Lets talk about spring wrap

Backwoods M Max

Backwoods M Max

New member
Joined
Mar 31, 2011
Messages
1,052
Location
New England
Ok guys,
I know nothing about how spring wrap effects the performance of the secondary. I am trying to get my mountain max dialed in after a bit of a disappointing year last year.

Even after stretching the sled to a 151 it still didn't give me what I know it can. By black line test I'm only getting 1/2 way through the primary and revs are in the high 8000 low 9000 range with 9300 being seen when it was time to pin it to win it. The track speed that I needed just wasn't there so for this year we're trying to fix that.

I currently have the setup from a highly respected yamaha guy from idaho in it. It didn't quite work like it should have. I don't know if I can get the performance I need by tuning the spring wrap angle in the secondary. In another post a respected tuner said that the primary was fighting the secondary because of too much spring. How much can I relax the wrap as I tune before I run into issues.

The current setup is. W-W-W primary w/8cr weights 17.2 inner 13.3 outer. Secondary is a silver spring at 60* wrap with the stock 43* helix. Gearing is 20/39 for a 1.95:1 ratio in the chain case drivers are the same 8 tooth changed to extroverts.

I will be changing the primary weights to 17.2 rivets in both holes, cleaning the clutch and heading out to tune once the snow is here. I also have the green spring still so I have the option of putting that back in and playing with wrap angles there too.

Thanks guys!
Braaaap On
 

Attachments

  • Clutch Magic.jpg
    Clutch Magic.jpg
    200.1 KB · Views: 13
  • Clutch Weight.jpg
    Clutch Weight.jpg
    200.8 KB · Views: 14
your geared deeper then 1.95 because you have 8 tooth drivers in the sled which makes a 20/39 gear set really a 2.19 ratio, so your removing lots of load off the engine and your result is high rpm. The reason your cluttchs only shift half way thru is you have a stiff rear secondary spring as well and the front clutch is trying to upshift, the rear clutch is trying to backshift because of the high tension, they fight each other and the belt stays in the middle.

As stated in the other thread you need to ADD weight to the primary weights to reduce rpm!

The secondary spring is NEVER used as a rpm tuning device as its job is not to tune rpm but to "control" the shift rate of the rear clutch which is torq. sensing.
 
I have the 21 top gear that came in it. I want to be at as close to 2:1 in the chain case as I can so the sled has low track speed craw ability.

Pioneer performance has a great chart with all the flyweights and their weights empty. Once I max out my 8cr weights (which 2 17.2 rivets will) can I go up to the next highest empty weight then start adding rivets to get the rpm's where I want, or does it not work that way?
 
you either have to add weight or install a weaker yet shift primary spring to bring down the rpm. theres numerous ways to make your 8cr weights heavier, install 4.5 gram rivets, also can use a washer on the rivets to make them more then 4.5 grams, or you can use nuts and bolts in them. The only thing you have to watch for is that the added material clears the inside pocket of the spider which is very simple to see without the primary spring and cover off the clutch, simply swing the weight thru its arc and be sure you have clearance in the spider.

I think what your not getting is with 8 tooth drivers it makes your gearing differnt then with 9 tooth drivers, so you say you want a 2.00 ratio with 8 tooth drivers youd need a gear combo of 22/39 to be at 2.00 ratio. Anytime you make the gear ratio numericly higher it removes load from the engine and it revs higher because of less load. So to bring the rpm down you either add weight to the primary clutch weights or reduce front primary spring pressure.

The secondary spring is not for rpm tuning but to control the shift. When you increase the tension and make the secondary resist the upshift via the front clutch, it also wants to backshift sooner due to the increased tension. A tight secondary clutch will eat up alot of power because its fighting the front clutch. This will show up very simply as heat. You only want as much tension on the sec. clutch as needed to hang onto the belt. Since its torq. sensing, it needs differnt applications for differnt conditions, such as wet heavy snow will require the sec clutch spring be set to a tighter twist, this is because the wet heavy snow will make the sled shift out faster(increased load of the wet heavy snow) and bog the sled. Powder snow requires less tension because of the decrease in resistance seen by the clutch or lack of load.
 
With the 17.2mm rivets in the weights and the stock green spring set at 60 wrap in the secondary what kind of primary spring would I want to be looking for in the table? The www is already softer than the ywy stock spring so what would be the next logical step down? Would I be looking to switch down to a red secondary spring with a corresponding drop in primary spring?

I'm not opposed to buying parts, I just want to minimize the buying of unnessecary parts to get it dialed in. Wouldn't a softer primary spring also give me better belt grab? I just want whatever combination of parts I need to make the sled shift out like it should.

Thanks for the help!
 
your going to have to do some testing. theres not really much cut and dry set up for long tracks without elevation.

too save some money on parts, look for a white/silver/white or white/green/white for the primary after you load up the 8CR's. keep a red along with the stock green for the secondary and play with the twist.

in a nutshell, the more twist the more rpm and the stiffer the secondary spring the more rpm. stiffer being silver, green, and red stiff to weak in that order. again, you dont want to tune the rpms with the secondary. don is leading you correctly, but lacks elevation tuning. although the principals apply, its up to you to test and tune. tom is more an altitude guy and although he is a long time business associate, he lacks experience in low elevation setups and he has a persuasive ability to get customers to buy into his bs(sorry tom).

multi angle helixes will help your tuning and i would guess somewhere around 48/40 for your area. you would be better served popping for some heel clickers with the hc black or gray spring. beats the hell out of drilling rivets and pounding in new.
 
Stock motor and pipes or ??? Any other mods other than the track and driver swap? With the 20/39 gearing when you factor in the reduction for the 8 tooth drivers you are actually in that 2.20 range as the 1.95 you indicted is figured with 9's. Shouldn't be that hard to come up with a set up that will work with what you have but I'd start by going back to a green secondary spring at 60 or 70. I'll dig through my notes and see what we used on our mountain max here in MN which is about 1500 feet
 
Yes motor is stock other than reeds/can. Has 145/143.8/143.8 jetting in it.

Thanks for the help guys I'm starting to get a better idea of the direction I need to head. My base elevation is around 1500' and there's not a place in New England where you can get to that's over 4000'. I'll look to see where I can get those other 2 primary springs and see what they do to it.

So moving forward to where I can get full shift out, how do I adjust spring wrap and rate in the secondary? Assuming I'm in deep snow and pinned for track speed with full shift out, as I get into snow with more bite and track speed slows down I would want the sled to back shift to maintain peak rpm with the track not over loading the motor and bogging it by back shifting too late?
 
before you go out and buy a bunch of stuff you need to only change 1 thing at a time or your really gonna be confused, and more likely out more money with parts that dont work. You have way high rpm we know... you need more weight, so buy the rivets and install them then pop your green dot sec. spring back in and see what rpm your at AFTER you ride the sled.

You cant fix it on the web and it be spot on with no testing.
 
Ok I have a w-s-w and a w-g-w primary and red secondary spring on the way. That should give me a bunch of test options to work through in one session so I can compare back to back and hopefully find the best combo.
 
youll never be able to use a red secondary spring on a long track sled, way too soft....................
 
No offense to you flat land guys, but all the research I've done has the chain case ratio at 2:1 not total drive ratio. I've ridden the sled with 21/39 gears in it and even that is too small. The sled just starts digging a hole, it loses all its crawl ability in soft snow at that point.
 
Backwoods M Max said:
No offense to you flat land guys, but all the research I've done has the chain case ratio at 2:1 not total drive ratio. I've ridden the sled with 21/39 gears in it and even that is too small. The sled just starts digging a hole, it loses all its crawl ability in soft snow at that point.
Click to expand...

ok, heres one last effort as to what you dont understand, maybe you are familar with cars or jacked up trucks or something and this will help you. If you change the diameter of the tires on your car you will also change the drive ratio(gears) thats set in the rear end, because lets say you went 2 inchs shorter tire. By going to a shorter tire the gears are now turning faster because the tires are shorter and have less rollout or more revolutions per mile. The smaller the diameter of the tire the more times it turns a complete 360 degree circle in a given distance then a larger diamter tire does. You will have higher rpm, speedo will read higher mph because everything is moving faster even though if you were checked on radar you could be going the same exact mph as when you were stock on a certain section of road,but.... it will be at a higher rpm on the tach,and the speedo will read alot faster then actual mph your achieving.

The opposite is true if you add larger then stock diameter tires to a truck/car,low rpm,low mph and no power becasue the engine is loaded more with a numerially lower gear ratio.

The same thing with your snowmobile chaincase and the track drivers, the 8 tooth drivers are smaller in diameter, your gear case is now multiplied by an extra 1.13 to the ratio, again like the car tire diameter because its the smaller diameter driver that turns the track, so for example if you had 20/40 which is 2.00 gear set, thats figured with a 9 tooth driver thats larger in diameter. With your 8 tooth drivers you really have 2.25 ratio because they are smaller in diameter and do the same thing as the shorter then stock tire example does, it turns the track faster because of the smaller diameter.

what I am trying to help you understand has ZERO to do with flatland vs altitude tuning, its basic clutch tuning that is, what it is, doesnt matter where you ride. Your going to get into more problems of poor performing sled and wrong rpm, and not too mention alot of useless parts your gonna be spending money on by listening to multiple peoples ideas at once on how to fix your problem.

In your other post I put you onto the fix, put heavier rivets in it and go back to your stock green dot spring, RIDE....the sled .........and see what your rpm is and adjust from there to be spot on. You need to take baby steps and get close, not just keep changing parts, your never gonna get anywhere doin that and surely not understand how it works, just guaranteed frustration from all the money youve spent and the poor performance that will yield because of it.
The more people you have telling you how to fix something the more outcomes youll have and most will be dissappointing! Everyone here is just trying to help you the same thing I am doing however you need to pick someone, and go with what they tell you to fix your problem. heck ..call Tom Hartman back up and go with what he tells you to fix it, keep notes and call again with your notes so he can keep adjusting his fix till you get the sled right!
 
^^^ now right there is some darn solid good advice!

what i have learned over the years is that the engineers that spec out baselines from yamaha are close in the altitude adjustments. they have formulas or calculations or incredible insight as to what happens to the power curve as the elevation rises. by comparing and doing a bit of math, you can see a pattern develop and follow it for your needs. i have taken don's low elevation tuning and percentaged it to my advantage to develop some accurate theories for elevation. if you have a good repoir with your local dealer, ask for a clutching poster pertaining to your model year.

part of your problem may be happening because your changing elevations between 1500 and 4000. i can flat tell you that what works at 15 dont work at 4. you need to tune for the area you ride most and learn to adjust your thumb for the in between. out my back door in the back woods of idaho is 2500' and i climb to over 7000. my sled is a bit boggy down low, but once up it comes alive. i just adjust my style on the way up and enjoy things when i get there. jetting factors in as well as snow conditions and air density.

the mtn max is notorious for trenching with the stock skid. some adjustments can tame it down a bit but it is what it is and doesnt matter if your 141 or 151. its the hook up and engagement in my opinion. i have toned my mtn maxes down to a just over 3600 engage. that 42-45 your doing is a trench. look into your skid setup and look to reducing your engage. hence to two springs i suggested. i have found that the high engagement contributes alot to the trench. you have to test and tune.

i will agree to disagree with don on the red secondary spring. in most cases its not the ulimate choice, but at certain elevations its a good choice to get the sled to shift out a bit quicker and avoid the trench if the engine and drive clutch can pull it. then again, multi angles on the helix factor in as well.

heel clickers are something to consider, just avoid their red primary spring.
 
You must log in or register to reply here.


Back
Top