69gto96z

iTrader: (13)

Installed a UMI torque arm relocation crossmember over the weekend. The car had zerodriveline vibrations, and now vibrates like crazy around 70+ and does it even worse when i let off the gas pedal. It feels like pinion angle to me. I installed the tq arm into the second from bottom holes as described in the directions for the stock height tq arm mount, and am still using the stock torque arm with a stock rubber trans mount.

I am wondering if the new crossmember changed the mounting angle of the transmission? It seems like my only option is either, 1) buy an adjustable torque arm and start checking and adjusting angles, or 2) get rid of the UMI piece, go back to stock, and pray i don't break my tail shaft.

UMI Sales

iTrader: (1)

You have to remember you're removing one of the areas that compresses under acceleration/deceleration by relocating the torque arm nose. Basically, before relocation, any vibration may be controlled by the torque arm mount, trans mount, and motor mount. Now any vibrations essentially must be controlled by the torque arm mount.

The other thing is the pinion angle is intended to be in factory location at the second hole from the bottom. That's not to say every vehicle will react perfectly to that location. It definitely won't hurt to try some of the other holes to see if the issue is alleviated.

An adjustable arm is definitely one way to cure the problem, and can be beneficial in more ways than just being adjustable.

guppymech

iTrader: (7)

When I installed a UMI relo trans xmbr it lowered my trans .375 inch compared to the stock xmbr. I shimmed up the trans mount to correct this. At that time I had the stock TA and used the 2nd set of TA mount holes from the top as these seemed to position the TA closest to the stock mounting points on the trans tailshaft.

69gto96z

iTrader: (13)

Did you shim it between the crossmember and trans mount, or between the trans mount and transmission?

01ssreda4

iTrader: (96)

You need to measure pinion angle then either correct with shims under the trans or crossmember or get an adjustable torque arm. No other solutions.

guppymech

iTrader: (7)

I shimmed it between the crossmember and the trans mount. I'd recommend re-installing the stock xmbr and taking a measurement of the trans to the body or the garage floor then install the UMI xmbr, measure again and correct as necessary.

69gto96z

iTrader: (13)

Cool, appreciate it.

vatechguy3

iTrader: (4)

Results?

Tony

Vicious95Z28

iTrader: (1)

UMI summed it up best. You have essentially removed 2/3 of the items that originally absorbed a ton of vibrations. I agree that you should do your best to get pinion angle correct but I think even after you do you're going to still have vibrations coming up through the body. You don't have stock JUNK in there anymore bro.

69gto96z

iTrader: (13)

Adjustable torque arm and setting the pinion angle correctly fixed most of the vibrations. Old thread here.

01ssreda4

iTrader: (96)

You're talking about NVH (noise vibration harshness), and the OP is talking about an actual specific vibration from an inaccurate pinion angle due to one new suspension part. Mine did the same thing when I installed it.

2JAWZ

iTrader: (1)

Ive been dealing with this issue myself. I have a adjustable BMR torque arm and at 70+ it vibrates and at higher speeds letting off the accelerator it feels like its about to come apart. I got it up level with the rear susp loaded and car level and was told should be -2 to -3 degrees by BMR. She was at about -3 1/2 and just my luck every adjustable wrench I have I left at work. Im not a racer,, so if I cant get a handle on it Im going back to stock parts because the vibration makes the car not fun to drive and that sucks complete *****

01ssreda4

iTrader: (96)

Go back to zero to see if the vibe will go away.

2JAWZ

iTrader: (1)

when I get a chance I will*

James Martin

if you know your pinion angle is correct at -2° and it's still there.... buy summits DS $360... problem solved. I went 5 months battling same thing. 2 used driveshafts " balanced" with new ujoints and still no change. Apparently all of the gear and axle shops in DFW don't do high speed/high rpm balancing, bit the new DS from summit comes that way. 133 mph..let off and still no vibe! I can actually get full freeway potential out of my SS now!

wannafbody

iTrader: (2)

But wouldn't a driveshaft vibrate regardless of the relocation kit?