JoeliusZ28

iTrader: (2)

A couple weeks ago I was doing a high speed pull (115 or so) and as I was engine braking back down moderately in 5th gear, my rear u-joint let go on me. Yes, it was a scary experience. Thankfully though, it stayed in place and it looked like i just busted a needle cap in half. A simple u-joint replace, and the car is back on the road. (I also determined the cause of this was a worn torque arm allowing the pinion angle to change too much, replaced this as well).

Ever since then, I've had a pretty bad vibration most noticeable from about 4500 RPM to 6000 RPM (my rev limiter) under heavy acceleration in any gear. It is also even worse when engine braking in the 3500+ range. At first I thought it was the driveshaft considering the abuse it probably took from u-joint breaking, but today I noticed it does it even when I free rev. I used to engine brake all the time after doing a WOT pull and the car was perfectly smooth. Now when I go full throttle i am finding myself stabbing the clutch and letting it idle as soon as possible because the vibration is scaring me.

My oil pressure is good and the engine runs as strong as always. Everything is functioning as normal. Is it possible my flywheel or pressure plate is coming loose? Or something in the transmission? I also notice a VERY minor vibration at 80+ highway cruising speeds that wasnt there before. Also goes away when i press the clutch and let it idle.

Thoughts?

Stroked96Bowtie

iTrader: (22)

When the ujoint broke, did the driveshaft bounce off the ground? Its usually pretty violent on the driveshaft when a ujoint breaks with the car in motion. Id first check to make sure your suspension angle is correct. There are lots of write-ups on adjusting and setting tq arms. If that doesnt work you should take the driveshaft out and up to a driveshaft shop to have it balanced. Sometimes it doesnt take much for it get out of balance.

JoeliusZ28

iTrader: (2)

I dont think its anything to do with driveshaft or rear end - it does it when i free rev with the clutch pushed in.

Torque arm is only a stock one, not adjustable. I have a UMI waiting to go on, but requires me modifying my true duals before it will fit.

LT1FirebirdSLP

iTrader: (2)

I'm wondering if you really jacked up your tailshaft on the transmission when you snapped the DS. Any visible maring/marks/dents/deformation on the tailshaft of the tranny? Bent it? I'm stabbing in the dark here. I had a problem a long time back where under similar circumstances I would feel a vibration and it sounded like a block of wood being shaken around in a tuperware box... It was the tranny mount. Little piece of rubber mounted to the tailshaft of the transmission.

SS RRR

iTrader: (2)

If that's the case then the vibration has nothing to do with your trans or anything further back. First thing I'd suggest is taking the trans out and having the flywheel and pressure plate checked.

JoeliusZ28

iTrader: (2)

Thats what I'm thinking also. I've been looking to replace the clutch anyway, guess I'll just yank it and hopefully kill two birds with one stone.

Stroked96Bowtie

iTrader: (22)

If you ONLY feel the vibration with the clutch pushed in...thats a good indicator of where the prob is. Sounds like you're getting there.

LT1FirebirdSLP

iTrader: (2)

Throw out bearing or pilot bushing would be my next guess

Luke1996ta

iTrader: (3)

Sounds like the same thing my car was doing went through 4 clutches because the pilot bearing pulled threw the pressure plate I was lucky every time it did it it was covered on warranty after the 4th time of taking the tranny out I told zoom clutches to give me my money back and I went with ram and never changing brands again I love this clutch not only were they pulling the bearing out It broke my clutch fork and slave cylinder and had to get a new fly wheel and zoom didn't even want to pay for the parts there product broke

MislMan

I'd check the tranny mount before going too far. If it got ripped up during the u-joint failure it may very well cause a vibration when free revving the motor. Sort of like the vibration some notice when switching to a poly trans mount.

Later ... Larry S.

JoeliusZ28

iTrader: (2)

The vibration is there with the clutch in or out, in any gear. Its not a terrible vibration. I trust the car with it now, ive gone full throttle with it several times since I started this thread and nothing bad has happened. Just an unusual and somewhat disappointing thing. Its for sure not the trans mount, I have a poly and I would notice that with an M6.

DisasterFormula

iTrader: (1)

Flywheel bolt may have backed out?