HELP!! 2 Shattered Clutch Plates in 4 Weeks! Why??

[nikki]

4 weeks ago I shattered a clutch plate. Fixed her up and shattered another this past weekend. Does anyone have any ideas why this is happening? Is there something "bigger" that I might be missing? I've had this bike since new and was problem free for 16 months. Using the same oil the whole time (Castrol 10-40 I believe). All fairly new baskets too. Just wondering why - so we can fix the problem asap.

Here is all the extended info:

4 weeks ago:

Riding with 5 hour old OEM inner/outer baskets and 5 hour old fibers and steels. Can't remember if we replaced the springs or not. After about 1 hour of on/off racing that day... I shattered fiber #3 (counting #1 as the closest to the outside). Still rode the bike for another 20-40 minutes after the shattter. Didn't know that was the problem until we took off the clutch cover.

So we cleaned out the pieces from the shattered plate. Filed down the rough edges on the inner hub. The outer basket still looked good. We just replaced the broken fiber at the time. Used all of the same fibers/steels/springs. Bike worked fine for 8 more motos (about 2-3 hours).

Saturday 3-30:

Raced the bike pretty hard on and off for 40 minutes (was revving pretty high in 2nd-3rd gear - sand track :) ). Then it happened again - shattered another plate. Finished the moto and tried not to touch the clutch too much. Took off the clutch cover again to check out the damage. Shattered fiber #4 this time. Not as bad as the first shatter. This time, though, the inner hub was grooved up pretty good and the outer had a little roughness to it, too. Pressure plate (stock - 16 months old) still looks good. This time we flushed out the bike really good to get out the remaining fiber. But I still have this fear that maybe we're missing a few pieces - like maybe they're hiding out somewhere. Any good tips to get all the debris out?

My plan of action:

I'm going with a new Hinson outer basket and a new OEM inner hub and pressure plate. New fibers/steels/springs. And hope for the best.

Does anyone have any ideas why this happened twice in a month? Weak fibers? (Yamaha's do have weak clutches - for example - Hinson only makes fibers for like 3 bikes and the YZ 125 is one of them). Or maybe in the first shatter a fiber suffered a stress fracture? Or maybe there was still a little of the first plate in there to mess things up? Or the springs got hot and lost strength? Or a warped plate? Or maybe something bigger...? :think

Thank you in advance for any help/opinions!

 

[jmics19067]

When you first broke a plate it I guess it would be possible that you over stressed the other ones pretty bad . It must of created a lot of heat when you where still racing while the clutch was slipping. You only replaced the one plate that broke. Then a little bit after another original plate broke? You don't remember if you changed the springs last time take a good look at them now. Although it is hard to decide if it is after the fact I would be just interested.Check and double check the clutch bearing ,thust washers , and pressure plate. I would also make sure the bearing that the transmission shaft sits in is still good. Hopefully it is not a semi sealed bearing and you can see it when you have the baskets out.

 

[wanrep]

Are you soaking the new plates in oil before installing?

Was it the original clutch you replaced 4 weeks ago?
If you're using non-oem plates and they're all the same brand that break, try a different brand or go back to oem.

Double check with the parts fiche to make sure you've got all the washers in the right place.

If you're going to replace the basket, get new bearings, washers and spacers also.

If you don't have one, get a clutch holding tool ($20) and make sure you've got the correct torque on the clutch hub nut.

Good luck

 

[nikki]

Thanks everyone for your help.

I have just ordered a bunch of new toys (Hinson outer basket, 2 sets Hinson friction plates, 2 sets OEM steels, 2 sets OEM springs, 2 OEM inner hubs, OEM pressure plate, OEM bearing/spacer/washers, and some gaskets).

So we're going to replace everything and hope for the best. We're also going to drill holes in the inner hub grooves to help cooling and oil flow - similar to the Hinson inner hub. Hopefully this will help. Thank you again for your replies.

wanrep - yes we soak before installation. And the YZ 125 OEM plates are known to be brittle - so now we're going with Hinson ones. I just replaced the one broken plate the last time... so no wonder another broke! :debil: