Has to be related to ride height...lowering the car changes the pinion angle on the prop shaft and thus throwing it out of tolerance...there is a threshold where the shaft has room to play but by lowering it past a certain degree throws it out of tolerance and places the shaft in a bind causing the vibrations some of you are experiencing. By continuing to drive with the prop shaft out of tolerance puts unneccesary wear on the support bearing and can affect how fast the pinion bearing wears (leading to failure of the carrier assembly and possibly wearing the housing of the diff). I come from the Mustang world and have had plenty of experience from support bearing failure/pinion failure/diff housing failure due to excessive lowering. The only way to resolve the issue is to raise the vehicle or to adjust the pinion angle to bring the prop shaft back within tolerance (on a mustang an adjustable upper control arm solves the issue)...surely there has to be a way to adjust the pinion angle on the IRS housing...

 

cdmassee,
When you wrote you had the same problem, I just want to confirm; you get a vibration under acceleration in 3 or 4th gear?

If so, I'm planning on getting these bushings. I have an '11 GSR w 21K miles; I have the 3rd/4th accel vibration issue as well. I got the car w 20K miles on it, so I'm not sure if this is an pre-existing or new issue.
Lowering springs? Yes. Tomei green.

As an aside: it's odd, this problem is not definitively solved yet - this thread just died down and looks like no new information.

TIY!

Hallster

 

Anyone have additional information they can add to this thread?

TIY,

Hallster

 

Yea I have the same problem I just gave up trying to figure it out. It only does it with my aftermarket wheel setup so I assume its something to do with that at least for me ne ways.

 

Thanks for the reply, hoobastnk90

My car does have aftermarket wheels/tires. Also lowered. Hmm... something to consider.

I ordered the bushing kit today. I should have those installed this week. I'll post up here w my findings after I get 'em isntalled.

Hallster

 

yea a lot of people with after market wheels end up having an issue because the evo wheels are hubcentric and most after market wheels are lugcentric. And this small difference causes some wheel vibration I believe. They do sell hubcentric ring adaptors though that some people have had success with.

 

any updates with this ?

 

Nope mine still does it lol. But when I swap back to my stock wheels for track days its all good. So for me im pretty sure its the lack of hubcentric rings

 

i raised my car up about a 3/4 of an inch ,(im on fortune auto coils) and it pretty much stopped ,, i think its the rear axles ?or cv joints .

 

No. CV, as in Constant Velocity, joints don't care what angle they're at. Unless your car has a lot of miles and one is worn out. And by a lot of miles, I mean a lot. Over 200k. CV's don't usually fail unless a boot cracks and they lose grease.

 

CONGRATS ! you know hove a cv works ...yay . so do i , but this is an axle bind issue , lower the car by a certain amount the axles become too short and they bind a bit , you just have to find the sweet spot to combat it .

 

ISSUE FIXED, guys!

I finally figured out a way to fix this grunt or vibration on 3rd/4th under boost.

At first i changed the driveshaft carrier bushings from torque solutions. Didn't do anything. THen I got the diff bushings (urethane inserts). The issue is 100% fixed now. I also bought the metal bushing that goes into the rear of the differential but i couldn't figure out how to take the old one out. It turns out that only thing you need is the inserts.

 

Thanks squid10r!

Could you post a link to the bushings you used? I found these, but this include the billet pieces as well:
http://www.torquesolution.com/product-p/ts-evx-003.htm

Thanks again!

 

I bought that exact kit. I only installed the urethane inserts. I wanted to get the aluminum billet piece in also but i couldn't figure out how to take the old one out.
Doing urethane inserts took the vibration away completely. I even checked it with my heavy 240lbs friend in the car hahaha
Be ready to spend some time getting those bushings pressed out. Mine were so seized that we has to use an air hammer to "fold" in the steel outer rim of the bushing inward to make a sort of a ledge to then press it with a socket. Otherwise, the steel part of that bushing is so thin that the socket was just wedging itself inside of the bushing and not pushing on the top of it. I hope that makes sense.

 

Info on my set up:
stock struts with H&R springs.