I was at Mosport internation speedway today, it was awesome running with 911 and other crazy cars. However, during one of the corner, I down shifted from 3rd to 2nd really hard. Afterwards, my car vibrated like crazy.....so I slow down and pull over. I thought I bended the valve springs or something. Went home, did a compression check..is all good.........my friend told me it might be that one of the engine mount is broken/crack?????Therefore sending all the vibraation into the car.....I will bring my car to a mechanic soon, can anyone tell me what is likely to be wrong with my car?????

 

yes, check the motor mounts. most likely one of them may be cracked from heat?

 

check your motor mounts , mine busted the first time i went to the track .


[Modified by Spoon1, 8:53 AM 5/25/2002]

 

THanx guys, I hope that is the only problem too.

 

Well it's either the motor mounts. Because the only thing else it could be is warp disc but thats only with the brakes pressed.

 

Check your axles. If you shifted hard, you may have popped the cv joints.

 

just woundering, what u guy mean "shift hard"? is that mean downshift without a speed match?

 

yes I did rev match, heel-toe down shift 3rd to 2nd

my mechanics open up the head, check all the valve, they found that one of the cyclinder can't hold compression..so they thought it might have mis-algin, but now, everything is put back together PLUS, new distrubtor cap, new valve adjustment.
I still get a small vibratoin only at 90km/h.....why is that?? PLEASE HELP


[Modified by lePetitePrince, 9:54 PM 6/9/2002]

 

could it be the tranny???? some ppl said it might be the LSD?? but i never heard anyone having trouble with the stock LSD.....

 

and also I have checked all the engine mount, they are all good.....

 

plsss I need help guys ..really....I don't know what to do now, pls.

 

does it shake only when the car is idling, when the clutch is depressed, released, or what?

 

it only shakes when the car is at 90km/h..once it passed throught the vibrations starts to go away..and it starts at 85km/h..no matter which gear I am in.

 

I really think its the motor mounts

 

If it vibrates at 85-90kph independent of motor rpm, I would say that cancels out any internals of the motor, clutch, and pp. I suppose it could still be inside the tranny, but more likely and wheel bearings.

Double check your motor mounts and check for suspension and bushing damage, maybe a flat spotted tire, warped rotor, bent wheel?

 

now, I was using the mazda Milliena rims, one of them was bend , I found out after that track event. It was bend when I bought because I didn't hit it.
But I change back to my 16inch rims, which is not bend..so bent wheel is out of the list.
my rotors are warped as for now, but I thought wraped rotors only vibrates when I hit the brake? which it shakes like crazy, but I will change them really soon. But can this be a problem when it is jsut crusing at 90km/h??

Now I am just afraid it could be the tranny..but what type of problems could it be?
LSD?? because I can go into each gear smoothly..

 

Ok wheel is out of the question, so:

Start from the wheel bearing/rotor, all the way to the countershaft. All these pieces move in direct relation to vehicle speed (85-90kph). Therein lies the problem if it's in your drivetrain. I think that if the rotor was warped bad enough, it could cause vibration, and it's resonant frequency (this goes for all parts upto countershaft) might have been changed and now you can feel a vibration.

However don't forget to look for a damaged or loose suspension piece and joints, a shot bushing, and double check the motor mounts. You didn't get into any mishaps on the track? It's even possible a loosened body panel could resonate/vibrate at that speed causing a vibration.

 

ok, I guess I will change the rotor, and check wheel bearing, and countershaft as you have suggested. I am sure the rotor is wrapped very bad, but is it possible that I only get the vibration at 90km/h?
I will double check all engine mount

 

Ha, it might be a little difficult to check the countershaft, I was just listing it as a remote possibility. I would guess the problem is coming from the rotor, if not a cv joint or hub. Can you feel it coming from a particular area?

 

it feels like it comes from the center of the car.....but I have no idea where though.