VIBRATION:

Okay, let me set story.

1995 Camaro Z28. The car was a 10 second Head, cam, nitrous car for a while and then I bought my 99 Formula in October 2004. By Jan 05 I started stripping the cars suspension and drivetrain to put on the Formula, I took the top half of the motor off and sold it, put a 10 bolt and all stock clutch, suspension back under it. However, the car has sat in the garage all the way up till May of this year when it was put back together with a Hotcam, stock heads/intake, wheels and the LS1 driveshaft.


I picked the car up from the guy who put it together last weekend in N.C. and drove it back home to Charleston, SC. While driving down I-95 I noticed a vibration around 60-80mph. I thought it could be a number of things
1. driveshaft
2. tires (been sitting on them for over 2 years
3. rotors
4. stock clutch
5. motor

Fast forward to today.
Here is what I tested and how I tested it to weed out what it is not.

Driving at speed, I pushed in the clutch (motor idled down to 1k rpm) and the thump/thump vibration sound stayed consistant with the speed of the vehicle as it coasted (you can feel it just a little in the floorpan)


Driving at speed, I've shut the car off and with the clutch in or out the vibration stayed the same with the speed of the vehicle
~~I would think this would eliminate anything in the motor

Driving at speed, I've pressed the brakes hard to see if I could feel a vibration in the pedal or steering wheel.
~~I would think this would eliminate the rotors being warped

So I came home and swapped out all 4 tires to some other wheels I have.
Vibration seemed to stay the same at the same speeds.
~~I would think this would eliminate the tires being flatspotted

Came back home crawled under the car and swapped out the aluminum
LS1 driveshaft for a stock steel one and the Vibration seemed to actually be a little worse, maybe because the steel one is heavier and magnifying the symptom. Thats grasping at straws at this point.
~~I would think this would eliminate the driveshaft

The car tracks straight down the road.
The suspension appears to be tight and in place.

Something I noticed while I was under the car is that I could basically rotate the driveshaft and the tires would barely spin, not to mention they were spinning opposite directions when I rotated one. I know the rear end fluid is probably in need of a change. Thats usually a tell tale.

Thats about all I can think of guys, if you can offer any insight, please let it rip.


Thanks,
Jeff

 

This is not a good assumption to make. Even though you pushed the clutch in, your driveshaft will still be rotating about the same speed it was prior to pushing the clutch in. This is because driveshafts are directly linked to your tire speed via your ring and pinion. The only way your car can be moving without your driveshaft rotating is: A) if your car is on a tow truck or B) if you twist the driveshaft and have yet to slow down .

If you are having a highspeed vibration, I would take the driveshaft to a reputable shop and have it balanced. Have them make sure it is less than 15 gm-cm of imbalance at each end of the driveshaft.

When you rotate your driveshaft by hand, the tires should rotate in the same direction if your car has a limited slip. If your car is on jack stands and you turn a tire by hand, the other tire should turn in the same direction if you have a limited slip. From what you are saying, your car either has an open differential or something is wrong with the limited slip that is in it. If this 10-bolt you installed came from a 6-cylinder F-body, then you more than likely have an open differential and what is occuring is normal.

 

I switched driveshafts. The car had the Al. LS1 shaft in it and vibrated. So I put a steel LT1 shaft in the car and it vibrated. What are the odds that both driveshafts are vibrating the same?

The rear came out of my 99 Formula. The car has been sitting for two years, odds are that the additive has settled to the bottom of the center section. Thats gonna get changed tomorrow however and should work fine.

 

I see this is going no where for you. Good luck with that. Hopefully changing the gear oil will take care of your problems.

 

I think I'm gonna try and find a shop that checks the balance of driveshafts. Do you have a phone book at your desk Ben?

 

Wholy FK, Joint and clutch wants $95 just to check it!!! Then "IF" it needs to be balanced its included in that $95. Thats just rediculous

 

i was talking to a mechanic about a warped rotor problem i had. he told me that it could be the hubs that are warped. you might want to check into that. even if your rotors are good the hub could still be bad. this could cause the problem even when not breaking from what this mechanic told me!!!

 

if hub was bent brakes would also shake how r the u joints tight loose or binding ?bad tranny mount ?it could be a few different things or even a loose tranny tailshaft

 

Well, that fixed 90% of the vibration The right Hub was flopping around and you couldnt hear it squeling, if it was, because the exhaust and motor are so loud. Thank you, that had not even crossed my mind or anyone elses I'd talked to. It was $120 but well worth it. We might replace the other side just to be on the safe side tomorrow. Farva, your the man!!!

Thanks,
Jeff

 

HA!!!!! It was actually both hubs!!! The right one was all wobbly, but the left one only had a minute bad spot but "bad" enough to make the same sound and feel. But $240 dollars later its smooth as glass, and nice and quiet like the tires should be!!! You're the man Farva!!!! I would have never guessed it!

Thanks,
Jeff