W201 Pinion seal change

[MBW201]

Hi, have anyone changed the seal with diff in the car here? I need to know the torque needed for measure the friction? Did see a picture of the original meter and it goes from 0-6nm and the original is priced to 1000euros

 

[Uncle Benz]

You’ll find it impossible to adjust the pinion bearing pre-load accurately with the differential assembled. Use a punch to mark the shaft and the nut. Carefully undo the nut, counting the number of turns until it comes off. Put it back exactly the same number of turns, and tighten until the punch marks align. Absolutely no further or the bearings will be too tight and it’ll begin to whine within 1000 miles.

 

[MBW201]

You’ll find it impossible to adjust the pinion bearing pre-load accurately with the differential assembled. Use a punch to mark the shaft and the nut. Carefully undo the nut, counting the number of turns until it comes off. Put it back exactly the same number of turns, and tighten until the punch marks align. Absolutely no further or the bearings will be too tight and it’ll begin to whine within 1000 miles.

Well its not impossible with correct tool and its the correct way of doing this, why you write its impossible when this is how MB have written how to do in manual? Its not possible to use the same nut because you already have destroyed the way to lock it up, if you buy new nut you will have problem to know that threads are matching when you start entering. And i dont see any point marking nut and shaft, you already have slot and the destryed edge on nut if you want to get it 100% back to where it was. So yes measure the friction seems to be the best way getting this back in place 100%, i ask again have anyone done this and know how much friction it is?

 

[Uncle Benz]

I couldn’t picture the type of nut in my head, because I do a lot of BMW with this problem too, and they don’t have a stake nut. You’re right, it’s a stake nut on the w201. I would reuse the nut and carefully re-stake it. The correct way to do this job is with the differential stripped, a new crush sleeve, and either the breakaway torque method or spring balance to measure the breakaway torque. If you try to measure the breakaway torque with the weight of the crownwheel in mesh you will end up with the bearings too tight. I would go with counting the turns if you are doing it in situ. Otherwise put it on the bench and do it correctly

 

[EmilysDad]

Well its not impossible with correct tool and its the correct way of doing this, why you write its impossible when this is how MB have written how to do in manual? Its not possible to use the same nut because you already have destroyed the way to lock it up, if you buy new nut you will have problem to know that threads are matching when you start entering. And i dont see any point marking nut and shaft, you already have slot and the destryed edge on nut if you want to get it 100% back to where it was. So yes measure the friction seems to be the best way getting this back in place 100%, i ask again have anyone done this and know how much friction it is?

You asked ... Uncle Benz replied with an answer. Seems like you want to spend €1000 though for a once only task!

 

[MBW201]

You asked ... Uncle Benz replied with an answer. Seems like you want to spend €1000 though for a once only task!

What answear did i get? I still havent got any answear to my question, what torque people get on the friction test, all the rest i already know and didnt ask about. Offcourse better to have both nut and friction to test when doing this and if you wanna check for more you go in the back and check contact pattern on the gear.

 

[Uncle Benz]

Unless you are planning to replace the crush sleeve with a new one there is not a lot of point in trying to replicate the breakaway torque. The sleeve has already been crushed to set the gap between the two bearings, and the point the previous person stopped crushing it was the correct breakaway torque (or so we assume if the thing was running sweet and quiet). If you crush it more it’s going to be too tight, and you can’t “uncrush” it. If you leave it too loose the bearings will hammer themselves to death. If you aren’t going to strip the diff and replace the crush sleeve with a new one , then my advice is to count turns and just butt the bearings up to the crush sleeve exactly where they were before.
If you do decide to fit a new crush sleeve, start the crush in a hydraulic press first, because they are damn hard to start.

 

[MBW201]

Unless you are planning to replace the crush sleeve with a new one there is not a lot of point in trying to replicate the breakaway torque. The sleeve has already been crushed to set the gap between the two bearings, and the point the previous person stopped crushing it was the correct breakaway torque (or so we assume if the thing was running sweet and quiet). If you crush it more it’s going to be too tight, and you can’t “uncrush” it. If you leave it too loose the bearings will hammer themselves to death. If you aren’t going to strip the diff and replace the crush sleeve with a new one , then my advice is to count turns and just butt the bearings up to the crush sleeve exactly where they were before.
If you do decide to fit a new crush sleeve, start the crush in a hydraulic press first, because they are damn hard to start.

Yes thanks for all the tips, but i still want to know what friction torque is here. I know its not 100% but atleast you have it in the range it was before and this is how MB recomend doing this in the papers from factory when you dont change anything else than the seal. If they was a little smart in the beginning they made a second slot on the pinion and it was possible to use the nut again, maybe the solution is to cut a new slot on the other side, problem is that the metal on these pinions are heavy duty...
Maybe you missunderstand why i need the torque, its just for me knowing the range on a dial gauge and not what others have and try to replicate to mine. Iam also curious why you write again that its wrong metod to measure friction to set the nut back in same position when MB have this in their workshop manual as the correct procedure?

 

[Uncle Benz]

I haven’t seen the instructions you have, but it seems unlikely to me that they would show what to do but not give you the numbers. You could measure the breakaway torque you have existing before you start taking your diff apart, if you can find an instrument to measure with. Spring balance maybe. You know, like a simple spring balance weighing scale to pull the flange and see how much weight it takes to start it moving. Bear in mind that with the crownwheel in mesh the greater part of the measurement is going to be with the crownwheel starting to move. What you really want to measure is in the slack bit of backlash before the crownwheel moves. The movement is small. Good luck with it.

 

[MBW201]

I haven’t seen the instructions you have, but it seems unlikely to me that they would show what to do but not give you the numbers. You could measure the breakaway torque you have existing before you start taking your diff apart, if you can find an instrument to measure with. Spring balance maybe. You know, like a simple spring balance weighing scale to pull the flange and see how much weight it takes to start it moving. Bear in mind that with the crownwheel in mesh the greater part of the measurement is going to be with the crownwheel starting to move. What you really want to measure is in the slack bit of backlash before the crownwheel moves. The movement is small. Good luck with it.

You can find it in WIS, this is manual used for all MB workshops and made from the engineers at MB. You cant give any numbers because they are not equal from car to car, they also want you to use the gauge made for MB that has high accuracy and you can turn in certain rpm because its round. I find it strange if its only MB that made this gauge. I know its going to be a short distance measure with a normal dial gauge, but you will have half a turn and it should be enough. Importan for everyone to know that the min torque is not same on all the diff, see in forums they talk about min180nm but thats the large and the small one is only min 90nm. WIS is very clear on if you dont get min torque you have to rebuild and change the crush.

 

[charlysays]

This may not be popular but before any large ish job I will usually try a well reviewed additive. So far this approach has avoided me having to variously reseal a diff, repair the valve body on a 722.6 and replace hydraulic tappets. Not noticed any long term harm from use of these lucas oil and wynns additives either. Nothing to lose in my opinion other than a tenner on an additive which may well stop or improve the leak to the point where it doesn't need doing.

 

[MBW201]

This may not be popular but before any large ish job I will usually try a well reviewed additive. So far this approach has avoided me having to variously reseal a diff, repair the valve body on a 722.6 and replace hydraulic tappets. Not noticed any long term harm from use of these lucas oil and wynns additives either. Nothing to lose in my opinion other than a tenner on an additive which may well stop or improve the leak to the point where it doesn't need doing.

Yes i saved mine for 6years extra with a stuff that soften rubber, but now its time and cant complain with over 30years lifetime of the seal. They dont make seal or anything in rubber like they did in the 80s, thats because all the demands of environmentally friendly.. So yes dont change anything before its a must on these cars, i know alot changes just for having things new on car but trust me it wont last long before you have to change again.

 

[MBW201]

Here is the gauge and its sold for all the Germans cars, so this is not a special thing only for doing the job on the MB cars. So if anyone see anything similar for a price that everyone can afford let me know. And if you are doing work under there with the diff off, try spin the diff and let me know if its 1nm or more like 6nm to make it turn.

 

[charlysays]

Yes i saved mine for 6years extra with a stuff that soften rubber, but now its time and cant complain with over 30years lifetime of the seal. They dont make seal or anything in rubber like they did in the 80s, thats because all the demands of environmentally friendly.. So yes dont change anything before its a must on these cars, i know alot changes just for having things new on car but trust me it wont last long before you have to change again.

Well done. 6yrs reprieve from an additive is a win. I remember when my previous C250 TD developed an apparent valve body issue the implication was an involved repair. Lucas transmission fix kept it working perfectly for 40k miles until it got written off in an accident- so I'm very glad I didn't do the repair!
I was repainting the OE original and still perfectly fine shocks on my W202 the other week as the lower part had got quite rusty.
Many would replace them as a matter of course but like you said, most replacement parts will not match the same quality and longevity, even MB ones on occasion! Do what you can to keep the original parts going where possible as new is not necessarily better.

 

[MBW201]

Well done. 6yrs reprieve from an additive is a win. I remember when my previous C250 TD developed an apparent valve body issue the implication was an involved repair. Lucas transmission fix kept it working perfectly for 40k miles until it got written off in an accident- so I'm very glad I didn't do the repair!
I was repainting the OE original and still perfectly fine shocks on my W202 the other week as the lower part had got quite rusty.
Many would replace them as a matter of course but like you said, most replacement parts will not match the same quality and longevity, even MB ones on occasion! Do what you can to keep the original parts going where possible as new is not necessarily better.

I did the additive in both W201 and the W202 and same result they stopped leaking and the W202 still dont leak. I think the reason why its easy fix on the diff is because of the thick oil, its very small margin from leak or not here, the W201 use 85W-90 and winter time with cold weather doesnt help for already hard rubber. My advise buy use additive every oil change and it will save you thousands in seal changes, if you wait till it leaks its sometimes to late because rubber is to hard and lost the ability to soften again.

 

[charlysays]

I did the additive in both W201 and the W202 and same result they stopped leaking and the W202 still dont leak. I think the reason why its easy fix on the diff is because of the thick oil, its very small margin from leak or not here, the W201 use 85W-90 and winter time with cold weather doesnt help for already hard rubber. My advise buy use additive every oil change and it will save you thousands in seal changes, if you wait till it leaks its sometimes to late because rubber is to hard and lost the ability to soften again.

What additive worked best for you?
Will add it at the next diff oil change.

 

[MBW201]

What additive worked best for you?
Will add it at the next diff oil change.

https://www.magnagroup.com/doc.php?id=813

Its only 177ml but for pre leak you only use 1%, leak 3% of the oil.

 

[EmilysDad]

Here is the gauge and its sold for all the Germans cars, so this is not a special thing only for doing the job on the MB cars. So if anyone see anything similar for a price that everyone can afford let me know. And if you are doing work under there with the diff off, try spin the diff and let me know if its 1nm or more like 6nm to make it turn.

you want a rolling torque wrench/gauge

 

[MBW201]

you want a rolling torque wrench/gauge

Why do i want this when i already have given a picture of the only gauge that is possible to measure 100% correct? I already write that you need to spin gauge in steady rpm to get the result demanded for this job. If you are doing this with diff out of car yes you can use a gauge like this but then in the correct nm for the job. Remember its to different measurements doing this with diff in car our mesaure only diff.

 

[EmilysDad]

Why do i want this when i already have given a picture of the only gauge that is possible to measure 100% correct? I already write that you need to spin gauge in steady rpm to get the result demanded for this job. If you are doing this with diff out of car yes you can use a gauge like this but then in the correct nm for the job. Remember its to different measurements doing this with diff in car our mesaure only diff.

you want to do as Uncle Benz says then ....