Offset rear sub-frame and diff 12mm?

[Massimo]

Hay guys.

I just posted this question in Wh33lhop build thread, then thought I should maybe get a few opinions.

Basically I am replacing my rear sub-frame and diff bush with AKG poly 12mm offset bushes, This obviously raises the diff 12mm. I have read that having the diff offset can play all kinds of havoc with the drive shaft center support bearing, is this true? Should I be off setting my diff so that it sits in the same position as stock?

Cheers

[der affe]

yes, just make or have 12mm spacers made to go between the rear sub frame and the diff to space it back down. that way you can still use a stock type diff bushing, otherwise you need an offset one.

i found out about this a little too late though, i made the diff spacers last week and this weekend i will be turning down my stock type AKG sub frame bushings and making spacers to shim it up the remainder of the distance to equal 12 mm.

[Wh33lhop]

If it really bugs you that much, just space the diff down (you can even just use washers). I've got a Powerflex stock type diff bushing if you want one. :p

[sharky]

I have put these in customers cars and had the DS hitting the pipe that goes inbetween the fuel tank, not cool. Absolutly need to shim the diff. Im not a fan of these bushings and much prefer the weld in camber/toe kits.

[FLG]

Not to hijack, but im putting in the offset bushings as well...but before ive got the car in the air i was wondering if the stock diff bolts will be long enough (mine are 10mm offset) to accommodate the spacer? And if there not, does anyone know the stock length/size of the diff bolts...will be much easier to have them ready to go rather than take it all apart and have to run to the store to find bolts..

Thanks

[nrubenstein]

Similar bolts are basically impossible to find locally. the thread is unusually fine.

[Mafiaracers]

Now I'm confused.

I bought the akg 12mm bushings, offset diff bushing, and eccentric adjuster kit a while back as part of my build. I recall reading/hearing about the chance that the drive shaft can make contact with the fuel line and or gas tank.

If I have the offset diff bushing, which is supposed to raise the diff 12mm, should I encounter this issue?

[Wh33lhop]

Now I'm confused.

I bought the akg 12mm bushings, offset diff bushing, and eccentric adjuster kit a while back as part of my build. I recall reading/hearing about the chance that the drive shaft can make contact with the fuel line and or gas tank.

If I have the offset diff bushing, which is supposed to raise the diff 12mm, should I encounter this issue?

You may. I am going to reuse the subframe bushing washers to space the front of the subframe down another 3mm in order to alleviate the issue. Just gotta get my lazy ass out of bed to do it.

[Mafiaracers]

I wouldn't want to shim the diff at the subframe housing as that will mess up the alignment. I think I'll just install it as it's supposed to be installed, watch the clearance and adjust as needed.

[Wanganstyle]

Similar bolts are basically impossible to find locally. the thread is unusually fine.

BMW OEM wheel bolts are the same thread, somebody should look into a diff stud kit (some people use studs instead of bolts for the diff to quick change)

[FLG]

If thats the case ill have to look into it...can anyone tell me the stock length/thread pitch?

Mafiaracers,

Problem is, by offsetting the subframe your also changing where your differential sits..thus changing driveshaft angle. By shimming the diff back to stock placement, your putting it back to the correct angle.

[Wh33lhop]

I wouldn't want to shim the diff at the subframe housing as that will mess up the alignment.

No it won't. It'll affect the rake angle of the diff, but it will actually improve the amount of bend in the rear universal joint if you think about it.

I installed everything today, it's not rubbing yet but I haven't put it on the ground. The clearance for me is a matter of millimeters.

[AndrewBird]

What is the purpose of moving the subframe up? Leveling the trailing arms on a lowered car?

[Mafiaracers]

I'm invisioning this....so the subframe bushing has the 12mm spacer on the bottom to raise the frame up. Therefore, the offset diff bushing should then be installed in such a way (offset hole in the 'up' position) to push the diff down to where it "was" prior to raising the frame....

Do we agree on this?

[petrolhead]

What is the purpose of moving the subframe up? Leveling the trailing arms on a lowered car?

What he said.

EDIT..
Well, raising the subframe puts rear wheel in a different spot of the toe curve, and it is just that, a curve not linear. In other words toe change per amount of suspension travel is less. Which is nice.
Camber change again, is linear.