850 G4 Summit

Click on the links below to take you to the ongoing information as progress continues working on clutch kits for the 850 summit models.  Thank you.

Hot belts - Blowing Belts

Helix testing

Primary clutch pivot pin and spacer testing

Clicker postion is NOT for changing engine speed at full throttle

GEARING summit 850, MY 2017 and Top track speed

pDrive force charts for clicker position

Latest flyweight grams for 967 @ 600~1750 feet.

Engine speed drifting low - FINALLY...woo!  :)

New primary spring

Flyweight legend (temporary)

Question - Joe how come I dont see you have any custom ramps?

June 15th 2017 Latest specs

PDrive pivot pin kit done finally Oct 18 2017

Belt heat, belt life, gear change, clicker position

Flyweight - pDrive flyweight ramp differences (lazy or crisp)

Flyweight - Getting used to the pDrive pivot system (external link)



I have an 850 x 154 x 3.  I doubt Ill have a kit until 2018 as it will take me a whole season to do competent testing.

As far as getting my hands on an 850 summit clutch, the blessings that been bestowed on me makes me not able to sleep at night regarding the clutch itself and who's helping me test again this season - truly honored for the ones who are helping me.

I started with this in June, but doubt i'll have anything competent until so much testing is done.

First have to get used to the sled and run it through the wringer.  Drive the sled everywhere as much as we can and find deficiencies.  It is the getting used to the sled and end up finding (I wish I had a little more here) and (I wish I had a little more there) and (I wish it acted different in this situation).  These slight deficiencies is where a clutch kit rises to the surface. 

The kit solves a bunch of little deficiencies like filling in the gaps where stock settings dont quite hit the mark to an operator thats able to overcome the capacity of the sled.

Now parts go out to my fellow test pilots all over snowmobile land from sea level to Alaska to BC to Colorado and Sweden.  Get feedback from all the riders and see what else needs to be done to make a competent tune.

As far as gains, there has to be a search to findgaps in the clutching performance where the sled is by an opinion, deficient.  That is my job to find these gaps in the performance of the clutch calibration.

The testing is good old fashioned side-by-side running and sees how much further we can get in track speed and backshift strength.

Breaking trail developing a new clutch kit has its growing pains.  I have to talk to the test guys and ask questions that requires them putting forth experience.

I learn a good amount of knowledge, so we get to "smell" and "taste" what the new clutching is like.

Here is the reason why - when we genuinely (iterate) struggle through a problem, we get to understand our product.   When one has done that "nail their own stuff down from stock (not a competitor clutch kit)" for years, we get a pretty good grasp of what we can do.

Stock clutching is the highest bar to overcome.


I want to find out all the mistakes, misinterpretations, things off the mark, here before it goes to market, this does take time.  Oh and fit that in between all the other things, support current products and eat and sleep and family.  (its a non-stop "work in progress" - where is the finish line?)

In the final analysis you will know we built a good clutch kit and we were the ones who actually built it (not bought a competitor helix, have it measured, whip up springs for the kit, then re-label it [ponchos sled shop clutch kit]

We will be able to answer you at multiple levels. If we were not the ones who developed it, we could get stuck on a question.  And then you can say to yourself "this person was not really the one who solved the problem"

As we roll along in time and I make progress, I will add a picture here or there of what is going on to move forward and have a great clutch kit for 2018

Yes I have pDrive clutch tools (not for sale yet) and (not the ones in the picture below either)  - the machine shop is just waiting for me to push the go button.

Happy trackspeed














Sept 5th





Sept 7th


NOV 17-16



Hot belts - Blowing Belts

im working my heart out on lowering temperatures. Up to a little over 450 miles now -
Im leaving all the factory installed fiber parts on, not modifying any of the clutch guard area. Leaving all felt linings in.

Not running a prefilter grill kit either - I want as much natural under hood heat & moisture to give "from factory" a good go.

Trying to break the system down into its component parts based on track speed.

Start of shift
I been doing slow wrong foot forward, sidehilling across hills, just fast enough to walk and after about 120 feet...."peeeuewwee....stinky belt smell" The engagement speed is too high at 3600 for the 967 ramp and im running enough pivot weight with tungsten down here to allow the use of that ramp.

I been trying the 967, 951, 968 ramp with 170 and 185 start forces (getting to try out custom springs) Next will be 150, 140 and 120 start forces.

Midrange track speeds (correspondence from a customer)
Some people have to travel long distances from the trailer to the deep

Mike) we are out of ID and where were riding have blown belts in 100 miles, this is going to be an expensive winter

Joe)Q1] Was there at any time ever on the hardpack to get up to where you both ride the sled, was there any time ever the sled reached a vehicle speed of about 72 to 75mph. Like say some switch back that has a long enough stretch on it to boogie up to over 72mph (yes or no?)
Q2]Do you two have to run a long distance on roads to get to where you ride to snow, like having to ride a distance at steady part throttle up or back from the snow?

Mike) the majority of what we did was breaking our trails into the back country so we maybe had 2 miles of hard pack riding to get to the snow. We did have one ride with search and rescue, 14 miles of trail to get into the stranded sledders. For most of those 14 miles we would have been in and out of half throttle probably keeping a consistent speed of 50 mph and hitting a top speed of 65 it's very very rare that we would hit a vehicle speed of 75 mph

Joe) but you could have hit 75mph even just once, yes? This is all it takes to start to damage a belt with gears that are in the latest summits.
all it takes is one to two times to get there and this happens
1] The belt "compression cogs" hits the roller pivot stud and
2] the angle of the secondary clutch where the sheave angles to straight up and down (overdrive portion) &ndash this "ridge" where the angle transitions to perpendicular wants to separate the belt in two - Separating the tension section from the compression section.

Belts will cumulative raise heat to overheat by...
High engine speed at part throttle, heating up the belt from steady running down trails.
Steady part throttle at long trails will raise temperatures of the belt because you are putting the belt on one small area, pulling from the primary clutch. When the belt stays in one area (Within a ½ inch of sheave travel) the temperatures will soar to 180~190 degrees. Eventually so much heat a chord will pop and sentence the belt to death.

Death sentence belt temperatures

Watch your belt sidewall color turn from green to brown to black(185 degrees and no rest)...*badoing*...there goes a chord.

Run the sled hard as you normally do, but stop every once in a while to check the color of the belt. Monitor the clutch temps and when you start to see the belt glaze from that point on it will start to turn brown. You'll end up knowing how long you can run the sled for whatever you do and that "timer" will be going off in your mind giving you a conscience "im at the point of ...or...im almost at the point of - giving the belt a rest. Pop the side panel off, clutch guard off and take a drink of water or whatnot to give the belt and clutches an "open air" break.

When running down hardpack, then vary the engine speed while driving, speed up, slow down, speed up, slow down.  Imagine you are able to watch your belt move across the sheave face.  Changing speed will move the belt across the sheave face and draw away more heat from the belt. Staying fairly one vehicle speed traveling will have heat localized on one area of the sheave faces and heat can not be drawn away from the belt.

Trail sleds can get away with long distances of steady part throttle because of their higher gearing, lower track loads and much lower engine speed at part throttle. Example an 800 trail sled can poke along at 60mph at 5500~6000 rpms to where I see on my own 850 x 154 x 3" running at 6900~7200 rpms at 50mph depending on load.

GEARING summit 850, MY 2017 and Top track speed

Track speed sentence belt to death
orange box maximum safe track speed
red box....starts damage and engine will take off into overspeed.



Clutch Pivot Pin testing







Helix testing



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Primary clutch pivot pin and spacer testing

Jan 8th / 17









Sunday past...(Jan 8th-17)
967 ramp +  32mm (15.5 gram) + 7mm tungsten (8.7g) = 67.8
Dalton primary spring W/T/W (150/305)

Still not happy with it.  Acts like a 417 ramp in a 800e.  I mean it rips (you can tell im frustrated) but fer cryin out loud, I make some changes and I still have to go down to clicker #1 and it just dont do what I can get a TRA clutch to do when I make a substantial change.

This is what I stuffed in tonight for next ride
967 ramp
+ 38mm pivot bolt (16.7g) +  7mm tungsten (8.7g) + 3mm BRP spacer = 27.4 grams of composites
TOTAL = 71 grams
I clickered up to #2

Trying to break this bitch and make it...Groan

My own ramps will be  more aggressive than this 967 and the rest of the BRP ramps to draw some meat out of this 850 and make it work harder.


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Clicker position is NOT for changing engine speed at full throttle

(NOTE - I will post force diagrams of different clicker positions to show what the positions do on the upshift and "Track speed" (shift ratio) AND engine speed change)

The clicker only changes the way the clutch pushes off the very bottom end.

You can make the clutch feel "revvy" or "less revvy" being more aggressive.

You must change engine speed with pivot bolt weight - THEE END

The clickers are NOT there to change engine speed like the older TRA.

If you put the clicker down to #1 it will be the most revvy....and still 7900-8000

If you put the clicker up to #5 it will be the least revvy, most aggressive...and still 7900-8000

If you are running say 8100 with 14.7 grams pivot then no matter what clicker you are on, you must add 1 full gram and go to 15.7 grams pivot to push the engine speed down to 7900



In position 1 and 2 the engine will reach its peak power rpm very quickly with some overshoot.  This means that the drive clutch will apply less pressure on the belt in its transition between engagement speed and peak rpms.  This could be desirable in fluffy snow conditions that offer little traction.

Position 3 represents a good all-around position where there is only minimal rpm overshoot. This position should give good vehicle acceleration in the normal snow conditions.

In position 4 and 5 the clutch will clamp the belt very early after engagement, slowing down the climb in rpm.  This can be beneficial in wet snow where a lot of traction is available.



Line upon line...

  • In position 1 and 2 the engine will reach its peak power rpm very quickly with some overshoot.  This means that the drive clutch will apply less pressure on the belt in its transition between engagement speed and peak rpms. 
  • Position 3 represents a good all-around position where there is only minimal rpm overshoot.
  • In position 4 and 5 the clutch will clamp the belt very early after engagement, slowing down the climb in rpm. 



pDrive force charts - clicker position

This adjustable drive pulley allows setting maximum engine RPM in the vehicle to maintain maximum power. The adjustment has an effect on high RPM only.

Ramp cam should be adjusted so that actual maximum engine RPM in vehicle matches the maximum horsepower RPM given in Technical Specifications.

To adjust, modify ramp end position by turning ramp cams (3x) [shows pic of clicker]
Each number modifies maximum engine RPM by about 200 RPM.

Lower numbers decrease engine RPM in steps by about 200 RPM.

For example: Ramp cam is set at position 3 and is changed to position 5. So maximum engine RPM is increased by 400 RPM



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Latest flyweight grams for 967 @ 600~1750 feet.

Jan 29th - 16
Feedback im getting from Colorado, WA, BC im too light on my flyweight gram calculation by 2.5 grams.  This is getting interesting.  Waitng for feedback from AK, BC(2), NB and Norway. 

38mm bolt
+ tungsten 3mm (grey color)4.1 gram
+ tungsten 7mm (grey color)9.7 gram
+ steel 3mm (yellow color) 1.7 gram
= 31.5 grams -was still running at 8000 rpms, clicker #3.  holy cow. haha

Setup for Feb 12th
38mm bolt
+ tungsten 4mm (grey color)5.3 gram
+ tungsten 7mm (grey color)9.7 gram
+ steel 3mm (yellow color) 1.7 gram
=32.7 grams, clicker #3  (gona break this som-bitches back)

Engine speed drifting low - FINALLY, woo hoo! :)

Holy Cow...Setup for Feb 26th
38mm bolt (17 grams)
+ tungsten 4mm (grey color)5.3 gram
+ tungsten 7mm (grey color)9.7 gram
+ steel 4mm (yellow color) 2.37 gram
+ steel 2mm (yellow color) 1.1 gram
=35.4 grams, clicker #3

............and still 8000 rpms full throttle.   Hmm,

This is the order they have to go on ALWAYS TUNGSTEN LAST.



I do this test of running down a hill, full throttle about 50mph, reduce throttle and back full throttle.  Full throttle 7700 rpms. YAY!...this is what i've been waiting for to make engine speed not recover.  Turn around, go back to start about 1/8 miles and change clicker to #4.

Again, full throttle about 50mph or so let off throttle, back on throttle and 7900 and up to 8000 again.  But I dont want clicker #4, I just want to prove something about the clicker and what its going to do for me. 

That test ive done several times this season but never got to make the engine labor by drifting rpms until recently.  The upside is most of the test guys have got these results earlier in the season - to get the engine to labor in deep snow and solve
the engine-speed-drifting with a different primary spring.

The downside of adding weight to the 967 ramps in the amount i've added is as the pivot bolt weight has increased, so has the engagement speed.  It went from 3200 to 3700 rpms.  Adding pivot weight in this amount causes the center of gravity on the ramp to move towards the tip; acting as-if it has more tip weight.  

What ive found is the engagement speed is slight high and makes it more difficult to do wrong foot forward becuase the clutching wants to "surge" and ever so slightly pull the handlebars away from your hands.    Talk about concentrating super hard on maintaining throttle control.  I have Bret Rasmussen voice repeating itself over and over as I practice wrong foot forward.  The higher engagment speed is making me tired and Im in good physical shape.


At about 80 feet I can smell the drive belt.  The rider behind me can smell the belt.  If I let Gino go first to do a wrong foot forward and then I follow his track, the load is lighter for me and I still smell drive belt.  Buddy has a MTNTK Blow hole on his 850 x 154 summit and all he smells is burning belt in his face all the time - YUK!   But man that Blow Hole works like a shot for moving air from the clutch guard.


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New primary spring - Finally

What a great supplier.  Earlier on in the winter I give Dale at Dalton a rundown of the data I been pulling in from the test guys.  The springs used, elevations, snow depth, engine speeds and comments.  This spring here I stuck my neck out for a suggestion to have Dale make.  I wanted 140 start and the best he could do is 150 start.  Ok, for me that's still better than 170 start.

Im hangin my hat on a handful of springs and this is the latest one.  Took Dale 7 weeks to get this one made.  Normally its 6 weeks but man, the waiting for this has been pure agony for me.

Joe) Dale, is it ready yet?
Dale) no
Joe) Dale...any news yet?
Dale) No
....haha, Sorry Dale buddy but you know me, my anxiety can only be quenched with the spring itself and / or......red wine!  haha

Part of the anxiety too is, the Fedex charges to get more than 6 but less than 10 of these springs out on 2 day air is like $540.   Truly you'd have a shit if you knew the total cost (less my own sled) of recieving parts, cost of the parts, sending out parts to test pilots all over God's creation.



Flyweight legend (temporary)

1)    38mm pivot + T7 +T4 + 4mm = 33.2
2)    38mm pivot + T7 + T4 + 3mm = 32.8
3)    38mm pivot + T7 +T3 + 3mm = 31.5
4)    38mm pivot + T7 + T4 = 30.9
5)    33mm pivot + T7 + T4 = 30.5
6)    38mm pivot + T7 +7mm = 29.7
7)    38mm pivot + T7 +4mm + 2mm = 29.1
8)    33mm pivot + 3mm +2mm = 28.8
9)    38mm pivot + T7 + 3mm + 2mm +2mm = 28.7
10)    38mm pivot + T7 +3mm = 28.1 gram
11)    38mm pivot + T7mm + 2mm = 27.6 gram
12)    33mm pivot + T7 + 2mm = 27.5 gram    
13)    33mm pivot + T7mm = 26.4 gram
14)    33mm pivot + T7mm + 2mm = 26.0 gram
15)    38mm pivot + T4mm +3mm +2mm  = 25.1 gram
16)    38mm pivot + T4mm +4mm = 24.6 gram
17)    38mm pivot + 7mm + 3mm + 2mm = 23.9 gram
18)    38mm pivot + 7mm + 4mm = 23.3 gram
19)    38mm pivot + 4mm + 4mm+ 2mm = 22.8gram
20)    38mm pivot + 4mm + 3mm + 2mm = 21.7 gram
21)    38mm pivot + 3mm + 2mm + 2mm = 21.1 gram
22)    38mm pivot + 3mm + 2mm = 19.4 gram
23)    38mm pivot + 3mm = 18.3grams
24)    26mm pivot + 7mm = 16.9 gram
25)    26mm pivot + 3mm + 2mm = 15.6gram

Flyweight package
BRP# 486017028 Tungsten 7mm  @ 9.7 grams – Qty 3
Joe's Tungsten T7mm 8.7 grams
T4mm @ 5.2 grams – Qty 6
T3mm @ 4.1 grams – Qty 3
BRP# 486016043 7mm – @ 4.0 grams - Qty 3
BRP# 486016042 4mm – @ 2.3 grams - Qty 6
BRP# 486016041 3mm – @ 1.7 grams - Qty 3
BRP# 486016040 2mm – @ 1.1 grams - Qty 6
38mm pivot  @ 17 grams  - Qty 3
33mm pivot @ 15.5 grams - Qty 3
26mm pivot @ 13.3 grams - Qty 3

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These are two average questions I been getting over the 2016~17 winter and spring.

Q) Joe how come I dont see you have any custom ramps?
A) I've made custom ramps in Sept 2016 so Im ahead of the game.  Im not offering anything until I believe i've exhausted testing the stock BRP ramps applied to the the custom springs I've had made for me.

Q) Will you have adjustable ramps?
A) At this point, the adjustablility of my ramps will be like the BRP ramps with the single pivot hole and clicker adjustment.  I will be tuning old fashioned like Aaen says to with flyweight grams and spring force changes.  

I have other things for the pDrive primary clutch up my sleeve im working on.

June 15th 2017 Latest specs for model year (MY) 2018

New ramps - 990 low elevation.  965 High elevation (146 to 175)

New helix - 42/38 (146" only)

Gearing - 21:49 (146), 21:49 (154 Hc Europe),  21:51 (154)  21:53 (165, 175)

I can't wait to stuff the 175 gearing in my 154 and test out the 990 and 965 ramps...woo!

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PDrive pivot pin kit done finally Oct 18 2017

I got the weights done for my G4 summit clutch kit pDiddy pivot bolt kit and does not matter what ramp the owner uses. They can use the 990, 965, 967, 951, 968. I have the weights done for every ramp and can go to at least 100 grams on the total overall ramp. Not ready to send out a kit yet, just saying I have all the configurations done. I have a few more loose ends to tie up.

For the iB 850 summit clutch kit, the elevations are laid out as a starting point. An owner of this kit can tune it for correct engine speed in about an hour of riding. Simple; use the belt change tool on the clutch guard to remove a pivot bolt and adjust the spacer size and/or pivot bolt size to correct engine speed at full throttle.

Pivot bolts require the tightness allowed by the original BRP belt change tool - the OEM belt change tool applies the correct amount of torque for the bolt every time when the tuner cranks it down, hand tight.

t=Tungsten, s=Steel, TI=Titanium
Example: t7mm = tungsten 7mm spacer. s3mm = steel 3mm spacer. TI35 = Titanium 35mm socket cap screw


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Belt heat, belt life, gear change, clicker position

Jacksen) how’s the 850 kit going to help the belt life? I know skidoo has warrantied the motor mount shims a new belt and gearing for the 17s. What are your thoughts on the new gearing offered on the G4 summits? Should I leave it or put the new in? And the clicker does what on this pDrive?

Joey) Core Value - The #1 way to keep clutch heat to its lowest is to have correct engine speed when full throttle – 7900. Lower or higher than 7900 the temperatures soar. Both over or underrev, the belt ceases to move across the face of the primary clutch face.

Core Value - Lower heat by lowering part throttle engine speed. So when (example) poking along at 40mph on the hardpack, from this snow area to that snow area, lower heat will be at 6200 rpms instead of 6700 rpms.

Subjective Value - Gearing lower is up to you. Me, I bet less than 5% of my total riding is on any hardpack. Im 90%+ in the trees or swamps or out back where its technical. Usually the only trail I drive on is the trail I made riding in – If I can help it. And by that time, im p00ped to drive hard. Haha. I choose lower gearing because I want the track to “roast” whenever I can and put my 154 x 3" up on its tail.
Some gear higher by 1 tooth on a G4 sled because they have a lot more riding on hardpack percentage and sometimes outright trail ride, even with a 3” paddle.
Gearing lower is up to you what you do with your sled.

lower number makes more “revvy”
Higher number makes engine lug harder.

My kit is designed to run in clicker #3 and then adjust the clicker to how revvy you want it or how much lugging you want the engine to be loaded. To change the pivot weight and correct engine speed, it will be a 5 minute adjustment anywhere you want to stop and change the pivot weight. Simply take the belt change tool off the clutch guard and remove the pivot bolt to change the bolt itself and/or the spacers to adjust the flyweight grams.

Say right now you are in clicker #3 and the pivot weight makes 7900 rpms.  Because of today's conditions you want the engine to feel more revvy off the bottom end to midrange - no problem.  Take the clicker and move it to #2 or #1.  Lowering the clicker will make the engine be more revvy.  The 7900 will stay about the same because the pinweight controls engine speed at full throttle.  Next example - Because of this different day conditions, I want the engine to be, and feel more loaded.   I want to do a bit of long hardpack riding to get to the deep snow location.  No problem, clicker up to #4 or #5 and the engine will have a more loaded feel.  Engine speed at part throttle on hardpack will be a few hundred rpms lower.

Thanks, Joey.


Kevin) Hi Joe, I changed gearing on my G4x154 from 19:45 to 21:45 because the stock gearing was too low for me. I mostly just boondock around here with short climbs of no more than 1000' vertical. That and most boondocking areas are connected by groomed trails and lakes so having a top speed of 130 km/h (80mph) is good so I don't have to hold the sled to the bar when I'm travelling between powder stashes.
So if your full clutch kit with springs and helix would work with my gearing I will probably get that. If not, I'll get your your pivot weight kit instead and run the stock springs and helix.

Joe) Hi Kevin. Oh that 21 top gear will be just fine. I kept my 19 top gear and the guys I ride with having older sleds thought my sled "rips" across the lakes and hardpack trail. Sometimes I have to run a bit of hardpack to get to the powder stashes, I drive not so fast to conserve fuel.  I try my best to run out a tank of gas and tap into my LinQ gas can.
Yes the clutch kit will work with your 21 gear and you’ll be able to do 130kmh(80mph) without damaging the belt. In fact after you been poking along the flat parts at 75mph with ease, when “you stop” and people with regular sleds “catch-up-then-rest beside you”, they are going to say “what-in-the-heck is in that sled?” HAHAHA.
You can set the clicker in 3 or 4. Remember the clickers do the opposite of what the old TRA does. The pDrive is higher lumber, load engine harder

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Flyweight - pDrive flyweight ramp differences (lazy or crisp)

Article, click on link above

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