Author Topic: 4 Speed gear box removal reseal and anything else needing replacement (Read 3622 times)

Pinder · « **Reply #25 on:** August 14, 2024, 16:32:21 »

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.

ja17 · « **Reply #26 on:** August 14, 2024, 18:13:27 »

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.

Pinder · « **Reply #27 on:** August 14, 2024, 20:01:42 »

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.

Pinder · « **Reply #28 on:** August 14, 2024, 20:09:10 »

Here is picture of fitting

Pinder · « **Reply #29 on:** August 14, 2024, 20:10:47 »

fittinginserted into grove of seal

Pinder · « **Reply #30 on:** August 21, 2024, 22:31:30 »

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.

Pinder · « **Reply #31 on:** August 21, 2024, 22:32:57 »

Paint used in picture attached. I got it from Amazon .

Benz Dr. · « **Reply #32 on:** August 21, 2024, 23:06:52 »

You're hired!

kampala · « **Reply #33 on:** August 22, 2024, 00:04:28 »

Pinder

Your skills and guts are quite impressive. Well done.

Pinder · « **Reply #34 on:** August 22, 2024, 12:32:15 »

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

Pinder · « **Reply #35 on:** August 28, 2024, 23:20:07 »

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?

Benz Dr. · « **Reply #36 on:** August 29, 2024, 06:54:47 »

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.

ja17 · « **Reply #37 on:** August 29, 2024, 13:21:07 »

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.

Pinder · « **Reply #38 on:** August 29, 2024, 16:05:06 »

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.

Pinder · « **Reply #39 on:** August 29, 2024, 23:31:12 »

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.

ja17 · « **Reply #40 on:** August 30, 2024, 13:31:29 »

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.

Pinder · « **Reply #41 on:** August 30, 2024, 14:45:51 »

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

ja17 · « **Reply #42 on:** August 30, 2024, 19:09:17 »

You can get them from the MB Classic Center or any Mercedes dealership.

ja17 · « **Reply #43 on:** August 30, 2024, 19:15:31 »

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.

Pawel66 · « **Reply #44 on:** August 30, 2024, 19:40:20 »

This is from the gearbox of my 190SL. There are two keys there, both available at Mercedes.

Pinder · « **Reply #45 on:** August 30, 2024, 22:34:00 »

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

ja17 · « **Reply #46 on:** August 31, 2024, 01:53:24 »

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.

Pinder · « **Reply #47 on:** August 31, 2024, 16:27:00 »

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.

Pinder · « **Reply #48 on:** September 05, 2024, 13:48:12 »

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).

Pinder · « **Reply #49 on:** September 05, 2024, 13:51:12 »

Picture of input / output shaft disassembled; order of parts are in sequence of disassembly.

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Author Topic: 4 Speed gear box removal reseal and anything else needing replacement (Read 3622 times)