Replacing rear diff rubber mount

[RenoRaines]

Today I noticed some drops of oil on rear guard. On inspection it looks like rubber diff mount (with hydraulic damping) is torn and it's leaking oil. According to TIS this mount should be replaced with regular one not hydraulic. In the picture below you can see exactly which mount I mean. Do you need to remove rear diff for this task or not? Anyone done this?

 

[GuidoK]

According to TIS this mount should be replaced with regular one not hydraulic.

No, TIS says that if you replace the hydraulic bmw mount (pre facelift) for the non hydraulic mount (post facelift), you need a spacer/shim between the diff and the bushing. You can choose for the original fluid filled bushing.

I think it's this shim:
http://bmwfans.info/parts-catalog/E85/Europe/Z4_3.0si-N52/2007/browse/rear_axle/differential_drive_output/#pos_4
But I'm not sure.

But meyle has a HD version of this bushing that is said to last longer.
Also powerflex and strongflex have a polyurethane mount for this.
So I'd go for one of those options but that choice is up to you :wink:

You have to remove the diff from the car and press the bushing out of the subframe. A polyurethane bushing can be installed by hand, but a bmw/meyle bushing has to be pressed in, and be sure that it's in the right position (top/bottom oriented).
Getting the diff out obviously means unbolting the driveshafts and the propshaft. Mark the position of the propshaft to the propshaft flange. It can by dynamically balanced, so it's best to refit it in exactly the same position.

I don't know if you have to remove the exhaust. Maybe you can remove the propshaft with only removing the tension bars/underplate, but maybe the heatshield above the exhaust sits in the way....
Removing the exhaust certainly gives you more room to work.
Rear stabilizer has to come off too.


Be sure to properly torque it down again.
Central diff bolt takes 165Nm, so quite a lot.

 

[RenoRaines]

On link rubber mount #9
http://www.etk.cc/bmw/EN/search/selectCar/E85/Roa/BMW+Z4+2%25252E2i/ECE/33/33_1138/

I was thinking going polyurethane or meyle HD. But replacing just one stress will be transferred to other mounts. I should be replacing all of them than.
That sucks. Removing the whole diff Probably because hydralic mount has a spacer between diff and mount which comes out only one way. Maybe I really need to think over about my LSD. If I'll be taking diff of it's a good thing to do the LSD at the same time. And maybe also shaft bearings.

 

[GuidoK]

Yes #9 thats the bushing, and indeed that's the TIS page. So you can't put in bushing B if bushing A is in place.
Bushing A is the (non hydraulic) facelifted design.

The bushing itself doesn't have a flange

These are some of the bushings that I pulled out of my rear axle:



The large one in the front (with some rust) is the rear diff mount.

From what I remember the bushing only goes goes out one way (in direction of the diff mounting eye) not because of the flange, but because if you want to press it out the other way it hits the bracket from the rear sabilizer. (not 100% sure on that...)

I went for poly bushings. I have the ones from powerflex, but now strongflex also have them (roughly same design) and much cheaper (I found the powerflex ones rather overpriced, also compared with their other bushings). Strongflex is imho generally just as good as powerflex, only strongflex uses a steel zinc plated inner sleeve and powerflex uses a stainless steel inner sleeve.
Whichever you choose, don't buy the polybushing from the brand PSB (available on ebay). It has a design flaw that the inner sleeve is too weak which causes the central bolt to crack! (me& some others all had that problem, that was the first polyurethane diff bushing on the market for the diff...)

The front diff bushings pop out relatively easy (not as tight as the rear one.

Installing a LSD is a whole other story though both in work, tools needed and skills. But if you're gonna do that yourself anyway....

 

[Lehla]

Hi I'm going to be trying to replace the Rear diff mount bushing by myself on my 04 Z4 3.0i. The rubber is very badly torn from my understanding. I already have the replacement bushing. Does anyone have any tips or advice for me on doing this? I've read different threads and watched videos but I'm still unsure about it...