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Clutch problems and possible solution (with pix)

30K views 16 replies 6 participants last post by  JCW 
#1 · (Edited)
Thanks to Crazyczech, I have two of these clutches on my desk and I can finally see where the wear is.

On the clutch basket, which is a cast aluminum piece, there are slots that fit the clutch plates tabs. Where each of these clutch plate tabs bears on the basket, there is a visible and palpable (that means I can feel it :teeth ) deformities in the soft metal. With time, these deformities increase in size and may lead to difficult clutch engaement and disengagement, with or without screeching and/or grabbing.







There has been theories of faulty oil pump sprockets and worn out clutch basket springs. But I think this is the cause of the majority of clutch problems on bikes over time.

I have contacted a machinist that is willing to make some billet clutch baskets and I am trying to gauge interest in this. I'm looking for 5 orders. Final price is still pending but will run about $600. The OEM basket lists for $780. The mod would require your clutch basket as the drive wheels are reused on the new billet basket. Alternatively, a core charge could be placed and I could use the spare clutch drive wheels and refund the money when you send your clutch back to me.

If anyone is interested, let me know. I'll be doing this with or without other orders. It'll just cost me a little more but I think it'll be worth it.

This should apply to the GT, S, R models. They all share the same clutch basket part numbers.
 
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#2 ·
JCW, as far as my knowledge goes, that sort of wear is very common in all of these type clutches.

I also fail to see why a billet clutch would be better..? If you want to minimise the tolerances that you point out wouldn't it be better to make harder faces where the wear is. Which in turn would make the plates wear - which are easier to replace though, but if they wear down too much you could have a catastrophic failure on your hands.

:dunno:
 
#3 · (Edited)
I was thinking a billet basket depending on the material would be harder than a cast aluminum basket. More resistant to deformation. What do you think?

Standard brinell hardness of 6061 T4 alloy is 65.
6061 T6 is 95
"aircraft aluminum" 7075 at T6 temper is 150.
I've seen hardness ratings for cast aluminum in the 20's. But they can also go up to 90's as well.

Brinell hardness test is standard testing that applies 500kg with a 10mm steel ball and measures the deformation to the impact.

Another thought is anodizing the clutch basket to increase it's surface hardness, but you would have to maybe machine a very minute amount of material off the stock basket and replace it with a similar thickness of anodized metal.

Another possibility would be to send the basket for analysis and heat treatment to see if the hardness of the stock basket could be improved. I do not know who would be able to do this, though.


The ridges over time will no doubt make it difficult for the clutch plates to slide when engaging and disengaging the clutch. My bike had less than 9000 miles and already shows some wear. CrazyCzech has more miles and probably heavier use (given his wheelie stories) and has more pronounced ridges. I'm guessing the iron butt rally guys that are eating clutches for lunch are doing so becuase of this. I've asked Meese where his wear is and he confirms that it is in the same place.
 
#5 ·
My clutch was replaced at around 8000 miles. I am not hard on it at all. The problem was not noticable until I replaced the slave cylinder. I think that jostled the stack out of its grooves and caused the severe "juddering" and inconsistent engagement points. I have 11000 miles on the current clutch and it seems fine, but I don't think I want to loosen the slave cylinder bolts to find out.
 
#6 ·
You're right on all points about the metal, JCW. However, tougher metal usually means more brittle metal. I don't know how far you can go on a clutch basket that rattles and gets beaten up frequently.

Shot peening is one solution to get things to wear better. Google it and you'll find videos etc. It's a very simple and effective technique.

I was thinking that you could machine some hard-wearing metal things onto the edges where the wear-problem exists.

Think two L-shaped edges that get put over where the edges - back-to-back. Then connect those two over the basket "tooth" and screw them onto the "tooth". You'd need to machine away the material that's corresponding to the "new edge".

This way they'd be home-replaceable once they're in. They'd also be nice hard metal.


Another thing; My clutch juddered a bit if the bike hadn't been ridden for quite a while, but it stopped after the engine got warm. I had some 16,000 miles on my bike and I didn't treat it with silk gloves when I was riding it (I put the slik gloves on when I got back to the garage). :D But still, it was fine. :)
 
#7 ·
From the Max BMW site, I see they changed out the clutch parts and basket in 2/26/2008. Something must have changed back then and it wouldn't surprise me they still ship some of the older ones out (as they did with some 1300 switch gears).

03 21217699629 lamellar package NA Part not available since 02/26/2008.
03 21217709459 lamellar package BUY 1 $642.83

05 21217680451 clutch housing NA Part not available since 02/26/2008.
05 21217716131 clutch housing BUY 1 $781.91


This sounds very similar to whatever happened on the Yamaha R-series around 1998 or so. I don't know what happened to the guy who owned the bike, but he did say they replaced his entire clutch unit at a very low mileage and he was in line at the dealer behind several others for the same switch-out.

The 2006 GT went through some sort of tranny reconfigure within the first 1/2 year of ownership:
04 23007693803 6-gear transmission, black - Up to 08/2006 NA Part not available since 10/26/2006.
04 23007705077 6-gear transmission, black - 08/2006 and above BUY 1 $3,251.12


The shift forks appear to have 3-contact surfaces on the older 1200 ones too. I thought they only had 2 per fork and the 3-contact points were part of the 84 mods made only to the 1300?

These bikes seem to be a smattering of whatever parts they can get their hands on rather than "THIS will fix THAT" - and often it doesn't, judging from their fantastic plastic idle control circuit.

Wish I could remember what material my old Harley clutch was made out of. I had it out for balancing, just that it was too long ago. Didn't need any parts as it looked good and miked-out within specs too. Never shuddered or slipped, but the clutch pull was enormous and they made some mod to the release lever that helped a bit.


Mack
 
#8 ·
I have an 07 transmission on the bench as well and it's still a 2 contact point shifter fork.

The clutch basket, my guess, was changed to get rid of the loose basket springs. May have made other changes as well, but from what I read, the new ones ordered don't rattle.

I wonder if they spec a harder metal treatment as well, or shot peening?
 
#9 ·
Seems the Yamaha clutch issues have been going on a lot longer than I thought. Still are having issues after 10 years!

This link with the response from Yamaha cracked me up. Response was, "Wear a larger helmet to cover out the noises." Really! Wait until BMW gets that one in their Customer Service Computer: "Wear a bigger helmet to mask engine noises." Why not just sell special $300 BMW earplugs too?

Fwiw, the Yamaha clutch baskets look far worse for wear than the BMW ones. I found these clutch basket photos in Photobucket off another Yammi site:
Direct link here.

Dunno, but if Yamaha is still struggling with clutch issues from owners for 10 years, I don't hold too much faith in BMW to sort it out anytime soon.


Mack
 
#10 ·
GMack said:
03 21217699629 lamellar package NA Part not available since 02/26/2008.
03 21217709459 lamellar package BUY 1 $642.83

05 21217680451 clutch housing NA Part not available since 02/26/2008.
05 21217716131 clutch housing BUY 1 $781.91

Mack
I went back through my records. My clutch was replaced at 12000 miles but it had been screwed up for about 1000 miles before I took it in for service. I got the 21217716131 housing but the plate pack is 21217699628. This was in November of 2008 and my bike is an '06, probably early '06. I have 7000 miles on this clutch now.
 
#11 ·
Re your yamaha clutch picture, the BMW uses a diapragm type of spring so you'll never see the damage like that caused by the coil springs on the BMW basket.

Yes, it's a common problem with die cast clutch baskets, unfortunately, all the manufacturer's consider this a "normal wear" item and take advantage of this by cutting costs with a cheap basket.

GMack said:
Seems the Yamaha clutch issues have been going on a lot longer than I thought. Still are having issues after 10 years!

This link with the response from Yamaha cracked me up. Response was, "Wear a larger helmet to cover out the noises." Really! Wait until BMW gets that one in their Customer Service Computer: "Wear a bigger helmet to mask engine noises." Why not just sell special $300 BMW earplugs too?

Fwiw, the Yamaha clutch baskets look far worse for wear than the BMW ones. I found these clutch basket photos in Photobucket off another Yammi site:
Direct link here.

Dunno, but if Yamaha is still struggling with clutch issues from owners for 10 years, I don't hold too much faith in BMW to sort it out anytime soon.


Mack
 
#12 ·
Finally on here again
thanks for your analysis, glad my basket was helpful.
Did you notice anything else that would explain why the clutch would never quite dissengage? Other than that the clutch was never an issue, the trannys were the weakest point.
 
#13 ·
I haven't had a chance to dissaemble the plates and inner hub and measure the thickness of the plates, but my guess is soemthing other than the clutch itself as the wear is there but shouldn't have been failing.

Wouldn't it be nice to have a basket like this???



These are durbahn's billet clutch baskets for a rc51. Stunning!
 
#14 ·
JCW said:
These are durbahn's billet clutch baskets for a rc51. Stunning!
I was mumbling "gorgeous" to myself before I read that it was Durbahns work. :)
 
#17 ·
No. there was insufficient interest for a low run high $ part.

If you do change clutches, consider upgrading to the k1300s. that will require a new oil pump gear as well. Maybe? the new clutch slave.
 
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