High-Speed Vibration
 

When I partially release the throttle, (like trying to maintain constant highway speed) at about 80k and up, I get a strange vibration coming from the rear. It gets worse when I drive faster then that. If I drive up to 120k then throw it into neutral, it vibrates until down about 70k. If I'm driving and putting a load on, it doesn't vibrate... (either foot fully on the gas, or completely off). The vibration is not noticeable at low speeds. I had it "looked over" at the shop today, and they couldn't find anything obvious (u-joints, bearings..etc).
There was a post of this nature "High Speed Vibration" posted by SupraRed in '05 or '06 with very similar symptoms, but no conclusions...

Any ideas?

thanks.

it may be some problems with your tires or the rims. check it out, or try to rotate em to the front to see if it changes the place of the vibration.

i have that same problem but mines the driveshaft. i need a 1 piece

I've got that vibey feeling too.

Check wheels and tires. Jack up the rear of the car, support with sturdy stands, block front wheels, and run the car in gear and watch the tire/wheel assembly for out-of-round, lateral or radial. Check the driveshaft center support bearing for play (up/down, side/side). Any runout in the tires or play in the driveshaft will amplify vibrations at greater speeds.

I just installed the one piece AL driveshaft. I'm not sure it has helped the vibe issue at all. It does get rid of the clunk during shifts and when starting from a stop, though. Gonna check my tires/wheels again.

I did have the car on a lift and was running it in gear. I was in the car, the mechanics were under watching. They are a tire specific shop, and didn't say anything about unbalanced or bent tires... We checked the drive-shaft for play as well... all of the bearings seem to be fine (little to no movement). I'm still looking for a fix...!

I've had more issues with tires and tire shops than I can remember. I'm 41 years old, and through my many years of tire-buying experience I have found a lot of shops don't have folks that can truly identify (or are willing to identify) tire/wheel problems.

It has usually been up to me to carefully watch them spin the tire on the machine and watch for runout.

Remember, you can balance an absolutely square tire on a spin balancer by simply adding the right amount of weight to the center of the sides, but it won't roll smooth across the ground.

Don't rely on the "tire guy" to tell you everything. If it is their tire(s), they have a vested interest in NOT telling you about what they might consider acceptable tire runout. They lose money on warranty exchanges.

I have contacted several tire manufacturers in the past for their runout specs, and they are usually in the >.05" lateral and radial range. This is almost visually imperceptible. Only a runout gauge (a dial indicator mounted to the balance machine that rests against the tire) can usually detect small but warrantable runout.

The home version is jack stands and a heavy block of wood/metal. While the tires are lifted a few inches from the ground, place the block of wood next to the tire, close enough to barely scrape it. Check for lateral runout at the sidewall and especially the bead area of the tire and rim.

Next, place the block under the tread section of the tire (be sure the wood is 'behind' the tire so it doesn't get grabbed and shot out from under the tire). Check for radial runout by watching the gap between the tread and the block. Anything more than about 1/8" will be noticible in a tightly suspended sports car such as the Supra. Old pickups wont care about 1/2'" of runout, but our cars do!

Dragging brakes, either the disks or the internal drum parking brake, can also cause vibrations at the rear.

Worn suspension components can do the same. Check the struts, linkage bushings, and wheel bearings for excessive play by prying under the lifted tire with a long pry bar.

I'll be posting a video of me checking my tires for runout. I'll post a link when I get it done.

Hope this helps.

I have similar vibration also, at highway speeds crusing. Bro-in-law and I have concluded its that shitty 2 peice drive shaft. We put it up on a lift and put our hands on opposite sides of the "center support bearing" and there was close to 1/4" to 1/2" play, plus the mounting bracket for it is slightly bent. The inline 6 just has way too much torque for that 2 piece shaft. We couldnt even name another high torque car with a 2 piece.

IMO even if we did check the play i still dont know how much play it actually has when its trying to move a 3,000 pound car.
Just food for thought

one of your rear axles... i had a honda accord that had a cv shaft let go...every thing was smooth until i hit 90km/h then it would shake so bad i thought the car was going to fall apart, get up to 120 and it would smooth out again....drove it from kamloops all the way to vancouver island (600k ish)lol

well see on my supra it has the stock two peice. and once i hit around 40mph it will vibrate and when i accelerate it will stop but when i left off it feels like im in a helicopter or a paint shaker lol. it will do it till i come to a stop. very scary feeling