Dragging clutch / notched basket?

[yo_marc]

Hey all,

The clutch in my 2000 RM250 is dragging pretty bad when disengaged. It's always dragged a 'little', but it just got worse on the last off-road ride I was on.  The clutch took some abuse on that ride.

I just took things apart, and the fibers and springs are in spec thickness wise.  I haven't found a good way to measure for any distortion in the driven plates.

My basket has what I'd consider light notching.  I've seen worse in examples online.  Does this look bad enough to cause heavy dragging?  It just feels like light dimpling.



The dragging is bad enough for the tranny to slam into gear and stall the motor when I select 1st or 2nd from neutral.  If I keep it running, the drag wants to get the bike rolling forward.  It's really a -heavy- drag.

Besides the basket, are there other things I should look for that would cause the dragging?

I don't believe it is clutch lever or cable related.  I removed all slack and pulled the (non reach adjustable) cable driven clutch lever to the bar.  Found the cable housing distorting a bit, so I swapped in my Magura hydraulic clutch.  Both do it.

With the clutch cover off, I can see plenty of throw being put into the clutch pack.  For whatever reason, I have a ton of drag.

Before the clutch went and started dragging heavily, at times it would snatch or chatter sharply at engagement. Not sure if that offers up any more clues.

I've hear that these clutches are prone to drag, and swapping in KX250 fibers and drivens are one fix.  Too bad I had just ordered a RM250 kit a day before this problem showed up.

Any thoughts or ideas? 

[yo_marc]

Link to full sized pic:

[Coop]

You can draw file those notches out.

To check for warp you need a good flat surface. I have a 1/2" thick piece of plexiglass like clear plastic I use for this. Then just try to slip a feeler gage under the plate to check for warp.

[yo_marc]

Thanks coop.  I like that plexiglass idea.  I can think of one or two panes of glass I have hanging around the basement I could probably look into using.

It's nice to hear those notches can be filed out.  I took another very quick look at things after posting this morning, and the fiber plates have very sharp edges and horizontal scraping on the edge of the fingers where they ride against the basket. (You can see similar scraping in the clutch basket notches). The fibers are aluminum plates, FWIW.

I figure I'll do as you said... file as needed, but also grab some very fine sandpaper and see if I can clean/polish the surfaces up and perhaps give the fiber plate fingers a TINY chamfer.

Still very open to other thoughts/ideas too...

[SachsGS]

Carefully examine the clutch basket/"pressure plate" itself to make sure that it is not warped due to heat and that the entire clutch assy. is not moving around on worn needle bearings and bushings.

[MyckMcClung]

X2 on what Sachs said. I'd swap out the aluminum plates for steel, less oil contamination, more flywheel affect. The hub and basket on my old yahama looks worse than that and it still works fine. I think you might be having issues with the pressure plate, double check the parts diagram too, you could be missing a shim somewhere too, either under the hub or behind the basket. Also, not sure about your model, but some clutch baskets use an elastomer around  around the pins/bolts that hold the basket to drive gear, check to see if they or the pins/bolts are worn out or loose.

[yo_marc]

You guys rock.

I do have another clutch pack in the mail right now.. It at least has steel driven plates - not sure about the drive/fiber plates. 

I forgot to mention this is all OEM hardware, straight from the crate, and very likely it's the first time things have been opened up.  With the way the clutch was behaving and reacting, I honestly thought I'd find visibly warped and blued driven plates and some thrashed fiber plates.

I hope to have some time to look things over tonight.. you guys gave me some good info to work with. Thank you.

[TMKIWI]

I had the same problem on my RM.
Changed the oil from Motu to Bel-Ray and problem was gone.
Some oils will cause the plates to drag.
Put your new plates in, try different oils and see what happens.

PS. I ran out of Bel-Ray when I did my last oil change on my TM and had some left over Motul which I put in.
Clutch plates now stick when cold.

[downonmonday]

Those notches don't look too bad? I would take other's advice on warping.

[yo_marc]

Thank you for the continued feedback - I really appreciate it.

I was only able to check things over very briefly last night.  The hub spins fine, and is nice and 'solid'.  The basket however, it does have some play to it...

There is a lot of oil-stiction, but the basket moves in and out about (I'm estimating / eyeballing) .02 to .03"

The basket will also rock side to side slightly if I push/pull/tug on opposite corners of it.  I didnt have a good reference point to try to get any measurement on that. I want to say it's a little more than the in/out play.

I do not think there is any vertical or horizontal play.

Is the basket expected to have some float or play like that?

[SachsGS]

When you say "The basket moves in and out 20 to 30 thou.",do you mean the entire transmission shaft assy.?If so,something is not right,have you been experiencing any shifting abnormalities?It could be possible that when you put the bike in gear the shift fork is trying to move the entire shaft assy in the opposite direction - reducing the clutch plate clearances with the clutch disengaged.

[yo_marc]

It is actually just the clutch basket itself, where it rides on the transmission shaft.  The clutch hub and transmission shaft assembly is all nice and tight in the case.

I would like to think it's ok... but I do question it slightly.

[MyckMcClung]

Could be the primary drive bearing is worn out.
If the hub is still installed and the basket is moving you could be missing the washer that goes between the hub and the basket or it could be worn.

[yo_marc]

To follow up on things...

I was able to spend some time working on the clutch last week, and then take the bike for a good ride on Saturday. Things seem to be working rather well.

I...

...Took a look at the driven plates. They are stamped steel.  One side of them has a nice natural chamfer, the other has very sharp 90* edges.  They way they were originally oriented in the clutch pack was sharp side facing 'out'.

...Took a look at the driven plates. The tabs or fingers were also worn (or stamped) in a way that gave them very sharp edge on one side of the plate.  I gave them a quick chamfer with a fine draw file.

...Sanded down the dimples in the clutch basket fingers.  They came out real easy with 1000 grit.

Again, these are original never replaced OEM parts.  All parts were in spec, aside from the lightly notched basket.  I could find no warping, blueing, or scoring to the driven plates.  Springs were in spec.  The pressure plate looked just fine.  I figured with all of those parts in good condition, the chance that my clutch basket bearing was worn and that play I found was 'not' normal, was rather slim.

I reassembled everything, with the driven plates 'sharp' sides facing inward.  I suspected that the sharp edges on some of the parts were catching on the hub and basket, not allowing the clutch pack to release when the clutch was disengaged.  With the sharp sides facing in - I'd let the even pressure from the pressure plate and springs ensure proper engagement.

Like I said, the clutch worked well.  A little drag here and there, but more often than not the clutch would allow me to actually snitch into gear.  Certainly no slam,.. not even a clunk.  That's much better than I EVER recall it working.

Thanks again for the help with this one guys.

[MyckMcClung]

Your cable could be stretched too