Clutch life in the city

[truegearhead]

I just replaced my clutch about 5,000 miles ago but I swear I can feel it wearing rather quickly. I live downtown and go through probably a dozen of 4 way stops/ redlights on my way to work and on my way home. Its never been a problem with the manual BMWs I've had but something tells me the Boxster clutch isn't up for it. Has anyone experienced this?

[ekam]

New clutch 5000 miles ago? It's just getting broken in...!

[pothole]

If you drive it right, start stop traffic isn't too bad on the clutch. The thing that really wears the clutch (apart from riding it wrong in start stop traffic) is not rev matching downshifts.

The clutch on my 2.5 was heavy and biting high when I bought it on 74k miles. It's now on 106k miles with the same clutch. And I drive it like I stole it. I just don't go in for heroics off the line and I rev match every single downshift.

[BYprodriver]

Originally Posted by pothole

If you drive it right, start stop traffic isn't too bad on the clutch. The thing that really wears the clutch (apart from riding it wrong in start stop traffic) is not rev matching downshifts.

The clutch on my 2.5 was heavy and biting high when I bought it on 74k miles. It's now on 106k miles with the same clutch. And I drive it like I stole it. I just don't go in for heroics off the line and I rev match every single downshift.

I fail to see how higher rev clutch engagement minimizes wear.

[Overdrive]

Originally Posted by BYprodriver

I fail to see how higher rev clutch engagement minimizes wear.

There's a lot less shock to the system if your engine speed is close to or matching with what it should be at the speed you're going before you engage the clutch. If you just depress the clutch, change gears, let the revs drop down and then re-engage the clutch quickly you get that big lurch and possibly even an instant of everything locking up because of the sudden shock. On the other side of it, if you ease the clutch out and gradually let the engine pick up speed as the clutch engages, you're prematurely wearing the clutch due to the slipping.

[thstone]

A new clutch should provide 50,000 miles of use at a minimum. I didn't replace my clutch until 92,000 and a lot of people get over 100,000 miles.

Can you describe why you think that it is wearing out early? What symptoms are you feeling? That might help the Forum to figure out what's going on.

[pothole]

Originally Posted by BYprodriver

I fail to see how higher rev clutch engagement minimizes wear.

Whether the revs are high or low is notthe issue.

It's whether the revs match road speed when you re-engage the clutch. When you change up it's not an issue so long as you make your changes reasonably rapidly. You lift off and push the clutch, the revs begin to drop, but you're already selecting the next gear and re-engaging the clutch. When you select a higher gear, the result is lower revs for a given road speed, so road speed and revs are naturally fairly closely matched as you complete an upshift - or pretty much perfectly matched if you know what you're doing.

On a downshift, you're selecting a lower gear which means higher revs for whatever road speed you're doing. If you just change gear without rev matching via the throttle, it'll be clutch friction that lifts the engine speed to match road speed. A blip on the throttle as you change gears, however, can match the two and if done well the wear on the clutch for a downshift is close to zero.

What you're aiming for is gear changes where you cannot feel the clutch engaging. The change is completely smooth.

If you do this, you'll dramatically increase the life of your clutch.

The big difference in clutch life in these cars is down to how they're driven and not the traffic or road conditions. Same goes for supercars. You hear about people getting through clutches in exotica in 5k miles, which sounds ridiculous.

But this isn't because they're driven hard or because the clutches have silly low life spans. It's because they're driven badly and in a supercar the loads are very high, so when you don't change gear properly, the wear rates are horrific.

Rev match all your shifts and you can spend all your time on track days and still wear the clutch less than some other guy who just pootles around town but can't change gear properly.

[Overdrive]

Originally Posted by pothole

...

What you're aiming for is gear changes where you cannot feel the clutch engaging. The change is completely smooth.

If you do this, you'll dramatically increase the life of your clutch.

...

Rev match all your shifts and you can spend all your time on track days and still wear the clutch less than some other guy who just pootles around town but can't change gear properly.

Absolutely. Nailing a rev-matched downshift is quite rewarding and just feels awesome...not to mention your passengers will appreciate the lack of tossing them around.