Has anyone with a crossmember mounted TQ arm experianced any bad vibrations. I have a Spohn model and have picked up a bad vibration after I installed it. The pinion angle is set to 2 1/2 degrees using the method of measuring the front yoke and the back yoke. about 3000 rpms in 3rd gear(th350) it will almost shake your teeth out. Its not that noticable at WOT but cruising its bad and it is at 60mph. I havent had the driveshaft checked yet but I think that is my next step. I have the normal clunks, had to beat the fuel line bracket in becasue I lowered the rear. Just want some input from those that have this setup. Thanks!

 

vibrations would be rear end, tires, driveshaft, etc etc. Anything that spins is now more centrally established to the drivers seat through the crossmember right below you.

 

if the pinion angle is not fubar'd, then the tq arm did not cause the vibration, it simply amplified it by tieing to the car more solidly.

 

Im gonna call around and try to find a driveshaft from a th200. If it still has the vibration then I cant live with that much, might to have to get the TQ arm adapter kit . I fell that it might beat the bearings out of the motor.

 

Describe your method of setting the pinion angle


Just looking at the difference between the front yoke and the back yoke is not going to give you an appropriate pinion angle because it doesn't account for the possibility that the transmission output is on a different plane than the rear end yoke.

An improperly set pinion angle will vibrate the crap out of the car. The goal of setting your pinion angle is to have the least amount of angle in your U joints under WOT to reduce friction losses in the U joints and to help the U joints live.

 

Definately

 

My shop Forman had just gone to a class and this is how they told him to check it. First measure the angle on one side of the front yoke and turn 90 degrees and measure it. Add together. Then do the same to the rear yoke. Subtract your numbers and that is your angle. I dont remember the specifics other than that. I had done it by measuring the angle on the rear cover and then measuring the angle on the driveshaft and subtracting it. I think I had about 2-2.5 degrees either way.

 

No vibrations here. The only time I've had vibration problems is with torque converters. Parked or driving I'd get a bad vibration till I clocked the converter to a different position, now it's smooth as silk.

 

I would measure the difference from the rear end yoke to the driveshaft. If you are vibrating at -2 to -2.5 degrees I would try reducing the angle and see what happens.

I have improperly set pinion angle in the past and it felt exactly what you describe. There is also the possibility that you have a bad U joint.

 

make sure the front mount is somewhat tight but not torqued down alot. the spohn mount needs to pivot, but it also cant be very loose. loose will vibrate sometimes but usually at lower rpms. may happen at higher rpms too tho

 

I have a very similar problem with my t-56 spohn tourque arm combo. I've tried every pinion angle between -3 and 3 and tried two different balanced driveshafts. Reading you post I realized we're both lowered too. I'm down 1.5" with a Hotchkiss setup, but have a standard length (non-adjustable) panhard rod, which I think is pushing the rearend off center. My vibration starts at around 70 and starts getting real bad at 100+. My wheels/tires are balanced and right now I'm getting a bit frustrated chasing this issue.

Anyone have an adjustable panard rod they're selling?

To the OP, do you have an adj panhard rod on your car?

 

No , it as all stock as of now. I was gonna weld up the LCA and panhard rods and put urethane bushings in them . I wonder if the LCA relocation brackets would help any?
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I'll have to check that.

 

ok...

First off, pinion angle has nothing to do with the trans yoke. Pinion angle is set by subtracting the ds angle from the rear end(pinion gear shaft/yoke) angle. If you have any vibration at -3 degrees or less that is caused by the angle, then you have bad u-joints. My car was lowered 2" and I ran -6 pinion angle w/o any vibration. Excessive, yes, but that's where my set-up worked(launched) the best. The need for that much negative angle means I would have been better off with a shorter tq arm, thus getting the same reaction with less pinion angle.

Secondly, as I said before, the tq arm is not the cause of vibration. The only way it could be construed as the "cause" would be if something(ds, exhaust) is rubbing it or its mount/crossmemeber. Excessive pinion angle could cause a vibration, a bad bearing somewhere, bad u-joints, bad trans output bushing, an out-of balance ds, out-of balance converter, improperly set-up gears, etc could all be the cause of a vibration, the new tq arm is simply isolating that vibration less than the stocker did. That said changing back to the stocker will not relieve any undue driveline stress that is being caused by this vibration, it will simply help isolate you from it again.

 

Well just for a little update, I loosened the pivot joint on the crossmember and it made a world of difference. I guess I had tighented the nuts when I had swapped convertors. It still has a light vibration that I can live with but its no where near the shaking that I had.

 

Another update::

I took out my lower springs from the rear and the vibration is almost gone. I had a set of stock springs from a '98 camaro and just decided to install them. Glad I did.

 

i have bad vibration from my umi tunnel mounted TQ. and it's becuase the new crossmember mount pushes the tranny up higher than factory, putting it at and odd angle. i need a shorter tranny mount bushing.

by taking out the rear springs the vibration went away?????? so do you think the springs were causing the vibration?????????? i can't imagine how

cause if they aren't you're only masking the problem, not fixing it

 

FYI: I tried both the ES and Prothane brands of transmission mounts, both had same result, vibration. Went to the stock rubber type mount, smooth as silk.

 

Most likely there was a height difference. You should have re-adjusted the driveshaft angle and it would have been fine.

 

Thank you so much, I never though of that. (sarcastic)

Honestly, I did get the vibrations down, but never as smooth as the rubber mount. I honest believe that rubber engine and tranny mounts are a must on a daily driver, but thats just me.

 

Krisb410...... i remember when i originaly swapped out my broken rubber tranny mount for the ES mount, the ES was 1/4" taller than the rubber mount, have you noticed any difference in heights betwwen the rubber/ ES/ other mounts? my ES mount gave me no vibration with the factory crossmember,


i think the poly mounts are usually abit taller. and the aftermarket crossmembers are also usually a bit taller.



in this post the problem was over tightened pivot/ too tall of a mount, the fix = cut/ reweld the mount/ loosen the pivot points
https://www.thirdgen.org/forums/afte...ight=spohn+buy

 

I read (on TGO of coarse) that the ES ones are taller. But I think I bought the Prothane one because it was supposedly correct (either read on here, or maybe it was Spohn's websight).

But after all the messing around with the adjustments, swapping to a different poly mount, I just gave up and put a new rubber one on. But since then, I finally see why I want my car with rubber engine and tranny mounts. Poly motor and tranny mounts are just not ment to be on a daily driver.

 

why not. had poly on my 350tpi on everything but the engine mounts. now i just installed them. i also have had poly engine/trans mounts on my 86 TA 305TPI. ive had no probs, no vibrations.

 

Hey, if you already know it all, why ask....

As for rubber is a must, that's BS, I have run solid mounts on daily drivers with a rubber or ureethane tranny mount. No vibrations ever. it's all in setting it up. Then again, you already knew that

 

I don't remember asking anything in this thread

I never said rubber mounts are a must. I BELIEVE, (which is my opinion and my preference) that on a daily driver, rubber mounts are more comfortable. Maybe all the cars I have ever driven/rode in that had poly mounts were all set up improperly . But you can feel a difference.

Anyways, I'm sorry that your opinion is different than mine.