Hi,

I come again with my vibration issue... who always evolve with every new work on the car but still remains present.

So to resume,
It is a speed related vibration, coming clearly from the rear end.
Tires, drums, driveshaft are equilibrated, wheels are round ok, pinion angle was checked and changed, new trans new clutch.
And recently new differential oil GM + 2 cans of GM additives for Auburn posi.
Since that oil change the vibration almost desapeared... when the car is cold. why ???

What is very strange and I don't understand is now the vibration comes when the car is hot, and vibration comes after a longer period at speed > 72miles/h. Just taken of the garage i could bring the car to 100miles/h no vibration. Later it was vibrating.

And then it is like it has always been, the vibration phenomenum is the rear shakes and when you brake you feel it hard in the wheel and everywhere in side, it's like it wobbles hard. Untill the car is completly stopped.
I mean if u feel it vibrating at 70 m/h and brakes down to 50 well vibration won't desapear. The car needs a dead stop for the vibration to end.

I really comes at the end of experiments on vibration tracing and I can't get rid of it please any ideas are welcome related to my observations.

Just a thought. Have you ever had the pinion depth and backlash checked on the gear set? You may have too much preload on the carrier bearings. If the gears and/or carrier has been replaced find a knowledgeable person with the right tools and have it checked.

I here you I am in the middle of the same thing with a s-10 truck...??? 65-70 thought it was the tires NOP. brakes were done and axles bearings and seals were too. I am checking the drums to see if they are balanced or out of round etc. there was a very faint vibration but now after doing this stuff to the vehicle it is magnafied. The vibration I have do body boom the truck but kind of goes away at lower speeds. Cold and hot is a noticable effect and also turning and changing lanes will some times seem to make the tires come in and out of sink like a balance problem between both sides of the vehicle...Crazy stuff...If i find out soon what it is a I will give you a idea of maybe what yours might be. Weird stuff? Just have to keep switching out stuff till you find it...will see. Jim

Did I understand right, When warm its starts to vibrate only after brakeing? In other words can you pull out the garage and drive on the highway for ever w no vibs until you brake?

Thu not related to warm...
Check for any paint on the drums where the rim is in contact...this should be a steel to steel contact in these spots.
If u have slotted rims...locate/center the rims with std tappered nuts, then replace with the correct nuts for yor rims one by one

I'll check for paint on the drums.

But no i didn't meant it is brake related.
One word about that :
When you feel the vibration coming (no braking), driving at constant 75, and than you brake, while braking the vibe doesn't stop it is still felt very strongly in your *** and also in the wheel while braking.
When you drive at lower speed after braking the car still vibrates.
For the vibe to stop you need to completly stop the car. 0 mph.
Frequency of the vibration is like between 2-3 cycle per second, so like a shake, not a very quick rate vibe.

About hot engine or not well that is something wierd. The thing for sure is that it takes a while for the vibration to come while driving at constant highway speed...
It is really not like when you have a bad equilibrated wheel that vibrates between a speed margin.

While testing after changing the rear end oil I really ran high speeds for 10 minutes with acceleration and decelaration braking and all and it didn't vibrated.
I was very happy i though it was gone !
Than driving home the vibe began...

The 'story' with braking is that it is kind of a test in my case to now if the car vibrates or if it is only a bad road, because while braking you feel the vibe harder.

I am really lost about all that stuff

Thanks for your comments


Marc

Marc you might want to have a look at your front end,, it sounds like its toed out or something is wore badly,,also check the tires good for a seperation, i ran a tire store for years and seen this a lot,, i know it sounds nuts too you but a vibe will run you crazy trying to track it down and cure it.Frank

OK I have my problem solved. Did you do a brake job recently? Rear drums newer? I did and the drums were NOT balanced correct and or no weights. I put on the old drums and referenced both tires with spray paint to make sure when I did the switch they wer on exactly as they were with the vibration. PROBLEM SOLVED....GEEZ . WHO would have figured it was the new parts. Can't believe it. Try the drums and see if you have any changes. Jim

If its "hot" or heat related I've got to start with tires,have you checked for a possible pulled belt in one or both of the rears.How bout the rear brakes...is it possible you have the emergency brake to tight...starts to rub...causes friction...heats drum and shoe...both expand with heat...vibration begins and gets worse with heat and time,just a thought. And way outside the box,again the rearend grease,okay cold,not okay hot,could still be something there.Last but not least, when is the last time you changed the outer axle bearings in this car?

It does kinda sound like the brakes are getting to hot, or air in the system is expanding and causing them to lightly come on. How is the brake pedal is it consistant and good all the time? --- post before said emergency brake. That too is it real tight. Changing the oil sounds like a quincendent, dought that is it. Just my two cents

I still think he should look at the tires and front end,,just from this statement he made""And then it is like it has always been, the vibration phenomenum is the rear shakes and when you brake you feel it hard in the wheel and everywhere in side, it's like it wobbles hard. Untill the car is completly stopped''' Just my opinion..Frank

Could be right jet, pat.

Hi,

Thanks for the comments. I didn't catch a chance to take some time on the car this w-e. I did take note of your comments concerning the rear brakes.

About the definition of the vibration again, it comes from the rear not from the front end. it shakes your back. when you feel the car vibrating and you brake the whole car wobbles and even in the front end you feel it. I don't think it is front end related i think it shakes so hard you feel it everywhere, but truly it is harder while braking.
Now if the car doesn't vibrate (freshly taken out of the garage) and that you brake, no vibe at all, nothing flet in the wheel but the flat road.

I can look at the rear drums, as I know there where painted.

I restored the front end 2 years ago, but it is true I have a brake problem actually the piston is always too tight on the rotor and the wheels are hard to turn freely. But don't know if it may cause some vibration.

I may look at the rear drums yes.

About the tires there are balanced and not out of round, what is there else to check?

I'll try to catch some time and let the car be tested.


Bebye

the brake fluid is new from the brake restoration and the brake pedal is smooth consistant, very good.
Like all camaros the rear wheel are the first too block on hard braking.

If it where MY CAR, i'd check the wheel bearings on the spindles. Any time I've had a problem simular to what you are descibing (front or back shaking) it turned out to be the wheel bearings. If they are not installed just right, they will manifest this failure after a few hundred miles. Or, if they are just plain wore out, they can make your hole car shake BIG TIME, until you come to a zero stop. :)

Hi guys!

Just let you know we found the vibration problem, it was due to the brake master cylinder changed by a bad mechanic that was not fitting with oil volumes needed, and it was blocking the brakes and creating vibration.

We changed the master cylinder and everything is fine! After such long years of nightmares and the car almost sold...

Thank for you help