Triumphrat

dogtired · 12-20-2009, 06:14 AM

Had the clutch out of my '71 Bonnie yesterday, and was really surprised with the simplicity of the construction. Nice low tech setup.

While I had it out, I came to the conclusion it was stuffed, the fingers on the bonded driving plates had considerable wear where they slot into the duplex chain sprocket/housing. There was similar, but not as pronounced wear in the housing slots. The driven plates, (the plain metal ones), had practically zero wear, and I could still see what looked like very feint regular "swirly" machining marks on the metal.

After inspection I stuck it all back together and set it by the manual. All works as supposed to, and have eliminated the slipping I encountered when on the dyno. Took it out the road and run it up to a bit over 80 mph up a hill a few times under full stress. (Damn I love riding this pig of a bike!)

As of now, the slipping looks like it was mostly from incorrect setup of the pressure nuts/springs from the P.O. and possibly poor setting of the adjuster pin on my part. I will continue to flog around on it untill such time as the clutch starts to give me trouble.

I never inspected the drive and rebound rubbers, (didnt have an impact driver) but will replace them when the bonded driving plates get done.

Now, the question.
Would I be right in assuming that I would only need to replace the 6 bonded driving plates, and most likely the duplex chain sprocket/housing? Or do the plates come as sets, and you need to replace all 12 plates?

OzBloke · 12-20-2009, 08:16 AM

Dogtired,

If the driven plates are OK on the fingers, and not overheated (burn marked) or scored, just get them garnet blasted (~$15), and stick em back in. Next time you're in there, check the springs for free length, and replace if short.

dogtired · 12-20-2009, 08:29 AM

Ozbloke, I didn't have a mic to accurately measure the springs, supposedly if they are a 1/10th of an inch short you replace them, but I did do a quick visual with a couple of straight edges to make sure there was not a short one amongst them, all the same length. I was mainly in there as a bit of a "look see" excercise and got a bit carried away pulling things apart.

There was no heat colouration of the driven plates at all, which I was happy to see.

Mind if I ask what garnet blasting is?
Is it done to just remove any near invisible residue on the plates, or to give the plates "grip" by applying a texture to the metal?

OzBloke · 12-20-2009, 08:34 AM

Garnet blasting = sand blasting with garnet particles instead of sand. Sand blasting will work just as well, I reckon. Just takes the polish of the surfaces, and gives it a bit more grip without making it so rough it chews out the bonded plates too quickly.

Caulky · 12-20-2009, 08:49 AM

I`m in the process of doing mine.
The tangs on the plates were burred, so I cleaned them up with various files. (needle and flat).

If your primary chain is off, (mines soaking in oil) it can be checked by drawing a line 12" long.
This should align with 32 links.
The compression and stretch shouldn`t be more than 1/4".
Ignore the lower 12 1/2" lines, they`re for the main chain, which is knackered.
Apologies for the poor quality, its been used