i have a 72 LeMans that has a vibration I can't seem to fix. It starts around 50 mph but gets worse up to around 65 mph. After that it does smooth out a bit but it's still there. It gets so bad the steering wheel will shake violently and the seats shake as does pretty much the whole car. It seems to be felt more in the seats and shifter but it's hard to tell since the whole car shakes. I have rebuilt the front end completely, had four new tires installed, BF Goodrich TA's 245/60R15. The tires are mounted on factory Rally II rims. The tires were rebalanced twice, and the driveshaft was rebalanced. The transmission was rebuilt last summer, and the driveshaft has new u-joints in it. I also installed new brakes all around (four wheel drums) and new wheel bearings front and rear. I even brought the car to a reputable driveline shop and they can't figure it out either. I have also tried switching tires and that didn't help either. Has anyone else ran into this sort of thing before? I'm at a loss and can't seem to figure it out. I should also note the vibration is there even when you shift the car in neutral and let it coast. The engine is a 400 small block Chevy, with a TH350. Any help on this issue would be awesome thanks.
I had a similar problem to this, but coupled with a mild growling noise, worst at 60-65 mph. After doing everything you did, new tires, wheels, balancing, u joints & shaft balance, ...even new front end parts twice etc.... Still had it even after a change of trans from TH350 to 700r4.
The solution in my case: Found the right (old school type) shop and they solved it by a fourth balance and straightening of the drive shaft with high quality U joints - improperly done the previous 3 times.
65 Custom Sport Convertible
I am actually getting a new driveshaft made next week, the mechanic at the shop I went to figures that's the problem. I hope it is since i have invested a lot of time and money trying to fix this. That's awesome though the guy was able to fix yours.
Have you thought about removing the shaft and having someone tow you? Risky, I know but it would definately tell the tale...
Having operated a Green & Ross Tire for 12 years under the orignal owners.
The company claimed bankruptcy in 1979, so the Active Tire is not the same, they just bought everything at the auction.
I am getting carried away....
Find a shop that does on the car balancing. It is likely only one or at the worst case 2 tire wheel assembly's that are the problem.
We had a car come in for a wheel balance. It had Quebec plates on it and he complained of a bad vibration. We brought the car in and pulled the wheels and balanced 4 of them with our Hoffman Balancer.
No noticeable problems as the tire rotated on the balancer... wheels were straight and no tire hop.
The customer returned within a half hour and indicated that nothing had changed.
We put the car on the alignment rack and every part possible had been replaced in the front end. Something was amiss...
We put the car back on the hoist and used the on car balance and the right front bounced violently to the point it was about to jump off the hoist.
Took the assembly off and dismounted the tire only to find about 2 quarts of water inside the tire.
As the car got up to speed the centrifugal force kept moving the water to a different place to compensate for the vibration.
We came to conclude that the customer had added air to his tires from a compressor tank that had not been drained. He got mostly water and a little air..
Road tested the car and all was fine. Our shop was a block away from the 401 so it was easy to get the car up to speed to verify that we had corrected the problem.
One of the most challenging jobs that we got....
Keep checking ... you will find the culprit. Let us know what it was.
http://canadianponcho.activeboard.com/t51640378/timbuks-first-invader/ http://canadianponcho.activeboard.com/t63146560/timbuks-second-invader/ vancouver island
Bent axle? Have someone drive behind you to check the car is not crabbing etc?
cutting a roof off a four door is NOT a convertible.....
65 Parisienne convertible project.
67Poncho wrote:Have you thought about removing the shaft and having someone tow you? Risky, I know but it would definately tell the tale...
Both axles are brand new, since the rear wheel bearings were bad and wore grooves into the axles. So I ended up replacing both the wheel bearings and axles. I did run the car up on jack stands and the vibration was still there. Even the Driveline shop did the same thing and that's why the only thing they can think of is the driveshaft. I will keep you guys posted next week since I am bringing my car in Tuesday to get a new driveshaft built.
I just went through the EXACT same thing.
What fixed my issue was an "old school" on the car balance. Worked wonders.
I had mine done at a "TireCraft" here in London. It's a busy tire shop with lots of experienced techs.
The guy who did mine, says it's an "old school" process and not many shops do it anymore.
Might be worth making some phone calls around your town. I'm sure someone will still do it.
Regards, Scott (LandShark ...)
Have you tried popping it into neutral at that speed? Have you done any changes to the rear suspension to alter the driveline angles? And it's definitely speed related not RPM?
'68 Parisienne 2+2 Convertible Matador Red (Resale Red but not for sale).
I ran a tire shop for 35 years one of the key things you said was that it had/has a speed in which it runs well
The suggestions are good ones running it to speed and putting in neutral can help checking out driveshaft
lots of time a vibration at a certain speed is a "balance" problem If you try a set of "known smooth running " rims and tires, do not change all 4 install one at a time.. when/if the vibration disappears you found the offending rim/tire
IF thats the problem
you have a 400 SBC is it running a externally balanced ring gear ?
427carl you have a 400 SBC is it running a externally balanced ring gear ?-- Edited by 427carl on Friday 19th of August 2016 08:15:16 PM
-- Edited by 427carl on Friday 19th of August 2016 08:15:16 PM
Good point Carl. And that's where I was going with the RPM thing. These engines are externally balanced. I have seen it before with wrong flexplate. Should vibrate in neutral same RPM.
Sherwood ParkAlberta, Canada
1981 Parisienne 400
Eric - Regina, SK
1935 Chev 3 Window Coupe - Standard
1967 Mustang Convertible
1969 Firebird 350 HO Convertible
1969 Camaro X11-V8 car
1969 2+2 was a 396 car
1980 Harley wide glide
1986 CJ7 Jeep