2011BlackRTR

Hi all, I drove up to Boston for a two week getaway from Virginia a couple of weeks ago, and while there my buddy and I installed some parts to help with wheel hop and handling in the rear.

J&M lower control arms (polyurethane)
Steeda 3rd link (adjustable, polyurethane)
J&M panhard rod (adjustable, polyurethane)
AM aluminum driveshaft (set rear angle to a difference of 3* facing up)

After the parts were in and everything aligned/adjusted, I noticed a horrible rear end whine when I let off the gas and while in gear. It seems to be coming from the rear of the car and can get fairly loud around 2K RPM in 4th gear, but can be heard at all RPMs. 6th gear on the highway is the least noisy. What's troubling me is that I hear the rear end now while in neutral or with the clutch disengaged and rolling to a stop -- nothing loud or anything, but definitely hear the gears in the 8.8er.

My question is, is this normal for the rear end (I have 3.73s from the factory) -- especially after the upgrades I did. The stock rubber bushings were really soft and had tons of play, I think that was to dampen the rear and prevent it from being heard in the cabin. I like the handling now a lot, and the driveshaft has no vibrations up to 130 MPH (fastest I've taken her up) and I really feel the difference in acceleration.

The whine only happens while in gear and not under load. There was NO NOISE whatsoever before I installed all the mods (all went in at the same time). The drive back to Virginia (8 hrs almost non-stop at 80 MPH) was smooth other than a little whine on deceleration in 6th gear, but that's it.

Anyone have any ideas? For a brand new car, a noisy rear is unacceptable. Should I take it to someone who's really good at installing gears, see if he can adjust them a little? I can't believe that the stock parts w/ rubber bushings really dampened all that noise...

EDIT: fixed minor typos.

Napoleon85

Perhaps someone with personal experience will chime in, but I've seen this discussed in other threads and it doesn't sound abnormal. I believe that your suspicions are correct and there is just more noise being transferred through the suspension components into the cabin.

2011BlackRTR

Grrrrr. I'm thinking I could sandwich some rubber or polyurethane in between the 3rd link upper mounting brace and the body of the car, but not 100% sure all the noise is coming in through the 3rd link. I wonder how much of it is making its way through the LCAs and panhard bar.

Mishri

my factory gears whined horribly... my aftermarket ones are silent. (awesome install). get some 4.10s

Napoleon85

I've been told to stay with 3.73 or 3.90 in rear with this transmission if you plan on drag racing since 4.10s will make you hit the redline in 4th shortly before the finish line.

What gears did you go with and who installed them?

Mishri

FRPP 4.10s, local shop in Billings, MT that specializes in Fords, he has done quite a few s197 gear swaps.

I dunno where 4th would end in the manual, and i haven't taken it to the track since i had the 4.10s installed, the track closed the first week of sept here

acascianelli

I have an older 2007 GT, I had absolutely no gear whine before installing my LCA's. But now, I do have a noticeable whine coming from the rear end. I just figured it was due to the poly bushings.

dcarlinf1

My aftermarket LCA's made a horrible whining noise. I removed them and could see they were damaged from being over tightened. I put the stock LCA's back on because the aftermarkets were ruined. They were over tightened because my torque wrench never "clicked" and the bracket was bending.

2011BlackRTR

I have a buddy who swapped in 4.10s and then was regretting it coz he had to shift into 5th and resulted in a 12.006 second 1/4 time, lol. I think I'll keep the 3.73s.

The LCAs may have been over-tightened, I need to pull one down and check. We were using an old, sh!tty torque wrench that may have been way off :P

I'm doubting the 3rd link now as it's still bolted to the stock huge rubber bushing on top of the pumpkin. Maybe the LCAs or even the panhard is responsible for most of the noise.

2011BlackRTR

Top of 4th gear w/ 3.73s is around 120 MPH, give or take a few. These cars run in the 12s for 1/4 mile at around 115 MPH. 4.10s will require a shift into 5th.