Crown wheel and pinion (1:3,92) for ‘71 280SL

[Berggreen]

Hello,

I have been so lucky to find a crown wheel and pinion (1:3,92) for an affordable price, which may fit my ‘71 280SL (aut.), where the differential feels worn.

However, as I bought the set used, but in good condition, I would like to confirm that the crown wheel and pinion will actually fit my ‘71 280S, before I pay someone to install them in my differential.

I have searched the MB parts library, but it only states the part number (A1113500839/A1123500939) for the combined 1:3,92 set, and not for the individual crown wheel and pinion.

But the crown wheel and pinion, I have bought, bears the following part numbers:
Crown wheel: A1123531712
Pinion: A1123532010

So the million dollar question: Does this crown wheel and pinion add up to the 1:3,92 set for a ´71 280SL (USA-spec)?

Thanks and hope you can help,

Christian

[Shvegel]

Unfortunately I can't answer your question.  I can tell you that fitting a new crown wheel and pinion is a hard job on our cars without the factory tools.  Our rear axles are not the same as a standard rear axle and getting pinion height and backlash could be really tough.  I am curious why you think your gears are worn?  What are the symptoms?

[Berggreen]

Unfortunately I can't answer your question.  I can tell you that fitting a new crown wheel and pinion is a hard job on our cars without the factory tools.  Our rear axles are not the same as a standard rear axle and getting pinion height and backlash could be really tough.  I am curious why you think your gears are worn?  What are the symptoms?

Thank you. Good to know that someone with the right factory tools have to do this job.

The symptoms are:

1) Especially, when cold it makes noises - like grinding noises. They gradually reduce, after driving some time, but does not completely disappear.

2) It is evident that there is some play somewhere in the power train, because especially when driving slow the aut. gearbox has problems shifting - sometimes. It seems like it cannot make up its mind and get messed up in the shifting by the play...at least this is how I feel it.

3) The differential is soaked in thick gummy oily substance. It does not drip oil right now, and therefore I don’t want to clean the gummy thing off, but I am sure it will, if I remove it.

What does these symptoms indicate to you?

Thus, my thinking was that as the differential anyway need to be taken down to sort out the leak thing, I could just as well change the crown wheel and pinion in the same process. Or am I to naive here?

I should also mention that in order to try remove some of the noises and to postpone the time, where the differential has to be renovated, we changed the diff. oil to a thicker type - 120W I think. It did not make any big difference, but this is what it has now.

Finally, ideally I would have liked to change the gearing to the European 1:3.69. But unfortunately the crown wheel and pinion for this gearing is so sought after to convert to European spec that these are extremely expensive here in Europe, especially if you want original parts - somewhere around 2-3000 EUR just for the parts, and then comes labour cost for installing them on top of that!! 

Thus, I decided to stick to the US spec 1:3.92, as I could get this set of original crown wheel and pinion for an affordable price (300 EUR).

Cheers,

Christian

[Shvegel]

It sounds to me like you have a bad pinion bearing but not necessarily bad gears.  You are right that the axle probably needs to come apart.  Unfortunately, I do not have the factory tools.  I am not sure if anyone does. What I can offer you is a tool I made to check the backlash and a tool that I made that might get your pinion in the right spot.

[Shvegel]

Tools.

[Berggreen]

It sounds to me like you have a bad pinion bearing but not necessarily bad gears.  You are right that the axle probably needs to come apart.  Unfortunately, I do not have the factory tools.  I am not sure if anyone does. What I can offer you is a tool I made to check the backlash and a tool that I made that might get your pinion in the right spot.

Thank you very much for your input and offer. That looks like a quite complicated job! 

Let me try to trace down a workshop around here, who has the guts to take on this job, and if they can then if needed maybe borrow your tools, then that would be fantastic.

Best wishes,

Christian