The Extra Mile

Hey guys!

I am in the middle of upgrading my car with a custom blackboost camshaft kit and will post about that soon in my build thread.

However another issue came up that has gotten worse over the years, a grinding noise from the rear diff. I decided to have the diff rebuild and also change the diff ratio to shorten the gears a bit before driving around with extra HP.

Now two different shops have told me that the diff can´t be repaired since the main bearings in the p30 LSD can´t be bought as replacement parts, only the complete diff can be bought.

I have searched through this forum and found a few threads with similar issues, but haven´t found a clear answer so far.

Does anyone here know if it´s possible to get replacement parts for the P30 LSD? What broke is the "Hauptlager" which I assume translates to "main bearing"? Not sure if that is the correct term in english.

Anyway, I would really appreciate any help that I can get since I really don´t want to fork out 3k for a whole new diff.

Thank you guys so much in advance!

Alex

sventastic82

Carrier Bearing: 230 350 03 49

Pinion bearings are not listed as a spare part by Mercedes below is a link with their manufactures part number.
https://mbworld.org/forums/c63-amg-w...ml#post6563023

Pinion bearing

The Extra Mile

Thank you so much!!

that is exactly the Info that I needed

sventastic82

Kein Problem! Hatte einige Stunden gekostet um die Teilenummer zu finden.

go team

This is very interesting as I made the gears taller to stay within the gears more.

AMGSIXTHREE

What did your diff noise sound like, and how did you pinpoint it?

I have a noise that sounds like the diff but I haven't been able to isolate it. Just found out about dyno mode, so that may help.

BLKROKT

Subbed. I’m also looking to go shorter to increase the effective torque and have more usable gearing on track. Interested to hear details as a few have done this but it was a pretty intense undertaking, especially getting the various codings to get along well.

The Extra Mile

Huh, well that´s another way to go about it I guess haha.

I am mostly interested in optimizing the performance and shorter gears should help with acceleration.

The Extra Mile

It was a grinding noise that started of very faint but got more and more intense over the past year or so. It´s hard to describe but it sounded a bit like what straight cut gears would sound in a racecar. It got to a point where I wouldn´t feel comfortable pushing the car, especially now with even more power.

The Extra Mile

Oh that might change things. I was under the impression that it is a purely mechanical change? The ecu and gearbox don´t "know" how the rear end is setup so what would need to be changed?

AMGSIXTHREE

Changing the gearing itself is purely mechanical, but the computers are monitoring wheel speed. It expects to see the front and rear spinning at about the same rate in a straight line (calibrated for the circumferences of the original tires). If you change the final drive enough it's going to see a big difference in wheel speeds all the time, and may interpret that as a problem. And that may also affect the way the transmission operates.
You'll want to find a tuner who is able to go in and correct that stuff.

The Extra Mile

Thank you so much for that! I will talk to my shop and see what they say. I don´t want to go through all that effort just to revert everything back to normal.

The Extra Mile

Oh just another quick thought, trying to think this through, the wheelspeeds would obviously not be different between the axles, otherwise I would do a permanent burnout haha. Just the RPM the engine would run at a certain wheel speed would slightly change, however that would be already the case for every single gear.

I think I will just risk it and see what happens, for science! Worst case is that I have to go back to stock ratio. I really think that it would transform the car for the better and would not want to skip this.

BLKROKT

Your car won’t run right without the appropriate coding. It’s not even mainly about the trans. The ABS/ESC system will flip out and be inoperable at best.

AMGSIXTHREE

Right. I guess it's not so much the wheel speed as the transmission output shaft speed vs RPM and load that might cause issues. Not sure how it interprets the front wheel speed vs vehicle speed (which it gets from the transmission) or if that matters.

BLKROKT

Wheel speed sensors. ECU and TCU coding is required. I don’t think the car will even move without it.

AMGSIXTHREE

The wheel speed sensors themselves shouldn't be affected. But whichever computers that are looking at wheel speed, and trans output speed, and vehicle speed, and load, are going to see numbers that don't make sense. I think it would move fine but you'd probably get a bunch of codes and weird behavior from the transmission.

It would be like putting a much shorter tire on the rear.

BLKROKT

@Celicasaur would be the guy to help answer this stuff if he’s still around. He went off the deep end on these questions.

go team

In Vediamo it’s VGS 3 once you’ve changed the final drive ration (also in Vediamo). I haven’t programmed the changes yet but have mapped the areas where the change needs to be done. I can try to update with findings. But again I’m going taller gearing similar to these guys marketing it

https://www.premiertuninggroup.com/c...-65-ratio-ring

AMGSIXTHREE

Neat. Thanks.

Why taller gearing?

go team

Just an example in 4th on 2.65 you’re topping out at 239kph in 3.06, 207kph. Powerband has wider use vs needing to shift sooner.

For drag you still probably want 3.06 but for road course it would depend on the course. I thought the Burg would benefit from tall gears!

AMGSIXTHREE

Interesting. Is this an MCT car?