djcondo

Hey all,
Just got a 99 cobra and i notice that it shakes a little under acceleration. If i rev the car there is no vibration whatsoever but when i am back in gear and accelerating it shakes. I have already checked the driveshaft u joints and they seem fine and have found and replaced one cross axis joint. The car has 165k on it..

Also there is a slight clunk in the front end somewhere when hitting the brakes hard or it is sometimes heard when turning

Let me know please, I am new to the cobra world

JC316

There are a lot of things to check, my money is on a motor mount, especially with 165k. Check the motor mounts, the transmission mount, possibly a wheel bearing, possibly the other CV shaft.

djcondo

Ok so I found out what the clunk was but still have the driveline vib. The bell housing was coming into contact with the K member brace. I threw a washer on the brace and no more clunk but still a vim under harder accel. The trans mount seems real tight i can not move the tail of the trans

JC316

I'm absolutely certain it's the motor mount now. If it's hitting that brace, then the mount is broken and needs to be replaced.

djcondo

how much space should be between the two?

JC316

I have no idea, but I do know that the bellhousing isn't supposed to touch. Shaking during acceleration + the bellhousing hitting that brace = busted motor mount. There is no question about it. Put a jack under the oil pan, with a block of wood to spread out the pressure and lift it up. If the mounts are good then the engine wont go up.

Steve@Tasca

I'd also suggest taking a real good look at the IRS mounts and everything out back, as these things get old they're going to run into more issues with worn out IRS mounts and shafts.

djcondo

Well threw in some motor mounts and that solved the driveline vibe. They are so trashed that the oil pan was touching the steering rack. I have seen some junk motor mounts but never this bad. One side had half the rubber gone and when I popped it out chunks of rubber was falling out.

On a side note. I now notice a slight miss/ stumble/ shake in rpm between idle and about 3000 ish. I don't feel it really when driving but when reving I feel it. Time to figure that one out. Let me know if you smart fellows know what to check with that.

Steve@Tasca

Maybe try getting the real wheels safely and solidly off the ground and then run it through the gears and see if it does it with the car off the ground.

djcondo

Well it seems like engine running rough not anything related to driveline and spinning. I was going to just pull one plug wire off at idle and see if any one does not make a difference to check my spark/ ignition system