FuzzyLog1c

iTrader: (4)

A lot of the transmission installation guides that I've read indicate that you should NOT remove the rubber coupler that serves as the interface between the driveshaft and the transmission. Why is that?

Related note/question: when trying to get the driveshaft to decouple from the transmission, I loosened both sets of bolts (all six), and the rubber coupler came off when I pulled the driveshaft free. Fortunately, I marked the driveshaft propeller flange and rubber coupler so that I could re-attach them in the same orientation relative to each other. However, I neglected to mark the transmission side, so there's a 2/3 chance that I didn't attach the driveshaft in the same orientation as it was in before.

With the new LS7 flywheel and clutch installed, I've been getting some significant vibration from the clutch pedal just as I press or release--but once the clutch is at least moderately engaged / disengaged, the vibration is completely gone (I've tested it up to 5500 RPM).

Question is: is the vibration a byproduct of the new flywheel, or do you think I need to remove / rotate the driveshaft relative to the transmission once or twice to get back to its factory orientation?

killernoodle

It shouldn't make a difference, the driveshaft is indexed in the output shaft of the transmission by a protrusion on an end of the driveshaft. Basically, the coupler doesn't serve to "center" the driveshaft to the output shaft, it basically just handles the torque forces. If you have driveshaft vibration, you need to have the driveshaft balanced around the pin that sticks out of the end of the shaft.

If you are getting vibration through the pedal, you may just need to break the clutch in some more. My Mcleod twin disc had a lot of chatter when I first put it in but now it has smoothed out a lot.

substantine

Did you ever fix the problem? I just changed both of the flex disc couplers and the rear differential bushing, the vibration started after changing the rubber couplers to aluminum ones. Then i changed a worn out bushing in the rear differential which minimized the vibration, but it's still there.

FuzzyLog1c

iTrader: (4)

Yes. It turned out that it was due to a brand-new LS7 clutch combined with my LS2 slave cylinder + a Katech spacer. When I upgraded to a LS7 slave, the vibration during clutch engagement/disengagement went away due to its larger outer diameter. The slightly narrower LS2 slave apparently wasn't actuating all of the LS7 pressure plate fingers equally.

cam3439

Sounds like you need to get the trans back into proper alignment; might need to shim it. The rubber couplers flex enough to hide this vibration, whereas the aluminum couplers don't flex enough.

substantine

Does this mean who ever worked on it before turned it and placed it back incorrectly? A friend says it's got to be misplacement of the shaft to the trans or the rear differential. Where do i find how to fix this?

DougNuts

iTrader: (1)

Is there a place that sells the factory GM rubber coupler?

substantine

You just gotta search online. I got mine from https://www.revshift.com/shop/cadillac.html, with a lifetime warranty.

DougNuts

iTrader: (1)

I have seen a couple urethane pieces, but I was hoping to find a new GM piece to try out. Can it be purchased as a single part anywhere?

substantine

I might have found my problem. But does anyone here know where to find a replacement for that bushing or carrier bearing?

DougNuts

iTrader: (1)

From what I've been told, it is non-serviceable and you have to buy a new driveshaft from GM.