2JZGTE 735i Rear End Refresh/Diff ratio change

[BMWTurbo]

Hi Guys,

Over Christmas I changed a bunch of things in the rear end of the E32 that had probably been there since they left the factory back in 1986 :P.

I bought a bunch of stuff from Schmiedman in preparation for this, subframe 'cans' (HD Meyle), front diff mount, rear diff mounts, read subframe mount, new tailshaft CV, and I also took the opportunity to rebuild the half shafts, and fit my rebuilt 3.64 large case diff.

I wasn't too keen on it, but I dropped the subframe from the car.
After removing the exhaust and tailshaf, I found it easiest to remove the trailing arms (with drive half shaft attached) seperately and then used a couple of jacks to lower the subframe with the diff still attached. I had the vehicle sitting on four jack stands.

You can see how bad the bushes were, I had no idea they were this bad until I dropped the frame out.




To remove the old bushes I used an Oxy/Acetylene torch to heat them up until the rubber started to burn and hit them out carefully with a hammer. I found it best to bang them out the side that you would start installing them from, ie the side towards the flared 'bellmouth'.

I was suprised how simple this was and after a quick clean up with a wirebrush/wheel I gave them a quick like of satin black paint whilst still hot so it cured immediately.

Now I'd previously put all the bushes in the freezer in order to give them every chance of pushing in easily. We ended up getting the subframe cans in fairly easily just with some plates and a large G-clamp. I did use some dishwashing liquid to aid them sliding in but they feel nice and firm once installed.

The diff mounts were a bit trickier to get out, but much the same, heat and bang them out. I found I needed a long peice of steel to be able to easily hit them out from a distance away, wasn't easy to get the hammer on the bush directly. These were harder to get in also, the new bushes seemed slightly too large in diameter and were hard to start, but once we got them moving using different sized sockets etc we got them in. The steel section of the new bushes did seem to crumple a fraction after inserting as you can see below, but bushes were firmly in place and I tapped the steel out to make it round on the ends again once installed. I don't think it bent the majority of the steel section, only the ends.






And the fun stuff, the new result of changing the rear end bushes and from the 3.15 diff ratio to a rebuilt 3.64 diff ratio

Log data from the E-manage computer suggests just over 4 seconds 0-100kph, but my G-tech Pro meter said 4.82 seconds for the same run. 0-60 MPH was 4.62 seconds.

Below is literally just standing on the throttle from stationary and backing off just over 100kph. When stalling and with slicks I think that will come down.

[ame]http://youtu.be/nSu4M4Ha9E8[/ame]

Will be interesting to see what it runs down the 1/4 now. It's much more 'lively' now, in first gear when the second turbo comes on it just instantly fries the tyres and will keeping them turning for a second or so into 2nd gear (you can see the speedo jump around a bit in the VDO

[Johal E32]

nice!

[shogun]

hehe, we did the same on an E32 750 Apina B12 on 29.12., which we bought as parts car as the previous owner had a front crash accident.
Took the complete subframe out with attached differential and drive shafts. But we had a lift which made it easier.
When all was almost lose, we lowered the lift, put 2 mobile jacks underneath and then slowly dropped the complete package on the 2 mobile hydraulic jacks and pulled the whole stuff backwards out.
Good that we were 4 guys, so on each side one could hold the drive shafts to balance the weight and the other 2 pulled on the jacks.

Will also completely overhaul it and drop in a 3.64 diff ratio.
But that will be in spring, was too cold on that day.
The other car without subframe we moved then from the lift with a large forklift into a corner of our wrenching building, will be used as parts car

[BMWTurbo]

Cheers Johal

Erich:- It was me working alone, so I had to account for lack of hands and strength :P

My Dad helped replace the bushes (did it as his house with his oxy etc) and he gave me a hand to guide the subframe/diff back in which saved some time, but the arms, etc all went back in fairly easily

I'd hate to have to deal with a std BMW exhaust though, my system is a fairly simple, 3.5inch single system with a 3.5inch CAT, centre and rear mufflers only, the BMW exhaust weighed a tonne when I removed it originally.