Replacing my 230sl differential...

[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
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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
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Download Attachment: pagoda-trailing-arms.jpg
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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
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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
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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.