2010 M8 clutching observation, etc.

[NoSoup4U]

I have tried a few different set-ups and thought I would pass along my experience for other to build off of.

I have tried 3 different springs in the primary clutch. All from SLP - the black/yellow, black/red and black/pink. These all have a 120 start rate and engage at around 4,000 rpm. The engagement is much smoother and more linear that the stock spring, and works better when boondocking IMO. I haven't experience any bog at the lower engagement RPM and all have held peak RPM well. The springs had the following effect on peak RPM:

Black/yellow (120/310) peak RPM was about 50 less than the stock spring.
Black/red (120/320) peak RPM was about the same as the the stock spring.
Black/pink (120/340) peak RPM was about 100 higher than the stock spring.

I think the SLP springs peak rate is overstated when compared to the stock spring as the SLP 120/320 spring had about the same peak RPM as the stock spring (140/290?) - at least in my sled.

Shift assist - I lost about 100 rpm after installing the shift assist. I don't know if this was due to less spring compression because of removing the the 2 black spacers or if the secondary was just shifting out faster. Overall, the secondary was smoother and held a more consistent peak RPM.

Cutler 65-75 grm adjustable wts. Running the bare 65 grm wt without any set screw - just an empty hole all the way through the wt - added about 150 rpm over the stock 68 grm wts. Shift profile feels the same and the wts work very well.

SLP 44/36 helix - this helix is great in my M1000 but it didn't work for me in the M8. It felt like I was in too high of a gear and my rpm's were noticeably lower. This helix may work for some of you that claim your running 8500 rpm with the stock weights, but it was too much for my sled.

SLP can - according to my scale it is 11/lbs lighter than stock which is what SLP advertises. Excellent fit and finish. Dimensionally the can looks exactly like the M1000 can, but according the SLP the internals and different and it was designed specifically for the M8. It is also 2/lbs lighter than the M1000 can. The exit down pipe sticks out about 1/2-3/4" below the snow deflector. I've noticed this on the M1000's with the SLP single set-up also. I don't know why the designed it like that, but I'm sure they had a reason. Performance so far has been flawless and I have seen a slight increase in RPM. However, I don't know if this was due to the can or not as my sled has slowly been gaining rpm as it gets for miles on it. Below 6000 rpm no one will suspect you have a can on as the sound level is very stock like. At higher rpm they will suspect you have a can on, but won't be sure because it has a throatier growl, but doesn't produce much more noise that the stock can. This isn't the lightest can available, but is probably is the quietest of the aftermarket cans.

Hope some of this info is useful...

 

[KAWGRN]

What altitude are you riding????

 

[Frostbite]

Nosoup4U, excellent post!

You have passed on some really helpful information!

I have a 2009 M8 with the SLP performance edition kit so the power levels should be similar.

I too have the SLP springs you mentioned above. I tried the Blue/Pink 140/340 today and my enagement dropped to 3,900 but, I am using MTX weights. I didn't feel any bog either. I think the black/pink 120/340 might be an awesome spring.

So, what were your impressions when going to higher total force springs? Did the sled feel snappier to you?

I haven't tried my Cutler weights yet. I'm trying to dial in my SLP MTX weights.

I too have a 44/36 helix and couldn't pull my target RPM. I found out my 44/36 was a 44/36 P helix. The "P" is progressive which means the intial helix angle starts at 44 degrees and gradually (progressively) moves to 36 degrees (if you ever get there) in the meantime, you could be climbing while your helix angle is 38 degrees one time and 40 the next.
You need a 44/36 M (Multiangle). It stepped instead of gradual. It too starts at 44 degrees for a short duration and then runs 36 degrees 90% of the time you are riding. It's easier to clutch because your helix angle while climbing stays constant at 36 degrees and with a 36 degree finish rate you'll pull a lot more RPM.

Thanks again for as great post!

 

[hatchers]

great post, i got a few springs i need to try out, the 43/36 helix i used today seemed nice and did what it should......but the pri spring is waaaaay off, trying my best to make one change at a time, gotta have a baseline

found this dyno sheet, sure looks like this engine has a ton of play in regard to RPM drop, set it high and this sheet shows it wont fall out of the optimal HP range....7800-8100 sounds a bit suspect to me??

 

[KAWGRN]

every one is claming a different RPM for peak!! I tried 8000 and 8200 and mine is faster at 8200 but your dyno sheet falls off hard at 8200, greg spaulding says 8300 and speed werx says 8200 but stock the sled comes with 68 and at 10000 feet it runs at 7800 dont know where to clutch to??? the factory chart and 63grams at 10000ft it turns 8300rpm Whos right??? hatchers your hp and tQ seem right just seems low RPM I wonder if that was a cold first pull or a really hot third pull I dont see water temps

 

[DonoBBD]

every one is claming a different RPM for peak!! I tried 8000 and 8200 and mine is faster at 8200 but your dyno sheet falls off hard at 8200, greg spaulding says 8300 and speed werx says 8200 but stock the sled comes with 68 and at 10000 feet it runs at 7800 dont know where to clutch to??? the factory chart and 63grams at 10000ft it turns 8300rpm Whos right??? hatchers your hp and tQ seem right just seems low RPM I wonder if that was a cold first pull or a really hot third pull I dont see water temps

Hit the torque number in the above power 7800-7900 all the way through the shift then on long pulls lit it creep to 8200. This is the best set up and will smoke along very well.

Don.

 

[dmkhnr]

My elev is 7-10k and my findings are that the SLP black/yellow had a lower engagement but the exact same top as the stock black/or.
I went ahead and threw the weights on the grinder taking them all down to 67# without the set screw, run the stock spring and am hitting low 8k r's.
The slp blue/pink looks like the one I want to try 140/340, as I found with the lower 120 start that the motor burbbled (never bogged but wanted too). According to the soupnazi I should pick up 100+ rpm and be right in the wheelhouse.
I'm waiting on the SLP pipe set, so I probably won't try anything else with this clutch setup.

 

[Frostbite]

I tried the Blue/Pink yesterday. It's a 140/340 and my engagement with 74 gram (loaded to 78 grams) weights was 3,900ish (3,800-4,100) with no bog.

 

[Woody67]

I would like to bring this back to the top so we can get some more feedback on what everyone is finding for the best peak operating RPM for the HO motor in the M8 models. At the dealer meeting Greg Spaulding mentioned more than once that the Pre-Production HO M-sleds ran better about 200 rpm less than the F and Crossfire models.

Please post the peak RPM you feel your M8 HO runs best at.

Thanks,
Woody

 

[WyoBoy1000]

the slp 44/36 should be in the 36* after 25-30 mph after that it should pull just like the stock one.

 

[dmkhnr]

67# and slp blue/pink works very well at 7-10k holding a solid 8100+ in a deep climb. In fact now that the motor has hit 300 miles it noticeably broken in and I'm seeing spikes of over 8200.
SLP pipe monday. I won't run the mtx weights, but slp says to use their 68# mtx weights and add 2 rivets which by my experience will be 66#.

 

[thumper450]

67# and slp blue/pink works very well at 7-10k holding a solid 8100+ in a deep climb. In fact now that the motor has hit 300 miles it noticeably broken in and I'm seeing spikes of over 8200.
SLP pipe monday. I won't run the mtx weights, but slp says to use their 68# mtx weights and add 2 rivets which by my experience will be 66#.

what sled 2010 162 or 153?? you grind down stock 68g weights?

 

[dmkhnr]

162 and I grind a gram.

 

[Rucky]

To me it seems apparent that throughout the life of my sled up to about 500-600 miles, it continued to wake up. So if you're attempting to clutch within those parameters, you may have inconsistent results. I'm still using the stock weights, with an Orange/White primary spring. Haven't had it in the hills since the new spring but it'd pull between 8100 and 8250 depending on elevation. The thing is, areas vary so much in elevation you just can't win with clutching.

 

[thumper450]

my orange and white seems to be working well, way less harsh engagement, which is good , still seeing good R's in the deep

 

[Rucky]

my orange and white seems to be working well, way less harsh engagement, which is good , still seeing good R's in the deep

You found it less harsh? IMO it's equal, if not more jumpy. I'm engaging around 45-4600 and my belt deflection is per spec. Some people hate the high engagement in the deep snow. Haven't ridden deep enough yet to really have an issue, but so far I don't mind it. It feels like a race sled.

 

[ripsass]

Is the finish rate higher on the orange/white than the yellow/white?

 

[aksnopro]

hm

the only time i notice the harsh engagement on my 2010 m8 153 is when im not throwing it around putsying around i find it engages and pulls the sled faster when i was wanting to just putsy.. other then that, that same engagement i like when im trying to throw it around cause it lays over snappier.
-Aksnopro

 

[ItDoAble]

Is the finish rate higher on the orange/white than the yellow/white?

A little bit ... the black vertical lines are where AC measures springs (SLP is measured different distances, this is adjusted for that).

 

[White Rad]

Anybody else notice that the slp springs are a slightly larger outer diameter than the cat spring? I have an slp black silver i was going to try because i was looking for something inbetween cat yellow/white and the gold. When I had the primary apart i measured the new slp spring at 1.2mm larger OD and it was very tight in the spring cup. with all the evidence of my original spring binding and rubbing on the spring cup i didn't put the slp spring in....