Clutch break in - Miles or shifts?

Qship5 · 11th April 2008, 05:09

I just had my new clutch installed and based on the posts I've read some people say to shift easy for the first 500 - 1000 miles and some say 500 - 1000 shifts. Which is my best bet? After the first 500 - 1000 miles or shifts can I just go straight from easy shifts to full on aggressive shifts? I have a local chapter DE/Club Race event in two weeks and am wondering if it is too soon after the new clutch to participate. Any thoughts? At the price of our clutch installs I don't want to shorten the clutch life unecessarily.

Thanks,

Mike

jetblack01m5 · 11th April 2008, 05:15

I've been told 500 miles or so of normal around the town driving before beginning to get aggressive with the shifting.

badboypolar · 11th April 2008, 05:22

The point of "breaking in" a clutch is to get heat into the organic compounds and the bonding agents to "solidify" the mix. While I don't suggest using the break pads break in routine, you can break in a clutch without babying it around for 500 miles. If you can get some good heat into the clutch without being aggresive then it would be sufficent enough for your track day.

If nothing else, use the 500 miles rule of 70% city, 30% highway as best you can.

Need4Spd · 11th April 2008, 06:02

Shifts. Think about it. Yes, there is the heating issue, but if you get on the freeway and into 5th or 6th gear and drive 1000 miles w/o shifting there will be next to zero wear on the clutch. Drive 100 miles in a city with stop signs at every other corner and you will have lots of wear. In any event, I would not rip into the clutch even when fully broken-in, as it is a known weak point (uses same transmission/clutch as M3 6 cyl., which has far less torque).

CSBM5 · 11th April 2008, 13:45

First posted by XrayMD, per BMW it takes 800-1000 shifts as seen below. Note the info below also includes a process for the tech to take for M5/Z8 cars to help initial break-in prior to giving the car to the customer (which I'm essentially sure almost none of them follow).

Shoot for ~1000 shifts at moderate rev differentials, no high rpm upshifts, no hard starts, etc., would be my advice.

Chuck

Quote:

BMW AG - TIS
RA: Breaking in SAC clutch
Issue status (03/2002)

Break in the friction linings of the clutch by applying light to medium loads, in the same way as for brake linings. This preconditioning creates a carbon layer between lining and metal friction surface which in the end generates the necessary coefficient of friction. Breaking in can take the form of either normal driving with many gearshifts or a specific breaking-in program on gentle gradients.

"Normal" driving will not damage the clutch. "Normal" driving conditions involve drive-off speeds of up to approx. 2500 rpm on a medium gradient, e.g. when driving onto a transporter. Normal driving off on a level surface at speeds up to approx. 2000 rpm are likewise sufficient.

Sporting driving maneuvers will destroy a new clutch! These include driving maneuvers at high differential speeds, overlaps or very high drive-off speeds, e.g. when driving onto a transporter.

When a vehicle is moved "normally", an empirically established figure of approx. 800-1000 gearshifts is applicable to an optimally broken-in lining.

Please conduct the following breaking-in program in order to avoid later customer complaints:

* specifically for M5 and Z8 vehicles

Breaking-in program for approx. 30 km on road

Vehicle subject to "moderate" shifting processes

Drive off at max. 2000 rpm; upshift 1->2, 2->3, 3->4; upshift at 3500-4000 rpm, downshift 4->3, 3->2, 2->1, downshift at 2000 rpm

Drive off 3 to 5 times on a gentle gradient up to approx. 12%, drive-off speed max. 2000 rpm

ecalcagnino · 11th April 2008, 14:41

Thanks for the official post CSBM5. Lots of up/downshifts at moderate revs (2k-4K) for 500-600 miles of mixed driving is what I was told by BMW.

By the way, isn't that new clutch smell scary and god-awful? Man...

Eric

jetblack01m5 · 11th April 2008, 16:13

Quote:

Originally Posted by ecalcagnino

By the way, isn't that new clutch smell scary and god-awful? Man...

Just like breaking in the brake pads... yum yum chemical BBQ smell.

Need4Spd · 11th April 2008, 16:36

Quote:

Just like breaking in the brake pads... yum yum chemical BBQ smell.

If you think that's bad, you should try the Centric Posi-Quiet brake pads. Yow what a smell! But it goes away after bedding-in and a few hundred miles, and the pads are super. As I recall, my Tubi exhausts smelled pretty bad on break-in, too.