NastyNate65

So i just put a new 5 speed trannsmission, clutch, and flywheel in my 91 mustang 5.0 and now whenever I go over 60mph the shifter vibrates pretty bad, but it gets worse when I take it out of gear and let it coast when cruising on the highway. If you have any actual knowledge of what was going on please let me know. I was wondering if I bought an aluminum driveshaft if this would help with the vibration. Thanks.

-Nate

ratrap1964

Did you mark the driveshaft before removal? Have you checked the u-joints? When you say new transmission what do you mean? Its possible its in the tranny. I would not start throwing parts at it until you figure out the problem.

Timspony

It's important to mark the driveshaft before removal! ...could be a bad u-joint ...vibration in the steering wheel or seat?

NastyNate65

The transmission was completely rebuilt by a guy in Kansas City who has a shop called Dan's T-5 Shop. He only rebuilds world class T-5 trannys and he is very good at it. He does 30-50 a year. I trust the transmission but not so much the driveshaft. No, I did not mark the driveshaft when I removed it, so is there any way for me to put it back on in the right position? And what do you mean by check the u-joints? And there is no vibration in the steering wheel, but there is a little in the seat, because some of the vibration feels like it is coming from the rear of the car.

ratrap1964

You will just have rotate the driveshaft on the pinion yoke. I would mark it (you can use whiteout or nail polish if you don't have a paint marker) and remember which way you rotated it. Drive it and see how it is. You have 3 chances to get it right.

Portmaster

I'd try just backing off on the U-Joint flange bolts and then torquing them down evenly. Lots of people crank down on the first bolt and then do the others resulting in a flange that isn't seated just right. It cost nothing but about 10 minutes of your time.

mustangsneverdie

wtf does marking the driveshaft do? I've never done it

mustangsneverdie

why does everyone say you need to mark the driveshaft but when I asked why no one can tell me

Portmaster

On a car that has the original driveshaft or one I disassemble I mark the location of the shaft with a yellow marker like they use at the salvage yards. I just like to put stuff back like I found it just for that extra security.

On a two peice driveshaft it is important to index the two shafts but on a 1 peice shaft if doesn't make a differance. The driveshaft is balanced before it goes in the car not while it's in there. If you can take a driveshaft from one vehicle to the next and order a new driveshaft that has never been in anything there is nothing wrong with changing the position.

If the need for marking the shaft was there you would be in a world of hurt during a gear change. I just mark the flange because my customers didn't want to pay me extra to wire brush the flange.

mjr46

marking the driveshaft on a one piece unit is often fro just piece of mind, cause what happens when you buy a new one such as an aluminum one, will it matter?? hmmm often hasn't for me but I always try and keep the old one marked , just incase a prob arises...............as for the vibration, when did it all start?? are the tires balanced properly???