High RPM vibration all gears

[USAFPILOT]

I first noticed it in third, but am now feeling it in 1st and 2nd. Maybe I didn't notice it before or it is getting worse.

I get a strong vibration which comes on at 6500 RPM or so and keeps getting stronger the more I keep my foot in it.



I am certain it is from the drive train somewhere. I feel it in the shifter mostly. Is my trans or clutch gonna puke on me soon? The car has 50,000 miles.

I'm taking ideas.

[gbmidyear66]

When I first got my car I noticed drivetrain vibration @ RPM, and I noticed that when I really got on it I could see the shifter height modulate by close to an inch.

Turned out that the transmission mount bolts were simply loose and this is a common situation.

Hope that is your case as it is a cheap fix

[tf95ZR1]

I agree, tighten everything up, but don't overtighten.

[rhipsher]

Hey Ryan! If your home today I can come by and check it out after work. I suspect Cbeam bolts are loose. Mine did the same thing when mine were loose except for the vibration. I would suggest getting a set of Bill B's beam plates on order.

[GOLDCYLON]

Install the ZFDOC's beam plates while your in there

http://www.zfdoc.com/c4beamplate.htm

[A26B]

I agree, tighten everything up, but don't overtighten.

+1, especially the c-beam bolts on the rear of the transmission. Overtightening will compress the tailshaft bushing & wear it out.

+1 on ZFDOC's beam plates. mmmmm good, I like 'em.

[USAFPILOT]

Well Rick and I sorted most of the problem out, but maybe not the underlying cause.

I had the shifter knob incorrectly installed so we fixed that and most of the audible noise is gone.

I still have a cracked plastic piece where the allen screw seats into the shifter which is making noise but not much.

And, there is still a pretty strong vibration coming through the shifter at high rpm.

It is doing it whether I am in gear or not.

We did make a dent into this project today though.

:cheers:

[FU]

"It is doing it whether I am in gear or not."
Well now that we know that the problem is being isolated ....
Dual mass FW gone bad :icon_scra
More back ground on the car please.

[XfireZ51]

When not in gear, have you tried whether it vibrates with clutch engaged or disengaged?

[tccrab]

When you say the vibration occurs in gear and out of gear, was the car moving when it was out of gear?

If the car's not moving and you get a vibration with the clutch in or out then the vibration is north of the clutch disk.

If the car is moving and the vibration is there clutch in or out, then it could be a U joint.

TomC
'Crabs

[rhipsher]

When I drove Ryans car the first thing I noticed was that the shifter nob was just free spining loose badley. And the set screw wasn't in the little seat on the reverse lockout pin so it was just sliding up and down freely. So the first thing I did was take the aluminum tee and put it on the driveway and give it a couple of whacks with a small hammer to make it a little wider so it would wedge itself nicley into the groove. Then a fixed and tightened the set screw in the reverse lockout. So with those two issuse fixed we took it for another spin. Much quieter. He still needs to lip the shifter boot up over the plastic piece right under the reverse lockout. So I said ok just take it up to 7k and I'll squeeze my hand around the loose shifter boot piece and it was totally quiet then. Ryan still thinks that there's a little to much vibration coming through the shifter. I tend to think the amount is normal. At 7k there's gonna be a little bit of vibration just from the engine revs and the transmission gears. But his Cbeam bolts are not loose. They are fine. I guess when I get new tires for mine Ill take it up to 7k and compare the amount of vibration I get to his.

[USAFPILOT]

Got the shifter boot up over the lip and the allen head tightened now. Still the same.

I feel the vibration when driving if I depress the clutch and free rev the engine or if I am running hard through the gears.

I haven't tried just leaving it in neutral and revving it yet.

Actually I cant remember if I did it with the clutch in or not.

Time for another drive.

[rhipsher]

But is it more quiet than when everything was loose?

[rhipsher]

If you disengage your clutch and you still have the vibration then it could be your duel mass like was mentioned. Because it rotates even when your disengaged. I don't hear much about duel mass flywheels going bad especially on a low mile car like yours. Unless some crank bolts have backed out.

[FULLPWR]

Its just the "LT5 MTA" (Massage Therapy Actuator) kickin in.

:mrgreen:

[rhipsher]

Its just the "LT5 MTA" (Massage Therapy Actuator) kickin in.

:mrgreen:Or maybe it's the "DMMOIRB" (Drive me more often I'll run better) condition.:D

[ittlfly]

I had a similiar problem when I got my 94. After getting new tires and rims, I had all 4 ''forced balanced" . It helped but the problem still persisted. I pulled the driveline and both half shafts; had them re-balanced with new u-joints installed. That finally cured the problem. ( BTW the car only had 17K miles on it at the time. ) :icon_scra

Good luck.

[rhipsher]

I agree that bad ujoints and unbalanced drive shafts can be a major source of vibration. But this seems to be more rpm related than speed related. It happens when the clutch is in neutral. Which could point to something further up the drive train. Like the flywheel. Also another thing that was noticed was that we were in neutral facing up hill in a parking lot so if your in neutral and you take your foot off the brake the car should roll backwards. It didn't. So my first thought would be badly frozen ujoint/joints may be frozen enough to slightly lock the wheels up. Toasted wheel bearings. I put my money on ujoints. When we were pulling out of the gas station we put it in gear and could hear that classic clunk noise of a bad ujoints. But Ryan hardly drives this car. I think he's put maybe 5k miles on it in 6 years.

[USAFPILOT]

I just flushed out all the old brake fluid and added new DOT4 and drove the piss out of it, it will now roll on a hill. I am sure it was my brakes not disengaging for some reason, but that is now solved. Fresh fluid, I never figured that would be all it took.

Vibration still there. Going to try the u joint route next; but I am still waiting on some Hawk HPS brake pads from Fed Ex.

I have some Slotted rotors from a previous car I am going to run, but I need them turned.

I guess I can get O'Reilly to do it, but NTB wouldn't. Gotta wait till my next day off.

It took NTB all afternoon to do an alignment, but after two attempts they nailed it.

I always thought my car was leaning to the right and It was. Those cams on the rear end were off. Sits even now!

[HIZNHRZ]

I always thought my car was leaning to the right and It was. Those cams on the rear end were off. Sits even now!

When you say "leaning to the right", did your car not sit level? If so, does leaning to the right mean the drivers side rear end was higher than the passenger side?

Thanks.

[USAFPILOT]

Yes

[gbmidyear66]

I always thought my car was leaning to the right and It was. Those cams on the rear end were off. Sits even now!

My car is sits high on the rear pass side.... Could you briefly explain the adjustment procedure?

Thanks

[USAFPILOT]

take it to an alignment shop...haha j/k.

I don't actually know how to do it, but you have the two big cams on the center of the bottom A arms. They adjust the lean of the tire. I think that is called camber. Basically the cams can push the bottom of the tire in and out. If you have more camber on one side than the other you get the lean.

:flag2:

[gbmidyear66]

I guess on a tire that wide that the alignment could make a material difference.

Your first response is probably the best advice - probably not something I should attempt alone in my garage....

Thanks

[USAFPILOT]

One other thing you should check.

Count the threads below the nut on the bolt that extends down from the rear springs.

All those bolts do is adjust where the body lies on the car. If one side has less threads showing the body should be lower on that side.

It is fairly common for the rear of the car to be lowered using those bolts. It is a tougher job to lower the front of the car. You have to remove wedges from the spring or something.

A C5 Corvette has the bolts like the rear on the front as well.

[gbmidyear66]

USAF,

My front driver/passenger height is within 1/32 of an inch difference to the wheel well lip

I'm 1/2 in higher on the rear passeng side. the spring locking bolts on the respective sides are visually within one thread count difference from each other (appx 1/16 of an inch). The bushing compression looks equivalent side to side.

Any idea on what would be consider normal manufacturing tolerance? 1/2 inch seems pretty sloppy to me.