How hig is too high for clutch engagement, and what's up with the bang on engagement?

Frostbite · Dec 23, 2009

How high is too high for clutch engagement,and what's up with the bang on engagement?

I finally loaded my 09 M8 in the back of my truck. This is the first time I have moved the sled since I had the SLP Performance Edition kit done. I noticed the sled didn't want to move when given throttle. With the stock Yellow/white 122/285 Cat spring last year the sled would engage at ?? RPM (I can't remember) but, clutch engagement was no where near where mine is now. The sled now starts to move at 4,600 RPM.

SLP recommends their Green/Yellow as their primary spring of choice for their Performance Edition Kit regardless of elevation. It's a 160/310 spring.

Now, in my mind 4,600 is WAY too high of an engagement speed but, now my sled has the SLPs MTX weights too.

So.........maybe they have to rev the engine that high to ensure the engine doesn't bog with the very aggressive profile of the MTX weights?

I have a 120/340 spring that I have never tried. I would guess I should try a 120/310 first (if my shift speed RPM is within specs) but, I sure like the idea of the lower engagement and high total force of the 120/340 so I can add more weight to my clutch weights (load the motor).

I'm thinking the Arctic Gold spring is sounding good to me. I hate to dig a hole when the clutch engages yet, that's exactly what it looks like I will be doing tomorrow.

What do you guys think?

slyrydr · Dec 23, 2009

i haven't tried the slp exhaust per se.....but i've had another that was similar....the 160 engagement spring is a little high in my book also...i like something in the 140-150 area, for an engagement of about 4100...120 works well for the 1000 with its' higher engagement torque, and my 1000 has a 120 and engages at 3600....but for the m-8, you may have some bog or some hesitation at 3600 rpm....

WyoBoy1000 · Dec 23, 2009

I would call them, after it gets some heat and movement it may loosen up. It is a ported motor that may need a little higher engagement but that seems high.

shredjim · Dec 23, 2009

Belt deflection?

Frostbite, what kind of belt deflection are you running? I've recently found that getting the belt fairly tight makes the engagement WAY smoother. My belt rides up as far as I can get it on the secondary. Rode 70 miles on Mt. Adams today, not all the time, but way too often my engagement is too rough too. Gonna try a new belt and see if that helps since it will be tighter.

colorado logger · Dec 23, 2009

Jim is absolutely correct, I ran mtx last season no bang.

Also good luck with slp recommendations.

diggerdown · Dec 24, 2009

I always shoot for a 4000rpm engagement with a tight belt deflection. Set the deflection so you get some track turn at an idle with the track off the ground.

SnowBound · Dec 24, 2009

Check the belt deflection. A loose belt will make for a rough engagement. Your belt should be resting slightly above the secondary sheafs about a 1/8".

Frostbite · Dec 24, 2009

Thanks guys!

My belt is as high up as it can go in the secondary. I wish it would go higher. It sits about 1/8" above the top of the scondary. SLP put in my clutch weights and "shimmed" my primary to match their weights when they were balancing it, so I'm sure that part is done right.

I rode yesterday and the engagement seems a little lower on the snow than on concrete (easier to move). Honestly though, I never did really look to see how much lower as the clutch was engaging.

The Arctic Gold spring sure souns good..................

bee1971 · Dec 24, 2009

SLP put in my clutch weights and "shimmed" my primary to match their weights when they were balancing it, so I'm sure that part is done right.

Well the bang on engagement , is your belt to sheave clearance on your primary

I would bee talking to SLP and how they "Shimmed" your primary - How is your belt
New or Old

If your happy with your overall top Rpms keep the 310 finish rate

Try a SLP 140-310 or a SLP 120-310 for even lower engagement

Frostbite · Dec 24, 2009

I did use my belt from last season that has less than 200 miles on it. I'll throw the new on on before the next ride and try to be gentle the first few miles.

I think I'll throw in the other primary spring (120/340) just to see how it works. That would give me a lower engagement and more RPM up top, just what I need.

The pistons and rings may still be getting to know each other again as well. I suspect my RPMs will come up as the sled re-breaks itself in again.

907KB · Dec 24, 2009

Belt to sheave clearance on your primary all day. With that being big and a 160 its going to bang. My clearance was like .050 and the bang was bad. Now I'm shimmed down .010 and its like butter

Norway · Dec 25, 2009

Adjustment help?

907KB said:
Belt to sheave clearance on your primary all day. With that being big and a 160 its going to bang. My clearance was like .050 and the bang was bad. Now I'm shimmed down .010 and its like butter

I'm all in for keeping the moveable sheave frombanging into the belt, but shimming the clutch is out of many peoples hands and your belt will wear.

I know some aftermarket billet covers have the ability to adust this, but has anyone seen a adjuster that just bolts on with the bolt to the primary?
Just replacing that washer with the colar?

RS

White Rad · Dec 25, 2009

man frosty starts some very informative clutching threads! when you guys are talking about belt to sheave clearance in primary is that the clearance on the side of the belt to the movable sheave? so if its too much like .050 the sheave will bang the belt on engagement. and if you shim spyder out it reduces the clearance? are you measuring this with a feeler gauge slipped in between the belt?

I'm going to try a gold spring (yollow/white right now) to lower my engagemet rpms and add glide washers to fine tune it if drops engagement too much. I also have a slp black silver 117/310 spring i want to try because it has a higher finish rate....

907KB · Dec 26, 2009

Yes,

Rad, The bigger your side clearance the harder the engagement. .050 is bad.
You want to test your clearance with a New belt and just slip a feeler guage in between the sheave and belt .015 is your goal. Even with higher engagement spring like 160 will be smooth with good side clearance.
Norway,
Most dealers will reshim your clutch for like $30.

Frostbite,
A higher finish rate will give you a few rpm, But peak rpm should be adjusted with primary weight.

diggerdown · Dec 26, 2009

Remember, some of your bang at engagement will come from the secondary reverse helix slots.

Frostbite · Dec 26, 2009

Diggerdown, you nailed it!

I think the reverse slots do make a big difference in the smoothness of the engagement. I notice after I use reverse, the engagement is particularly hard.

There's probably not much one can do about the reverse slots?

diggerdown · Dec 26, 2009

If the defledtion is close and your primary sheave clearance is .010 to.015 at an idle the belt should creap a small amount and take up the slack in the slots.

wiley75 · Dec 28, 2009

Frostbite,
Please let me know if you get this figured out. I put SLP's performance edition kit on my sled this year as well and have the same problem. Holy cow does it bang hard. I'm actually worried about blowing up the diamond drive. I found that releasing the brake just a split second after the primary starts to engage helps the problem, but it's still really noticeable. FYI I'm not running SLP's MTX weights, I'm running 73 gram CAT weights. Both sleds do it so it's obviously not related to the weights themself. A non-scientific examination shows that my primary sheave to belt clearence is the same (by eye) as my girlfriends 09 M8. But I better get out the feeler gauges to make sure. Her's has a very very small clunk, hardly noticeable compared to mine. My guess is that it's the spring itself but haven't invested the time or $$ to try another one.

Frostbite · Dec 28, 2009

I ordered three more SLP springs to test with the kit but for now, I plan to try the black/pink 120/340 once it snows again.

Make sure your clutch weights move easily by hand. If the clutch weight bolts are a bit tight it takes a lot of centrifical force to overcome.

Perhaps a tiny bit of silicone on each of the O rings holding the weights wouldn't be a bad idea either?

Make sure your belt is high up in secondary and your belt deflection is within specs. You want the track to creep just a bit without the belt howling.

The belt to sheave clearance on the primary is huge. The closer the better without squealing.

Mr. BB · Dec 28, 2009

For info on the engagement banging see the thread "Nasty rough clutch engagement" post reply now on page 2 of this forum by Mr. BB. This is one cure.

How hig is too high for clutch engagement, and what's up with the bang on engagement?

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