Pagoda SL Group
W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: Pinder on July 23, 2024, 01:02:16
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Hi everyone. I have not posted much recently with life stuff needing taking care of but I am at the point I want to tackle a leak on my manual gearbox. I’ve read through volume 3 1 and 2 in pagoda notes. I’ll be doing this work on my own. On jackstands . My primary concern is to fix the leak. I plan to order the seal kit from authentic classics but if there is a better source worth considering please advise.
While the gearbox is out I plan to clean up the transmission tunnel and the gearbox. Any advice on color code to use to paint gearbox and where to purchase would be really appreciated. I asked my daughter to make some videos who is off school for the summer I’ve enlisted her help in documenting the process / journey.
Any advice tips and tricks would also be appreciated.
Best regards Pinder
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Every seal is a different and a unique challenge. The front seal is in the clutch throw-out tube and difficult to remove. A special tool is required to install the new one. I found a hole saw the right size and made the tool by grinding the teeth flat before using it to press the seal in the throw-out tube. You'll need to remove the front cover to do this. Remember all the bolts holding the front and rear cover on are threaded all the way into the gear box. they will leak fluid unless you carefully clean the threads and bolts and use a sealing compound on the threads. The rear seal is more difficult since you will have to remove the rear out-put flange. To do this the slotted nut must be removed. A special "pins socket" factory tool is used on the slotted nut. If your handy with a little grinder or cut-off tool you might be able to make one from the rights size socket. You will need to uncrimp the lock ring around the slotted nut before you can even get the socket in place. think about getting a new lock ring for re-assembly. The torque spec for the slotted nut is 87 ft/lbs and can be difficult to remove unless it has worked it's way loose over the years. There is a special factory tool for holding the output shaft flange from turning when your loosening or tightening the slotted nut. With a little imagination, you may figure out another way to hold the flange to loosen and tighten the slotted nut. Once the slotted nut and flange are removed the rear cover can be removed. Remember to seal the bolt threads before re-assembly. The rear cover holds the transmission rear seal and the speedometer cable drive seal. There is also a paper gasket to replace for the rear cover. I always use some sealer or gasket shellac on the paper gasket since I am sealing the bolt threads also. Once the rear cover is off, the rear seal can easily be changed by pressing or tapping it in place,
using the correct sleeve/ socket or what-have-you. The small seal for the speedometer drive is extremely difficult to remove and can be tricky to install. The small drive gear for the speedometer cable is pressed on its shaft and the shaft must be driven or pressed out before you can install the new seal. The old seal is almost impossible to removed. I suspect a special seal puller is used normally. I made mine by modifying an off-the-shelf internal puller with long slender legs. You cannot get behind the seal with anything to drive it out. If you had exactly the correct size reamer, you might be able to machine it out. Be sure to install the new seal in the correct direction (spring end first). You must drive or press the speedometer drive shaft in exactly the correct distance as previously installed when the seal has been replaced. There is a very serious hidden danger when the slotted nut and output flange have been removed. You must avoid rotating or disturbing the transmission. The slotted nut keeps the internal gears, keys and synchronizers in place. When removed the internals can shift causing a miss alignment with a shaft key. Shifting problems will result. Of course, a special factory tool is used to prevent this also. You can make a sleeve out of some PVC pipe to keep the gear cluster tight while your working on the rear cover assembly. Simply use the slotted nut and the correct diameter and length section of tube to hold the gear cluster snug. The seal in the top shift cover is a different challenge. You have to disassemble all the forks, rods, springs, balls and spacer sleeves in the cover to get to the seal. There are some special nuts to unfasten which are deformed when installed and should not be used again. Be careful or you will have tiny springs and balls flying everywhere. Every fork and spacer must be returned to it's exact location during re-assembly. Considering the degree of difficulty, you might opt not to change this seal. It is at the extreme upper part of the transmission, far above the fluid level and not subjected to much splash. It never seems to be a source of leakage. If you decide to go ahead, stay in touch and do your research!
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Thanks Joe for a very detailed guide. I will read it carefully as I proceed.
The slotted nut had worked loose, and I had tightened it but I’m pretty sure I should be able to get it off. I do plan to make a socket for it.
Regards
Pinder
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I have removed the gearbox but need to disconnect the round plug that looks to be an electrical connection . Should this plug out or do I need to remove the nut behind it. Please see picture.
Thanks Pinder
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I have removed it and put it on a stand . First thing I will do is to clean up 50 + years of dirt and grease. It seems like transmission fluid dissolves grease
I had to remove the starter motor too. I was able to do all of the unbolting from under the car with various extensions . I did not have to remove any access plates on the tunnel.
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What would be a good gasket sealer to use? i plan to use it for the paper gaskets.
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I think the input shaft has a lot of play laterally and in and out. Where is a could place to get the front bearing . Maybe that will help with end play?
Regards
Pinder
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Top view with top cover removed
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When you remove the Bellhousing , you will find shims to set up preload on the front bearing.
I would use a product like 'Indian head shellac' for the paper gaskets.
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Thank you . I was looking at using shellac because I was thinking if I used anything too thick it may interfere spacing.
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Joe,
Thank you for the detailed explanation. I always wondered how you’d get the seal from the shifter shaft out.
I’ve got my transmission out and need to do the seals. Great explanation.
Kevin
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Joe's reply above speaks to the slotted nut and also an internal nut (i think) that holds the speedo drive in place. I have no first hand knowledge of what holds the speedo drive in place, but when I had my speed rebuilt recently (Palo Alto) they were very specific that rebulding the speedo would not cure its bouncing if the problem was whatever holds the speedo drive (inside the transmission) in place.
Maybe someone who has been inside the transmission can elaborate, or maybe Joe's reply above covers it. but clearly the time to ensure that matter does not become an issue is before you reinstall.
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I have not gotten to the removal and install of the seal for the Speedo. I’ve found on prior post a way to pull the seal out using an expanding bolt .
So far I have the bell housing off and have removed the input shaft seal. The seal kit I ordered had the input shaft seal missing so now I’m waiting for that to arrive.
I am also looking for where to get new bearings for input shaft and output shaft.
I found what I think is the correct one at pelican parts. I figure if it’s not overall expensive that I’d replace with new even though I do not know if my existing bearing is ok or not.
Looking forward to getting back to working on it when I get back from being out of town.
Pinder
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Leester, the brass gear which drives the speedometer is not keyed to the output shaft. It depends on a tight gear cluster to turn. If the slotted nut comes loose the gear cluster loosens and the brass speedometer drive gear, on the output shaft (not keyed) becomes loose and slips or stops spinning altogether.
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im at the point where I am trying to press out the speedo drive shaft from the rear cover. it is not moving at all. I want to confirm if it should be pressed out from the small cover cap side or from the side where the speedo cable is inserted? Ive been doing it from where the small cap is removed from.
Regards
Pinder
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Probably best to push it from the cap side and out the speedo cable side. Try heating the gear with a small butane or propane torch. Be careful not to use too much heat or you can damage the aluminum casting.
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Pry the small cap out and drive the shaft out using a punch. They don't move easily because it's an interference fit. Follow Joe's advice and use a bit of sealer around the cap as you install it. Shaft seal is installed before you replace the shaft.
Done right, it won't leak and will work well for years.
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Thank you for that. I have managed to shift it. About half way there. I used a propane torch and warmed up the gear.
Regards
Pinder
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I’ve managed to get the shaft out and also clean up the housing glass bead blast. What a messy job that is.
Thanks to Joe and Dan for your valuable advice.
As advised with your expertise. I used an 1:4 inch extension and beat it out with some gentle heat from a propane touch warming it up a little .
Tomorrow I’ll be that lost soul at Home Depot looking for the right expansion bolt to extract the seal out…
Regards
Pinder
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The back side
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The expanding bolt idea did not work for me. it would not hold (more likely I was afraid to over tighten, Instead I used a bolt of approx. 1/2 inch shaft diameter and threaded it onto the seal and then beat from the cap end with some considerable force and it came out that way. I suspect the speedo cable side has been tightened a little too much in the past and closed the hole tad bit .
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Picture of bolt and dimensions show here. The seal is still attached to the bolt. New seal is next to it .
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I've been told that an internal slide puller will remove the seal.
I drilled all of the plastic out on the seal which leaves a small metal ring. Using a cape chisel I was able to collapse the ring and then fish it out after.
Interesting how the seal is installed. There's an actual cavity behind the seal which leaves a void once it's installed. I imagine this is so that the seal will expand as the shaft is driven home. Clever bit of engineering there.
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Good idea Pinder. I'll try your method next time!
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Im pretty sure I had purchased that bolt from home depot. its the perfect size to thread into the seal.
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I have managed to install the new seal for the speedo gear and the output shaft seal. So now i will go into installing the seal in the bell housing.
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Make sure that the speedometer drive shaft is pressed in far enough, so that the pronged end is even with the ridge in the bore. In this way the cable will engage correctly and the seal is positioned.
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Hi Joe
I measured the amount the shaft is pushed in from the cap end; in my case it was in 7.75 mm. i put it in the same amount. i test fitted the cable and it seems to sit as before.
I have also installed the input and output shaft seals. Then input shaft seal I used a plastic PVC fitting that fit perfectly in the groove of the seal after i ground down the threads on the pvc fitting, and i pressed it all the way to the lip in the housing and it went in fine with no damage to the seal walls.
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Here is picture of fitting
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fittinginserted into grove of seal
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I have put in all the seals and gaskets in place and did some cosmetic work . Painted the gearbox using the paint suggest on this site. It’s a very close match to the original paint.
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Paint used in picture attached. I got it from Amazon .
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You're hired!
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Pinder
Your skills and guts are quite impressive. Well done.
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Thank you for the encouragement. Let’s hope it works well once back in the car. Hopefully in the process I did not mess up any gear alignment etc . But I did mock up the gear leaver installed on it on the bench and it shifted fine in all gears.
I had replaced the shifter bushings about 9 years ago. I ordered new ones and as I have it out I will replace those again even though I’ve driven the car less than 500 miles since I have had it. Yesterday I received the rubber boot for the clutch throw out fork. Old one had fallen apart.
Regards
Pinder
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I created a new slotted nut tool so I could tighten the slotted nut down to 87 fts /bs. Now when i start to tighten it fully i find that the gearbox locks up. Even in neutral I am unable to spin the shaft unless i loosen the slotted nut. Im thinking that I need to remove the shims or whatever reason. Has anyone come across this situation?
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Yeah, I think I have.
There's a thick washer on the rear main shaft and it can only go on one way. You may have it on backwards so take the rear cover off and turn the washer around.
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Make sure you didn't get any of the front or rear cover bolts mixed up. Some are longer than the others and if installed in the wrong place the bolts will go to far into the case and hit the big gear on the upper shaft and lock up the transmission. You might try loosening the top rear cover bolts to check.
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Thanks Gents. I’m investigating this. I have the cover off and I do see the fat washer does look different on each side . One side is completely flat and one has a rim. This may be it.
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So I dismantled everything again. And removed the shafts . I find one of the bearings for the lay shaft is stiff. This maybe causing the binding. But I have also found 2 other items to address.
1. The key in the layshaft is broken and I noticed that the gears had play in them.
2. The second slotted nut that’s in the gearbox is loose. I can move it a few degrees left and right by hand. The lock nut is stoping it coming totally loose but I think this should be fully tight not loose.
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Yes, it is common to find both of the keys damaged or broken. Sometimes the keyway slot in the gears get worn also. Since there are two opposite keyways in each gear, just use the other keyway that was never used for a perfect fit. Use new key. Check carefully for wear or damage to the smaller key in the upper shaft also. That key will need to notch into the slotted washers (top and bottom) as your assembling the 3rd and 4th gear cluster. It is critical to keep the 3rd. and 4th gear cluster tightly held together during final assembly so the key and slotted washers do not shift out of place. You must pay close attention to this situation until the slotted nut is finally tightened!
You can use grease to hold all those pesky needle bearings in their cages during assembly.
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Thanks Joe
I dont know where to get the keys. I was thinking to make my own from keys I can from say Advanced auto and grind them down to fit. I could not find a source online.
Regards
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You can get them from the MB Classic Center or any Mercedes dealership.
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The factory part numbers for the keys are:
#186 991 03 68 (large lower shaft key)
#120 262 00 81 (small upper shaft key)
I always order these in advance, they normally need replaced.
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This is from the gearbox of my 190SL. There are two keys there, both available at Mercedes.
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I think my binding issue is caused by the flat key, as i see its been crushed and the splined washer that the flat key was to engage in was not in the notch. I probably did the same error Joe had initially described about the key getting out of alignment when the slotted nut on the output shaft is removed. I'm happy that i have found the three major issue and am able to correct it properly.
1. broken key in layshaft. (just like how Pawel showed).
2. lose slotted nut on input shaft. (i could turn it a few degrees left and right).
3. flat key on main shaft was not engaged into the splined washer.
I cant wait to correct these and get the box back in the car and see how it shifts.
This has been a great learning experience so far. I now how a gearbox works some what.
Regards
Pinder
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Be sure to install the big key with the rounded end pointing inward opposite the snap ring. Otherwise the snap ring will not have enough room to fit into its groove.
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Hi Joe, I will make sure that I install it the correct way. I did notice that the rounded end would interfere with the snap ring.
I sent the Mercedes classic center an email if they have the keys. most places do not have them in stock.
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So Mercedes Classic Center have both keys ($29) for both keys. Just waiting for them to arive so that I can put it all back together. (as Joe mentioned, its best to order these up front and replace anyways).
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Picture of input / output shaft disassembled; order of parts are in sequence of disassembly.
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I finally put everything back together and re installed the gearbox. I had to disconnect the drive shaft from the diff in order to be able to re install it. First short drive went well, no issues noted. It was a little tricky to lift the box in place using a regular floor jack.
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Hello Pinder, well done! i've thoroughly enjoyed reading this post, so glad to see such a good result
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Thanks Bob.
I could not have done it without the expert advice I received along the way.
I made a few mistakes along the way but was able to correct and proceed foreword.
Along the journey I took the opportunity to bead blast the aluminum parts and paint the cast iron box and polish up the shifter rods and protect them with some clear coat. I also reviewed the shifter bushings even they I had replaced before as they are cheap.
In addition to resolving the gearbox leak it feels good knowing I replaced the broken shaft key and replaced the seals.
It really looks clean under the car now . My next improvement to the car is replacing the exhaust system from time valve. I put my order in but there is a few weeks delay before they can start making my exhaust system.
I’ve enjoyed working on this gearbox project.
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Picture of gearbox with shifter installed to test out ability to shift into all gears.
I also prefilled the gearbox before installing it into the car to save the hassle of using the fill hole.
Also I tested the 2 switches worked (that continuity works when they are engaged.
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took the car out last night for a 30 min drive and drive it hard. shifted great. This morning I inspected for any kind of leaks and happy to report zero leaks. For the first time in 9 years, I have an oil free garage floor. My two main leaks were from the power steering Box and the gearbox. Both now resolved.
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Chasing leaks on an old vintage car can be frustrating and expensive. Eventually new ones or the old ones can return over time. Hopefully not for a long time!! Great Job!