StreetStalkerZ

iTrader: (1)

On the way home from the track i started getting a bad vibration through the driveline from 60mph on up to 70-80mph. I have never had a problem with this before. I'm thinking i knocked a weight off the wheel but i have yet to look at the car (on vacation right now). The only other thing i have changed on the car is the relocation kit for the BMR adj. torque arm to get it off the transmission tailshaft. I'm wondering if my pinion angle is wrong because i only got one good 60ft. of the day but blamed that on a green track. Hooked a 1.45na on the third pass and the rest were 1.70s-1.60 60fts.

Could my pinion angle be off and causing the vibration and if so how is the proper way to check the pinion angle and set it? I tried a different way this go around to get more aggressive with it and all was fine on the street for the last 3 months up until the track visit.

Pilsner

iTrader: (4)

u-joint or tire balance

SS SLP2

iTrader: (8)

My guess is tire balance which will normally show up with in a 10-15 mph bracket at highway speed (55-70 ,65-80).and you will normally level out SOME after a given point

u-joint or drive line problem normally come in at 40-45 and get worse as speed increases and you can not out run the vibration
my $ 0.02' Johnny

StreetStalkerZ

iTrader: (1)

U joints are brand new so i ruled that out and i figured a driveline problem would have showed itself early on but i wanted another opinion. Me and a buddy think that it might have slung the weights off the wheel during one of my burnouts but to me i never get off that easy on a problem with this car First thing im going to do is pull the wheels off and have then spun on a balance machine and do a once over on the underneath of the car.

01ssreda4

iTrader: (96)

Take all that stuff out and put it back to stock.....

dlandsvZ28

IMO it's your pinion angle that is set wrong or your tranmission is now lower than when it was mounted on the stock crossmember. There is a sticky on the proper way to set pinion angle.

The height of the transmission in relation to the front ujoint angle back to the rearend is critical.

I have a Yank transmission mount and have been fighting drive line vibration ever since I installed it. I finally had to place spacers between the rubber transmission bushing and the transmission crossmember. The spacers raises the transmission causing the front ujoint to be level or pointing down towards the rearend. If the transmission is too low it will cause vibration.

We could actually see the front ujoint vibrate on the drive-on lift (special lift to load the drive train on the lift and put the car in gear and run).

The vibration sounded as if the ujoint was bad. After raising the transmission the vibration at the front ujoint stopped.

Note: the front ujoint angle must be correct before you set the pinion angle at the rear ujoint.

IMO torque arms that slide back and forth into a poly bushing on the transmission crossmember don't unload freely because the front of the torque arm is pointing down when it slides inside the bushing compared to the stock torque arm that is level when it is connected to the transmission tailshaft bushing.

Torque arms with a swivel joint in the front like Spohn will swivel back and forth freely on the transmission crossmember and will load and unload freely under acceleration and deceleration.

formula98ws6

Check the tires. You may have spun them on the rims if they are not screwed.

StreetStalkerZ

iTrader: (1)

I plan to check the pinion angle again but if this were the culprit it should have showed itself way back when i installed it.

4bangermustang

iTrader: (24)

stock Alum. driveshaft?

dlandsvZ28

Check the front end of the torque arm that slides in the poly bushing. It is possible that it is bent because of the hard launches at the drag strip. If it is bent that would explain why it doesn't unload under deceleration. If it isn't unloading then the pinion angle might be way off during normal driving conditions.

My UMI was actually bent (where it slides back and forth in the poly bushing) when I removed it. Because it was bent it wouldn't unload properly. IMO the angles aren't correct with this type of torque arm. You can imagine the amount of torque the rearend places on the front end of the torque arm during a hard launch when it can actually break off the transmission tail shaft with a stock torque arm.

My Spohn was very noisey and it is why I decided to try the UMI tunnel mount style to reduce noise during loading and unloading.

Out of frustration with the UMI design I replaced the UMI with my Spohn model that has a swivel joint on the front end. I also replaced the front pivot joint with their new Del-sphere pivot joint. It is now very quiet.

Tires: Did you run very low air pressure at the track and possibly slip a belt in the tire which can cause severe vibration.