Just thought I'd try and get some input from all of you. I'm just getting my car going after having it set for about 8 months, and just finished up putting in a T5. I took it to a cruise night this weekend, and had to fight a bad vibration the whole way. When I get up to speeds around 70-75, I can feel a vibration coming through the driveline. I had the rear tires balanced right before I parked my car last fall, so I'm thinking that's not it. I tried taking the spacer out of my ES transmission mount, as I had read that it might cause vibrations. It seemed to help just a little, but definately did not fix the problem. Any suggestions? My other thoughts were possibly a driveshaft out of balance, u-joints (replaced them not long ago either though), or possibly incorrect pinion angle (my car has been lowered with Eibach springs). I know that the vibration was there before I did the T5 swap, but I don't recall noticing it immediately after I lowered it. So, any help would be greatly appreciated.

 

Step 1: figure out if it's at wheel speed, or drive line speed.

Leaving a car sitting on the tires for 8 months will put giant flat spots in them. Needless to say, that will create a vibe from Hell. You can balance them as much as you like, but they will never run true as long as they aren't round.

 

Thanks for the tip. I think I'll try putting it on stands and checking that out tonight. Would I notice the vibration at lower speeds as well with flat spots? Also, I did get my car out about every month while it was setting, so it shouldn't have been setting on the same spot the whole time. Anyone else have any good ideas?

 

Ok, I tried running it up to speed with the car jacked up, and I still seem to have a vibration, so I'm guessing it's not tires. Any more ideas?

 

Is your vibe at wheel speed, or drive line speed?

See step 1.

 

How do I tell if its at wheel or drive line speed?

 

Does it go uh-uh-uh-uh-uh as you drive down the road, or does it go rrrrrrrrrrr ?

The drive line turns about 3 times as fast as the wheels. Which speed is your vibe at?

 

It is a very high speed vibration, which would lead me to believe it is at drive line speed. Kind of the rrrrrrr you are talking about. It happens at about 70-75 MPH, and as far as I know, doesn't ever come out of it as I accelerate faster. It is a constant vibration, and isn't affected by acceleration at all.

 

OK...

We can safely leave the tires, wheels, axles, etc. out of the mix then.

You should be looking at universal joints, pinion bearings, the drive shaft itself (balance and straightness), the drive shaft yoke where it plugs into the transmission, the bushing in the rear of the trans that the drive shaft yoke fits in, and the pinion bearings.

Keep in mind, your car probably came with 2.73 gears; so the drive shaft RPM with the 3.42s at 70-75 mph, corresponds to its former RPM at about 95-100 mph when the car had its original gears. People often discover drive line issues when they change their gearing, because that makes everything spin faster.

Probably the best place to start would be to take your drive shaft to a drive shaft place and have new U-joints pressed in and the balance checked; have them check the OD of the yoke, to make sure it isn't worn down and sloppy in the bushing; and then to a trans shop for a new bushing.

 

I was involved in the big thread with the driveline vibration, we have pinned down many causes. Somone sent me a message a couple days ago stating that their vibration problem was simply loose transmission mount bolts.

Start with the easy, and less expensive stuff first. U-joints, wheels/tires.

Also, one thing I would think about would be the angle that your new transmission was mounted. If it is only a small bit off, it could cause these vibrations... loosen the mounting bolts, check the angle (also pinion angle) and tighten them down.

Also, you might want to check into your axels being bent.

But... seeing how this came after your transmission swap, I put my money down on that being the source of your problem.

Mine went away by acident when I was replacing my entire driveline... but I don't reccomend doing that just to get rid of the vibration.