Installed UMI tranny brace, now horrible vibration!
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Installed UMI tranny brace, now horrible vibration!
OK, I just installed my UMI tranny cross-member that relocates the tq arm and re-used my stock torque arm. I made sure everything was good and tight and when I took it for a spin, there is an awful vibration at 50+ mph and seems to get worse as speed increases. I haven't driven the car much yet so I can't say for sure about the mph and all. It almost feels like the driveshaft is out of balance now. I also installed my adjustable tq arm today thinking that might help cure the problem but it still does it. I'm not real sure what else to check but if this doesn't clear up I guess I'll put the stock cross-member back on or something. Any help is greatly appreciated! Will give more info as it is available.
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Would it still vibrate like that with the stock ta installed? I can understand the angle for the new one's probably off but its odd it did it with the stocker on there also.
OK, updated info... The vibration gets "faster" the faster I go. When I hit the brakes from say 40 mph, it sounds worse. I will check the pinion angle tomorrow and try to get that set correctly to atleast rule out one thing. Keep the comments coming!
OK, updated info... The vibration gets "faster" the faster I go. When I hit the brakes from say 40 mph, it sounds worse. I will check the pinion angle tomorrow and try to get that set correctly to atleast rule out one thing. Keep the comments coming!
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I'm going to have to put it on a drive on lift or something because it's damn near impossible for me to check the angle with the car completely level with all 4 tires on the ground. I will post up the results when I can. Thanks for the replies thus far.
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I'm having the same vibration you are describing with the same setup you have. My pinion angle is set to -2* and I still have the vibration, just like you said, it feels like a driveshaft is out of balance, but I had no vibrations before I changed it. maybe its the nature of the beast?
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Did yours do the same thing with the stock tq arm? I don't think this is a vibration I'm willing to deal with...in fact I know its not. What method did you use for setting your pinion angle?
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Best website ever for learning about driveline angles:
http://www.vibratesoftware.com/html_...tm#Information
Andrew
http://www.vibratesoftware.com/html_...tm#Information
Andrew
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It did not do it with the stock torque arm at all, but then again, with the 4.11s I have now, the driveshaft is spinning faster at normal speeds so it could be an out of balance driveshaft.
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Did you guys have poly torque arm mounts before the install? Poly mounts add vibration as well as the new floor mount t/a. After a thousand miles or so the poly mount should "loosen up" a bit and the vibration should go down.
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I can accept a little vibration, but mine sounds like you shouldn't be driving the car. The more I read about it, the more I think merely installing the brace threw off the pinion angle enough to cause this. I'm getting an angle finder to check it.
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OK, latest updates... I attempted to measure some angles today to see what might be wrong...and here's what I found. I used a very generic method for measuring but I think it's pretty close. The tranny is up 2 degrees, the driveshaft is down 4 degrees, and the rearend is down 1 degree. If there is a 3 degree tolerance, then the front angle is twice that! I do have an adjustable tq arm but I need to know what the next step is for correcting these problems? From what I've read, I want the tranny nose up a little which is fine, but how do I "raise up" the rearend to take away some from those angles? I've got a Moser 9". Any help is greatly appreciated!
Let's say I raise my torque arm to be up 1 or 2 degrees...would that be enough to put things back in line?
Let's say I raise my torque arm to be up 1 or 2 degrees...would that be enough to put things back in line?
Last edited by WS6 GreeN; 07-05-2007 at 11:42 PM.
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well with the adj tqr arm, you want to pull the rear end in, this will cause it to pivot on the mount thus raising the overall driveline angle. m6? A4? a for a m6, the angle should be -2 degrees. best thing is to get a magnetic angle finder, like this, http://www.lmperformance.com/6564/8.html
with out one your spinning your wheels and looking for what feels good. you going to hear abit more for sure, but that is good, your stiffening things up. also, you might try changing the front mount to a different location, you are in the upper mount now right??
with out one your spinning your wheels and looking for what feels good. you going to hear abit more for sure, but that is good, your stiffening things up. also, you might try changing the front mount to a different location, you are in the upper mount now right??
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Subscribed... I'm about to install a tunnel mount adj TA with new 3:90 gears. Just a guess, but on your problems, I'm gonna have to point a finger at an out of balance driveshaft.
Last edited by jmdale1984; 07-08-2007 at 01:06 AM.
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Originally Posted by lastcall190
I have horrendous vibrations after putting in my poly trans mount
So I am going to get a tunnel mounted torque arm and this thread will be helpful.
/ hijack
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Originally Posted by lastcall190
Subscribed, I have horrendous vibrations after putting in my poly trans mount I wanna know how to adjust these things too...
-J
-J
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I still have the rubber trans mount. All I've done is moved the tq arm off of the tailshaft and the tq arm bushing is now poly instead of the rubber piece.. I have recently installed a brand new aluminum d/s rated at 1000 hp for my 9". Right before this install, there was no vibration so I can't believe it'd be an out of balance driveshaft but I'm not above having it checked. I've tweaked on the angles but haven't had a chance to drive the car due to weather conditions. Will report back tomorrow hopefully.
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Just a theory but here goes..
Since you had a rubber tranny mount, vibrations coming from the rear end through the torque arm were not felt. Now that the torque arm is relocated off the tranny, obviously the tranny mount is doing nothing to help this. So now you have moved the torque arm to a body mounted bracket, with only the poly torque arm bushing dampening vibrations. Before, you had the rubber TA mount, and the rubber tranny mount to absorb it. Now you only have one poly.
Like I said, its just something I thought of, so I am not even sure if the vibration you are feeling is coming from the torque arm or not. Its another place to start though.
-Jeff
Since you had a rubber tranny mount, vibrations coming from the rear end through the torque arm were not felt. Now that the torque arm is relocated off the tranny, obviously the tranny mount is doing nothing to help this. So now you have moved the torque arm to a body mounted bracket, with only the poly torque arm bushing dampening vibrations. Before, you had the rubber TA mount, and the rubber tranny mount to absorb it. Now you only have one poly.
Like I said, its just something I thought of, so I am not even sure if the vibration you are feeling is coming from the torque arm or not. Its another place to start though.
-Jeff