Time for a new clutch

[rphillips]

Yep, I'm curious about everything I'm not sure about... Thanks for helping the community possibly learn something.

[Cipher]

I thought about trying to sand them but I think I'm just going to try new frictions so I can be done with it for good. I will dry a few off and take pictures though, for those who are curious. I'll see if I can see a glazed surface and if so, try to capture it with a camera.

The Manual has a series of specifications for the plates and fibres. its quite shocking how little material there is to wear before slippage occurs. The measurement may well show sufficient thickness and a glaze may be root cause instead of friction material loss.

A sheet of glass and some silicon carbide wet dry sandpaper will break and remove glaze. I've done this and my fibres which were glazed by repeated quarter mile drags are just as good as new.
You can feel the difference in friction between fresh cork and glaze. its really quite marked.

Use a grit that just enough to break the glaze and finish with 1000. Rotate the fibre constantly and use little pressure.

[Grimly]

I that cork or cooked flaked off glaze.

Yeah, it was a kind of mix of flakes and fibres.

[Suzukian]

Glazing only happens if all the Clutch material is worn off and you get metal to metal contact.

[rphillips]

I never saw anything near that worn on any oil clutches I've seen. The fibers always look kind'f new. The oil clutches just don't seem to ware hardly at all. Years ago I did quite a bit of st., and some track drags. Always rode (slipped) the clutch taking off, but no ware, just busted hubs and broken plates.

[93Bandit]

Yep, I'm curious about everything I'm not sure about... Thanks for helping the community possibly learn something.

Of course, anything to give back to the community that has been an invaluable resource for me.

[93Bandit]

I never saw anything near that worn on any oil clutches I've seen. The fibers always look kind'f new. The oil clutches just don't seem to ware hardly at all. Years ago I did quite a bit of st., and some track drags. Always rode (slipped) the clutch taking off, but no ware, just busted hubs and broken plates.

You might have convinced me to try sanding them... We'll see how they measure and how lazy I'm feeling once I get them out and inspected.

[Cipher]

Yeah, it was a kind of mix of flakes and fibres.

On a few boy racer drag sessions I had my clutch plates stick solidly together.
its harrowing to pull in the lever only to find the clutch won't release.
running out of runway frantically trying to gear down to neutral.
all the cool kids laughing at your post run gesticulation and lamentations.

[93Bandit]

On a few boy racer drag sessions I had my clutch plates stick solidly together.
its harrowing to pull in the lever only to find the clutch won't release.
running out of runway frantically trying to gear down to neutral.
all the cool kids laughing at your post run gesticulation and lamentations.

Yikes, that sounds like an experience to remember.

[93Bandit]

I torn into the 850 yesterday. I took the clutch plates out and measured all of them. I measured thickness at 4 spots on each plate, 12, 3, 6, & 9 oclock.
Spec per the OEM manual for the frictions is 0.106-0.114" with the limit being 0.094", and steels spec is 0.080" with no limit specified.
My clutch plates measured the following:
-The friction plates measured 0.107-0.109", most being 0.107".
-The steels measured 0.075-0.077", most being 0.077".

So my frictions fall within spec, although all are at the low end. All the steels are below spec, but only by ~0.003". None of the steel plates are scored or look worn. Only one plate has 3 areas of discoloration due to heat which you will see pictured below. Also, I dried off the frictions well and gave them a close inspection. They definitely have a shine to them so I think they are glazed. I also noticed that when wiping the oil off them the friction material was flaking pretty heavily and felt somewhat brittle in places. See pictures below.

Here's the only steel plate showing signs of overheating. It's not warped and still has a smooth even surface so I will be reusing it.


Here's a few pictures of the frictions. You can see the shinny hard surface.




Here you can see where some of the friction material flaked off.


Also, when I took the clutch plates out I noticed the basket was loose. Come to find out, the basket hub nut was very loose, the only thing holding it on was the washer. So I need to take that apart to see why it came loose. Hopefully there's nothing damaged/badly worn and I can just retorque it.


I think between the age of the clutch, the brittle friction material, all the plates measuring at the low end of spec and the glazed appearance, I am going to opt for installing new friction plates. My biggest fear is the material being so brittle, I don't want that coming apart and contaminating the engine, clogging oil passages etc.

Let me know what you guys think!

[93Bandit]

Be sure to keep us updated.. Also, I've always heard of plates glazing, like mentioned up ^^^ there. I've don't remember hearing what causes it, but have heard the thing about wire brush, steel wool, or sandpaper to knock the glaze off works. Hoping when you get there, just for curiosity, you dry some of them off, and try to look for a glossy, glaze look on the plates.

Per your request...

[rphillips]

Thanks, All your clutch looks like "I" think it should. For sure it hasn't been abused much at all. Very slight grooves in both inner and outer hubs, plus the "dogs" on the fiber plates show no wear at all, mine were always flattened pretty bad. I don't know why, but I've seen those hub nuts loose several times, You'd think the locking washer, bent up tightly, should hold them, but for some reason sometimes they don't. May want to bend up more sides of that washer. I sure couldn't blame you at all for replacing those old 30K plates, but they sure just don't look, or seem, anywhere near bad enough to cause the problems you've explained. But cable adjusted properly and new springs, I can't think what else could be the culprit. Good luck.

[Cipher]

[QUOTE=93Bandit;n1720890]I torn into the 850 yesterday. I took the clutch plates out and measured all of them. I measured thickness at 4 spots on each plate, 12, 3, 6, & 9 oclock.
Spec per the OEM manual for the frictions is 0.106-0.114" with the limit being 0.094", and steels spec is 0.080" with no limit specified.
My clutch plates measured the following:
-The friction plates measured 0.107-0.109", most being 0.107".
-The steels measured 0.075-0.077", most being 0.077".

So my frictions fall within spec, although all are at the low end. All the steels are below spec, but only by ~0.003". None of the steel plates are scored or look worn. Only one plate has 3 areas of discoloration due to heat which you will see pictured below. Also, I dried off the frictions well and gave them a close inspection. They definitely have a shine to them so I think they are glazed. I also noticed that when wiping the oil off them the friction material was flaking pretty heavily and felt somewhat brittle in places. See pictures below.

Here's the only steel plate showing signs of overheating. It's not warped and still has a smooth even surface so I will be reusing it.
[url=https://flic.kr/p/2oBMFc

[/QUOTE]

Yeah time for new fibres. They look glazed and being a cheap bastard id sand them and maybe shim the springs.
doubt its worth the effort though.

[Cipher]

Thanks, All your clutch looks like "I" think it should. For sure it hasn't been abused much at all. Very slight grooves in both inner and outer hubs, plus the "dogs" on the fiber plates show no wear at all, mine were always flattened pretty bad. I don't know why, but I've seen those hub nuts loose several times, You'd think the locking washer, bent up tightly, should hold them, but for some reason sometimes they don't. May want to bend up more sides of that washer. I sure couldn't blame you at all for replacing those old 30K plates, but they sure just don't look, or seem, anywhere near bad enough to cause the problems you've explained. But cable adjusted properly and new springs, I can't think what else could be the culprit. Good luck.

They are glazed and sanding would likely take them past min spec.

[rphillips]

For me, clutch plates at, or below, factory spec., does not mean the clutch is already slipping as this one was. The factory spec. tells you it's time to maybe replace so it doesn't start slipping.....Telling you problems are getting near. Kind'f like the factory spec. for brake rotors, they tell you the rotors are nearing the time they may (could) cause a problem. Would be no reason for the min. spec. if the item had already failed when it got to min. spec. Plus they will always give themselves a little wiggle room for safety and for selling more replacements.