Rearend Issues
03-17-2014, 11:33 AM
#1
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Rearend Issues I just bought a 1999 Trans Am about a year ago and whoever owned it before treated it like crap and didn't know what they were doing. Anyways the car has a bunch of UMI performance rear suspension parts installed along with the torque arm relocation mount and subframe connectors.
The more I get used to a car the harder I tend to push the car to find it's\my limits on how or what the car is going to do. Anyways last night I notice when I make a fast hard right hand turn I hear the driveshaft hitting. Then later at night when I was getting on the freeway the on ramp is REALLY rough and littered with pot holes and when I hit that part of road I once again started hearing the driveshaft hitting again.
Can someone give me some suggestion of where to start looking at to fix the issue. I can't believe that a beefed up rear suspension would have that much lateral movement.
The only thing I can think of is that the rear axle is more to one side than the other in my case closer to the drivers side.
The more I get used to a car the harder I tend to push the car to find it's\my limits on how or what the car is going to do. Anyways last night I notice when I make a fast hard right hand turn I hear the driveshaft hitting. Then later at night when I was getting on the freeway the on ramp is REALLY rough and littered with pot holes and when I hit that part of road I once again started hearing the driveshaft hitting again.
Can someone give me some suggestion of where to start looking at to fix the issue. I can't believe that a beefed up rear suspension would have that much lateral movement.
The only thing I can think of is that the rear axle is more to one side than the other in my case closer to the drivers side.
03-17-2014, 07:18 PM
#2
Can you tell where it is hitting. If it's in the front its a very good chance its the trans mount. If you are sure the rear end is getting lateral movement it might have something to do with the panhard bar.
03-17-2014, 08:17 PM
#3
TECH Senior Member
I just bought a 1999 Trans Am about a year ago and whoever owned it before treated it like crap and didn't know what they were doing. Anyways the car has a bunch of UMI performance rear suspension parts installed along with the torque arm relocation mount and subframe connectors.
The more I get used to a car the harder I tend to push the car to find it's\my limits on how or what the car is going to do. Anyways last night I notice when I make a fast hard right hand turn I hear the driveshaft hitting. Then later at night when I was getting on the freeway the on ramp is REALLY rough and littered with pot holes and when I hit that part of road I once again started hearing the driveshaft hitting again.
Can someone give me some suggestion of where to start looking at to fix the issue. I can't believe that a beefed up rear suspension would have that much lateral movement.
The only thing I can think of is that the rear axle is more to one side than the other in my case closer to the drivers side.
The more I get used to a car the harder I tend to push the car to find it's\my limits on how or what the car is going to do. Anyways last night I notice when I make a fast hard right hand turn I hear the driveshaft hitting. Then later at night when I was getting on the freeway the on ramp is REALLY rough and littered with pot holes and when I hit that part of road I once again started hearing the driveshaft hitting again.
Can someone give me some suggestion of where to start looking at to fix the issue. I can't believe that a beefed up rear suspension would have that much lateral movement.
The only thing I can think of is that the rear axle is more to one side than the other in my case closer to the drivers side.
If its due to the axle moving laterally then thats "normal" for a PHB setup. If you have an adjustable PHB you may be able to adjust it "away" enough that whatever is rubbing doesn't rub anymore. The other option is to look into a watts link.
Also on a side note if you are taking corners invest in some good shocks (like Koni SA's), you will thank me the second you drive the car with them.
03-18-2014, 10:28 AM
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When I looked under the car last night I could see the driveshaft was hitting on the driveshaft safety loop which is like 5-6 inches behind the tailshaft of the transmission. I will see if I can take some pics of the car tonight and inspect the transmission mount.
03-22-2014, 01:06 PM
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Sorry it took me so long to get back on here guys but I have 4 kids and got a surprise visit from my wife's best friend that is staying with us.
Anyways upon further investigation it would appear the my driveshaft is in fact hitting the UMI torque arm bar. The UMI Torque arm is an adjustable one but I would think that those adjusting bolts would only change the arm angle to either preload or unload the rear end. Here is the pictures that I took of the "clearance" of the driveshaft and the adjustable torque arm.
Anyways upon further investigation it would appear the my driveshaft is in fact hitting the UMI torque arm bar. The UMI Torque arm is an adjustable one but I would think that those adjusting bolts would only change the arm angle to either preload or unload the rear end. Here is the pictures that I took of the "clearance" of the driveshaft and the adjustable torque arm.
03-22-2014, 01:35 PM
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It still might be worth taking a look at pinion angle. If there is too much negative angle there, since adjusting pinion angle with the TQ arm rotates the differential, it might be able to move the u-joint too close to the TQ arm and cause what you're experiencing. You can get an angle finding tool from harbor freight for around $10. Since someone else set it, I'd at least take a look and see where it's at. I'd set it at UMI's recommendations.