Shifting too soon?

Franklin- Low revs will not cause clutch wear as long as the revs are matched. Same with high revs. The test for clutch slip looks for rising revs and no increase in car speed before the clutch locks up. It is done at an engine and car speed where the results are noticeable, not because that rev range is causing more wear.

Taz
Terry Phillips

 

Its not low revs that cause clutch wear; it is too low revs in a gear too high for that engine speed. A high gear at a very low engine speed places a higher load on the clutch which results in the extra wear.

 

How can low engine speed place a higher load on the clutch?
I think you are confusing what you feel when you shift with what the clutch "feels" when fully engaged. Yes, if you are trying to start the car from rest in 2nd gear you will have to slip the clutch a lot. But that is a different issue from the clutch failing to transmit the load when fully engaged.

 

I think the OP was just talking about "easy does it" driving at part throttle. Pretty low wear and tear on things that way.

If the clutch is shuddering or the engine is lugging you're doing it wrong.

 

A clutch suffers NO wear when fully enguaged; just like brakes suffer no wear while cruising donw the interstate at a constant velocity. The only way for a clutch to suffer wear is if the two disks are slipping.

THus, idiot drivers can suffer clutch wear by trying to use a numerically high gear than corresponds to the rotatioial rate of thw eheels and holding the clutch partially enguaged to keep the engine from blucking.

But if you foot is off the clutch pedal, the healthy clutch is suffering no wear.

For me, in my F355, I can use 6th gear down as low as 1150 RPMs, a slow gentle prod on the gas pedal and the engine picks up speed smoothly.

 

Franklin- Baloney. A mismatch of revs will wear more at a higher torque rpm than at a lower torque rpm and there is no clutch wear on an engaged clutch that is not slipping, regardless of rpm. How is something going to wear when it is locked up solidly? The clutch could care less what the engine is doing once it is engaged. That is why the engine stalls if you release the clutch too late as you come to a stop. The solid connection shuts down the engine because nothing is budging the clutch connection, even in first gear with the highest torque multiplication available.

If that is a pet theory, it does not float. Lugging is bad for the engine, but does nothing to the clutch.

Taz
Terry Phillips

 

Maybe in theory, as there IS friction even though clutch is fully engaged. And friction, even with a fully engaged clutch, causes wear in theory, although, may be hard to measure.

But in reality/practical world, how much is this a factor in a clutch wear? I would gamble any day the other factors like bad clutch engagement//riding clutch/shifting too often (as opposed to moderating traffic and avoiding changing gears)/jack rabitt starts from a red light/etc etc are more to blame-by far.

 

Of course there is friction when the clutch is fully engaged. But provided the clutch is working properly there is NO slip, and hence no wear.

 

Good point, loss of friction is a sign of the cluch wearing out.
Also to the OP question, lugging an engine is never good and if you can't tell by feel/sound when the engine is happy you should drive an automatic.

Russell

 

Crud, a clutch is all friction when locked up, but no slip is no wear.

Taz
Terry Phillips

 

AND he's pretty fond of public breast feeding I hear as well....





Jedi

 

Right. Thats why I said in theory. Just cuz you have no "slip", doesnt mean you have no wear. friction causes heat, and heat causes wear. You can not have heat generated without a consequence. But this type of wear is NOT noticeable. Thats why its in THEORY and not easy to actually measure or even notice.

The causes I listed are the ones that cause noticeable wear.