problems with refurbishing rear axle 4,08 to 3.25

[ja17]

Yes, the control arms are not the same. They are slightly angled inward and do not come off the axle at 90 degrees. In this way they are a right and left angled in opposite directions.

[Rodolfo]

Yesterday I had all under the car again. Went for a testdrive (10 km).

I have some noise, but expected that: I did not put full load on the pinion nut to avoid overpressurizing the bearings and sleeve. Did a small turn further, less noise. But still some. But the nut is not possible to move further, although I still have some play. This play I expected after a testdrive: The oil gets warm, the pinion gets back pressure (after a while I did full accelerations) , so the pinion can creep a bit further to the front of the car. My plan was to take away the play after the testdrive. But as mentioned the nut seems to be stuck. Maybe I will put a washer just before the nut. It could be that the thread is not free enough to go further with the nut. I will try that the next evenings after work.

But: the drive was great! The 3,25 ratio is perfect for the 230 sl manual.

I will post my progress with the nut later on.

[GGR]

I may be wrong, but it seems to me that the more you tighten the nut, the more you pull the pinion forward and the more play you end-up with. There is a collapsible sleeve in there that needs to be put new. Once it's collapsed too much, then you need to replace it with a new one. I've also seen some spacing rings put on each side of that collapsible sleeve, though they don't seem to show on EPC. The other adjustment you have is that big nut on the right side of the differential carrier. But same thing: the more you tighten it, the more play you have between the crown and the pinion. If you need to get the carrier and the crown more towards the right, it can be done by adding spacer washers behind the left bearing race in the wheel tube. In the meantime, you can try a thicker oil to reduce the noise.

[Rodolfo]

I didn't mean play between ring and pinion. I ment a small play of the pinion shaft in its bearings, which appeared after a testdrive with full power on it. So I can put more torque on the pinion nut and collapse the sleeve a bit more. The bearings on the pinion shaft were very narrow. So probably they went on further, since heating the differential by driving, heats up first the bearings and gears and keeps the shafts cooler. So bearings can sometimes slide further and so making some play. I gues that is what happened. Means I can tighten the pinion nut a bit further. But that is very difficult. It is like a hard stop, while I still have some play in the bearings of the pinion shaft. That is why I would try to first install a washer and then again the nut and try to tighten it further.

After that I hope I don't have to much play between pinion and ring gear (since the pinion will go forward to the car, as you mention). Then I shoudl indeed adjust with spacing washer on the left bearin in the wheel tube.

[GGR]

Oh, I see. And do you have play between the ring and the pinion? i.e. can you feel some play when you turn the drive shaft flange back and forth? If so, how much? With time, everything first seats into place and then with wear, you end up having more and more clearance everywhere. So the less play you have between ring and pinion at the beginning, the best it is. So try to tighten that pinion shaft as little as necessary. 

[Rodolfo]

To be short:

did several tesdrives. Progressively I have put a bit more torque on the pinion in between. The noise went further away, until completely dissappeared.

Now I am very happy: the 3.25 is great on the 230sl. It was a lot of effort, but I am very pleased with the result.

Not only is cruising at 120 km/h perfect now, but all the gears fit very good now in a progressive way while pulling up.

Thanks a lot to all people who helped me on the forum. A few persons were very close following and giving very good advices, special thanks to them.

Rudy

[Rodolfo]

This weekend I drove 700 km with the car: from Belgium to Germany (Monschau, Bad Munstereifel) and back. No problems. Back home I checked all bolts with torque wrenches. Only a little bit adjustment needed.

So I am glad all is OK now. Now I would like to decrease exhaust sound through the bonnet. But that is another topic,

thanks Rudy


PS I saw a white Pagoda just over the border of Belgium in Germany. We used both our horns. Don't know it was a German or a Belgian driver.

[GGR]

You may consider replacing your diff oil after 700 to 1000 km with new ring and pinion.

Someone at the Williamsburg 50 gathering had glued a sound dampening material on the inside of the hood (bonnet). You may need to make sure that all your mounts (front subframe, engine and transmission) are in good shape as otherwise it may decrease clearance between the valve cover and the hood which may be a problem with the added material.

[Rodolfo]

Good idea about the diff oil. That is the wise way to go.