clutch spring tightness

[disonny]

I'm putting the clutch together and I don't see anything about how tight to tighten the nuts for the clutch springs. It just says to have the pressure plate move evenly. How tight do I go with those nuts?

 

[NicaJohn]

I'm putting the clutch together and I don't see anything about how tight to tighten the nuts for the clutch springs. It just says to have the pressure plate move evenly. How tight do I go with those nuts?

Not sure of bike but I found this for cr125

 

[Vinskord]

If your referring to pre Mag clutches - I've been told anywhere from one to three threads showing above the nut, then bend over the lock-tabs. Wade Summers, in Husky Newsletter issue 12, suggests using 14mm length dowels (Honda part # 94301-08140) to ensure uniform spring compression and eliminating the lock tabs.

Both Husky Newsletter issues 12 and 13 have good articles on pre Mag clutches and how to improve them.

 

[disonny]

Sorry, it's a 75 wr250 with the small clutch.

 

[Jeff B]

Your 75 has a Mag clutch. I use a feeler gage to "feel" the gap between pressure plate and plates. Make sure the gap feels about the same all the way around. This allows even clutch engagement and release. If the nuts are too loose...the clutch will slip. I just guessed on how far to run the nuts down. It worked. You might try the clutch arm from Huskyjunk. It is longer and reduces lever pull. I have thought about making dowels to make life easier. Jeff

 

[Gord]

I really like the idea of the dowels. Thanks Vinskord. At only $1.16 a piece, they're worth a try. I usually start with one thread showing and then go round and round loosening and tightening so the plate lifts off evenly all the way around.

 

[Crashaholic]

Turn the nuts down anywhere from being level with the top of the studs to a point where four or five threads are showing depending on the wear that has occurred in the plate stack and how much the springs have collapsed over the years. A few millimeters makes a difference although it seems to me the 250 wouldn't be as critical as the 400. My experience with the small pre mag clutch is exclusively with the 4spd 360 and 400 motors. Also as Jeff B said, be sure and check that the pressure plate is the same distance from the top metal disc all the way around when the clutch is disengaged. Adjust individual nuts to make the gap even all the around.

I've found that a well used clutch has two wear areas that effect how far the nuts should be turned down. A new clutch with new plates, discs, and springs would require approximately one or two turns below the top of the studs. As the clutch components wear the fiber plates and the springs don't do as good a job keeping the clutch from slipping. As the plates wear the clutch stack is shorter and as the springs loose tension they become weaker so the nuts require more turns.

Another thing I found that has a big effect on the clutch is the green Barnett clutch fiber plates. The surface area is much greater than the stock plates. When using these I found that the spring nuts can be backed off a couple turns from the position they would be in when using the stock plates.

Another area of adjustment that's critical is the play in the push rod. A rod with a lot of play won't allow the clutch to disengage until the lever has pulled half way to the bars. And of course to tight and you risk having a slipping clutch when the motor gets hot. A good clutch cable is also critical as one that stretches when under pressure will cause the clutch to malfunction as well.

When all you can afford is used clutch parts its not uncommon to have to pull the clutch cover once or twice and make adjustments. For me a clutch that doesn't work right takes the fun out of riding.

 

[Kartwheel68]

Put the bike (or engine if it is out) on its side and set up a dial indicator on the pressure plate. Rotate the clutch and adjust the tension on the clutch until you get little to no change on the dial indicator. Penton/KTM engines have the same kind of clutch spring setup and that is how I do it. For a Husky, I would just dump the small Mag clutch and put a '75+ big clutch in it.

 

[disonny]

Thanks for the input. I wound up going in a few threads on most and a little less on a couple. The clutch seems to disengage evenly. The plates measured about 27mm thick. The manual shows 25mm as a minimum thickness. I have a new cable and the clutch works pretty good as it's adjusted now. As for the push rod, I adjusted it as the manual says. I have a 79 cr390 motor for parts. Will that clutch fit the 250?

 

[Kartwheel68]

It will, but you would need to get a 250 clutch basket and crank drive gear to get the correct primary ratio. I would not bother until the clutch plates you have wear out.