Opening up the spring cup on an M series clutch?

Blk88GT · Nov 19, 2009

Who has done this? How much did you remove, how was it done and what did it cost to have done?

I took my primary apart last night and my spring has the paint worn off the bottom 2-3 coils. I've read this is caused by the spring cup area not being wide enough. It can't be good for performance!

Is there anything else I should know before I have it done?

Rprecision · Nov 19, 2009

I have read of folks machining them for a shiftassist type bearing. I thought SLP made a derlin washer to help with this

mmsports · Nov 19, 2009

Spring

So you are thinking that it is going to be better if that spring can Twist?

I think it is not suppose to twist but I could be wrong. In all the clutches I have worked an all of the springs are tight.

Rprecision · Nov 19, 2009

As I understand it, the idea is to minimize coil bind and alow the spring to rotate as it is being compressed.

I dont think anyone would argue this is more efficant, just dont know how it translates to performance.

Blk88GT · Nov 19, 2009

I have no idea what the end result is, but I can't imagine the coil binding up on the outside of the cup is a good thing? I'm not suggesting it should spin, but it should compress without the sides of the spring being forced into the sides.

Am I way off base?

ACMtnCat · Nov 19, 2009

I'd like to know if there is a spring that is less likely to bulge and bind than others?

Be it a Ti spring or Speedwerx alloy, or are the Cat steel springs less likely to bind than those?

jakecease · Nov 19, 2009

I followed someone elses idea on this about 2 years ago, and did it on my M7 clutch... Not sure how much I actually took off. I have a friend with a lathe, and I had to remove the spider inorder to have this done. I just brought the spring down there with me and checked the fitment after he would take some off. After its done the cover will hold the spring in place, but I wouldn't suggest going nuts in removing material. Before I had this done I was in the same boat as you... You'd look at the cup and see all sorts of paint and your spring was extremely worn where it would rub on the cup. Titianum springs must grow alittle more or something when they are compressed because I actually bent one of those before I did this.

At the same time your doing this I would suggest checking the belt to sheave clearance in your primary (with a new belt) and getting a new step shim or machining your old. I can't remember if I set mine to .030 or .025? Before it was at like .080 or somthing like that. I was running a stock yellow/white at the time but my clutch engagement was still really harsh. Hope this helps!

Blk88GT · Nov 19, 2009

If I have to pull the spider to do it, I won't bother. I just figured this would be a worthwhile change for minimal expense.

likkerpig · Nov 19, 2009

DonoBBD has a write up over on HCS detailing exactly what he did, probably will have to do a little digging as I think it's been a while since it was discussed over there.

RickM · Nov 19, 2009

Blk88G

Read all the comments here on coil bind, This was discussed a couple years ago on the M7, still same principle today,
I used a dremel tool or porting tool to bevel the outter edge of my spider, I also beveled the outter edge of the clutch cover. Both these areas were causing coil bind. It doesnt have to be much, just take your time and you should not have to worry about messing up the balance, just do it evenly.
Also check your clutch weights to see if they pivot with a small amount of force.Tight pivoting weights cost you performance also. I looked for pictures that I save, but apparently I deleted them. Hope this helps you out.
RickM

minet · Nov 19, 2009

did it on a number of them ,, well my dad did it for me anyhow..

think it was .060 from the bottom cup and .030 from the top cup .. but like mentioned hcs has detailed info on it ,, we brought this up last year i think and it was quikly dismissed on the chat boards here /shrug something about mountain sleds not needing full shift out or something.

oh and my dad never took the spiders off any of them , but i think he did have to find a 4 jaw lathe to do it like he wanted , only had a 3 jaw at the time.
you can pretty much take as much away so the cup meets the arms ,, or just shy of the arms.

if your real carefull i could see a dremel tool working but i would be hesitant to do that myself. you should be able to find a local person to do this for under 100 i would think

m-fire8 · Nov 19, 2009

I believe hi performance engineering makes things called glide washers like 20 bucks shipped i'm trying them we will see.

Blk88GT · Nov 19, 2009

Thanks for the info guys. I'm going to drop the clutch off next week to get it cut, a broken bolt pulled and then balanced!

ItDoAble · Nov 19, 2009

I also clean up the burrs/sharp edges on the spring with a dremel.

Ski-Laxn · Nov 19, 2009

I have done this on two. The first I had machine the second did with a grinder. I have not achieved full shift out. but the piece of mind is better for me. As for the weights binding that bothers me. I remove the black orings and replace with a plastic washer I purchase at Ace Hardware.

slyrydr · Nov 21, 2009

coil bind in the drive clutch has been a problem on big bore machines for a number of years....putting a delrin washer (slp has them), or similar nylon washer in the cup between the spring and the clutch face plate will solve the problem....the drive clutch will shift smoother and be more consistent..well worth the effort...added benefit, is a much less chance of having a spring break in the backcountry....

m7ascent · Nov 22, 2009

What I keep thinking is that the cups are not a bad thing, they should keep the vibrations in the spring to a minimum when being compressed and vibration breaks springs. I would think that a friction washer would be a better way to go because it would allow the spring to twist instead of forcing it to grow out and bind up in the cups.

minet · Nov 22, 2009

i think the theroy is something like ,, if it binds then as it compresses it twists ,, without an outlet for the potential energy of the twist effect on the spring your basicly changing the spring rate ( higher )

Team Pigeon · Feb 3, 2011

There can be two different issues with spring cups:
A) spring cup width- shift binding
B) spring cup depth- no full shift out

A) if you have rub marks on the outside of the spring- on either inside or outside (ID / OD), you have a width issue. IF your spring is all beat up, paint it, re-install it and see where it's rubbing. Focus on machining that side first. In my case and some of by fellow kitty riders, it's been on the OD of the spider side of the spring cup. I've milled about 1/4" out the cup width- right up to where the ramps curl into the cup there. I've also kept the cutter about 1/8" from bottom to help keep the spring in it's location. I've also given a little skim and chamfer on the cover to have it look good. It's real easy with a three jaw too.

B) If you have rub marks between spring coils, you won't be getting full shift out. IT is unknown to me why there are so many variations b/w clutch setups. My girlfriend's M8 had mostly correct belt to sheave gap and hasn't had much of any rub marks on her spring. Go figure.
Anyhow back to milling.
Compress your spring in a vise. Measure it.
Install clutch cover without spring in. Take a smoke, toothpick, sliver of wood, straw, tig wire, pencil and cut it to that length. Insert your new go/no-go gauge into the spring cup. Slowly close the clutch (close the spring cup) until it lightly touches on the object. Measure your clutch width--- say outside face to outside face. Remove home fabbed tool and re-close your clutch and measure again.
Chances are your measurements will be be different. Essentially when the spring binds, it prevents the clutch from closing anymore which will cause the belt to cease rising along the clutch faces and causing those black marks on your clutch faces where your belt is slipping. And breath...
Years ago I read to mill out the cover...
But I don't remember why right now- not sure why, I'll have to try and look it up on the other sites...

Thunder101 · Feb 3, 2011

were can I buy one of these derlin washers for the drive ? looked on SLP site , couldnt see one for the drive ?

Opening up the spring cup on an M series clutch?

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