I posted a while back about some noise/vibration coming from under the car. Ujoints were tight, tranny mount and engine mounts fine etc.. Pulled the drive shaft out yeterday and took it to a local shop to have it spun. He called me at work almost laughing! He said it was WAY out of balance and was surprised I have been driving it. He said u-joints were fine but he replaced them with heavier duty units (no charge) and balanced my driveshaft. Going back in tonight and could be the easiest $40.00 I ever spent to solve a problem. My ? is.. How did it get this way? This combo has been in my car since 1982. All I diid was rebuild the motor, suddenly the driveshaft is bent? How does this happen? I don't really expect an answer, just wanted to share.
I did the same post a few weeks back, only I found that my shaft was not necessarily out of balance, just not straight. I have a hole in my floor where the shifter used to go, and I once looked down and saw the shaft was "wobbly". Put a ball point pen down the hole, and slowly drove with the pen resting on the shaft. I had about 1/4" deflection. This thing shimmied all over the place at high speeds (above 70). We talked about "phases" and I turned my shaft 180 degrees around in the u-joint seat, and I lost most of the shimmy. How did it get bent? Was it bent from the factory? Still don't know. Does your car feel different now that you have it balanced? I wonder if mine has been balanced to correct the bend at the factory. Keep in mind that this car has 58,000 miles on it. The first 55,000 were put on by my wife's great grandmother (really), and she never went over 55mph. Now, the last 3000 miles I put on, again, seldom over 55mph. But, I get to 55 very quickly
I will go out on a limb and say (opinion not fact based at all) that most shafts are out of balance and have some runout strait from the factory. Tolerances were much greater "back in the day" Today cars have to be silent,smooth, and otherwise perfect for people to be happy with the product. As we modify these cars/disassemble them and get them back together the problem is magnafied. Since we are looking for every noise/vibration and are more in tune with car since we just spent way to much money and expect perfection. I used the Aluminum FRPP for the fox body mustangs and it is smooth as silk. I do have a slight vibration from the rearend as the gear set lash needs to be set again as it has some wear and tear or a bearing is starting to go. I know a few others have used the same shaft. I had to get a different U joint for the rear. Precesion U Joint Part number 347 or 331(been awhile). I did have to use cups from the mustang u joint. On a nine inch rearend I think the mustang u joints fits the pinion and no swap is needed. The shaft is tad on the short side but so far no problems other than a broken u joint(I didn't have a saftey loop either, did after that experience ) Happy Mavericking.
Hmmm, ran smoother. BUT!!! I mentioned in another post that while under there I saw rub/scrape marks above the u-joint in the tranny tunnel. Uh Oh.. I painted it black, came home and installed the "new" driveshaft. Test drive, rub marks! I felt it under HARD acceleration. SO.. Put a jack under the tailhousing with the driveshaft out and jacked it up slowly. The transmission lifted off the mount slightly on one side! Err, pulled the pipes, crossmember etc and removed the mount but for the life of me, can not see a crack or a break. What gives? How flexible should these mounts be? I will try and post a pic of where it was lifting.
Hmm, can't seem to be able to put an arrow on here! Lifting on bottom left corner of pic. It is seperating from the mount on he tranny and the crossmember on the drivers side. Ideas?
New mount from autozone. Compared to old one, big difference..We will see in the am. Txs for the comments. Scott
I bent my original dshaft. Had to get a larger one built for me. They sure are skinny shafts from the factory. Dan
