Thread: HELP - Spinning primary pinion (I think)

binding on the spigot bearing is a possilbility......

another cause is a bent clutch plate during install....

or rust/dirt on the input shaft splines...

Thanks DZ

Here's what else I've tried. The input shaft and clutch were new incidently.

I've brought the idle speed to just under 500rpm to see if that would stop the primary pinion spinning - no luck [img]style_emoticons/<#EMO_DIR#>/sad.gif[/img]

If I engage another gear, and keep the clutch depressed for a while (to bring the spinning primary pinion / layshaft to a halt, and then with Jedi speed shift to reverse I can get it in with a slight "crunch". If I don't use the Jedi reflexes and hesitate for a split second, reverse grinds.

Obviously the primary pinion can spin independently of the fly wheel (clutch in, gearbox in gear). But why does it catch?

I did change the engine mounts while I was at it, and jacking the front of the motor up, may have put the primary pinion on a slight angle relative to the spiggot bush. Maybe I should back off all the bell housing bolts (just to take the tension off) and start the car up and see if it all "falls into place."

Any ideas on that one?

(As you can tell, I'm lost and I do not want to beleive that I may have to pull the box out again :x or )

does pumping the clutch pedal help?

I reckon if the clutch is disengageing the plate is bent and draging. Easy to do if you had the wieght of the box on it while putting it back in. Check all the hydraulics first.

Is the spigot a bush in that model?

This sounds very similar to a problem I had with my Rangie, the spigot bush had migrated out of the flywheel very slightly, which had allowed the gearbox input shaft to run out of square dragging the clutch slightly (if you can understand that).


Bushie

Pumping the pedal makes no difference, there are no hydraulic leaks or air in the system.

The clutch engages / disengages smoothly, it does not bite and it engages at mid-stroke; not too early and not too late.

This model does have a spiggot bush. I smeared some oil on the bush and the shaft, just prior to assembly. When I renewed the clutch plate the bush seemed very firmly placed.

I feel it's something to do with the spiggot bush, either the new shaft is slightly (microns) wider, is sitting on a slight angle or has by some other means jammed the primary pinion. It can't be too drastic a grab, because the car is still able to go in and out of gear and the shaft obviously stops spinning with the motor when the gearbox is engaged and the clutch is depressed (provided the t/case is engaged). This is clearly demonstrated by the Jedi manuevre for engaging reverse. But when there is no resitence, the primary pinion spins with the motor and in turn spins the lay shaft.

Thanks for the responses thus far. Please keep ideas and speculation coming as it will help me nut out this problem and consider every angle. I'd rather spend 2 days thinking than two days pulling a gearbox out only to find the solution could have been found without such a hassle.

Is it possible that the clutch plate is in backwards (wrongway round)? as the clutch would then drag enough to give slight problem engageing but the hydraulics would operate smoothly, the pressure plate would exert enough pressure to not show slip unless under hard acceleration

Thanks Rocket,
the clutch plate is in with the boss end toward the gearbox. It's an aftermarket clutch, but it had flywheel written on the otherside and that's how I aligned it.

I'll double check when I get home from work incase the writing on the clutch was wrong.