Offset rear sub-frame and diff 12mm?

[Wh33lhop]

I'm aware of the geometry changes. I am also relieving stress on the CV joints by spacing the diff up.

[AndrewBird]

Did you pre-load the CSB when you installed it?

[Massimo]

I have mine back on the ground and running with the spaced down diff, no problems. Though my space down was a little dodge ;-) ill post some pictures tonight.

[Mafiaracers]

I don't like the idea of spacing the diff away from the subframe. Be it shims and longer bolts or what have you. The diff tunnel and driveshaft hoop etc are aligned properly when its bolted up flush. Moving the diff down 12mm relative to the already stationary hoop sounds like a recipe for issues later on.

[E30_fiend]

Just get an adjustables diff bushing and you're set. No washers, no shims.

[FLG]

I think you guys are missing the reason for spacing down the diff.

Due to the 12mm offset subframe bushings the differential is no longer aligned with the center bearing like it was factory, nor is the driveshaft at factory angle. Weather this truly is enough to make a difference in wear for either the center bearing or the u-joints, or if it will cause vibrations...dont know. I do know that factory set its correct and happy, so by spacing the diff down the difference you just spaced the subframe your now correcting the misalignment you caused and the driveshaft angle is back to where it used to be factory, along with the diff bushing.

[Eric]

I don't like the idea of spacing the diff away from the subframe. Be it shims and longer bolts or what have you. The diff tunnel and driveshaft hoop etc are aligned properly when its bolted up flush. Moving the diff down 12mm relative to the already stationary hoop sounds like a recipe for issues later on.

if you move the subframe UP 12mm then moving the diff DOWN 12mm will keep the driveshaft in it's original position. Not sure what the confusion is here...

[Wh33lhop]

I think you guys are missing the reason for spacing down the diff.

Nope.

[E30_fiend]

if you move the subframe UP 12mm then moving the diff DOWN 12mm will keep the driveshaft in it's original position. Not sure what the confusion is here...

EXACTLY!!!!! I'm glad someone gets it.

That's why the diff bushing needs the slot to adjust the diff back down to where it needs to be. APPROXIMATELY 12MM.


Taylor

[Massimo]

I was trying to confirm if moving the diff 12mm will actually cause problems with your CSB or weather this is just a myth, thought wh33lhop has answered this as his CSB was chewed up with the diff raised 12mm.

[FLG]

EXACTLY!!!!! I'm glad someone gets it.

That's why the diff bushing needs the slot to adjust the diff back down to where it needs to be. APPROXIMATELY 12MM.


Taylor

Isnt the diff bushing not mounted to the rear subframe, so by spacing the diff back down your back in OE location thus a std bushing will be fine. The offset diff bushing is if you space up the subframe but dont space the diff back down.

[E30_fiend]

The point is, you should NOT have to put spacers or washers in between your diff and subframe. The bushing does the EXACT same thing that the spacers would do except you leave less room for operator error.

Do you guys really like the idea of having your diff floating away from the car?? The bushing is thr corrective measure that needs to be taken.

Space the subframe up, and the adjustable bushing allows the diff to sit its the correct STOCK position to not cause any problems with the driveline.


Taylor

[jlevie]

Space the subframe up, and the adjustable bushing allows the diff to sit its the correct STOCK position to not cause any problems with the driveline.

I'm sorry, but that is wrong. If you raise the subframe you also raise the differential, which means that the differential is not in it's stock location. That in turn means that the half shafts and drive shaft are not operating at their design orientation.

If you raise the subframe you need to lower the differential by the same amount. Which means that you can then use the OE differential bushing.

[Mafiaracers]

What I was saying was...

the diff and subframe, in their oem form, are connected with no shims or spacing. Moving the whole assembly up or down as a unit is all well and good. However, moving the frame up, and spacing the diff down to "OE" position is all my issue was. I don't like the idea of separating the diff and subframe via shims or what have you in order to clear something.

thats all

[jlevie]

If done properly spacing the differential down won't materially change the forces acting on the bolts. That would mean spacers with generous surface area. I'd hazard a guess that solid spacers of 1-1/4" diameter would be the minimum and a single solid plate would be the best.