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Discussion Starter · #1 ·
Sled is a 98 Mach ZR w 230-320 primary spring, running adjustable pins at 20.3 grams, 52-46 coated helix on A5, 26/44 gearing and an 1 1/4 Predator track.

On hard pack the sled shifts out quick, pulls hard and the clutches run pretty clean (the term raped ape comes to mind!). When conditions are somewhat "looser" it still pulls good as long as I use proper throttle control to minimize track spin but if I get carried away the belt starts to slip in the secondary causing a decrease in acceleration. It appears that this setup may be a bit too aggressive for normal riding and I was wondering if a primary spring with a stiffer finishing rate (such as a 230-350 spring) would help slow down the final shift rate so I don't end up in too tall of a gear too quick. Am I thinking about this correctly or going about it all wrong?
 

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Discussion Starter · #3 ·
... the slippage in the bottom of the secondary.

Normally when it feels like it's starting to slip I back off and then slowly roll the throttle back on to get my pull back (sucks when your drag racing - pretty hard to win when your forced to back off!). If I don't back off this picture would be a lot worse (I have heat cracked a couple of belts because of this).
 

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Discussion Starter · #5 ·
doo900 said:
are you using the white or beige sec spring,? i was running similar set up but found the 44 finish of the helix with a white spring @A3 worked , nice and cool belts too. OH and what are you using for ramps?

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I'm using the beige spring with 286 ramps (clicker on #3). Last year I was running 22 gram pins, the stock 50- 47 helix on B1, 27/44 gearing and the original 3/4" track. This setup seemed to perform well but under hard accelration (i.e -when drag racing) I had more belt slip than I do now and the clutches were hotter to the touch (I had the same problem with heat cracking my belt if I got too carried away).

I put the 52-46 helix in mid-season and initially had quite a bit of slippage on the suggested setting of B6 so I tried C5 followed by A5 which is where I am now. At the end of last season I installed the 1 1/4 track and 26 tooth top gear but then found I could not always achieve peak rpm. Thinking that maybe 22 grams is now too much weight with my improved traction I tried 19.5 grams and then ended up going to 20.3. This seemed to correct the problem and now my clutches run cleaner and cooler than they ever have so i think I'm close, I just need to eliminate the secondary belt slip problem and was hoping to get some feedback as to what I should try next.

P.S. - are you sure your on A3? That's only 4 lbs according to the following chart.
 

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To reduce slippage at shiftout I would recomend a HPV-27 RER sec with Dynamo Joes kit in it.This combo will really put the clamp on the belt,something I was unable to do even with 25# preload on a formula sec with straight 44 helix.I can tell from the torn belt cords in the pix that it is slipping,when you get it clamped up tight you won,t see that any more!
 

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Discussion Starter · #7 ·
marsheng said:
To reduce slippage at shiftout I would recomend a HPV-27 RER sec with Dynamo Joes kit in it.This combo will really put the clamp on the belt,something I was unable to do even with 25# preload on a formula sec with straight 44 helix.I can tell from the torn belt cords in the pix that it is slipping,when you get it clamped up tight you won,t see that any more!
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I've heard good things about Dynamo Joe's kits but I don't have electronic reverse (or the $500+ to spend on a new secondary). I was hoping that I could correct this problem with some small inexpensive changes to my existing setup since it appears that I am close.

Although the belt cords may appear torn in the first pic this is a new belt with less than 100 miles on it. It came with some of the cord showing and some of it not as most of them do. I was having a problem with the cord separating in previous years when I was using a straight bar to check my alignment but haven't since I bought the proper CK3 clutch alignment bar (I just have the belt slipping/heat cracking issue when I ride like I stole it).
 

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Discussion Starter · #10 ·
motorbreaker said:
Sounds like you have to little preasure on your secondary, Try putting
some pondage to it.
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I was told to try it at about 20 lbs but ended up at 23 lbs (wasn't sure if I should wind it any tighter since the stock helix was only at 16 lbs). How do you know when it's too tight? I'm only getting slippage at the bottom of the secondary if I'm in powder and suddenly have to accelerate hard and hold it to keep from getting stuck or if the snow is a bit loose and I start spinning a little too much and don't let off. It seems as though the secondary is getting caught in full shiftout at too slow of a forward speed under these conditions and when it starts to hook back up it can't react quick enough.
 

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Discussion Starter · #11 ·
doo900 said:
positive on a3 cause i am refering to the white spring

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Doh! Sorry, I guess it would make sense that the white spring would have a different chart. How many lbs is A3 supposed to be? What is the difference between the white spring and the biege one?
 

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looks like it is slipping on top end to me, this is caused by a few things 1; not enuf pin weight to overcome either preload from sec or helix angle. 2; too shallow a helix angle for the pin weight you have , or 3; too much spring preload on the sec for the amount of pin weight. i would back off your sec preload to 18-20#s and see if it helps first, the slippage at high rpm is because your primary cant overcome the sec for one reason or another so start there and let us know how you make out.
 

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Discussion Starter · #13 ·
machz1 said:
looks like it is slipping on top end to me, this is caused by a few things 1; not enuf pin weight to overcome either preload from sec or helix angle. 2; too shallow a helix angle for the pin weight you have , or 3; too much spring preload on the sec for the amount of pin weight. i would back off your sec preload to 18-20#s and see if it helps first, the slippage at high rpm is because your primary cant overcome the sec for one reason or another so start there and let us know how you make out.
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When I first put the helix in I tried it on B6 (20.5 lbs) and was getting quite a bit of slippage. I then tried C5 (21 lbs) and it wasn't much better. Next I tried A5 (23 lbs) and this seemed to cure the problem. After putting on the 1 1/4 track I then found that I couldn't pull my rpm up top with the 22 gram pins I had in it so I dropped to 19.5 grams (before I never had enough traction to bog it down with the old 3/4" track). I then found it would over rev on the top if I kept the throttle down so I bumped it back up to 20.3 grams. Now everything seems fine except for the loose snow situation I referred to in my posts.

I was out yesterday when traction was great and my clutches ran totally clean and cool (FWIW it was minus 25 degrees celcius). My belt even cleaned off the slipping marks near the bottom of the secondary for me! I was hoping to get a lot more feedback than I have so far (considering the amount of "views" my post recieved) so that I make a step in the right direction and avoid heat cracking any more belts trying to eliminate this problem (I don't mind the trial and error part, it's the replacing of belts that hurts!).
 

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I would bet that your secondary is shifting too fast. I was getting a TON of slippage in the primary with the stock helix and gearing in my sled (1997 Mach 1). I went down to 25/44 last year, and the heat in the secondary went way down. With the stock 26/44, my secondary was always HOT. If a lighter rider rode my sled, then the secondary would be pretty cool.

I also geared down, and then used a helix with a smaller angle than stock, so now I am shifting to SLOW. Clutches were very cool, and no slipping was happening anywhere. I have replaced with a steeper angle, but haven't had time to test it out.

Running a steeper angle helix like you are, your secondary is shifting too fast, but you also are running a different spring.

What happened to the HPV27 secondary that came on that sled? 98 Mach Z R, right?

I would try a brand new beige secondary spring, with a 20 lb preload (B-6 for most people), and your helix you are running now, and see what that does for you. If your spring is worn out, it would cause more slippage, too.

If it still shifts too fast, and you are getting belt slippage, then you need to think about getting a helix with smaller angles.
 

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Discussion Starter · #15 ·
97mach1 said:
I would bet that your secondary is shifting too fast. I was getting a TON of slippage in the primary with the stock helix and gearing in my sled (1997 Mach 1). I went down to 25/44 last year, and the heat in the secondary went way down. With the stock 26/44, my secondary was always HOT. If a lighter rider rode my sled, then the secondary would be pretty cool.

I also geared down, and then used a helix with a smaller angle than stock, so now I am shifting to SLOW. Clutches were very cool, and no slipping was happening anywhere. I have replaced with a steeper angle, but haven't had time to test it out.

Running a steeper angle helix like you are, your secondary is shifting too fast, but you also are running a different spring.

What happened to the HPV27 secondary that came on that sled? 98 Mach Z R, right?

I would try a brand new beige secondary spring, with a 20 lb preload (B-6 for most people), and your helix you are running now, and see what that does for you. If your spring is worn out, it would cause more slippage, too.

If it still shifts too fast, and you are getting belt slippage, then you need to think about getting a helix with smaller angles.
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What exactly is the HPV27 secondary (I have my stock secondary clutch but have never heard it referred to as a HPV27 secondary)?

Both clutches have new springs and bushings (probably less than 500 miles on them). Even with my stock 50-47 helix I still had problems with belt slip under aggressive acceleration (never did quite solve it). Of all combos I have tried over the years the setup I have now seems to pull the hardest and the clutches are cleaner and cooler than they ever have been. Having said that I think that I am close, I was just thinking that if I could slow the final shift down slightly I wouldn't end up in such a high gear so quick in the loose stuff.

I also tried a straight 50 helix but found I like the 52-46 the best and would like to keep it in if I can (this helix is a lot of fun on hard pack, I get tired of hanging on after a while!). I was thinking a primary spring with a stiffer finishing rate might accomplish this but at the same time will it loosen the grip of the primary so it starts to slip (I also don't want to end up buying a 230-350 spring only to find out I should have bought a 230-380 ). The two other options I have been considering are increasing the preload of my secondary from 23 to 25 lbs or putting my stock 27 tooth top gear back in (thinking it will load it down more holding back the shift somewhat and reducing track spin). Are all three options a step in the right direction? Which change is most likely to solve this probelm?
 

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clues:
...when primary is hot and secondary is cool then you could be at the point of overrev. Need more flyweight in primary.

...when secondary is hot then you could require lower helix angles and/or higher spring forces to clamp the belt.

If you know that the secondary is offering great belt clamp forces then still have heat after few runs then what is primary temperature? hotter, no?! Then still are at the point of overrev. Need more flyweight in primary.
...don't be shy.
 

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Discussion Starter · #17 ·
Dynamo^Joe said:
clues:
...when primary is hot and secondary is cool then you could be at the point of overrev. Need more flyweight in primary.

...when secondary is hot then you could require lower helix angles and/or higher spring forces to clamp the belt.

If you know that the secondary is offering great belt clamp forces then still have heat after few runs then what is primary temperature? hotter, no?! Then still are at the point of overrev. Need more flyweight in primary.
...don't be shy.
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So what your saying then is I should try more spring pressure in the secondary (go from 23 lbs to 25 lbs)? How do you know when your secondary is wound too tight? Can you hurt anything by too much secondary tension?
 

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I would look at the secondary spring, not just adjusting your preload, but a spring the has a higher finishing rate, then start at the stock preload (Eg.18lbs) and test from there. A higher finishing rate = better belt clamp. This is only my opinion.
Good luck.
ptt
 

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Discussion Starter · #19 ·
ptt said:
I would look at the secondary spring, not just adjusting your preload, but a spring the has a higher finishing rate, then start at the stock preload (Eg.18lbs) and test from there. A higher finishing rate = better belt clamp. This is only my opinion.
Good luck.
ptt
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How do you know what the finishing rate of a particular secondary spring is (I thought that info was only availiable for the primary spring?)?
 

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How I do it is put the spring on a scale (shim the spring so it's vertical use a piece of wood) zero out the scale, then use another piece of wood putting enough pressure to compress the spring (bottom it out). When the spring is bottomed out read the scale, record the weight. Then it's off the the next spring.
Hope this helps.
ptt
 
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