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I can't provide any constructive comments as I only learned a few months back why some of the "old school racers" use the reverse cams for drags. But, my buddy put a reverse cam on his 800 REV open mod this weekend. I think It was GP-37/50, but talk about AMAZING hole shot! I've never felt that amount of G's on a sled before! But, to try and answer your question - the cam holds the belt better on hole shot then as as the sled shifts out in the secondary and the angles increase, the cam starts to release the belt near top end. At least that's how I understand it. When your drag racing you want lots of pin weight any way. That weight should keep your engagement down to where you want it regardless of the shallow start angle. I wouldn't use this setup for any other application other then drag racing...

My 2 cents.
 

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I have been reading your information on clutching for about a year. I do grass drag and did pretty good but wow look at all this info for dialing in better. It is amazing stuff and I have learned alot. I plan to be dialing in several sleds, both modified and stock, for grass drag racing. I was wondering if there is a way to get a troubleshooting flow chart for any problems I may encounter. For example, if the primary clutch gets too hot, what should I do to correct this, it all here in this site but would take a great deal of time to put it together?
I do believe that some of the best tuners are on this site. I am hoping that I can get a flow chart put together from some of the best people on this site. I think that all the information I need is available here, but I am looking for an compiled way to access what we all need. I have printed out about a book's worth of information.
On most of these sleds, I will be starting from scratch. What is the most important thing to do first? Should I concentrate on gearing and dialing in the primary? I would hope that you all would have fun giving out info from a start to finish on how to dial in a grass dragger, with all the problems that anyone would encounter on the way. My test mule was a 97 Mach 1 177hp @8800 with grass track 38 bored out, reeds, domes etc. I am buying Tsa and starting to dial in a month from now, after freshning up the motor new pistons, seals, squaring up the motor and frame.

I am hoping this will strike a lot of interest.

Thank you
Bubba
 

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* I’m assuming your mention of higher engagement would be to help it upshift faster since you have a lower start angle? And the same with the finish angle to help it shift out quicker?
*"Some guys go for crazy track spin and clutch for it." want to elaborate on that?
I mention higher engagement to purely get closer to where the torque starts to rise on a dynograph. Example: My little 440 has no ballz until 5800~ "thereabouts" and the torque starts to climb from 5800.
When I leave at 5200 rpms, the hp there is only about 40 hp. At 5800 there is 50 hp and the torque curve starts to climb nice and fast at that point.
I "brake-rev" my engine to 5600 at the last second before the light/flag goes and have decreased my E.T.'s by a 10th to 2-10ths. I have a little timing system and this is repeatable repeatable repeatable. The sled comes out of the hole smoother with less bounce...etc and quicker ET. The smaller the engine you really have to work to get the sled off the line.

Now me mentioning trying to get higher engagement; Where would you want to engage?
40 hp? Or 50 hp?

These guys who hold their engines w.o.t for 5~6 seconds without letting off the gas at the start line are building pipe heat for a gain in peak hp, however they are losing torque at lower rpms. The hotter they get the pipe, the more peak hp at peak rpms...however suffers torque loss at lower rpms. What rpms would you want the engagement at? Regardless of pipe temperature, you want the engagment near or where the engine starts to produce torque.
***The secondary is torque sensing. The sheave opens when torque is applied and retracts when torque diminishes.

and using the 56 42....use the 56 to load the motor heavy at the start to actually lug or bog it down so it doesn’t "flash" to peak rpms. Is that the theory with that?
***The secondary is torque sensing. The sheave opens when torque is applied and retracts when torque diminishes.

I mention hot pipe, now I mention cold pipe. With a cooler pipe you get increased torque at low rpms than with a hot pipe, however for a loss of peak hp at peak rpms. More torque at lower rpms with this pipe condition you take advantage of extra foot lbs. in the bottom end with larger helix angle and as "pipe heats up/hp increases/torque diminishes" then you want to take advantage of hp and higher rpms with lower helix angle.

My mantra that I live by is for the tuner to learn to use "The helix angle required for the speed they are going at"

Gasolineman writes:
But, my buddy put a reverse cam on his 800 REV open mod this weekend. I think It was GP-37/50, but talk about AMAZING hole shot! I've never felt that amount of G's on a sled before!
I have a setup that does not use reverse angle where upon your return removing your helmet you'd say the same thing. :D

BubbaDoo writes: For example, if the primary clutch gets too hot, what should I do to correct this,
I always like to take temperatures of both clutches on the sheave surfaces, especially the sheave surface of the secondary and not on the outside of the sheave. I like to test where the belt actually touches. To keep this short I have found that when clutched good for the trail regardless of sled I've played with, the primary sliding sheave and both sheaves of the secondary are cool. For some reason I have no idea I always find the fixed sheave on the engine warmer or hotter than the other 3-sheave surfaces.
If I find the secondary sheaves cooler than the primary I always suspect over revving or if it does not seem like overrev then I still will add slight flyweight to make the primary push harder. If you are not pushing hard enough in the primary then the belt will slip through the primary sheaves more than the flyweight should allow. More flyweight will push harder and have less belt slip at any imaginary point going across the sheaves as upshifting is being altered.
In the end, I have lowered temperatures by adding slight more flyweight.

What is the most important thing to do first? Should I concentrate on gearing and dialing in the primary?
I always go for a troubleshooting approach. I like to hone my skills making more effective solution at solving or anticipating problems in clutching. If you pay attention to small elements that collectively make for a good system then you will eliminate problems you won't ever second-guess yourself.

When someone brings a sled to me regardless of mods or stock I always check these elements and make sure their values are right.
1]Secondary Belt Height. I like to have the chord slightly showing in the secondary. [Personal pref]
2]Good Belt Deflection = Track Movement. Fluid movement, jerking slowly or can move with fingers.
3]Primary Belt to sheave clearance
If you have the first 3 down good then you will never have to worry about a bog coming from any of those details...

4]Primary Clutch Weight
5]Find where exh pipe starts to work.
6]Adjust engagement
7]Secondary Pretension
8]Cam Selection
9]Gearing Selection

Belt Selection = combination of 1,2,3.
 

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I have a setup that does not use reverse angle where upon your return removing your helmet you'd say the same thing. :D

Oh good, cause I was going to hit you up for a good drag race set up / kit ;O)

This doo factory open mod is awsome! 170+ hp and she easily hits 94 to 100 mph way before 500' mark on the 660' strip. Nothing could touch it out of the hole. We put in a reverse cam for $hits and giggle and low and behold it worked great. As you can tell I don't know much about drag racing cauze I never really got into it. Frankly it always kind of bored me. But, my interest has been resparted. My bud gave me an old Polaris 650 triple that i want to refurbish and transform into a drag sled. But back to the reverse cam - I can understand the principle of it and they are probably most effective on high hp, high torque motors but, I would presume they would be delinquite of considering the available torque produce and the amount of load required to haul it down the strip? With the litte bit of drag racing I have done (nothing to brag about) I've always use and had a bit of success with steep dual helix angles. I'm just starting to inderstand "conformative thinking" doen't always work in drags....

2 cents.
 

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I want to thank everybody for info. Here is something to think about what about stepping or notching the helix at the top of the angle, has this been done?

Bubba
 

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I tried a few times. At first I sent a drawing to Dale at Dalton and asked him to make me a helix with a start angle of 30 degrees for about .050" and transition to a 50 angle and he said "umm, no!"
Ok, I had a whack of straight 44 helix's and took a bunch to work. On a milling machine w/a dividing head I had a machinist whittle a 25, 30, 35 deg angles then I put them on a belt sander to make the transition to the 44 deg.
The 25 I broke a fairly new set of rollers. I would pin the gas and the engine would go to 9000 rpms and the sled did not shift. Went about 5 mph. he he $100 set of rollers down the drain.
I got my father to make me a set out of slider plastic and flattened them too. Same results when pinning the gas. All rpms, no forward movement to speak of and crushed rollers.
Got my father to make me some aluminum rollers and with the helix's the same results, engine rpms right off the tach, slight forward movement.
I gave up.
 

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DJ what about a less drastic bit of a change, i was thinking of seeing if i could get one cut with a 47 step for a tiny bit for traction then into a progressive 54/40(just an example) something er other.
 

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Heh, so the shape of the profile would slightly look like an "s" curve?

What character do you think the engine will take on with the 47 then transition into a 54 in your example?

I'd like to know what you mean of "tiny bit of traction" What are you trying to avoid?...What are you trying to improve.
 

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whoops i meant to say "...for a tiny bit(of the helix ramp), to get traction". like now my sled has 48 44. i do not hook up well im going from 120 to 168 studs. but im thinking if i went with a normal 53 40(the finish angle 40 just for example) i would just blow out bad. but with a small portion of the helix at 47 degrees that would theoretically allow me to gain traction off the line then it would step into normal progressive 53 40......

I have no idea what character my engine would take going from the 47 to 53. i guess thats what they made the word testing for. probably will be a bad money and just cost me $$$
 

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Originally posted by Mikadoo@Apr 8 2003, 06:05 PM
I too would like to hear some opinions on clutching.
I need help in understanding what different spring poundages in the primary do, also all the different ramp profiles.
Here is a setup I want to try next winter on my 809Z
280 ramps
200-380 spring
19gm pins
50/44 helix
21-23# tention
24/44 gears
230# rider
1 1/4 long track
stock pipes, stock engine
I just want a good all-around go fast set up, not all out racing only.
Any opinions??
280 ramps are very quick to shift out, your stock pins should be 16.9 grams and your spring should be 230 380 giving you an engagement of around 4000-4500 approx, if you go to a 200 380 with 19 gram pins she'll fall on her face at engagement because 1; the lower engagement of the 200# spring 2; the added weight of the 19 gram pins 3; the 280 ramps very aggres, aka its a lower rpm ramp designed to shift quick for draggin,speed runs etc etc.also if you decide to increase pin weight keep in mind you'll need to run between 24-26 pounds pretension on the secondary to prevent belt slippage, approx b-5 position with a beige spring. your helix sounds perfect for a proggresive, if you decide to try a straight i would reccommend starting at 50 and working down till you find one that feels good to you. for general trail riding with that sled i would go 286 ramps 230-380 or 250-380 pri spring, try the 19 gram pins and watch your top rpm you want to be at about 8400 if your rpm gets pulled down to low on top switch your spring in pri to a 230-410 or 250-410.you can adjust your clickers from there.try and keep your clickers in the lower numbers cause your sled will pull harder due to the ramps standing straighter up and down relative to the crankshaft exerting more pressure on the belt.one more thing, pri springs, lower poundage on bottom number= lower engagement,lower poundage on top number= lower rpm on top,and vice versa.helix's, higher angles=faster upshift (50),lower angles=faster backshift(44)
 

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Joe; what do you think attribute to more belt squeeze on your helixs?
Is it the low finish angle or is it that the secondary actually twists more to get to full shift giving more tension.

Have you compared the final shift force on a secondary with the same spring and your cam and say a straight 50 which has about 1/4 inch less travel?


Going testing this weekend on the asphalt again and have added more weight again using your helix. Actually hope to make the sled puke down the track and then take out some weight to find were I can go with this.
 

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KRAGAR]...Joe; what do you think attribute to more belt squeeze on your helixes?
JOE]...More belt squeeze than what helix or who's helix. It's slight difficult to answer from your question.
I'll say from most of the talk you see on any of the sled forums and common helixes mentioned, my helixes progress to a low angle that tuners are not too much familiar with.

KRAGAR]...Is it the low finish angle or is it that the secondary actually twists more to get to full shift giving more tension.
JOE]...If you have a torsion spring in the secondary then you have both the "increasing pretension" and "Angle progressing lower" that adds more belt clamp.
More spring force > more clamp.
Lower helix angle > increased resistance to the sheaves opening > more clamp.

With the compression spring secondary the spring rate is constant so to neglect the helix in the problem the only way to add additional clamp force by the sheaves is to install a spring with a higher final compressed force.
Add in the helix angle now, as the helix angle gets lower the length of the button/roller path becomes longer. [its a geometry thing] So now your button/roller path gets longer the angle gets lower, the sideforce against the belt increases as the shift increases.

KRAGAR]...Have you compared the final shift force on a secondary with the same spring and your cam and say a straight 50 which has about 1/4 inch less travel?
JOE]...I have not tested with my helix. I have tested a straight 50 against a str.34, prog 50/36, 46...and a few other helixes.
I don't know if you can look at this page or not. The information needs to be tuned and I have notes for it that are slight easier to understand.
http://www.picturetrail.com/gallery/view?&...id=17807801#top

KRAGAR]...Going testing this weekend on the asphalt again and have added more weight again using your helix. Actually hope to make the sled puke down the track and then take out some weight to find were I can go with this.
JOE]...Hah...Good luck doing that. lol Lay clicker down and break the engines back. Regardless of holeshot, in fact you can neglect it just for testing purposes, load the engine just to see how it pulls with the lower clicker and/or more flyweight.
Heh...check the backshift. he he
 

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I have never had a chance to radar and test my set-up and was wondering how far off base I am. I way in at 180 lbs.
Heads are shave .040
jugs up .060
air box gutted
delta v2 force reeds
410 main jets
fresh rings with 147-145-145 compression
crankshop pipes and cans
295 ramps
green /white spring #5 clicker
black ice 52/48 helix
beige spring 20 lbs
25/ 43 gears
 

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@ski-b]...Clutching is a very personal preference........As long as a person is happy with there set up just ride it and have fun, that is what it is all about having fun.

Joe]...Yes, Regardless of this clutch or that clutch or an old p.o.s. to the flavor of the week - If the tuner knows basic principle of clutching they have the power of a flow chart to make a decision for the next direction on getting to calibration that they like.
...in the end, the sled tells you what is wrong.
You use principles to guide you what to change.

I will say something about me...I have learned to filter out the crap and know what the parts do. I've learned what the parts do by learning the principle of it.
This is a part, it works this way and it has a specific function.
This is another part, it works this way and has a specific function..
This is another part, it works this way and has a specific function...

Principle
*Clicker number influences the "response" of the system.

Need quicker responce = Raise clicker #.
Need engine to push harder = Lower clicker #
Any higher clicker than #1 = quicker rpms. [TRA lever pushes less hard]Any lower clicker #6 = engine pulls harder. [TRA lever pushes harder]

Clicker 1 tra lever pushes hardest ~ Clicker 6 tra lever pushes least hard.
If...this problem.
Then...it comes from the calibration of this part
Consider...The function of the part. What the sled told you.
Change...the part shape to change the calibration.
Test...[/b]

My engine runs 8000 rpms.
I don't want to change the flyweight.
I am in clicker 3.
I make a run up a hill at w.o.t. and get correct rpms. As I get higher track speed while accelerating, the load changes. I go thru a dip then over a hump and land and lose 400 rpms while i maintain w.o.t. The engine rpm hangs 7600 unless I can turn the sled away to let the rpms recover.
The engine is sluggish to respond to my throttle cycle.
***I don't want to change the flyweight***
What can I do with a clicker change?

*If...Rpms drop when the load changes. Rpms are difficult to recover.
Consider - For the present flyweight and clicker number the TRA lever is pushing too hard and low rpms are revealed.
I don't want to change the flyweight.
I can change the clicker.

*Then...Knowing principle [Any higher clicker than #1 = quicker rpms. [TRA lever pushes less hard]]
I change from clicker 3 to clicker 4.
Test...


Consider...The function of the part. What the sled told you.
Change...the part shape to change the calibration.[/b]

@RonS]...Snowmobile clutches are more efficient at low/mid shift points-not as efficient at high ones.
Joe]...I don't believe in black art. I believe everything can be measured. A clutch setup that works to suit your personal requirements is a "Measured Success"

That statement can be proved right and it can be resolved with a clutch being extremely efficient at high ratios. If you have the internal details to offer low temperatures at high ratios, then the clutch is efficient at high ratios. "Power in" is not being lost to heat.

Heat in a great setup is a curious problem...
I have taken the clutches from identical 600's and switched them sled to sled and the hot clutches seem to follow each other with little calibration change.
There are setups that upshift and backshift with low hp engines that still produce a large amount of heat.
There are high hp 200+ setups where under w.o.t. acceleration produce cool temperatures.
I suspect that the surface of the sheave may be a culprit/factor. I have asked an engineer to help me learn what kind of information I can get from Relative roughness experiments.

==============================================================================================================================

Regarding a spring;
Question - What is the "final force" of A spring?
Answer - The amount of force whan the clutch is fully shifted (the sliding half can't travel any further)
Regardless of primary or secondary - Given a 70/140 or 85/115 spring then would be the xxx/140 final force or a xxx/115 final force at full shift o.d.

Principle:
Spring force resists the push of the TRA Lever.
TRA lever push = (Current flyweight - spring force)
[/b]
My engine runs 8000 rpms.
I don't want to change the flyweight.
I am in clicker 3.
Primary - 100/290
I make a run up a hill at w.o.t. and get correct rpms. As I get higher track speed while accelerating, the load changes. I go thru a dip then over a hump and land and lose 400 rpms while i maintain w.o.t. The engine rpm hangs 7600 unless I can turn the sled away to let the rpms recover.
The engine is sluggish to respond to my throttle cycle.
***I don't want to change the flyweight***
***I don't want to change the clicker***

*If...Rpms drop when the load changes. Rpms are difficult to recover.
Consider - For the present flyweight and clicker number the TRA lever is pushing too hard and low rpms are revealed.
I don't want to change the flyweight.
I don't want to change the clicker
I CAN change the final force of the primary spring.

*Then...Knowing principle [TRA lever push = (Current flyweight - spring force)

IF...TRA lever pushing too hard = (Current flyweight - xxx/290)
THEN...TRA lever will push less hard = (Current flyweight - xxx/320)
(Lever pushes less hard because you added spring force)(Spring force resists the push of the TRA Lever.)

The TRA lever is pushing too hard with the 100/290 so I can go to a 100/320

Test...

Consider...The function of the part. What the sled told you.
Change...the part shape to change the calibration.[/b]
==============================================================================================================================



Rpms are determined by the combination of the 3 components. Clicker, spring force, TRA Lever flyweight.
If you have an rpm problem as in the previous examples then this is the final part you can change the shape of to alter the calibration "where" you had the problem.
.
.
.
Regarding Flyweight

*Flyweight determines rpms*
*Need less rpms; Increase flyweight mass, The TRA lever pushes harder.
*Need more rpms; Reduce flyweight mass, The TRA lever pushes less hard.
[/b]
My engine runs 8000 rpms.
I don't want to change the flyweight.
I am in clicker 3.
Primary - 100/290
Flyweight - 13 grams.
I make a run up a hill at w.o.t. and get correct rpms. As I get higher track speed while accelerating, the load changes. I go thru a dip then over a hump and land and lose 400 rpms while i maintain w.o.t. The engine rpm hangs 7600 unless I can turn the sled away to let the rpms recover.
The engine is sluggish to respond to my throttle cycle.
***I don't want to change the clicker***
***I don't want to change the spring force***


*If...Rpms drop when the load changes. Rpms are difficult to recover.
Consider - For the present flyweight and clicker number the TRA lever is pushing too hard and low rpms are revealed.
I don't want to change the clicker
I don't want to change the primary spring.
I CAN change the flyweight.

*Then...Knowing principle; Flyweight determines rpms.

IF...TRA lever pushing too hard with 13 grams.
THEN...TRA lever will push less hard with 12 grams.

The TRA lever is pushing too hard with the 13 gram flyweight so I know the Lever will pull less hard with any flyweight less than 13 grams.

Test...

Consider...The function of the part. What the sled told you.
Change...the part shape to change the calibration.[/b]
==============================================================================================================================






Calibrating with a secondary spring.
Regarding a spring;
Question - What is the "final force" of A spring?
Answer - The amount of force when the clutch is fully shifted (the sliding half can't travel any further)
Regardless of primary or secondary - Given a 70/140 or 85/115 spring then would be the xxx/140 final force or a xxx/115 final force at full shift o.d.

Principle:
Spring force resists the push of the TRA Lever.
TRA lever push = (Current flyweight - spring force)
[/b]
My engine runs 8000 rpms.
I don't want to change the flyweight.
I am in clicker 3.
Primary - 100/290
Flyweight - 13 grams.

Secondary
225/300 RER spring

I make a run up a hill at w.o.t. and get correct rpms. As I get higher track speed while accelerating, the load changes. I go thru a dip then over a hump and land and lose 400 rpms while I maintain w.o.t. The engine rpm hangs 7600 unless I can turn the sled away to let the rpms recover.
The engine is sluggish to respond to my throttle cycle.
***I don't want to change the clicker***
***I don't want to change the Primary Spring force***
***I don't want to change the flyweight***

*If...Rpms drop when the load changes. Rpms are difficult to recover.
Consider - For the present flyweight and clicker number the TRA lever is pushing too hard and low rpms are revealed.
I don't want to change the clicker
I don't want to change the primary spring force.
I don't want to change the flyweight.
I don't want to change the helix.

I CAN change the final force of the secondary spring.

*Then...Knowing principle [TRA lever push = (Current flyweight - spring force)

IF...TRA lever pushing too hard = (Current flyweight - xxx/300)
I look around in the aftermarket and find several secondary spring options. It just so happens that a company has a 200/335. 35 lbs more final force than my present secondary spring.

THEN...TRA lever will push less hard = (Current flyweight - xxx/335)
(Lever pushes less hard because you added secondary spring force)(Secondary spring force resists the push of the primary clutch (TRA Lever.))

The TRA lever is pushing too hard with the 225/300 so I can go to a 220/335.
Will the loss of 5 lbs at the start going from 225/xxx to 220/xxx be an issue? I doubt it.

Test...

Consider...The function of the part. What the sled told you.
Change...the part shape to change the calibration.[/b]
Your new data should reflect a change after a run.

Run #1
clicker 3.
Primary - 100/290
Flyweight - 13 grams.

Secondary
225/300 RER spring
Loss of 400 rpms at a point of load change and difficult engine rpm recovery.

Run #2
clicker 3.
Primary - 100/290
Flyweight - 13 grams.

Secondary
225/335 RER spring
Loss of maybe 400 rpms at the point of load change yet engine rpm recovered while I kept the throttle pressed to the bar.
 

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i would like to know what work is involved to add reverse to my 1993 formula plus x. i have a complete 1991 mach z formula with a blown lower end. so i think i have all the parts i will need if the 2 sleds are compatible. also will a top end off a 617cc fit on my 583cc with a straight swap and if so will htere be any performance gains.
 
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