strange vibration.. need help

kammi10

kammi10

Club Member
having a weird vibration go on with my car right now and cant seem to narrow it down. the car is an 89 camaro with a lq4 turbo / th400 rvmb with a 9 inch rear end. the vibration is not rpm related and seems to only happen in 3rd gear when im going 100+.. it gets worse when u let off the gas and start to slow back down. it seems like its coming from the front or middle of the car not originally the rear like i thought it was. also the engine/trans has to be warm in order for it to happen.

ive checked all the bolts under the car dealing with suspension and rear end,
checked the rear end itself and everything seems fine there
torque arm is all tight and straight
driveshaft is still straight and the weight for balancing it still there
all wheel weights are still there
pulled the spark plugs out of the motor and they all still look great
the car drives perfectly fine up until u get on it in 3rd gear and get up to 100mph. after that is when it starts.
it wont do it in 1st or 2nd gear only 3rd gear..

anyone else have any idea's?? my gut instinct thinks it has to be something in the trans since it only happens in 3rd gear only... but im not real sure..

any help would be greatly appreciated.. thanks guys
 
Have you rotated the tires to see if it moves with that?

Is the converter locking up and not releasing when above range of operation?
 
Beigg said:
Have you rotated the tires to see if it moves with that?

Is the converter locking up and not releasing when above range of operation?
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not able to rotate tires with bigs and littles on it.. converter is a non lock up converter..

larry - maybe i will have him re check the driveshaft to make sure its balanced.. but why would it just now do it after 800 miles and not since i got it?
 
is it only around 100mph or can you pulled third early and still have the issue?
last time i had something of this issue it was the wrong u joints on the car.
 
no its only around 100-125ish.. didnt wanna take it any farther then that.. even if i pull 3rd early and just run it up in 3rd the whole way it does it. u joints are still just like new..
 
I had something similar in my car, it would vibrate like crazy once I got past 80 or so. Manual trans is in it though, but it was the driveshaft bolts that hold it to the flange on the pinion were loose. It was fine when I was under 80, but after it was out of control. But if you checked that, then not really sure.

Im not totally sure on an auto, but the stuff is all turning the in every gear. You wind up first and its still spinning the third gear stuff, I know different stuff in enabled, but....I would think if it vibes in 3rd, and it was the trans it would vibe in 1 & 2 also...maybe?
 
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Driveshaft/pinion angle. It changes slightly under deceleration. Pinion should be pointing downward 1-2%-not straight.
Same angle at the transmission-preferable the same amount at the pinion as the trans,
 
Detroit Gearbox said:
Driveshaft/pinion angle. It changes slightly under deceleration. Pinion should be pointing downward 1-2%-not straight.
Same angle at the transmission-preferable the same amount at the pinion as the trans,
Click to expand...

nothing has changed for the last 800 miles and i dont see how it would not do it when the car is cold...
 
so just to clearify, when you grab onto the driveshaft and try moving it, shaking it, theres no movement in any direction?
mines was mostly noticeable on decel
 
kammi10 said:
nothing has changed for the last 800 miles andi dont see how it would not do it when the car is cold...
Click to expand...

I did not see you mention anything about tempature. I still would be looking at the driveshaft and or angle as the source.
Do you have to be driving it, or will it do it in the air at ride height?
 
Detroit Gearbox said:
I did not see you mention anything about tempature. I still would be looking at the driveshaft and or angle as the source.
Do you have to be driving it, or will it do it in the air at ride height?
Click to expand...

last part of the first paragraph... considering it only happens when im at 100mph i dont see how it could do it when its up in the air..

there is no bad vibration when your just driving the car.. hell it drives great at 80.. just as smooth as normal.. its just when u make a run up to 105-120ish u can feel it start and then when u let out it gets worse
 
You vibration is rpm related, just not engine rpm related. Its output shaft & drive shaft or wheel rpm related.
Im interested in see if it does it with no load.
I inspect vehicle often for strange noises and vibrations. Most can be found if I duplicate the rpm on the hoist, supporting the vehicles axles at ride height. Chances are you will feel it in the air and be able to narrow down the sourse. Driveshaft vibrations tend to be/feel fast. Wheel/axle vibrations tend to be a slower vibration.
 
Detroit Gearbox said:
You vibration is rpm related, just not engine rpm related. Its output shaft & drive shaft or wheel rpm related.
Im interested in see if it does it with no load.
I inspect vehicle often for strange noises and vibrations. Most can be found if I duplicate the rpm on the hoist, supporting the vehicles axles at ride height. Chances are you will feel it in the air and be able to narrow down the sourse. Driveshaft vibrations tend to be/feel fast. Wheel/axle vibrations tend to be a slower vibration.
Click to expand...

im going to pull the driveshaft out and take it back to the guy who built it and have him re-balance it.. its cheap so its not a huge deal.. im not a real huge fan of putting the car on stands and running it up to 100mph and seeing if its there. but i guess that may be what im going to have to do..
 
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