oil (this was the case for both old and "new" differentials). I initially assumed that oil must have seeped in from a leaky pinion seal or axle boot, but while reading section 35-5 of the BBB (cars starting 1968) regarding installation of the right axle supporting tube, I came across the statement "grease connecting bolt and slide through from the rear...". This implies that the surface between the connecting bolt and the tubular carrier mount must also be greased. Is this correct? Note that I'm doing this from the front (having left the connecting bolt undisturbed within the axle/differential hinge). So why was the bolt oily and not greasy when I pulled things apart? (or perhaps it was both and I did not notice) So do I use regular grease or something special?   (BTW the old tubular mount rubber was completely shot!)

Waqas in Austin, Texas

[A Dalton]

They grease the pivot pin for re-assembly. Once the cinch bolts are tightened . the pivot pin is locked to the hanger .. that is why it is so important to have the hanger at 90 degrees to the left axle tube c/l before tightening.. this keeps the rubber in the tube at no suspension load at zero camber.. As the axles moves up/down in travel, the rubber flexs to the load condition.  As I stated in early post, if the rear pinion seal shows signs of long time seepage/leaking, it most likely has ruined the rubber inside the tube, along witht the fact that the original tubes had a two section rubber sleeve that was far inferior to the one piece replacement..
 The greese points for pivot pin are at the pivots . front and rear , of the right axle tube joint...

[waqas]

Let me get this straight: when the car is jacked up and the axles are hanging down, since the hangar/carrier is still supposed to be vertical, does the tubular mount rubber rotate/flex to allow the left axle to hang? This would seem to be the only option, as the outer tube of the mount is held in place by the hanger/carrier, and the inner tube is held in place by the differential front plate cinch/bolt. Does the carrier trunk mount also flex to compensate? (leaving the carrier non-vertical while axles are hanging) I guess I find it hard to imagine the tubular mount rubber (only 4-5mm thickness) flexing non-destructively to allow a 10-15 degree rotation... or am I missing something fundamental here?
Thanks again for your patience in helping me understand all this...

Waqas in Austin, Texas

[A Dalton]

The suspension . when loaded , does not have the drastic angle of a
lift hanging differential..but much more pressure.
 The changes in camber of a loaded suspension are in the flex design of the lower mount .. the early 2 piece would rip, so they were replaced with the stronger single piece construction and it does do the job.
 ..so , you can see why they want it at zero camber/90 degrees/no flex load when installing.. that allows  equal flex for both +/- camber ..using no load/zero camber as a base line..
 You will find many Benz suspension parts with rubber insert/mounts
that are recommended to have loaded suspension before tightening the parts down.. and this is an example of the parctice and their reasoning...
 I imaging that all these mounts [ top mount . centering strut. spring mounts, etc . ] all share the total load, so the flex pressure on each in travel is well distributed.

 Note***
 If you look at the hanger/tube mount pictoral, you will notice this rubber cuff sector is referred to as "Flex Mounting"..

[waqas]

A Dalton- thanks for all your detailed explanations.

Update: I changed the pinion seal (how folks pry out the old seal without removing the entire front plate is beyond me!) and found that there was a slight difference between the old seal and the replacement. The old one has a metal backing (on the differential side). I'll post a pic later today. I went ahead and used the new one  anyway. Setting the torque on the crush bearing was tricky, but I think I got it right (surprisingly, the grooved nut did not require much torque to achieve the 24-26 inch-lbs flange turning torque....hmm...)
Download Attachment: pagoda-pinion-seals.jpg
36.21 KB

I measured the axle thickness on each end (both left and right), and found that they are not tapered as indicated earlier in this thread. They came in at exactly 68mm, so I went ahead and levelled the top of the left axle, and got the differential carrier/hanger perpendicular to the axle (trusting that setting was tricky-- I wish I had a long bolt with the same threads as the trunk mount bolt, to make vertical levelling easier). Incidentally, the BBB discs I got from MB don't list torque settings for all bolts-- probably has the later version, as A.Dalton mentioned below. Such a pity.

I mounted the new bushings into my newly painted trailing arms. The bushings on the axle side were much easier to mount than I thought. I used a long threaded bolt and some washers/nuts (same setup as my spring compresser h/w listed earlier) to compress the bushings and insert the lock ring (I trust re-using the old rings is not a horrible idea?)
Download Attachment: pagoda-trailing-bushing.jpg
39.77 KB
Download Attachment: pagoda-trailing-arms.jpg
47.99 KB

As I prepared my axle/jack rig thingy, I noticed the brake drum cylinders looked a bit corroded, so I thought I'd check the brakes out before installing the axles (easier to work on with everything out). Lo and behold! Both my brake cylinders are corroded tight, and the hand-brake pulley is also jammed (cables are fine). I pulled everything apart, and it seems I'll have to drill out the pulley fixture bolts. Ack! Why didn't they just use steel?!@?

Luckily, my drum setup from the old axle is working. I think the axle is from a ponton, as the diff ratio is 4.10, and the brakes are slightly different-- larger wheel cylinders, adjusting wheel, etc). The picture shows the 230sl cylinder (lower- thinner), vs. the old cylinder (upper- thicker):
Download Attachment: pagoda-brake-cylinders.jpg
52.79 KB
Anyway, I'm going to scavenge parts from there until I have time to refurbish the corroded cylinders and brake cable/pulley assembly. Anyone know if there is a cheap cylinder refurb kit available? (new boots, pistons, etc) Reasonable would be $10-20, since new cylinders cost only about $60...

Anyway, I guess things could be a lot worse (like Apple switching from PPC to x86- yikes!)

Waqas in Austin, Texas

[ja17]

Hello Waqas,
The differential is probably from a W111 coupe, which also used the 3.75. Actually no ponton rear axle had a compensator spring. Those emergency brake cables will be longer if this is the case.

The wheel cylinders are in inch sizes! Just measure the internal bore and go to your local auto parts store. Ask for the size and not a certain car application.  If you get a good counter person he will be able to look up the diameters of the kits to find the right size for you. Save your hard parts to re-use and replace all the rubber seals with new. You should be able to find kits for just a few dollars. The modern seal materials will hold up much better than than the originals also.

Joe Alexander
Blacklick, Ohio

[waqas]

Hi Joe:

As per your suggestion earlier, I removed the differential breather tube and flushed it clean with degreaser (I use Marine Clean, as it's less toxic). However, there seemed to be an obstruction within the tube, so I pried open the top and discovered a little foam pad (an air/dust filter/guard?).
Download Attachment: pagoda-differential-breather.jpg
39.55 KB

It seems pretty gunked up. Any ideas for a suitable replacement pad?

Waqas in Austin, Texas

[waqas]

Well I finally installed the differential, and am in the process of attaching the trailing arms. I have the left side already done (spring and all), but it seems the one on the right is not aligned-- the front of the arm is falling 1.5" to the right of the chassis mount point. i didn't find anything with the search feature, so I thought I'd ask someone who's done this before: is this normal? Do I need to pry/squeeze the arms inwards to make things fit? Are the arms supposed to be under [sideways] tension like that? I've tried to align things with the axles in various swing positions, including horizontal. I also made sure I correctly chose the L/R arms: the welded seam underneath the arms are on the inside (pointing toward the car center). I've measured both differentials and they have the same spacing (within 5mm) between the two trailing arm axle mounts, so they seem identical. The only thing that's different is that I'm using the trailing arms that came with my 'new' axles. Any suggestions here?

Waqas in Austin, Texas

[jsaylor]

Wagas,

I had the same problem when I reinstalled mine.  I pulled, wiggled and pried to get it aligned.  What did help a great deal was to place a thick wood block  w/ a 2" hole in it on my jack.  I then jacked the trailing arm up to the mount.  This kept the slightly missaligned bushing from popping out.  I think that when you get driving thins will settle into place.  I'm currently haveing new floors and rockers fitted and will recheck the rearend for propper alignment after I'm on the road.

Good luck,


Jim Saylor
Kauai, Hawaii
'65 230SL

[waqas]

Thanks for the re-assurance, Jim. I finally got the trailing arm and spring installed. The compensating spring was surprisingly easy to re-install using the method I outlined earlier in this thread. In fact, a 12" threaded bolt was sufficient. I'm now just re-installing the various little brake lines and cables.

My questions of the hour: when I initially disconnected the drive-shaft from the differential flange, there was a thin little washer-plate thingy (shaped like the flange) inbetween the drive-shaft and the differential flange. I didn't see this anywhere in the parts manuals, and mine is pretty destroyed. Any ideas about this? (is it a shim? or does it serve a different purpose?) Also, the connecting nuts/bolts did not have any lock-washers, and I feel uneasy about re-installing without any. It's not obvious to me if and how they might have used the metal plate/washer above to try and lock down the nuts. I'm thinking of simply using conventional lock-washers to secure the drive-shaft. Any further suggestions?

Waqas in Austin, Texas

[waqas]

All I had to do was look further upstream along the driveshaft to see what should have been obvious (if only I could think AND type)-- the washer thingy is actually attached on the outside of the flange joint, placed beneath the nuts; once the nuts are tightened, the corners of this plate/washer are bent over to prevent the nuts from coming loose. I remember the nuts/bolts loosening pretty easiliy... no wonder! someone had placed the lock-plate/washer BETWEEN the differential flange and the driveshaft! Anyway, until I get a new lock-plate/washer, I'm sticking with individual lock-washers...  anyone know the part number for this plate?

Waqas in Austin, Texas

[A Dalton]

I prefer lock washers myself, but the lock plates are 111 994 02 09

 They use 2 .. one on each side bridging two bolts

[waqas]

A Dalton-- I've a question regarding the nifty axle alignment tool you posted some time ago: Your dimension for the centre-centre distance between the two trailing arm to chassis bolts came to 877mm. Is this a factory-supplied number or as measured on your car? What's the acceptable tolerance for this? Mine came out to 874mm, and I'm wondering if the chassis mount bolts may have been slightly damaged/re-welded/etc since manufacture. Barring this slight discrepancy, I was pleasantly surprised as the lateral strut turned out to be perfectly aligned from the right axle mount point (lateral distance to differential carrier bolt is 417mm as per your directions). Of course, I will probably need to re-adjust after driving a little distance. Assuming only one of my mounts is off, this would mean my centre-alignment is off at most by 3mm.

I can't wait to get this beast back on the road!

Waqas in Austin, Texas

[A Dalton]

All specs/data for my alignment jig are taken from the 113 Chassis Frame Measure Charts and body geometric schematic spec/data sheets from the factory. Along with factory alignment spec/data ..

 The reason the tool uses the step bearing mounts for relative measure is cuz of their geometric convienience to tool construction.

 The actual measure for the pivot offset is for the offset spec measurement to be that distance to the right of the actual chassis C/L.. This can  be found by using the Center Bore holes in the chassis.  The tool was just designed around the other mounts for ease of measure without having to deal with the C/L bores [ which would entail dropping lines , etc]. But , these center bores locations were used in the tools geometric design..the tool simply allows one to not be concerned with  C/L Bores, as the measures are taken from step bearing C/L to reach the same conclusion.
 So , to answer your question.. all specs are factory and if you do not have total distance between step bearing centers, one is off and
which one can be determined by measuring each sides actual distance from chassis C/L. However, my Frame Measure Charts show a +/-1 mm tol. for each side from chassis C/L, so allowing 1mm each side puts you out a  total 1 mm, which I would not even consider..remember too , the tol. for pivot pin location  has a +/- 2 mm . So...there you go. You should be fine.
 

[A Dalton]

PS
 I have the chassis geometry schematic in jpg. format, if any members need one..

[waqas]

It's alive! ALIVE! (in Dr. Frankenstein voice from 1931 movie)

Just returned from quick spin... runs like a dream and I think I was screaming for a significant part of the drive! (understandable after waiting 2.5 months since the differential failure). Poor thing needed a jump (something leaking current I presume). Thanks to all who helped me get here (especially A.Dalton and Joe Alexander!) I still need to check some alignment issues, but that can wait until tomorrow.  

Incidentally, I had drained the fuel tank during all this (needed to replace some fuel hoses), and before driving anywhere, I had to add some fuel. I added exactly 2 gallons, and upon starting (she didn't even hesitate!), my refuel light came on. Glad to know it works (I'd never seen it before, as I never let my fuel level drop too far), but my question is: at what fuel level is it supposed to come on?

(also something bizarre: my full-beam light now works-- it's never come on since just after I bought the car)

Anyway, all is well in Austin Texas tonight...

Waqas in Austin, Texas

[graphic66]

My 66' 230SL 4 speed auto, 4:08 rear axle, drum brakes, took of from a stop and went bang, no zoom. Drive shaft turns just fine but tires don't turn, no noise whatsoever, just a nice smooth spin with my hand.
   This just happened, but I believe it may be best to drag up an old thread here instead of starting a new one.
    I have not jacked up the car yet. I have read through this thread and others and I believe my first step is to jack up the car, and if nothing looks bad from the outside I should pull the right axle, a subject that has been covered and I feel confident in doing that. And have a look for a loose bolt inside of the right axle tube. From there I would next, if the "bolt" is tight from reading this thread assume the universal joint female spline has snapped off. How can that be confirmed? What other things should I look for. My preference is to keep my axle, I love the low ratio and those big bad finned drums.

    OK, now for the interesting part. I have a "parts" complete 250SL, 4 speed standard It has disk brakes and I do not know the ratio is yet. Will this axle work? In changing from drum to disc do I need to just add the proportioning valve for the brakes; Where is that thing anyways. Can I use my existing master cylinder? Will my drive shaft bolt right up? How long should this job take in my home shop with a helper?
   Sorry for all the commotion, but I am just entering the beginning stages of withdrawal and I am a little wired.
   If anybody has any other info that might be helpful I would appreciate hearing your opinion. I am preparing for the worst and hoping for the best.