Thunderace clutch rebuild.

jcr · Post by **jcr** » Fri Jun 17, 2022 10:56 pm

i have started to get clutch slip when i enter the powerband, so im guessing new plates are needed. engine is on 34500 miles.

i took the plates out this evening and will measure the wear tomorrow when its light.

where is the best place to go for parts? is it best to stick with oem?
is a Yamaha dealer the place to go?

jcr · Post by **jcr** » Sat Jun 18, 2022 12:32 pm

thanks for the reply.
recently did an oil change and used Castrol power 1 10w40 4t semi synthetic.
which is the correct oil according to the Castrol website.

measured the plates and springs today and everything was within service limits.

one thing i did notice though, according to the Haynes manual, the final friction plate should have a notch in one of its tabs, which aligns with some marks on the clutch housing.
i have no idea what purpose/function this serves, but the outer plate in my clutch is the same as all the other friction plates. which im guessing is not good.

jcr · Post by **jcr** » Sun Jun 19, 2022 10:03 am

ive looked at the outer housing and there are no aligning holes. so its looks like Haynes have got it wrong

thanks for all your help creed.

i used an impact gun to release the clutch nut. the Haynes method of putting the bike in gear and having someone press the back brake didnt work.

will it be ok to use the the gun to tighten the nut back up?

Goshreally2 · Post by **Goshreally2** » Sun Jun 19, 2022 8:08 pm

In my search for a decent clutch boss for my genesis I have been looking at exup, yzf 750 and thunderace. Anyway, don,t mean to confuse the alignment mark issue on thunderace but if you look at ebay item number 114891628974 it shows a complete item and there are alignment marks on the left of the housing in the picture. I can,t see a plate notch but the clutch is out and probably not aligned after removal. I have bought quite a few parts from this seller and they are always good, what he says they are and well priced. I have phoned him before and he is a reasonable individual so he could probably answer your question as he will have seen a number of these.

jcr · Post by **jcr** » Sun Jun 19, 2022 10:21 pm

im not seeing any marks in the photo?.

Goshreally2 · Post by **Goshreally2** » Sun Jun 19, 2022 10:56 pm

Look down the clutch plate tabs. Above the drive teeth on the area that pokes out like a bay has two dots on one of these bay areas and not the others, the two dots are the alignment marks.

Goshreally2 · Post by **Goshreally2** » Sun Jun 19, 2022 11:01 pm

I think you are right. Springs are the best and probably cheapest way to go first.

Post by **nuggitt** » Mon Jun 20, 2022 8:36 pm

I think I need to book in at Specsavers. Are we talking these marks?

Goshreally2 · Post by **Goshreally2** » Mon Jun 20, 2022 9:27 pm

If you go up about 1 cm from the tip of the arrow in your picture you will be at the point where the housing bulges out. There at two raised dots on the top lip of the bulge. If you hover over the ebay picture it picks them up much better. It seems these marks appear on genesis, exup and thunderace. If you have a Haynes manual for genesis and exup it seems its they have the clutch right. The diagram in the Haynes manual that shows these dots is on page 3.26 diagram 19.24. if you buy an ebc clutch kit they do away with the plate spring but have an alignment notch on the outermost friction plate. I suspect most aftermarket kits do this as the plate spring leaves really nasty marks in the boss. I will say I had drag issues with ebc plates and refitted my old set and one ebc plate - but I took the edges off the ebc friction plate tang slightly to help it move in the housing. If I was to refit another clutch set it would probably be a surflex. I am still looking for a good condition boss - over to classifieds.

YAMAEXUP · Post by **YAMAEXUP** » Mon Jun 20, 2022 11:36 pm

I fitted Barnett heavier clutch springs to my Exup-R not long after buying it back in '93. I also bought OEM friction plates, soaked them in engine oil & awaited the time when I would need to install them....& that was 55k miles ago.

Post by **nuggitt** » Tue Jun 21, 2022 9:02 am

Don't worry I'll catch up in a minute.

Are these the marks?

Post by **nuggitt** » Tue Jun 21, 2022 9:22 am

I think I've got them?

jcr · Post by **jcr** » Tue Jun 21, 2022 10:09 am

nuggitt wrote:Don't worry I'll catch up in a minute.

Are these the marks?

not quite nuggit. if you look at the black hole just below your arrows, that is oval shaped in the pic. where the friction plate edges slot. theres a tiny circle mark each side of the ridge at the base of the hole.

Post by **nuggitt** » Tue Jun 21, 2022 10:18 am

Third time lucky. I hope.

Goshreally2 · Post by **Goshreally2** » Tue Jun 21, 2022 1:20 pm

Yes that's them.