DeStonn

I am having the same issues as you. Right at around 80 mph my vibrates and feels like it is about to fall out. I have tried adj. uca and adjusted the pinion angle to where the - angle from transmission and + angle from the pinion were the same and still a vibration. I had a BMR adj UCA and this week I am going to Steeda.

I might have to try rotating the driveshaft so everything is the same as the original setting but that is gonna be a challenge because I don't think the original installer marked it. [:@]

I have the Coast 4" and the guys at Coast are always willing to help but I can never get it right. Almost ready to give up.

Vapour Trails

I have a steeda alum. DS that is sitting on my basement floor because the previous owner said it vibrated at about 80 mph. He removed it, but gave it to me when I bought the car. I'm still debating whether I want to pay a shop to install it and find out it sucks. This problem seems extremely common.

jbailer

The problem is extremely common but only on automatics as far as I've heard. I'm guessing you guys have automatics that have experienced the problems. If so, I'd recommend going with the spyder shaft. I haven't had any problems with vibration at all with it. -Joe

STi Rob

I brought the car to the shop today to try and find the cause of the vibration and no luck. The factory shaft is back on the car but the vibration is ever so slightly still there but not noticeable until over 100mph and even then you have to know what your looking for to notice it. The car will go back in the shop in a couple of weeks for one final attempt to remedy this situation.[/align][/align]Rob[/align]

STi Rob

My carhas a standard transmission. What weve come up with to this point is that the shaft isnt to blame it just does a great job of transmitting the vibrtaion. I also think the lca's aid in this also. My shop is goingto try one more thing (something to do with the pinion) to try and get rid of the vibration if that doesnt work I guess its put her back to stock and get something else.

Rob

moosestang

If the problem gets worse on decel then you need to adjust your pinion angle up some. When you let off the gas the pinion rotates downward. When you are on the gas the pinion rotates upward. I wish i new how to upload the ford service manual instructions on measuring and setting the correct U-joint angles, because they are very different from what most people will tell you.

I don't know how your shop installed your driveshaft, but it's important to use the exact same orientation as the stock shaft. I would even go as far as to make sure the pinion flange and trans flange remain in the same orientation by marking them before removing the stock shaft.

Take a look at this picture.



That's my stock shaft at the transmission. Now imagine rotating the shaft 90 degrees in either directions. You can see you'd still be using the same holes, which is what you want, but the U joint is not the same on each side and this caused a vibration on my car over 70 mph. It is very easy to remove and reinstall the driveshaft at the trans. All you need is to support the car and a 12 point 12mm socket and breaker bar. You'll need a torque wrench to tighten the bolts back to 76 ft lbs. I would start by rotating it 90 degrees and see if it helps. unfortunately you don't know if your shop used the same holes, but you might be able to tell when removing the driveshaft. the stock driveshaft does a great job of absorbing vibrations at speed, not so good at being quite while driving slow and shifting though. No aftermarket shaft is going to be as smooth at speed, i'm afraid.

Keep in mind when you make something lighter, it usually means is will not dampen vibration as well.

You may need to turn the shaft at the pinion as well and even turn the adapter plate if you have one. It's going to take some trial and error at this point. Keep track of what orientations you've tried by marking it with a sharpie.

STi Rob

Thanks for your input moosestang. I cant say for sure the exact procedure the shop uses when installing driveshafts but they do install alot of them with only one other complaint of vibration (that customers car was fixed simply by turning the shaft)other than me. The shop has one other thing they are going to try, Ill try and explain but Im no mechanic so I might get a few things wrong. I beleive it has something to do withthe way the piniion flange mates to the rearend or pinion gear, they said it is within ford specs but they felt it could be out enough to be causing my issue. If some one more knowledgable than me canexplain this a little better Id greatly appreciate this.

Rob

Vapour Trails

Sounds like they are talking about the angle of the pinion flange.

sd07gt

PM SENT !!!

STi Rob

Thanks.

Rob