My car starts to vibrate at about 70MPH on any road surface. I don't know what it is. I just got my tires rotated and balanced today to see if that was the problem, and it wasn't.I have heard that it could be the driveshaft not being balanced, but I don't know how I would go about checking that.

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Does it feel like front or back end?
Propshaft joints on the way can really shake a car about, check the u\js on the shaft. Usually thats apparent at most speeds tho.
Vibration at that speed is nearly always wheel balance, but you have done what i would have suggested first, so jack up the front, check the wheels, grab hold and check for movement out of the normal, same with the rear but its harder to tell unless you know what to look for.
There are firms that will balance a propshaft, thats a job for yellow pages or the internet.
You could put it up on stands at the back, and put it into gear [make sure its secure] gently rev it and see if theres body shake, maybe a friendly garage could do that on their ramp for you?
That should indicate if its prop or rear axle.

 

It shouldn't be the U joints, because I replaced them when I put in my rebuilt TH350 tranny about 3 or 4 months ago. I'll check to see how much each wheel moves by shaking them back and forth. How much should they move for it to be safe?

 

Ideally virtually no movement in any direction.
You can have a little front wheel bearing play, that wont harm anything, at the rear no play at all.
Just double check you dont have an out of shape tyre, they can still be balanced, but will get further out of shape with speed, i'm assuming you have a good tyre place, not like some of these Quik-Fit firms that couldnt spot a duff wheel if it fell on them.
Most vibes come from tires and rims, i see so few rear wheel drives anymore [cept BMWs Mercs etc and my TransAM] i have to start thinking hard again.

 

I got the tires put on at Tire Kingdom,and that's also where I got them balanced and rotated at. I checked the play in the wheels, and there is none at all in the rear, and the front moves maybe like a 1/4" or less. Would upgrading to an aluminum driveshaft be a good decision if I am going to spend the money to get mine balanced?

 

Theres a thread somewhere, someone asked about aluminium props, and got no answer i think.
Personally the amount of horsepower my puny 305 puts out , an alloy prop would worry me.
Why? Because i'm old fashioned.
Personally i would'nt buy one, it would be cheaper to get a new standard one.
1\4" on wheels this size is negligible, probably i would adjust your front wheel bearings to spec, and i bet you wind up with no play, so if your happy with the wheels etc check the prop, after that your getting into checking engine mounts, torque converter, and flywheel stuff, but thats a last resort.

 

Thanks for the help, I think that I'll get the driveshaft balanced just to be safe. How would I go about tightening the wheel bearings?

 

If you need to tigheten wheel bearings you should to replace em. Have you check em for play? They really would cause more of a tire wear and handling problem before they would cause a high speed vibration though. If it is the driveshaft it might be cheaper to just get another one, steel ds's are a dime a dozen. An alum. driveshaft would be a good choice, and they are fairly easy to come by. Most if not all LS1 f-bodies come with em and they are a direct fit into a 3rd gen. As you probably know the old 1LE cars came with alum's as well in 3rd gens. There was also a TSB for high speed vibrations back in the day and the fix was to simply swap out the crappy steel shaft with a 1LE alum. ds. GM did quite a few of em under warrenty so they arn't too hard to come by. R1 why would you not want to use an alum. DS? Corvettes have been coming standard with them for years as well as high proformance F-car's. Never heard of a problem with one..

 

Is replaing a wheel bearing easy?

I guess tommorow I will make a run to the local junkyard to see if they have some aluminum driveshafts, or would that not be a good idea?

 

You just dont get them in the UK, well Corvettes are rare enough, nevermind ally shafts, everythings front wheel drive. .
Still i'm old fashioned, but if they work ok, and it seems they do, use em.
Send me one for "evaluation" please.

You can adjust a taper bearing without replacement, its a regular job for me, if you still have play or roughness after adjusment, then yep, sling it and buy new.

 

I might as well just replace them, I would rather be safe than something happen while I'm driving.

 

Just a suggestion but go get the tires "road forced balanced" this balancing makes the tire think its on the road. With this balancing we have found many tires to balance out properly with normal balancing but with the road force, the tires turn out to be junk.

 

Thanks 92lt1 I'll have to try that. The tires shouldn't be bad seeing as they only have about 4,000 or so miles on them, and have been properly inflated all of those miles.

 

Something to check,
I had a similar vibration that I could not locate. Like yours, it only hapened around 70. I finally got myself convinced it was the torque converter and took it to a shop to put on a new flywheel and converter. They went to begin and found that ALL of the trans bellhousing bolts were loose
It was a stoooopid thing, but the problem went away with a simple turn of the wrench. Only cost me $10 cause the guy was really cool about it.

 

I chased a road speed vibration problem on another vehicle type literally for years. I had the tires rotated, balanced, different ones put on, no difference. I had the driveshaft balanced, u-joints replaced, transmission mount replaced, tailshaft housing bushing replaced, nothing changed. Checked the transmission mount bolts, torque converter bolts, nothing.

Finally, one tire developed a bubble on the sidewall. Replaced all 4 tires, bingo, problem gone.

Turns out there was always at least one bad tire on the vehicle, regardless of where they were or which ones I happened to have installed. When all 4 were replaced with quality tires, no further problem.

I'm betting a bad tire or two. Doesn't always show up in an unloaded balancing job.

 

85camaro255...
At the dealership where i work, we have the latest in tire machines from hunter and they are the best in the world. Read this section from the hunter webpage. http://www.gsp9700.com/pub/technical/4202T/5THEO004.cfm
This is what i was talking about earlier. Brad

 

Do you feel the vibration thru the steering wheel? OR thru the seat?

Did the vibration change at all when you rotated the tires?

What type of balance machine did the shop use? There is a shop where I live, that their balance machine is pretty much useless, as I had to re-balance my tires elsewhere immediately after having them mounted.

On a side note, do the stock wheels on your camaro have the same offset? (backspacing) IIRC, there IS a difference between front and rear STOCK wheels, and simply swapping them front to rear is a bad plan.

 

I feel the vibration thru the steering wheel.

The vibration did not change after I got the tires balanced, and I have no idea what type of machine they(Tire Kingdom) used.

I don't have the stock wheels anymore, I'm using aftermarket American Racing wheels(don't know what model).How would I check the offset?Is it on the rim somewhere or do I have to contact the company that made the rims?

 

One thing i forgot to add, usually if its tire\wheel balance problem, you can drive through the vibration, ie increase speed to say 80mph, does it vanish?
If its through your steering wheel, its a sound bet its originating from the front end.

 

Actually that's the one thing I forgot to add. As long as I'm in the 70-79MPH range it vibrates,but as soon as I hit 80MPH it stops.

I had a feeling it was the front end, but what could it be. Maybe the ball joints?Or maybe some of the bushings are worn out?I"m just taking wild guesses, but those are the only things that I can think of.

 

Thats nearly always wheel balance, out of shape tyre, or a buckled rim.
Not always, but a very high percentage usually are.

 

I guess I need to go get my tires road force tested to see what's wrong with them. If I have any new information when I get back I will let you know.

 

Ok, well I got the problem fixed. I went and got the tires road forced balanced. Everything was fine with both the tires and the rims.The technician said that one of the tires was on backwards, and needed to be switched. He did that for no charge. On the way home I hopped on the highway,jumped up to 70MPH and sped through til about 100MPH. There was no vibration, the car handled even better, and there was less road noise.

I didn't think that all this could be cause from a tire being put on backwards(tread facing the wrong way),but I guess the thing you think of last is the problem.Thanks for all the help, I wouldn't have figured this out without it.

 

Ahh i forgot about directional tyres, having a Fireblade atm and motorbikes over the years, you forget these are new to most cars.
A nice cheap result tho, if only everything were that easy to fix.

 

It made me kinda mad finding out that was the problem. I guess they didnt notice it since it's really hard to tell that I have directional tires. I guess they should have inspected them more or I should have thought of it to tell them.

 

no they were lazy, they should have inspected the tires better.