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M7 Clutching and Clutching Related Info compiled by "Upjohn"

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Steering Wheel Holder
Staff member
Lifetime Membership
Mar 22, 2005
Larkspur, CO
M7 clutching INFO-

**Loose fasteners bulletin**
Got my recall notice today on my M7 for the three bolts on the secondary clutch, two bolts near the secondary, the gas tank bolts, and bumper bolts. I was pleased that it gave photos and instructions so you could do the work yourself, as opposed to just saying, "take it to your dealer."

The bolts for the secondary are small T-25 (I think) torx bolts. The instructions say to tighten to 33-37 inch-lbs. For those without an in-lbs torque wrench, here's the best way to approximate it: After you put Loctite on the bolt, put it back in using just the torx bit. As soon as the head of the bolt seats against the aluminum, give it 1/8 turn more, and you should have right at 35-37 in-lbs, based on what I saw from my own torque wrench.
The two behind the secondary get 20 ft-lbs. I was able to get to one, but not the other. The others were easy as well.
Secondary bolt torque- Artic Cat's service manual says 32 ft-lbs, they also say to use #243 Loctite on it.

-Primary clutch loose weight pins
Everyone keep an eye on your bolts that hold the weights in on your primary clutch. The little plastic/rubber washer that sits under the head of the bolt on the outside of the clutch have been breaking off. Mine did and I just noticed it after the head of the bolt has started to grind on the aluminum gapping the alum bad enough to need a new section of the clutch. Dealer said this is the second one he has had come in with the problem.
-Primary clutch loose weight pins
Everyone keep an eye on your bolts that hold the weights in on your primary clutch. The little plastic/rubber washer that sits under the head of the bolt on the outside of the clutch have been breaking off. Mine did and I just noticed it after the head of the bolt has started to grind on the aluminum gapping the alum bad enough to need a new section of the clutch. Dealer said this is the second one he has had come in with the problem.

-Diamond drive secondary adjuster
How does the BD one work without shims?
Once you assemble the adjuster on the secondary, it works by turning the adjuster..
On the new metal adjuster, you loosen the allen head screw that replaces the bolt that hold's your secondary on, make your adjustment and tighten the allen bolt back up, and your done..
Complete kit with the allen wrench included..... .
Don't have a o-ring and washers to mess with, and have a broader range of adjustment, and nothing is going to back out on you,since you tighten the allen bolt against it.

-Primary belt side clearance
The only thing I noticed after the first weekend was the side clearance on the belt to primary sheeves was way to loose, (.075), should be .015 to .020,. You have to remove the spyder and reshim to change this. Also it affects balance so you may have to reindex the clutch. The belt clearance should be set with a new belt only. Sure the clearance will increase as the belt wears but not to the point where it affects performance. It is a pain to reshim the primary so do it only once. By the way I checked 4 other sleds at the dealer and they were all correct. Does not seem to be a universal problem on all f7s. Dave E.

-Secondary spring change
its simple
-- pull off the clutch 1 bolt
-- take off sheave adjuster
-- take small aluminum cover off
-- make 2 marks 1 on secondary spring adjuster [plastic] one on clutch
-- count the turns it takes to take it out mine was 8 3/4 turns

-Secondary Springs
M7 not holding rpm on hillclimbs. Tightened sec. did not help. I have a maroon d&d spring to try. Stock is 110/260 d&d spring is 130/340. That seems a lot stiffer, what do you guys think. I am new to this clutching thing.

I went to a AC green which is 110/280. It helped some. I've got the D&D maroon on the way. Should be the ticket.

The M7 secondary from the factory are set incorrectly. They should be measured from the OUTSIDE of the aluminum cover to the white disk with calipers. The measurement should be .52 I set mine just a tad tighter to .56 and it launches perfect. This measurement is from cat.

-Clutch Springs
I have checked the driven titanium but at 2.2 and 1.1 i get 195 and 340
the book shows 110 260 which I get at 2.9 and 1.6
2.9 is the preload measurement, 1.6 is shift out, it cannot get to 1.1

reason I checked it was because I got one of those maroon driven springs, it said it was a 160 260 at 2.2, 1.1
well if I check it at preload 2.9 it is only 105, and at shift out it is only 200, that is way less than the stock Ti or white!
don't know why they check it at 2.2 and 1.1, clutch can never get the spring to 1.1, in the tester it is almost coil bound. I have 2 new ones (maroon) and they both measure the same, but their weights are measured at 2.2 and 1.1, the spring installed is about 2.9, and it is at full
shift at about 1.6
Drive- 114@ 2 9/16 -- 267@ 1 5/16

Clutching - helix / spring
My guess is on a stock m7 you will not pull that 44/40, I know some guys who tried it last year
he should have the straight 36, you will now fairly quick if it will work or not
I know guys have had success with the 42 /36
I would try the 42/36 and get a heavier spring fett brothers has a 160/265 maroon

Stock M7 secondary spring-
0648-718 SPRING,DRIVEN-TI-110/260 LB (WHITE)
this is from the parts breakdown, that measurement is made at just under 2.9 and at 1.6,
if you measure the Ti spring at 2.2 and 1.1 it is 195 ,340
the white spring is identical in weight.

-platinum spring (the only stock AC spring that works for me) not the titanium spring.

You guys know you can change the secondary spring on the sled right. Just take the deflection ajuster out and take the three small torques out of the end of the helix. Turn out the ajuster and bang go spring is out. Pop in the new one lock tight the three small torques and back on the trail.

-Secondary clutch deflection
Spoke with Diamond Drive at the snow show..and there is available a steel threaded adjuster to replace the plastic one...it gets very worn (plastic one) from adjusting belt deflection to removing the belt.....also there is a tool for greater leverage for compressing the secondary spring, neat and simple..

-there is one clutch tool in the oem tool kit, it is for loosening the white plastic nut that all of the clutch shims ride on, supposedly belt deflection can be adjusted by loosening/tightening this nut but you have to take the nut out of the clutch, and add or remove a shim and then tighten the plastic nut tight again. removing shim(s) will increase belt deflection (loosen the belt, lower it in the sec. sheaves) and adding shim(s) will decrease belt deflection (tighten the belt, raise it in the sec. sheaves)

-M7 belt deflection adjust -
The plastic adjuster needs to be tight, the plastic belt deflection thingy has left hand threads?,You use the shims to increase or decrease the belt deflection. Adding shims decreases deflection and subtracting them increases deflection, just the opposite of the older cat driven clutches.
The plastic nut is not meant to be the adjuster. It is the stop that controls the belt width adjustment by means of the shim that you put on it. The more or less amount of shim that you install controls where the nut bottoms and thus where it stops the sheave. If you leave it loose it will back out as the clutch opens and closes. It need to be tight and the shims used for width adjustment.
That is what the shims control. If you put more shim in there the nut tightens on the shim earlier which lets the sheave come closer together. If you take shims out, the nut will go deeper and push the clutch open, but if you leave the plastic nut loose it will work looser as the clutch operates. The shims just control how deep the plastic nut tightens against the clutch.
You screw the plastic adjuster nut all the way out and the shims slip over the end of it and are held on by slipping over an o-ring. There should be a stack of shims on it as it comes and you can add or subtract more to get what you need. The three torx screws you are looking at just hold on the cover plate and outer bushing assembly, you shouldn’t have to take it off. Hope this helps, I know it's a lot different animal than the old cat roller clutch which means my stack of helixes and springs won't work either, damn it!

-Slow back shifting secondary tension
I find when i have to back out of the throttle for a moment on a hill, when i get back into it, its not shifted back as fast as i would like.
Tighten up your secondary spring a little bit. This will help. I turned mine about 1 full turn and it helped quite a bit. turn the preload up on the sec. spring that it will help the backshift

If you look at the end of the secondary, you will see a white plastic piece on the inside. This adjusts the spring tension. You have to take the small white piece off the end with the tool in your kit, it is reverse thread. Then you can possibly reach in through the slots in the end plate with a tool they should have at your dealer. Sorry i don't have a part number, or you can take the end plate off for better access. Remember to use a little bit of blue loctite on these three little screws during reassembly. The proper tension according to arctic is about 3/8 to 1/2 inch, I have been running mine on the tight side and getting pretty good results.

The M7 secondary from the factory are set incorrectly. They should be measured from the OUTSIDE of the aluminum cover to the white disk with calipers. The measurement should be .52 I set mine just a tad tighter to .56 and it launches perfect. This measurement is from cat.
it should be .52" from the outside of the aluminum sec cover in to the white plastic piece (measured thru the slots on the cover). Most (or all?) of them were way off- like only .25" from the factory. It takes a lot of turns, one adjusting slot at a time to get to .52".

-Clutch belt deflection
You have to be careful how much your belt "squeaks" at an idle. If you have your deflection too tight (deflection and alignment are two different things) the belt will not allow the clutches to release during off throttle or light throttle (especially with hot clutches). This forces the springs to do more work and slows the backshift dropping your rpm and again causes heat. Basically if you have any less than 1" with very little pressure (1 to 2lb) you are too tight. These basic adjustments are what separates the good ones from the bad ones. Don't count on your dealer to do anything more than the factory specs unless you have a good one. Geo.

- Secondary clutching M7 / TPS settings
Stock helix 36 deg straight - stock primary weights 70 gram high elevation / 72-75 low elev.

I had the same problem when I hit a bump going up a hill I would lose 4 to 500 rpm. I did adjust the secondary but it didn't make much difference. What I did find that helped the most was loosen up the track. I believe what was happening is when the suspension compressed hard it tightened the track so hard it would shift out. Anyway if your in powder position try loosening your track until you can put 3 fingers in the sag gap. This will help your suspension a ton and it made my problem with rpm on a hill go away. Your track can even run looser but didn't see much benefit past 3 fingers. If your in hill climb you can't run that loose but your probably having different clutch problems anyway. We are going to try a steeper helix for tracks that hook up good but haven't tested yet.

I have found that by going to a much stiffer driven spring you will do nothing but gain in performance. You might have to play with weights but you can get the m7 to run with the 900 cats. The problem is the belt slipping in the clutch. Next time you ride try to fill for rpms but no accel. Try D&D maroon or tan with stock helix. Rpms should go to 7600 right away then pull to 7800-7900 if you want it fast or 7700-8000 if you want power. My exp. is at 8000-10000 elev.
What I am talking about is if you want the sled to accel. to it's max as soon as you grab a hand full you should start to tac at 7600 then climb to 7900. If your main goal is power you want to set it up to go to 7800 right now. -------------------------------------------------------------------------
Your HP. curve is at 7800-8000 your torque curve is at about 7400-7600.
If you don't make the sled pull in torque curve your acc. will be slow. The hard part is to clutch so you don't fall below the torque curve on a hill climb or back shift. I call it wasted hp. but if your rpms are in the hp. curve you have more room to loose rpms without falling out of torque curve, which is where you will feel sled slow down or load up. You might also want to have your dealer check your TPS at full throttle I have checked 12 sleds so far & not found one in spec. They can most of the time be set it in spec by taking the slack out of the throttle cable. You don't want them to set the TPS it will void warranty on throttle body. Then You will have to back off oil pump because you just made it richer by tight cable. Three to four turns on the oil pump arm. If the TPS is set your rpms will hold SOOOOOOO much better you won't believe it's the same sled. The higher the elev. the more the TPS affects the way it will run. The TPS is what changes your timing to where you have the throttle pushed. PS don't try to advance timing with TPS use a timing key. Hope I answered your ???s.
Their is something wrong cats throttle cable or tps setting is off. Take it to your dealer & have him check tps at full throttle & at ideal. If your ideal is low you usually have a hard time restarting sled at high elev. pulling rope 4-8-?? times to start after you shut it down. It seems the higher the elev. the more trouble you will have. If you are low TPS full throttle you will have trouble holding rpms & won't be running at full throttle the higher the elev. the more problem you will have. If you think high elev. is up to 7500' you won't normally think it's not running right but 9000-11000 there is a huge diff. Yes I'm talking about upper end of travel they are not opening all the way the tps specs are what got me to start looking. You are also right on the oil pump but if you get to the mark sooner than you should you will be rich on oil. The D&D maroon is 130-340 cat white/tit. is around 90 comp. if at lower elev. 5000-7500 D&D tan may be better ?? 110-320 the specs our in thier book.

Polaris soft belt for 036 replacement
Polaris part number 3211104
P.S. if you use the 440IQ belt part number 3211104 you will need to drop 2-5 grams of weight because of how well the belt sticks. I can’t tell you how long this belt will last but I can tell you it sticks like glue!
Get your hands on a 440IQ belt it will slide right on the M sled and crossfire. It will stick like glue. Depending on your HP you will need to drop 2-5 grams of primary weight if you use the IQ belt. The New 044 belt seems to be softer than the stock belt.

M7 clutching recommendations-
IF your in the powder the 38 is the most I would go. If you trail 50/50 the 40/38 is nice. If you want to run the 40/38 or even a 48/38 you should run the Fett-brothers maroon secondary spring 165/260 to slow the shift rate.
Then go two grams more than what stock states for elevation (Dalton pro weights) and go to the cat orange/white primary spring.

Taking apart secondary---
Take out the deflection adjuster. Un-bolt the secondary. It will slide off the DDrive shaft. Make sure you put the rings that are behind the secondary back in. Don't loose any.

Now take the end cap off the helix. It is on the out side of the helix. There are three torques holding this part on. Some heat from a propane torch may be needed.

Take the white spring rate adjuster out of the center of the helix. A tool might be needed to get it out. Spin this out there is some pre-load on the spring but not enough to take your head off.

ON the back of the sheave that has the helix attached to it you will find 6 torques. Heat is needed for these guys too. Turn them out and you have the helix out.

Now I was not sure if the sheaves are balanced individually or not so I marked the end of the sheaves place meant to each other and helix before I took it apart. When putting in the helix line up these marks you made and you should never have a problem.

Now there is a ring under the helix that will need to go back in. You don't need to mark it as it is totally balanced it self.

Put here back to gather and you’re done. I have found that if you have a roll of packing tape you can set the clutch down on it the one end will slide in the tape roll. You can then put the spring back in by hand with out much spring pre-load. This little trick really helps.


100-150 Grit Emery Cloth instead of scotch brite
Brake cleaner first then clutch cleaner

STOCK DRIVEN SPRING - #0648-693 wht 110-260
Replace w/
#0648-774 orange 175-280

STOCK DRIVE SPRING - #0646-229 yel/wht

STOCK WEIGHTS # 0746-672 75 gram 0-3k ft


IMHO, (very polite eh!, just joining in on an age old discussion) WB you over simplified and only considered full throttle and RKT your kit (being made in various forms by many reputable company's now) still requires the owner to come up with a spring-helix combo that suits his sled, area, and desired feel (some people are short shift diesel owners and some are high rpm rice rocket owners). In my experience diesels go through the deep and steep better (wait 'till you see the difference between the '07 and '08 M8 stock set-up).

Nublin, if you get to the SP green spring, you are close to the compression only springs in rate. Check it out. It was never intended to twist 36 degrees or go through that amount of travel.

If you published a book with all the correct theory, charts etc., and wrote it one way 40% wouldn't get it. If you wrote it another way the other 40% wouldn't get it. 20% always do get it.

My take from my experience with compression only type secondary (Doos, Cats, and Teams) in point form (for mountain use, what else is there?). I gave up on twist spring types because of clutch wear (flattened rollers?). Maybe that is why many stuck to button type set-ups or steel rollers back then.

- a 162" needs more helix angle than a 121"
- a 1000 needs more helix angle than a 370
-a 900 lb (sled and rider combo) needs more helix angle than a 650lb package
( All the above are 'cause, more squeeze is required, clutch diameter is the same, right. If load and power are greater than you needs more squeeze to keep it from slipping. The friction factor (belt to aluminum sheave) is the constant. Note the secondary recommendation differences between the '08 m1000 and '08 m800. Stickier belt on the 1000 too.)

-a 50 degree helix backshifts quicker than a 36 degree but it is unlikely to provide enough squeeze for today’s tracks and torque with the springs available ( I'm still waiting for a dual or triple rate, cross over set-up like shocks, that would be adjustability)
( This one will be disputed because of lessons from the old twist spring type secondary. On the old school stuff the more you twist the spring the more backshift help from the spring. On the new school stuff the more you twist the sheaves during up shift, and that is what provides the squeeze, the more the sheave has to twist AGAINST the rotation of the secondary clutch to return to a lower gear.
This effect is greatest, in both directions, at full throttle, the hardest backshift to achieve. If the backshift is too slow, the gearing is too high for the load (small diameter in the secondary, less belt contact) and the belt starts to slip. Once it starts to slip it will continue to slip and build heat till you back off, then you lost. Don't confuse this with losing rpm due to improper front clutch set-up.
With the new school secondary 2 degrees is noticeable.)

-nylon rollers flatten due to heat
(If your clutches are hot your set-up is wrong for your sled, weight, area. Dry powder is different than heavy wet snow.)

-spring rate provides 100% of the backshift signal, shallower helix needs more signal (spring rate) at full throttle that a steeper helix (remember what needs more helix)
(Can you have too much backshift signal? Ever chop the throttle on a slow downhill and almost gone over the bars? Sort of like the stock set-up on most sleds. Too much backshift signal and you lose upshift, performance, trackspeed.)

- part throttle feel and instant track speed is 75% spring and 25% helix
( I like riding areas with short steep pulls, a few trees in the way and little if any approach, like ravines. Very rarely do I get to the areas with a 1/4 mile run at the bottom and pin'er till you run out of steam anymore. If I did I would care less about the part throttle feel or instant track speed, only about holding the grip at full throttle.
'Cause of this I pick a spring with less initial rate, like the AC green (same last 1/2 as the orange, but soft first 1/2 like the white). With the adj. spring preload I use (same as '05 and '06) I can crank in another 3/8" preload on the days I go out of the trees with the "Big Dogs" ( the ones who hate to get stuck without gravity to help them get unstuck).)

You can have what you want either way, but you have to know what you what first.
There is nothing wrong with the DD secondary except diameter. Because of the diameter it has to go through the gears (ratios) more, and set-up is more critical.
Alignment, deflection, and cleaning the crap that comes in them from the factory has to be your first step. Then tune.

Lots of good info here and a lot of great professionalism (tongue biting). But because of it, a lot more useful info is being presented.

I have a bit of experience on the same track Dyno Arctic Cat uses. Its an Eddie Currant braked track dyno with all kinds of bells and whistles. Lots of aftermarket/custom programming to do far more than 99% of the track dynoes in use. The way you can upload a program to LOAD the sled for in field/like conditions is what really makes this one different. Lots of winning hill climbers and teams have been setup on this dyno.

One thing I would highly recommend to everyone looking for more belt grip, is the XS belt. Clutch heat bye bye, because the hotter things get if they ever get hot the stickier the XS becomes. This belt and everyone Carlise makes is tested by this dyno on just about if not EVERY sled currently being sold on the market, yesterday and today.

One very important FACT that I am not sure everyone knows is in the DD system the secondary is the dominant converter unlike past models. I am sure some of you have read this in your race manuals or at race seminars. Therefore its supposed to control backshifting and upshifting rates and speeds from its torque sensing abilities. A stiffer than normal spring is required to provide instant shift changes in the DD secondary, regardless of helix.

Fact taking Geo up on his offer and having successful results will sell more kits than any other method to date and crush any credibility issues.
Fact the helix provides ATLEAST 90% of the belt grip.
Fact the bigger the helix # the faster it shifts up and down.
Fact the smaller the helix # the more grip you will have.
Fact springs control the up and back shifting in the secondary.
Fact a light spring will ALWAYS out MPH a stiff spring
Fact just before and after the DD secondary reaches 1:1 ratio is when it has problems regardless of belt compound. Much improved with a softer belt.
Fact the XS belt was far better heat soaked or not, even on a mountain sled and under ridiculous amounts of stress. It still is stronger and more durable than the stock belt.

I know some of this was already stated in previous posts in this thread but these are facts. And working with and around these KNOWN factors are a huge help to making any combo work better.
IMO and from data I have seen the torsional kits are a bandaid at best, as are many of the parts being sold for the DD. Can they be made to work better in ONE area than a standard DD parts setup. YES. But not even for a full pass or pull. The one biggest improvement over a STOCK setup was initial acceleration, long pulls or overall shifting and grip are sacrificed during the run. The single biggest improving part was the WEAK torsional spring, it added lots of upshift forces and more MPH, as does any weak spring in the secondary. Unfortunately it was also the biggest contributor to inconsistency. Inconsistency was the biggest downer. Once a good setup was achieved for one application it did not take more than 1% load change to ruin it completely. So I hope the snow you tune in doesn't change conditions.
From what I have seen heat is the biggest cause of flattened rollers, improperly replaced rollers that do not or did not roll freely. side note: Spring bind from a spring that its bases will not spin freely hurts consistency bad. The D&D shift assist thrust bearings are a MUST. They showed a positive and consistent improvement in shift force and consistency from run to run. Not all sleds have this issue, but when you hit a wall and it just won’t go faster, this is what it was. Side venting screens are nothing more than a bandaid for wrong clutching. Cause the cause of the heat has not been eliminated. With the torsional kit the primary had to be made to do the work of both clutches, ie backshifting too. Heavy springs and odd weight profiles. This lead to a very narrow application and inconsistencies for changing conditions. As the primary usually would overshift for atleast half the run causing the secondary to play catch-up and inconsistent rpms. Clutches chasing each other.

Overall the stock like components worked best IMO. When considering consistency, broad application for one setup, max track speed held under increasing loads or changing loads( jumps-trech crossing,chopping throttle) and max HP to the track, when tested. At 1:1 and further a helix with less than 40 was best for temps/grip and MPH. The torsional kit did provide max Track HP but not always and with a very light spring. Anyone that has a track dyno knows what that does to your HP #'s. Its like messing with the load cell/torque arm.

With the XS you will have to reduce the primary weight, it will lower rpms about250-500 depending on setup and what belt you are switching from. I am not sure how long it takes to break in but I do know while racing it takes about 5 passes before it starts to settle in and be consistent. I have run NOS with the XS belt with no changes. the aded rpms from the NOS about a 50-60 shot brought it right back up there , and holy cow does it grab. Belt sheave clearance can be run very tight with the extra grip too without burning the belt ever. Even when being stuck. i had to reduce at least 2 grams.

Also the primary clutch damper when removed will reduce heat about 20 degrees. When it gets heat soak it really holds the heat in the primary. And yes you will notice the inner sheave will always be hotter and about 30-50 degrees hotter than the outer sheave.

I know with out looking at it that your primary spring is hanging up stopping your shift. You will need to mill out the spring cup wider to let the spring grow with out hanging up. Other thing to look for is one of the weights shifted over out of perfect center. The weight can catch a milled edge in the tower and hang up too.

The straight 36 back shifts very very well with the white spring, but is not strong enuff on the start rate. Finish for the 36 is great. The T660 spring works better in the ups and the straight 36.

Damage I would try the Goodwin dark blue/yellow before you go nuts buying parts. Trust me on this. IF you think the orange spring is fun to ride on the trails just try the blue/yellow and the 44/40. The RTK kit will have you chasing your tail even more if you don't have time to play with it. Most all clutch books will tell you that you want to pull 200-300 less then max hp numbers to hit the torque number and then the RRR's will creep up 200-300 after the weight of the sled gets to speed.

My reasoning for running a fairly shallow and straight helix on the M's-
The M7 is notorious for being a bit "lazy" feeling off the bottom and at low speeds, even with my ET900 it retained that classic M7 feel off the bottom. A shallow helix makes it feel "snappier", and an aggressive upshift can still be had with an aggressive primary setup. Also, the DD secondary isn't exactly known for it's aggressive backshift capabilities, it feels nothing like a Team or Doo secondary as far as backshift speed and force. A 36 helix will allow it to work as good as it can in the backshift department.
To reinforce this theory, look at what Cat did in year 3...that super high force orange spring as a "band-aid" to get a acceptable backshift white using the heavier primary setups that are necessary with the 800 and 1000.
IMO a shallower helix and a moderate spring will be more efficient and allow the primary more freedom to do its job.
Also, take a close look at the cat progressive (actually most are a dual angle,not progressive), look at where the angles transition and where the rollers ride, a 44/40 for example....the rollers are past the 44 portion soon after the sled begins to move so a straight 40 is virtually identical in function.
I haven’t looked at all the various Cat helix's so others may be different.
My basic theory for a mountain clutch setup is always control the upshift with the primary setup, and setup the secondary only for the backshift you desire...I know they effect one-another and it's much more complicated than that, but if you want an aggressive up shift the helix is not the place to look, up shift is driven by the primary so that is where the focus should be. Steep helix's just make for a lazy backshift, fine for the flats and drag racing but have little use with big tracks and steep hills. JMO-

The numbers are the angle of the helix ramps in degrees. There are 3 types....straight, multi-angle and progressive. First number is the starting angle and the second is the angle at full shift.
Basically a shallower (lower angle) will provide more belt squeeze which results in a slower upshift but a stronger/quicker backshift, and a steeper angle less belt squeeze, quicker up shift and slower/weaker backshift.
In MOST sleds I would agree that a progressive is usually the best route, but on a Cat with the Diamond drive I really think a shallow/straight angle works better in the mountains with a long track.....not necessarily the case in the flats though.
Helix's are marked with their angles unless it's aftermarket, then they may put a code on them so it's more difficult to know the angle.

My opinion.

A 36 backshifts slower than a 40 on the compression style helix.
I,ve never had a backshift problem since I shelved the 36.

If you can't feel a change or see a change on your tach with a spring change or large adjustment in preload, you are using too large or too small a helix.

I always seem to return to the 44/40 on my 153" sleds and fine tune with the spring.

My 800's will not pull out of a full load donut with anything larger than a 44 start. The 46 is good if the hills are shallower or more progressive. I believe the larger start is important to get the ball rolling so to speak and most Team set-ups use it. If you could watch the belt in the secondary during a ride You would see it in the upper parts of the secondary more often than you think.

The orange spring is a good balance in the back when combined with the high start springs in the front (like the yellow white or orange white). Not a bandaid by any means, but maybe a bit on the stiff side for the first 1/4 of shift. It works very well with a higher start angle helix.

Haven't tried a full progressive but would like to but don't need to.

One person’s opinion of the age old question of what will make my sled haul ssss.

I believe highlife is right; the belt deflection is how much 'slack' is in the belt when you push down on it. kinda like the track tension.

joeyslushr, the part that is being machined is the spider in the drive (primary) clutch. you have to pull it off, and pull it apart, then you have to mount the whole thing in a vice - be careful not to damage the thing, and heat the spider with lots of heat, and use a really big dude, or a really really big wrench to unscrew the spider from the body. then, you machine down the surface of the spider so the sheaves are closer at rest. (make sure you measure the distance between a NEW belt and the sheaves before you take any of this apart.) I think most if not all of the m7's came with some ungodly amount of play in here. Im betting that some moron back at 'cat thought he was a drag racer and he was the idiot in charge of the set-up specs on the drive clutch.

I shot for about .015" of an inch, and ours were pushing .050", so we machined off .030, and .035 on the two we had to get them there. then re-assembled the clutch, (used green loctite, not the sleeve retainer one though) and put it all back together. works much better.

Primary Drive Spring ------- The AC Gold part # is 0646-376 – 75Ib / 275Ib

Drive Clutch Springs
P/N.......(Rate @ 2-9/16") (Rate @ 1-5/16") Color

0646-148 53 lb 224 lb Red/Blue
0646-150 72 lb 188 lb Silver
0646-149 74 lb 228 lb Red
0646-376 75 lb 275 lb Gold
0646-147 114 lb 267 lb Yellow/Green
0646-673 114 lb 267 lb Yellow/Green (titanium)
0646-155 121 lb 240 lb Purple
0646-229 122 lb 285 lb Yellow/White
0646-248 143 lb 290 lb Orange/White
0646-684 158 lb 290 lb Black
0646-376 75 ob 275 lb Gold

Driven Clutch Springs
P/N........Color..Rate @ 1-7/16" compression

0748-025 Green 157 lb
0648-114 Red/White 116 lb
0648-674 Red/White 105 lb (titanium)
0148-227 Yellow 92 lb
0648-012 Blue 79 lb
0648-010 White 58 lb
0148-176 Black 42 lb
0648-702 Red/Black **140-240 lb @ 1.1-2.2".
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