[hassmaschine]

Originally Posted by Volasko

I took the following video, even with upgraded M3 diff mounts the diff does move alot!

a lot is relative. it moves exactly as much as it was intended to.

[justpete]

Why not just install solid diff bushings? What am i missing here? Not that diff movement matters other than being part of the driveline windup problem...

[Taskmaster]

Originally Posted by hassmaschine

Z3Ms had single ear diff mounts and the same subframe as the E30. Not even comparable to an E90.

I know, I had 2 Z3s, I've never been under the e90, but I don't see how it would different. Then again, I don't believe in any excess bracing, never personally found enough tangable evidence that they had any objective benefits (outside a full cage)

[hassmaschine]

Originally Posted by TheAxiom

I know, I had 2 Z3s, I've never been under the e90, but I don't see how it would different. Then again, I don't believe in any excess bracing, never personally found enough tangable evidence that they had any objective benefits (outside a full cage)

the single ear diffs can move a lot more because it can twist quite easily and there's only 1 bushing. From the E36 on they used dual-ear covers that mount it a lot more rigidly to the subframe, and the diff can't really twist like it could before.

Some guys with big power even convert to the dual ear covers and weld in another support to the car, but you'd have to be putting down extreme power for it to be worthwhile..

[Tom Droze]

Originally Posted by justpete

Why not just install solid diff bushings? What am i missing here? Not that diff movement matters other than being part of the driveline windup problem...

I have the MFactory differential bushings installed, which are stiffer than OEM bushings but not as stiff as polyurethane. I know this because prior to the MFactory bushings I had polyurethane bushings installed for about three months. I had an issue with a bad clucking noise which was traced back to the polyurethane bushings. My thought with the brace, given its ease of install, was to use it just for track days only. But based on the feedback on this thread, it's probably not worth it. Solid bushings are not an option because I want to maintain some resemblance of comfort for my daily driver.

[justpete]

Originally Posted by Tom Droze

I have the MFactory differential bushings installed, which are stiffer than OEM bushings but not as stiff as polyurethane. I know this because prior to the MFactory bushings I had polyurethane bushings installed for about three months. I had an issue with a bad clucking noise which was traced back to the polyurethane bushings. My thought with the brace, given its ease of install, was to use it just for track days only. But based on the feedback on this thread, it's probably not worth it. Solid bushings are not an option because I want to maintain some resemblance of comfort for my daily driver.

Understood, thanks. I haven't noticed any issues with Delrin/Aluminum bushings from Turner other than some whine under heavy deceleration although admittedly the trans mounts, dual plate clutch, and solid flywheel add enough gearbox whine to compete... Neither seem to impact comfort, per se. The suspension pretty much does away with that whole concept all by itself. yow

[chris82]

Originally Posted by hassmaschine

wheel hop is a function of spring & shock stiffness/rebound. making the diff stiffer isn't going to change that.

I am loving your comments on this subject, very informative

[gmagnus7]

Originally Posted by hassmaschine

I didn't want to type this on my phone - but basically, that thing does nothing.

Firstly, BMWs have had IRS since what, the 1960s? How exactly does making the diff more rigid make the rear end "more planted"? nonsense - the suspension is attached to the subframe, not the diff.

Second, it doesn't even really stiffen the diff, because if it did, that bracket would fail miserably. Those 4 little bolts are attempting to create a sort of "moment connection". If there were any significant forces through them, they would rip right out of their threads (or shear off). And the flat bar piece is going to be really flimsy along the length of the car (it would just bend at the welds), while the shape of the flat bar is wrong to resist force in the horizontal direction (even seen a flat bar being used as an I beam or tube? nope!) .

All it tells me is with stock bushings, the diff doesn't move much to begin with, because that bracket would fail if it did. And even if it did move a lot, it wouldn't translate into the suspension anyway. Plus, we have pegleg diffs and put down maybe 220wtq. Older BMWs with single ear diff mounts (and LSD) can put down way more than that without any problems.

So I don't mean to be rude but you clearly haven't looked at the differential bushings that come from the factory. You can squish them with your hand. You can see that video that shows even with the M3 bushing there is still movement even under very light load. You can literally feel it squirming around around corners if you know what to look for.

[Eagle1oh7]

What's wrong with upgrading your diff bushings over this brace?

[feuer]

Originally Posted by Eagle1oh7

What's wrong with upgrading your diff bushings over this brace?

There are only 3 diff bushings so even if they are solid the diff will experience movement under loads. These braces that are welded from random metal pieces are prone to cracking. I would go with VWetish plate intead. http://www.n54tech.com/forums/showth...=38313&page=13

[streetpro]

I have just installed this set and I am very pleased with the results... no more fish-tailing when on/off WOT... it just works :-)