quik55

Hey guys, it's been a little while, I hope everyone is doing well!!

So rear subframe front bushings are TOAST. Rear rear look ok.

Would really prefer to do a Quant style full poly setup back there so looks like they won't be addressed until we drop the entirety of the underbody of the car. As well as driveshaft, straight pipe new diff etc hopefully.

Aside from rear springs being "cracked" they should be good for now and the rear suspension change prompting this investigation I think is going to be held off for now as the bilsteins seem to be in nice condition.

So I jacked the rear end up and took the wheels off. Put her in drive and was funny to watch one rotor spin while the other just can't do anything lol. Gave it some gas, that was probably a bad idea lol traction lights and weird noises. But when I hit the brakes I could see the driver rear which usually always gets all the power for some reason?? Raise up an inch or so, sway bar end link toasted. Going to replace the bushings and endlinks, luckily cheap right!!!

I tightened up the rear exhaust clamp and seems to have taken away the exhaust leak/high pitch squeal WOT approaching redline, I'm curious if the back pressure change is making the the PCV run better? But idk anything about that.

SO.... onto the task at hand.

The Differential. Bushings seems ok, but it is a 2001 with 182k miles and I am the 4th owner and have had it since 2017 @155k. I haven't touched the transmission fluid OR diff 😬😬😬😬.

When removing the trans cooler, replacing lines etc the fluid looked pretty and red and smelled beautiful so I think that's OK for now.

But im gonna need your guys' help with the diff flush.

1. Where can I find a magnetic drain plug for our diff?
2. What fluid should I use, how many quarts does it take etc and how can I get away with not spending $90 on just the fluid.

Any improvement after changing fluid that anyone knows of? I think it should take away the nice clunk I get after doing som spirited driving.

Thanks guys, really appreciate all ur help !

Khan 55

I dont know about the magnetic drain plug for diff but I would go with the MB fluid. Its decent for good quality diff oil. Others will recommend what they have used. After changing it, it should feel smoother at the rear. Probably not but old oil loses its viscosity properties over time. I think the agents recommend buying two bottles of their fluid and not all of the 2nd bottle is used. I am sure its just under a litre of oil but could be wrong. Check the owners manual if you have one pr just ask at the dealership

quik55

Lol I wouldn't ask the Mercedes dealership
If they paid me! But thank you so much exactly what I did not want to hear but you my friend are a gentleman and a scholar.




Anyone else have any info on the magnetic drain plug for diff?

Dokus

Motul makes great stuff, check them out. You wont need much fluid so it should not cost you that much.

I would go to Mercedes for the plug, if not check fcpeuro or esc.

quik55

**** me. Fcp carries 75w90 LM or redline.
i may just blow it and go quaife

I think I'll go liquid molly but priority is the magnetic drain plug as of now, any leads?

Also...I'd like to do a cams and nos setup

I'm getting the spring compressor for my bday so I'll be able to do front poly bushings and once I do rear subframes front bushings and rear control arms the Benz will be 100% mechanically restored at 182k miles.

also planning on getting a jb4 for the 19 s4 unless anyone has any other suggestions.

also just picked up a 2020 m340i any suggestions for that?

thanks guys