I have a really bad vibration went my car reaches speeds of 70-75mph but its not bad if your on the gas hard or the car is off center, now and again it will be smooth but not more times then not its vibrating. I have had my U joints redone a month ago, my relocation brackets are on, and I just had 3.73 gears installed in place of my 2.73s. At speed below that its smooth, quiet, and all i hear is exhaust. The car feels like new at below 70mph.

Could it be the axle bearings, tires, u-joints?????

 

Tracking down a vibration problem is frustrating, start by having the tires rebalanced, then you might want to get the driveshaft balanced. If you still have it then have all of you mounts checked, Trans and motor.

 

thanks man, it is very frustrating. I just hope its not the axle end bearings and the axles are pitted up so that I don't have to buy new axles.

 

too much pinion angle? 2*-3* neg will get you close

 

Update, Chevy dealer pulled shaft, both u-joints have flat spots and pinion seal is leaking now. I'm having them replaced. I don't know what could have cause them. I put the relocation brackets in just a bit ago, could the poly trans bushing have messed up the angles.

 

The relo's could of possibly put some neg. in the pinion angle. Sears sell a angle degree guage for a reasonal price. $8-$12
Do you have an adjustable torque arm to adjust the pinion angle?

 

I don't have an adjustable torque arm. I got the car back from the shop, the vibration is better but didnt dissappear at 70mph. I am at a total loss for where to go from here. I think I'm going to have the guys at New Era check out the pinion angle, if that is bad then I'll trade my non adjust for the adjustable TA.

 

The 2:73 cars come with a steel driveshaft. I have a 02 and had 2:73's and my driveshaft is steel. Anything above 3:42 they suggest a aluminum one to prevent vibration. I am thinking about getting a aluminum one. I don't have much of a vibration, but still want to change.

 

Yeah thatz what the Mike said at New Era but I can't believe that an aluminum shaft will make that much of a difference. I am having New Era take a look at the problem, I just don't have the time anymore now that I'm working six days a week. Where and how much can I get a good aluminum shaft for?

 

All the M6 cars have aluminum ones and any wrecking yard should have some. Also aftermarket ones are about $300. The aluminum ones are supposed to be balanced better than the steel ones. When adding the different gears the driveshaft turns alot faster at highway speeds and that is where the better balanced shaft helps. Seen a guy do a test on both to see if there are any h.p gains and he gained a couple h.p too.

 

Left car at New Era to have pinion angle checked and rode tested. Now if I have to replace the axles and axle bearings, I have to get four channel abs axles because I have ASR/ABS right.

 

I'd say its the gears! I put 4:10 in my car and had the same problem. I had the driveshaft (steel) balanced and still the same. I put an alum. driveshaft in and it was ALOT better, but still there. I didn't go away until I put in the stock gears. Now it has a 12 bolt with 4:10's and no problems except its loud as ****.

Only other thing I have had to cause drivetrain vibrations was a twisted output shaft. hope this helps.

 

Yeah I sent the car out to the guys that put the gears in so they can see whatz up. I feel pretty confindent that will be honest with the situation and get the vibration resolved. If it is the gears then they will fix the problem, if it the axles or shafts then I have to pay for the problem.

 

New Era just got back to me and said that they swapped out the steel shaft for the aluminum shaft, no vibrations. I guess so many good things come from aluminum, smooth F-bodys, beer, LS1,2,6,7 , did I mention beer.