vibration after clutch install

[dunderkofler]

2500 miles ago, in Alabama, I installed a con-ofe. Immediately after, I got a vibration occurring in fifth gear between 55-70 mph. The vibration is not there at the same speed in fourth nor does it happen at the same rpm in fourth. It is really only noticeable in fifth. The vibration can be felt in the seats and makes the inside rearview mirror useless. We chased the issue through the Thanksgiving holiday without luck. U-joints didn't appear bad but I only had a two foot lever to apply pressure. The center bearing felt good and the rubber surround wasn't visibly damaged. I talked to Southbend and they say that they are almost certain that it is not a clutch issue but rather a driveline issue but maybe it would go away in a few hundred miles. Well I'm back in California now and so is the vibration (and the rubber around the carrier bearing is now ripped in all four corners).



I just got back from a dealership and they say it's not in the driveshaft and they think that it's somewhere in the transmission, possibly in the tailshaft housing. That REALLY is not something I wanted to hear. The dealership isn't where I wanted to take it... but the only decent driveline place in the area is in the process of moving out of town. :{



Any thoughts?

 

[betterthanstock]

If it's not happening in 4th, then it may be a torsional resonance. The center springs of the clutch may be at the frequency (given by the stregth of the springs and the inertial mass of the shaft) that resonates the rear driveshaft.



Did they remove any damper that may have been attached to the front of the the d/s ? Did they remove the center rubber booth, so that the phasing may have been misaligned? Probably not.



Did they drop the shaft? Though it would be out of balance in 4th also.



What about coasting? Drive 10 mph above the offending speed, then take it out of gear, and coast down. Try again, coasting in gear, both gears.



If it's the center springs, then maybe hook up a heavy trailer, and tow it accelerating hard a few times (especially in 4th with the smarty turned up) to see if the springs soften up a bit.

 

[dunderkofler]

Thanks for the response.

No damper was removed and the driveshaft was not disassembled or dropped.

I don't remember it being noticeable while coasting (or even steady throttle for that matter) but I will try again today in both gears and out of gear.

 

[GCroyle]

Might want to check---

Try neutral, set parking brake, accelerate to high RPM. If no vibration, not clutch or F/W.



Drive in 4th at the RPM that it vibrates in 5th, does the vibration occur?



If it is gear specific, not 100% sure, might be a chipped tooth on gear. We had a Ford in the shop one time that had a chipped tooth, bad news as far as vibration goes, gear specific.



Good luck.

 

[dunderkofler]

What about coasting? Drive 10 mph above the offending speed, then take it out of gear, and coast down. Try again, coasting in gear, both gears.

Can't feel it while coasting either in gear or neutral. Only under power.

Try neutral, set parking brake, accelerate to high RPM. If no vibration, not clutch or F/W.

Slowly revved to 2500 in neutral without vibration.

Drive in 4th at the RPM that it vibrates in 5th, does the vibration occur?

No.

 

[GCroyle]

Based on specific to a gear, are you starting to think transmission?



And the driveshaft has been scrutinized?



I don't know the layout of power flow through the gearbox, but if you drained the oil and popped a PTO cover off you can see into the gearbox a bit, don't know if you would see the offending gear or not. 5th gear is in the extension housing and can be seen with it removed. The picture shows a NV4500 that has the 5th gear nut issue so the gear is not in position.



I'm not sure where to continue to search, but I just re-read your original post. It started just after the clutch replacement?

 

[lmills]

When you removed the drive shaft from the rear, did you mark it and reinstall it the same position?

 

[betterthanstock]

It could be something simpler, like a bad u-joint that only jams under power. Accelerate hard in 4th at the same speed, then compare to when you accelerate in 5th. Feel u-joints for heat after driving.



If not, then I would still suspect the center springs. Or did you buy a solid plate (no springs) disc?

 

[dunderkofler]

Based on specific to a gear, are you starting to think transmission?

I don't want to think that. Was fine on the trip to Alabama (and 112,000 miles before that). Gut tells me no, but... .

And the driveshaft has been scrutinized?

Eyeballed + a short lever on the u-joints. Couldn't feel anything loose but I also couldn't apply as much torque as the mighty Cummins.

It started just after the clutch replacement?

Correct. I know... what could I have done to cause this???

When you removed the drive shaft from the rear, did you mark it and reinstall it the same position?

Yes. We also tried it 180 degrees out without making a difference.

It could be something simpler, like a bad u-joint that only jams under power. Accelerate hard in 4th at the same speed, then compare to when you accelerate in 5th. Feel u-joints for heat after driving.

I'm actually hoping for a u-joint. If the vibration is there in other gears it is much less pronounced and happens at a different rpm. I can, maybe, feel a slight vibration in fourth at ~1300 rpm (as opposed to blurring the mirror from 1800-2100 in fifth). As for heat they all feel about the same and none are warm to the touch. In any event, as soon as the driveline shop finishes moving, I need to get the center bearing replaced as stated in the first post. I may as well have the u-joints done and get it balanced too, right?

If not, then I would still suspect the center springs. Or did you buy a solid plate (no springs) disc?

The clutch is just a standard, sprung hub, mu13-1. 25 con-ofe that so many others have installed without issue.



I do appreciate all the help and suggestions everyone has been giving. Thanks.

 

[Motorhead]

Looking at another angle... Was the clutch pilot bearing changed?

 

[dunderkofler]

Looking at another angle... Was the clutch pilot bearing changed?

Yes. Pilot, throwout, pressure plate, driven disk and flywheel were all replaced.