How to check if there is a cracked clutch?

[2007Z6ALL-LED]

Reading through someone else's post about cracked clutch getting into the crank and damaged some teeth...It's someone example make others being aware of the possibilities of having crack clutch..

How do I know if my clutch have some plate being cracked? Do I have to open the clutch cover to check it..etc?

Thanks,
jh

 

[FinalImpact]

Prelude.. .. .. If you:
- Drag race
- Slip the clutch under load
- Repeatedly Slip the clutch during take off to prevent wheel spin / allow higher torque from engine to rear tire

These things burn the clutch plates making them weak and **may cause** them to fail.

If in doubt, order some quality parts and remove the cover and replace them. If you just wish to inspect, they should be TAN in color. If black or dark chocolate, I'd replace them. Of course there are specs in the FSM for steels and frictions regarding wear limits too.

 

[ChanceCoats123]

Agree 100% with what Randy said above. Cracked clutch discs should not be a common problem for riders who aren't racing or slipping the clutch with high loads/rpms.


If you're really interested in checking on yours, or just opening the bike up, you'll want to grab a new clutch cover gasket (or be very careful with the one currently in the bike), and pull the clutch cover. As Randy said, normal clutch discs are tan in color. If you see darkened marks, it's a sign of discs that got burned at some point. The burning of the discs is what weakens their structure and eventually leads to failure under future stress.

 

[2007Z6ALL-LED]

Got it...I'm just riding the bike for commute, glide through traffic but not really burn-out or racing at all..I guess mine should be ok...

I will sometimes later to open it up to check as that the only way to see if there is any cracked disk

Thx you all!

 

[The_Paragon]

My question/thought:

Would you be able to find a cracked clutch plate before it granades?
Or do you think that the plate cracks and granades all in the same moment?

 

[TownsendsFJR1300]

My question/thought:

Would you be able to find a cracked clutch plate before it granades?
Or do you think that the plate cracks and granades all in the same moment?

I've never heard of seeing the fiber plate with a hair line crack (or otherwise). They usually fly out of the clutch basket once they fail...The steel plates will discolor / warp, etc but will NOT disintegrate like the fiber plates..

Obviously, as posted above, if you dog it hard, yes, you substantially increase the chances of failure.

For normal riding, redline, etc, its really not a problem. Its when you drop the clutch hard, burn outs, etc that'll catch up with you..

My local shop had an R6 they had to pull the engine out of as when the clutch fiber plates came apart, pieces lodged into several gears. They literally locked up the engine. They had to manually pull the particles out. The shop preferred to pull the engine apart but the owner didn't have the $ to go that deep. And yes, the bike was dogged big time..

 

[ChanceCoats123]

My question/thought:

Would you be able to find a cracked clutch plate before it granades?
Or do you think that the plate cracks and granades all in the same moment?

I've never seen it personally, but I would assume the cracks develop slowly over time due to heating and cooling cycles of the clutch discs. Eventually, enough force from the neighboring discs would cause one of them to grenade.

This could be avoided though, by keeping an eye on the clutch disc colors. I assume you're asking because the discs may not be cracked when you look at them, but could crack down the road. To this I would say that if you see discoloration, it would be a good time for a new clutch to be safe. The EBC racing clutches are less than $200 and you've already got the bike open. There are other even more affordable clutches for those with a strict budget as well. If there is no discoloration of the discs, I think it's safe to assume there won't be cracks either.

 

[fazil]

This issue is for wet clutch bikes i think. BMW bikes, they have the clutch basket in a different place. They can use regular car oil also. Old fashined but solid.

 

[FinalImpact]

At the risk of loosing throttle response from adding mass, having a friction discs on STEEL backed plates would be a win over the aluminum ones grenading.

Both types have a place and can live healthy lives when all is OK. But the stress and heat of Slipping a clutch under load, i.e. 6000 RPM AND, attempting to accelerate down a drag strip without spinning the tire places huge load on the friction discs both thermally and physical stress wise.

Like a brake pad with thermally induced stress cracks, the friction material cracks, induces stress on the OEM Aluminum plate its attached too and then continued thermal change plus stress induce failure.

What I find interesting is the adhesive is not failing like a steel backed friction disc often does. So its the load Plus the centripetal force (inside edge vs outside edge shearing)and some thermal factor induce failure...

Watch a modern dragster make a run. Rather than spinning a tire, they slip the clutch pack with 3000HP. They have LOTS INVESTED!

 

[FinalImpact]

This issue is for wet clutch bikes i think. BMW bikes, they have the clutch basket in a different place. They can use regular car oil also. Old fashined but solid.

I've never seen a dry clutch use an aluminum plate as a backing. Almost always steel. But once again, if you apply max Torque and SLIP that clutch, How long will it work properly?

 

[fazil]

I mean, if the clutch dissolves, it won't hurt engine parts. So it's safe with the dry clutch bikes, if you break any friction plates.