Jerking clutch pedal mostly under a load?

That’s what I have seen when the pads/buttons are cupped

 

What does it do in reverse

 

Look very close at the engine mounts on the sides of the flywheel housing
If they’re loose the engine/ trans will twist separate of the frame and sometimes make a very uncontrollable clutch engagement but usually only in one direction.
Probably would be much cheaper fix and either way it’s going to need fixed if there loose or worm out

 

2007 International 9400i, ISX-15, 10-speed Eaton.

 

Both my rear mounts were shot. Like REAL F'N shot. Fixing them made the gearshift stop moving four inches both ways, and stopped the clutch pedal from moving around, but it didn't change the "instant engagement" at all.

 

Make sure if you are going to have a new clutch put in that they do the full complete 100% job.

That means replace the motor mounts if needed. Front and back.

Also replace the cab mounts if needed.

-New rear main seal
-New, not reman genuine clutch
-Resurface the flywheel
-new ring gear if needed
-new pilot bearing
-new transmission shaft and bearing
-new forks
-new clutch brake
( I prefer the two piece so that it is easier to change later if needed)
-new cross shaft bushings and shafts
( most shops skip this. Make sure if it is needed which it probably is, that it is done very important)
-And make sure all linkage eyes and any pivot points that need to be replaced are replaced

And after you have all of this done make sure that you grease the throwout bearing and the cross shaft bushings every time.

I do mine every 3000 miles but make sure at the very least it's done regularly.

If you do all that your clutch will be smooth like a baby's rump roast.

 

Excellent advice!

 

Other than motor mounts, everything he's talking about is in the Eaton installation kit. Even comes with a new input shaft and bearing for the tranny. Plus new gaskets for shift tower and bellhousing. And that's a good one to change. The whole kit is like $350, and you shouldn't go without it in my opinion. Too many goodies for a low price.