wrp
01-30-2008, 06:14
I went to the single piece DS a couple of years ago. At first everything was smooth and there were no issues. Then, after installing 3.91s an almost gradual vibration appeared. Watching the threads I initially concluded it was the DS itself. I put a camera under the car and video'd the DS at speed on a dyno. Nada, smooth as a baby's butt. On the road, when crossing 80 MPH it would start to vibrate and definitely vibrate when I let off the accel. Anything over 130 was difficult as the vibration would get bad enough to effect handling. Top of the traps in the 1/4 mile was about the limit.
Well after looking at the DS we figured maybe the half shafts. We tried all that rotating 180 degrees and crap. the differential with the 3.91 install was starting to howl too. I went back to get it fixed and they rebalanced the DS which was not out of balance. We had the Transmission out and replaced the shift guide plate (a hint there was some internal stress on the tranny), shift fork pads, and a couple of synchronizers. Still vibrated so we rebuilt the entire rear diff and replaced the existing one with the new rebuilt unit. During that process we found the old diff with three bolts finger tight and one cinched. The adjustment ring keepers on the side of the differential were missing. Apparently the guy was a little rushed assemblying it after replacing the shift guide plate.
We rebuilt the rear end and replaced it and took it out, still vibrating but at a higher speed, like 105. Conclusion was the angle of the DS Pinion was changing as the car suspension compressed. Stiffening the rear with the Konis seemed to help which led us to the conclusion.
Then last November, broke the front yoke on the 1000 HP DS. There is a clue. Replaced it with the 200 MPH Ds, longer yokes, and two days later broke an axle stub. Replaced that with stub to hub and took her out. Still vibrated. this tiime started about 150 and got so bad at 170 had to let off. Okay getting better. Then the clutch started going, its like the whole driveline had self destructed from back to front. so with new DS, new stub to hub, we went to put in the clutch and I asked them to go through the tranny and put a kit in while it was out. Also changed to the Hurst shifter feeling the brutality of the GMM may have been causing synchronizer/shift guide plate and shift fork/pad problems. No ding on the GMM, I beat the chit out of the shifter and was having a hard time keeping the stop bolts adjusted right, bolts were getting pounded out of shape by my shifts. Just liked the look of the Hurst and figured the springs would buffer the shock some.
When they tore down the tranny they noticed the 5th and 6th gears on the main shaft were loose, these are press fitted gears I think. Also the bearing cage on the back of the shaft literally crumbled when they pulled it (http://www.putfile.com/pic.php?img=7582030). SNL has a guy that works magic on these things and he fixed it. they had to rebuild the material on the press bearing race on the mainshaft for the gears, regroove some of the splines and remachine and balance the whole shaft. They also replaced the rear bearing and shift guide plate, shift pads, and synchronizers.
Son of a bitch!!! I touched 170 last night with no hint of a vibration other than the tires/road noise. Here are some thoughts.
Probably every vibration problem is different, maybe not though. Maybe each feeds on the other.
My car was hard to shift the day I bought it. To go from 2nd to 1st when stopping was noticably difficult.
First time I rebuilt the tranny had a broken snap ring (http://www.putfile.com/pic.php?img=7582010), worn synchronizers (at 40,000 miles) (http://www.putfile.com/pic.php?img=7582011), and the reverse shift fork position was blocked by a bent tab.
Five clutches burned out (http://www.putfile.com/pic.php?img=7582026) all showed the same heat distress patterns on the flywheels and wear patterns on the pucks (http://img2.putfile.com/thumb/1/2901140660.jpg) but the failures varied from 2,000 to 20,000 miles.
One reputable repairman told me the tranny problems I was having indicated pressure greater than intended on transmission internals, led me to that revival on clutch lines and I got a Classic Tubing Stainless Steel one (http://www.putfile.com/pic.php?img=6527566).
Rotating shaft and axles did nothing to improve the vibration
Tightening rear diff and undercarriage suspension arm bolts seemed to help
new driveshaft helped
stub to hub helped
Mainshaft repair cured it
Don't know now whether these are all interrelated but I suspect they are. That one point of failure will lead to the others failing. I am speculating that the guys with OEM DS could have the problems but not see the early stages since the rubber connectors on the propeller shaft will dampen the vibration and effects.
High HP and torque guys with vibration issues might consider on the next clutch replacement having a rebuild kit put in the tranny and having the main shaft looked at specificially. Guys and gals with vibrations not coming from battery powered devices might want to consider having that checked. A hint is that on a lift you can feel play in the output shaft of the tranny. I am not sure if that is a sure sign but you never know.
Well after looking at the DS we figured maybe the half shafts. We tried all that rotating 180 degrees and crap. the differential with the 3.91 install was starting to howl too. I went back to get it fixed and they rebalanced the DS which was not out of balance. We had the Transmission out and replaced the shift guide plate (a hint there was some internal stress on the tranny), shift fork pads, and a couple of synchronizers. Still vibrated so we rebuilt the entire rear diff and replaced the existing one with the new rebuilt unit. During that process we found the old diff with three bolts finger tight and one cinched. The adjustment ring keepers on the side of the differential were missing. Apparently the guy was a little rushed assemblying it after replacing the shift guide plate.
We rebuilt the rear end and replaced it and took it out, still vibrating but at a higher speed, like 105. Conclusion was the angle of the DS Pinion was changing as the car suspension compressed. Stiffening the rear with the Konis seemed to help which led us to the conclusion.
Then last November, broke the front yoke on the 1000 HP DS. There is a clue. Replaced it with the 200 MPH Ds, longer yokes, and two days later broke an axle stub. Replaced that with stub to hub and took her out. Still vibrated. this tiime started about 150 and got so bad at 170 had to let off. Okay getting better. Then the clutch started going, its like the whole driveline had self destructed from back to front. so with new DS, new stub to hub, we went to put in the clutch and I asked them to go through the tranny and put a kit in while it was out. Also changed to the Hurst shifter feeling the brutality of the GMM may have been causing synchronizer/shift guide plate and shift fork/pad problems. No ding on the GMM, I beat the chit out of the shifter and was having a hard time keeping the stop bolts adjusted right, bolts were getting pounded out of shape by my shifts. Just liked the look of the Hurst and figured the springs would buffer the shock some.
When they tore down the tranny they noticed the 5th and 6th gears on the main shaft were loose, these are press fitted gears I think. Also the bearing cage on the back of the shaft literally crumbled when they pulled it (http://www.putfile.com/pic.php?img=7582030). SNL has a guy that works magic on these things and he fixed it. they had to rebuild the material on the press bearing race on the mainshaft for the gears, regroove some of the splines and remachine and balance the whole shaft. They also replaced the rear bearing and shift guide plate, shift pads, and synchronizers.
Son of a bitch!!! I touched 170 last night with no hint of a vibration other than the tires/road noise. Here are some thoughts.
Probably every vibration problem is different, maybe not though. Maybe each feeds on the other.
My car was hard to shift the day I bought it. To go from 2nd to 1st when stopping was noticably difficult.
First time I rebuilt the tranny had a broken snap ring (http://www.putfile.com/pic.php?img=7582010), worn synchronizers (at 40,000 miles) (http://www.putfile.com/pic.php?img=7582011), and the reverse shift fork position was blocked by a bent tab.
Five clutches burned out (http://www.putfile.com/pic.php?img=7582026) all showed the same heat distress patterns on the flywheels and wear patterns on the pucks (http://img2.putfile.com/thumb/1/2901140660.jpg) but the failures varied from 2,000 to 20,000 miles.
One reputable repairman told me the tranny problems I was having indicated pressure greater than intended on transmission internals, led me to that revival on clutch lines and I got a Classic Tubing Stainless Steel one (http://www.putfile.com/pic.php?img=6527566).
Rotating shaft and axles did nothing to improve the vibration
Tightening rear diff and undercarriage suspension arm bolts seemed to help
new driveshaft helped
stub to hub helped
Mainshaft repair cured it
Don't know now whether these are all interrelated but I suspect they are. That one point of failure will lead to the others failing. I am speculating that the guys with OEM DS could have the problems but not see the early stages since the rubber connectors on the propeller shaft will dampen the vibration and effects.
High HP and torque guys with vibration issues might consider on the next clutch replacement having a rebuild kit put in the tranny and having the main shaft looked at specificially. Guys and gals with vibrations not coming from battery powered devices might want to consider having that checked. A hint is that on a lift you can feel play in the output shaft of the tranny. I am not sure if that is a sure sign but you never know.