Ls1 swap

[cutlassmann]

I have a 1972 cutlass and I have done a LS Swap before the swap I have had the rear end and 4 wheel disc plus new tire and rim from bonspeed put on and now I'm getting a bad vibration/shaking today I left a car show and the car shake so damn bad that it felt like the wheels was coming off i was going around 60-70 MPH So I was like the hell with it I didn't stop so after a while it stop I need help I have had the tire balance 4 time someone says have my rear end check it docent do this every time that what go me confuse PLUS I HAVE HAD THE DRIVESHAFT REBALANCE TWICE NOTHING THEY PUT NEW JOINTS IN IT NEW NEW UPPER AND LOWER CONTROL ARMS SHOCKS EVERYTHING POSSIBLE ITS DONE ONCE AGAIN IT DIDNT START DOING THIS TILL I HAD ALL THIS ADDED BRAKES TIRE AND RIMS AND HAD THE REAREND BUILD WITH 3.42 POSI GEAR.

[minendrews68]

Did you have the wheels an tires balanced? Are you sure the wheels are against the axles and/or hubs? Just somethings to look for.

[csouth]

I know you had this issue in a previous post. You probably want to get this moved to suspension just so it gets traction as an issue. Also, I cant remember if you had the tired road force balanced or not?

For my own peace of mind I would check the torque on ALL the suspension components that were swapped including the brakes. I know the driveshaft has been balanced, but have you checked the driveline angle?

[cutlassmann]

I didn't think the drive line angel would be a issue because it didn't start doing this till I change the suspension?

[dhutton]

I didn't think the drive line angel would be a issue because it didn't start doing this till I change the suspension?

Did the new rear arms change the pinion angle? If they are different lengths they did. Are the upper arms adjustable?

Don

[cutlassmann]

No they are not adjustable but a had them on the car before I had the rear end and front done and I never got a shake at all

[csouth]

No they are not adjustable but a had them on the car before I had the rear end and front done and I never got a shake at all

You need to double check that driveline angle. Download the phone app from Tremec's site, it will give you a good idea of your working angles. I know you said nothing has changed, but its knowledge for yourself. The biggest thing when asking for help via the net is to perform some of the tasks that people ask and post the results so you don't get the same suggestions everytime. Checking the driveline angle requires the weight of the car to be on the suspension so you'll need to find away to do that if you are going to tackle it on your own.

I know its tedious, but have you checked the torque you all your suspension parts? You will be surprised what can be missed. Find the specs, get a loaner wrench from autozone and make it happen. Just my .02 cents

[minendrews68]

What he said...

[rickierockit92]

Also make sure the driveshaft is properly installed (I'm sure it is but won't hurt to check) I had a real bad vibration around there as well and realized that I just put the driveshaft back in ... The u joint on the shaft wasn't properly lines up with the u-bolts (which holds the shaft to the rear) if you can use old school alignment rack that would be a great way to check suspension and have room to crawl underneath.