[squartus]

I have a 2010 M3 I had to replace the rear diff bolts on twice because of the sloppy rear diff mounts that come stock on car. This is with 20k miles on car non tracked, went with solid delrin diff mounts and vibra-tonics engine mounts to fix the issue.

Car is MUCH more planted and responsive, downside is you do get a drivetrain whine in cabin even over aftermarket exhaust.
They even had to reshape the frame a bit because the hole was egg shaped from it having so much play with the stock mounts.

Ton of guys having these problems, some getting serious damage when bolt snaps and rear diff drops down on highway.

[solishe]

Anybody recently paired m3 subframe bushings with Turner Solid Delrin Diff mounts? If so, any significant NVH you noticed? Looking for more data points before I decide whether to replace the diff mounts when I get the wavetrac LSD in.

[dcaron9999]

Originally Posted by solishe

Anybody recently paired m3 subframe bushings with Turner Solid Delrin Diff mounts? If so, any significant NVH you noticed? Looking for more data points before I decide whether to replace the diff mounts when I get the wavetrac LSD in.

Im getting a Quaife LSD installed this week, and already have the M3 rear subframe bushings installed on my 135i. I had the same questioning as you while preparing for the LSD install - whether or not to upgrade the three diff bushings "while I was in there". After some research, I opted not to do it. I learned that this mod is not worthwhile, at least not for 135i/335i platform. The subframe bushings are the items that will make the most difference. So unless there is visible damage or cracks in your original bushings dont bother. You will also definitely increase NVH with solid bushings, and hear some differential whine noises in your car when you coast.

[solishe]

Originally Posted by dcaron9999

Im getting a Quaife LSD installed this week, and already have the M3 rear subframe bushings installed on my 135i. I had the same questioning as you while preparing for the LSD install - whether or not to upgrade the three diff bushings "while I was in there". After some research, I opted not to do it. I learned that this mod is not worthwhile, at least not for 135i/335i platform. The subframe bushings are the items that will make the most difference. So unless there is visible damage or cracks in your original bushings dont bother. You will also definitely increase NVH with solid bushings, and hear some whine noises in your car when you coast.

I agree but my only fear is that with the increased grip I may start getting rear end squirm or dog legging upon hard acceleration. I would hate to discover that after they were in there and have to go back in....

[GreekboyD]

Originally Posted by solishe

Anybody recently paired m3 subframe bushings with Turner Solid Delrin Diff mounts? If so, any significant NVH you noticed? Looking for more data points before I decide whether to replace the diff mounts when I get the wavetrac LSD in.

I'd be able to answer this for you in June.

M3 subframe bushings are already on my car and I've had the Solid Delrin Race RDM sitting in my house for over a year. I'm getting the LSD in late May.

[solishe]

Originally Posted by GreekboyD

I'd be able to answer this for you in June.

M3 subframe bushings are already on my car and I've had the Solid Delrin Race RDM sitting in my house for over a year. I'm getting the LSD in late May.

Ah yes I remember seeing you had those mounts almost a year ago....I'm leaning towards not installing them and I guess risk the double labor hit if I get wheel hop or non straight launch issues...

[GreekboyD]

Originally Posted by solishe

Ah yes I remember seeing you had those mounts almost a year ago....I'm leaning towards not installing them and I guess risk the double labor hit if I get wheel hop or non straight launch issues...

I'd agree with your views there. A guy on the diesel side of the forums had extensive work done at VAC Motorsports including the installation of a Quaife. They recommended not putting them on. At some point you need to draw the line between a daily driver and a track car.

[SSW]

Originally Posted by CALWATERBOY

Plenty posted on this....

This is a really cute "do a search" string. I'm going to copy the "coding" for it for future use. Thanks!

[cvc 22349a]

If I were installing a lsd and didn't want the nvh that comes with solid or poly mounts, I'd install these with a new rear oem bushing:
http://www.ecstuning.com/BMW-E92-335...ial/ES1844489/

[solishe]

Originally Posted by cvc 22349a

If I were installing a lsd at didn't want the nvh that comes with solid or poly mounts, I'd install these with a new rear oem bushing:
http://www.ecstuning.com/BMW-E92-335...ial/ES1844489/

Good recommendation. Anybody out there installed these?

[whosdady]

Originally Posted by solishe

I agree but my only fear is that with the increased grip I may start getting rear end squirm or dog legging upon hard acceleration. I would hate to discover that after they were in there and have to go back in....

I have a VAC built quaife lsd, powerflex subframe bushings, and a host of other suspension mods. I have severe rear end squirm or dog legging upon hard acceleration. I can't even keep the car in the same lane. I've had the alignment done twice at the dealership, shooting for Harold's specs with no increase in control. Next week I will be adding powerflex diff bushings and uuc blue racing tranny mounts. Then I will change my specs from Harold's alignment specs to Vac's. For some reason they are very different. For the record, Steve from VAC is not certain the bushings will help. At this point I'm willing to do anything. I will report back.

Originally Posted by whosdady

I have a VAC built quaife lsd, powerflex subframe bushings, and a host of other suspension mods. I have severe rear end squirm or dog legging upon hard acceleration. I can't even keep the car in the same lane. I've had the alignment done twice at the dealership, shooting for Harold's specs with no increase in control. Next week I will be adding powerflex diff bushings and uuc blue racing tranny mounts. Then I will change my specs from Harold's alignment specs to Vac's. For some reason they are very different. For the record, Steve from VAC is not certain the bushings will help. At this point I'm willing to do anything. I will report back.

Post up both alignment specs...I'd be interested in seeing the difference.

[cvc 22349a]

Originally Posted by whosdady

I have a VAC built quaife lsd, powerflex subframe bushings, and a host of other suspension mods. I have severe rear end squirm or dog legging upon hard acceleration. I can't even keep the car in the same lane. I've had the alignment done twice at the dealership, shooting for Harold's specs with no increase in control. Next week I will be adding powerflex diff bushings and uuc blue racing tranny mounts. Then I will change my specs from Harold's alignment specs to Vac's. For some reason they are very different. For the record, Steve from VAC is not certain the bushings will help. At this point I'm willing to do anything. I will report back.

Do you have aftermarket rear toe arms? They help reduce rear end squirm under hard acceleration. I'd love to hear nvh feedback of the the poly diff bushings but if you're replacing the tranny mounts at the same time (why wouldn't you to save time and money) I'm guessing your car is going to be pretty loud..g/l

[whosdady]

You may have seen this in another thread but the before and after of the last alignment show both specs. Believe it or not, the before was actually better at -2 camber in the rear. I could post the before from the first alignment but I had the adjustable toe arms installed so it was way out of spec.

[whosdady]

Originally Posted by cvc 22349a

Do you have aftermarket rear toe arms? They help reduce rear end squirm under hard acceleration. I'd love to hear nvh feedback of the the poly diff bushings but if you're replacing the tranny mounts at the same time (why wouldn't you to save time and money) I'm guessing your car is going to be pretty loud..g/l

Yes, I have adjustable toe arms. For me they did very little. I'm hoping the diff bushings and tranny mounts help. My car has a lot of tq and the ST's are maybe a little soft. Plus I'm lowered which doesn't help either.

[nitehawk]

Originally Posted by whosdady

Yes, I have adjustable toe arms. For me they did very little. I'm hoping the diff bushings and tranny mounts help. My car has a lot of tq and the ST's are maybe a little soft. Plus I'm lowered which doesn't help either.

You should be able to match your rear camber from left to right. Try and do that in your next alignment. Everything else looks ok to me. What is the condition of your tires?

[whosdady]

Originally Posted by nitehawk

You should be able to match your rear camber from left to right. Try and do that in your next alignment. Everything else looks ok to me. What is the condition of your tires?

Sorry, the tech at the dealership said the left and the right in the rear were equal. That it was fixed correctly but the tech next to him bumped it and the read out is wrong. I didn't know this was possible but that is what he said.

[HP Autosport]

Originally Posted by whosdady

I have a VAC built quaife lsd, powerflex subframe bushings, and a host of other suspension mods. I have severe rear end squirm or dog legging upon hard acceleration. I can't even keep the car in the same lane. I've had the alignment done twice at the dealership, shooting for Harold's specs with no increase in control. Next week I will be adding powerflex diff bushings and uuc blue racing tranny mounts. Then I will change my specs from Harold's alignment specs to Vac's. For some reason they are very different. For the record, Steve from VAC is not certain the bushings will help. At this point I'm willing to do anything. I will report back.

Trans and diff mount bushings will not help with the issues you are having. You should look at adjustable rear toe arms if you don't have those already. Is the Powerflex subframe bushings softer or harder than the OEM M3 ones?

You may also want to look at the guide rods for excessive deflection, both at the rod itself and its bushings.

Rear toe settings should be much more than 0.08 each side if you don't have adjustable toe arms and 0.08 or less if you have them.

One last thing, how much does your car squad in the back under hard acceleration? Rear toe changes drastically as the suspension moves up and down.

[whosdady]

Thanks for posting. I do have adjustable toe arms and I have the powerflex subframe bushings, not the inserts. (I thought they were stiffer than the M3's but I could be mistaken?)

After I install the diff bushings and tranny mounts I will invest in some M3 guide rods. Honestly, it's amazing how much I have spent on this suspension.

The car does squat a little but not enough to see the hood rise like it did on my supra.

[CJ421]

In addition to the M3 guide rods, you can also upgrade to M3 rear wishbones. They are pricey.

I still have to make a slight steering correction under full acceleration despite having upgraded all parts/bushings in the rear besides the three holding the differential. Those must be the key.

Originally Posted by whosdady

Honestly, it's amazing how much I have spent on this suspension.

Yep ...

[whosdady]

Well, I will put the wishbones on the list if the guide rods don't do the trick. I'm hoping to install the diff bushings this week and guide rods next week, followed by a new alignment. I will report back.

[rob1024]

Originally Posted by whosdady

Well, I will put the wishbones on the list if the guide rods don't do the trick. I'm hoping to install the diff bushings this week and guide rods next week, followed by a new alignment. I will report back.

The rear upper control arms are not that pricey. Can get a set of 4 from TRW (same as oem except the price) for $440 at ECS tunning. They also have a great price for oem m3 spec toe arms at $150 a pair. I noticed a big difference with the m3 rear bits. Car just corners a lot better. Btw I also have pretty stiff AGK black 95A durometer subf bushes. Next will be the $75 a set whiteline diff bushes. Look the same as powerflex for a fraction of the cost. They are I believe rated at 75a durometer so should be nice streetable upgrade over stock without excessive NHV of solid diff bushes.