Help with vibration
Thread Starter
Burning Brakes
Joined: Jul 2000
Posts: 1,045
Likes: 3
Help with vibration
I have a 79 with 70,000 miles. Been chasing a high speed vibration for a long time. Two differant motors but same acc. drives are off the orignal motor.motor mounts, trans mount Two diffirent flywheels,clutch, rebuilt trans, balanced drive shaft, new u-joints, rebuilt rear pumpkin, rebuilt wheel bearings.Two sets of wheels and tires. new poly bushings. The vibration comes in at about 75mph. If you slip the clutch the vibration does not go away. I think it gets worse when you decelerate. Next is balance the half shafts and replace the u-joints again. Am I missing anythings. What have everyone else did to find a vibration???? :confused: :confused: :confused:
Race Director
Joined: Sep 1999
Posts: 11,360
Likes: 382
From: Plano TX
Re: Help with vibration (toyvet1)
My take is driveshaft. Most shops do not spin them very fast when balancing. There was a very interesting article in one of the mags about just this problem. Guy had tried everything including balancing the driveshaft several times. Finally took it to some pro shop with a high dollar vibration analyzer and they found the problem was the driveshaft. Their machine even told them the exact spot to put the extra weight. Presto; vibe gone.
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Re: Help with vibration (toyvet1)
I had a vibration that started at 62 mph and went to 70 where is dissappeared and came back at 90. Even if you took it to 80, pushed in the clutch as you passed from 70 back to 60 you passed through the vibration with the engine idling.
I got a new 3 inch driveshaft this winter, 2 new front tires , replace the rear gears and matched the down angle of the transmission with an up angle of the rearend.
I had the transmission on a 1 degree down angle so I made the rearend 1 degree up so the 2 angle would cancel.
My car is now dead smooth to 80 mph where my test quite last night. I was also checking the alignment after doing some work and took it for a test drive forgetting to install the cotter keys in the front castle nuts. Stupid thing to do , if the nut had suddenly walked off I could have been is some trouble.
Anyway not a hint of vibration up to 80. Next time I will test it higher.
I got a new 3 inch driveshaft this winter, 2 new front tires , replace the rear gears and matched the down angle of the transmission with an up angle of the rearend.
I had the transmission on a 1 degree down angle so I made the rearend 1 degree up so the 2 angle would cancel.
My car is now dead smooth to 80 mph where my test quite last night. I was also checking the alignment after doing some work and took it for a test drive forgetting to install the cotter keys in the front castle nuts. Stupid thing to do , if the nut had suddenly walked off I could have been is some trouble.
Anyway not a hint of vibration up to 80. Next time I will test it higher.
Le Mans Master
Joined: Sep 2000
Posts: 6,036
Likes: 2
From: Westfield Indiana
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Re: Help with vibration (toyvet1)
I also had a vibration in my 79 around 60 or 70 a few years ago. Part of it was because I'd thrown a wheel weight, but after getting that fixed, the vibration was still there, just a little less. I had the drive shaft balanced and told them to balance it for high speeds. Problem cured, and they even painted the driveshaft. They had removed the small weight that was from the factory and installed a larger weight in a different location.
Melting Slicks
Joined: Dec 2000
Posts: 3,407
Likes: 2
From: Carmichael CA
Re: Help with vibration (toyvet1)
Take the batteries away from your wife and the vibration will go away. :jester
Seriously though, I get a vibration from my rear bumper...specifically the center support that presses against the middle of the bumper. The screws were kinda stripped out...haven't fixed it yet cause it's not that loud...yet. My vibration only kicks in under mild acceleration in 3rd gear...weird, but I know it's where it's coming from cause there was no vibration until I replaced the rear bumper.
Seriously though, I get a vibration from my rear bumper...specifically the center support that presses against the middle of the bumper. The screws were kinda stripped out...haven't fixed it yet cause it's not that loud...yet. My vibration only kicks in under mild acceleration in 3rd gear...weird, but I know it's where it's coming from cause there was no vibration until I replaced the rear bumper.
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Re: Help with vibration (toyvet1)
I bought a really good magnetic protractor. It is about 4 or 5 inches long and reads angles to 1/2 degree. With the drive shaft out I place it on the end of the output shaft after making sure there were no burrs. It read 1 degree down. I then placed it on the pinion of the rearend and it didn't match the front so I raised the rearend pinion snubber.
The front angle must be exactly opposite to the rear. If one is down the other must be up.
The front angle must be exactly opposite to the rear. If one is down the other must be up.
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Drifting
Joined: Apr 2002
Posts: 1,720
Likes: 19
From: Manhattan Beach Ca
Re: Help with vibration (toyvet1)
One source I found out is when the water pump bearings start to go out, the vibration can be felt. I know you disengaged clutch but just incase. I have same vibration at 75 also, still working on it. I think it has to be half shafts.
Thread Starter
Burning Brakes
Joined: Jul 2000
Posts: 1,045
Likes: 3
Re: Help with vibration (Surfer69)
I tried to match the trans and rear end angle and am stumped. The trans is 4.5 degrees down and the rear is 0 degrees. I tried to shim under the tail shaft with three thick washer between the bottom of the tail shaft and the center crossmember to get it raised. Got maybe 1.5 degrees of the 4 degrees.
Tried to shim between the front differantal mount and the frame, to lower the rear nose so to get some down degrees. With three thick washers all I could get was about .5 degree down.
So now I have -.05 down in the rear and -2.5 down in the front. I'm still quit a bit differance, and have run out of room for adjustment. Any Ideas?????? :confused: :confused: :confused:
Tried to shim between the front differantal mount and the frame, to lower the rear nose so to get some down degrees. With three thick washers all I could get was about .5 degree down.
So now I have -.05 down in the rear and -2.5 down in the front. I'm still quit a bit differance, and have run out of room for adjustment. Any Ideas?????? :confused: :confused: :confused:
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Re: Help with vibration (toyvet1)
Matching angles are very important. Well not matching. If one is down the other must be up. They must cancel. Even 3 degrees difference is way too much and having both down just adds them up.
I raised my tail stock until the transmission was touching the floor and ended up with 1 degree down.
I ended up heavily modifying the pinion mount to get the rearend pointing up by 1 degree. I did a few posts at one time on this including stringing the motor , the tail stock , both ends of the driveshaft and rearend and moving everything into alignment to try and eliminate all vibration.
Anyway last night I took it too 105 mph and not the slightest hint of a vibration. I would have gone alot faster but the cops are really cracking down on street racing and with me doing over 100 mph regardless of the highway I would be gone so even though there was no other car on the stretch of highway I was on nor any cross roads I didn't take it any higher. There is absolutely no vibration from the shift **** either.
I buy the 4x4 books and they go into vibration and drive shaft angles alot. Because of the misalignment of the supper short drive shafts constant velocity joints are used.
Good luck
I raised my tail stock until the transmission was touching the floor and ended up with 1 degree down.
I ended up heavily modifying the pinion mount to get the rearend pointing up by 1 degree. I did a few posts at one time on this including stringing the motor , the tail stock , both ends of the driveshaft and rearend and moving everything into alignment to try and eliminate all vibration.
Anyway last night I took it too 105 mph and not the slightest hint of a vibration. I would have gone alot faster but the cops are really cracking down on street racing and with me doing over 100 mph regardless of the highway I would be gone so even though there was no other car on the stretch of highway I was on nor any cross roads I didn't take it any higher. There is absolutely no vibration from the shift **** either.
I buy the 4x4 books and they go into vibration and drive shaft angles alot. Because of the misalignment of the supper short drive shafts constant velocity joints are used.
Good luck
