Clutch plates

[tlanders]

I stalled at the starting line at Casey due to a grabbing clutch and a schitzoid starter guy. I pulled the clutch apart last night to discover one of the steel disks was warped. The bike has the 250 stack up of 2 steel, then fiber then steel alternately for 6 fibers disks total. The warped disk is the one between the first two fibers disks on the engine side of the clutch. I mention that because I had to replace the same disk on my '78 MC5 because it was warped and making the clutch grab.

Have any of you experienced this warped disk problem? Why is it happening? Is it just heat and if so why is it always the same disk? What do you do to prevent this? I don't believe I'm slipping the clutch that much, don't need to on a Mint 400!!! Is it just at the start line that I'm overheating it by revving the engine up with the clutch pulled in and in second gear? Maybe it's residual heating damage from a previous owner? How smooth should the tangs on the clutch basket be? The edges of mine undulate a little from wear from the tabs on the fiber plates. Should I smooth these out with a file or will this make for too much distance between them and then too much movement for the tabs on the fiber plates? I am using Dextron III ATF for my tranny fluid. Any advice, comments, etc will be greatly appreciated, I'm putting it back together tonight.

There is one thing I do know for sure, when you stall the engine on the starting line, it makes it REALLY HARD to get a hole shot!!!! I did get the hole shot in the first moto, grabby clutch and all!!!

Teddy

 

[Rocket]

Teddy,
When you assemble the clutch and install the pressure plate nuts, how do you check the runout on the pressure plate?  I always set up a dial indicator, pulled the clutch lever in and taped it to the handlebar and then turned the clutch to get a zero runout on the pressure plate.  This helps keep the clutch from dragging when sitting at the line in gear.  I would also switch to on of the good brands of MC gearbox oil for the tranny.
Just my opinion,
Rocket

 

[tlanders]

I thought that AFT was the best fluid you could use for the clutch??? There have been POG posts many times before about this subject and I thought the final word was AFT was the stuff to use. I do use a dial indicator to check the runout of the clutch when it is disengaged. The hard part is that the nuts that compress the springs are not infinitely adjustable, they move in 1/2 turn increments so you can line up the cotter pin hole in the screw with the slots in the nut. Thanks for bringing the runout check up. What about the filing issue?

Teddy

 

[Mick Milakovic]

I also remember a post saying that a good quality gear oil cut with a small amount of ATF satisfied both the clutch needs and the gear needs.  I haven't tried either yet since my project isn't on the track.

Mick Milakovic
Delphi, IN
765-268-2570

[Steve Minor]

For what it's worth, my manual says: "...put in two quarts of Hi-Point Gear Lube. Check crankcase vents for obstructions. ATF (automatic transmission fluid) will facilitate clutch release"...."Oil capacity: Old style clutch cover 1.4 Liter (1.5 qt) New style profile case 1.2 Liter (1.3 qt)"...

 

[tlanders]

I always put in two quarts of the ATF. Do you guys think that it is the ATF that is making the disk overheat?

Teddy

 

[Rocket]

Ted
Sorry about not saying anything on the notches on the tabs.  It won't hurt anything to file them down and that will also help with the clutch releasing problem.  The more dragging the more heat builds up.  I don't ever remember putting in 2 quarts of oil.  If you pull the oil level check plug and add oil, I think you will get in about 1200cc's if I remember correctly.  I would still use the modern day gearlube in the tranny, maybe the lightest weight you can find.
Rocket

 

[john durrill]

Teddy,
 i have noticed in many different engines that clutch wear is not consistant through out the friction and steel plates.
 I dont know why that is the case but it is.
all you can do is check all the plates for wear and distortion , then replace any that are damaged. a fine cut flat file and some care will take care of the clutch basket so long as the undulations are not very deep.
the friction and steel plates are usually stamped out from flat sheet. that leaves one edge rounded and the other side sharp. for that reason we try and put all of the plates in with the sharp edge faceing the same direction. that could help with some of the drag.
 wait as long as you can to put it in gear at the start ( you already know that chuckle chuckle). we are trying the maxium lt 75 weight in our trannys. will let you know if clutch drag is more pronounced than with the ATF we were useing. Dwight recommended the Maxuim LT 75 wt.
 ATF did help with clutch drag back when the bikes were new. Thats the main reason we used it.
John & Peter

 

[tlanders]

Put it back together last night with the warped disk replaced with a flat one. Turned the nuts in an equal amount and found the runout to be about 0.014". adjusted the nuts to get it to a maximum of 0.004" runout. I had used a 0.035" diameter stainless wire to go through all the spring bolts/nuts instead of using cotter pins, but when I took it apart, I noticed that some of the nuts had tightened, turned in, escaping the wire!!!! Do we need left hand spring bolts/nuts?? Probably I just need to find some small cotter pins again.  I did a little filing.

Anyway, the clutch works fine now. The question is for how long!!!

Teddy

 

[Mike Lenz]

Teddy, I just make sure that the clutch comes out evenly when you pull it in. I just do it by eye and feel and have never warped a plate. That is caused by alot of heat by it not being completly free while you are on the line. If the clutch is set up right you should not have much trouble getting it back out of gear on the line if you need to. A steady rpm a bit above idle and it should come out whithout too much trouble. The nuts moving on you are because you are turning them in too far and the wire or cotter pin slips over the top. Start adjusting the balance of the clutch with the nuts only on far enough to get the wire through. This will give you room to turn the ones that need it in a turn or so and still not be in so far that the wire will miss the slot in the nut.

 

[john durrill]

Teddy,
 we tried the maxuim 75 LT tranny oil out yesterday on a 50 mile ride with Rick G. No noticeable drag on the clutch over ATF . It does provide more protection to the gears than ATF so it should work well for you if you care to try it.
John & Peter