The Stovebolt Site Forums The Shop Area Driveline Clutch test?

Yesterday, I noticed it seemed harder than normal to get the truck moving from a stop. Had to rev more and nothing happened until very top of pedal travel.

1951 truck with late 235/sm420. (Thus, I’m taking off in 2nd) Unknown miles on engine/trans/clutch, but would not shock me if the clutch is plumb worn out. I would say, up until yesterday, the clutch has always worked quite well since I’ve had it back on the road.

I need to check the free play adjustment. When I’ve done that in the past, it’s always seemed fine.

As for the testing the clutch itself….put in high gear with brake applied, slowly let out clutch, and see if it dies or stays running. Does that sound about right?

I’ve owned a lot of manual vehicles in my lifetime. Guess I’ve just been lucky to never have one with a bad clutch. New territory for me.

Update:

Should have walked out and checked the free play before I posted that. Have a definite lack of free play. No time today to crawl under and see if there’s any adjustment left.

Am I right in assuming that cab mounts and motor mounts might play into this equation? Geometry of clutch linkage? I do have reason to suspect at least some of the mounts are shot.

As for the clutch function test itself, I’d still like to hear some ideas on that for future reference.

Motor mounts might make a difference in clutch free play, but not cab mounts. The pedal shaft is mounted to the frame, so the cab position has no affect on clutch adjustment.

Your clutch test sounds about right.
I've had a clutch that wore out on a truck and could hammer the go-pedal in high gear going down the highway and have it slip. Of course drag racing the truck couldn't have had anything to do with that, right?

Good point. I do figure the cab mounts might make the pedal arm drag on the floorboard, however.

Not to add confusion to the mix but, do you have any oil leaks that may have contaminated the clutch assembly? As for your test, that is how we would do it on the Military Trucks.

Best and easiest clutch test is to drive along in 3rd or 4th approx 2500 RPM, clutch fully engaged (pedal up) and increase throttle quickly. If RPM’s increase and speed does not; your clutch is ill.

I knew for certain Ol' Roy's clutch needed replacing and that the problem wasn't a worn out engine or bad carburetor when it wouldn't drive up a pair of ramps in the driveway.

Pretty sure the truck passed this test multiple times on my long drive yesterday. Maybe more of an adjustment problem then?

No NEW oil leaks. They’re all ancient and scabbed over.

Yup, if it passed this then probably an adjustment issue.