Bucking after new clutch install

[NoHaveMSG]

Originally Posted by blsfrs

Back in the good old days, Chevys used the same input shaft on everything they made. We had an input shaft alignment tool that worked on anything GM from the 1940's thru the 1980's. Even the bolt pattern on the transmissions was the same.

I would say that 98% of the time, the plastic tool will work just fine, if you are careful.

Most Subarus are the same too.

It's overkill if you are being careful but there ain't no kill like overkill.

[Ultramaroon]

Originally Posted by blsfrs

I would say that 98% of the time, the plastic tool will work just fine, if you are careful.

Agreed.

[jeepmor]

Originally Posted by MX-5RACER

This could also have been clutch chatter from oil being left on the pressure plate or flywheel during installation. I have also seen cases where someone lubes up the transmission input shaft a little too much and flings grease onto the clutch.

The oil on the contact surfaces causes slip/grip and hot spots and can lead to chatter.

Not on this one, second shop stated install was actually squeaky clean. Unless the failing oil seal did get some on there. But still doubt that, issue was present the second I drove it home from initial clutch change and never changed.

Originally Posted by blsfrs

I know that this subject has been discussed ad nauseum is other posts, but I still don't understand the logic behind using the Gilkin tool vs a plastic one.

If the clutch disc is successfully "aligned" to allow installation of the transmission, what other "alignment" is relevant? I do not feel that I can move forward into the new year without understanding this concept.

Agreed, the spinning on the spline assembly would self correct on the first powered engagement cycle. Unless the tool leaves crud behind leaving it off balance, even then, it'd on the order of thousandths of an inch. If you can assemble it, it should self correct on the first engagement, that's how they work.

Originally Posted by Ultramaroon

I've wondered about this many times and the only potential issue that I can picture would be deformation of the friction disc about the hub as the input shaft is loaded to mate with the pilot. That seems like a stretch but the end result would be a dragging clutch.

This one could be tolerance stacking all the wrong ways. IMO, namely the throwout bearing snub bit would have the highest alignment tolerance, and if too far out, hold the TOB off center from the input shaft. I did quite a bit of tolerance stacking analysis in solar due to upstream material being utter shit and being the end of the line engineer who had to explain why my upstream teammates modules sucked pond water.

It adds up quick, but short story. It's the square root of all the respective squared values of each tolerance in the system of parts. The real tolerances provided by the equipment (add poor tech operations), not the pie in sky charts they created off a few runs produced by the best techs in the factory. The stack with all the slackers running the show and slipping the material out of spec material through. I was also the metrology engineer, I had the actual data. All of it. But that's different story.