STM secondary vs. stock helix angles.

[STAIN]

Has anyone done any testing between the STM secondary vs. a stock secondary as far as tuning options?
Question is helix angle comparison, say a Yamaha roller 35 degree acts like a 45 degree on the STM?
It seems like the angles dropped @ 10 degrees on the Sidewinder roller clutch vs. the old Yamaha button secondary for a similar application.

 

[KnappAttack]

STM angles do not match any others out there Stain but I believe you know that. They are more aggressive on the angles than posted on them if thats what's your asking. It will mess you up if you try to compare them.

 

[Fleecer]

If anyone running an STM driven clutch wants to part with their stock roller, I'd take it off your hands. Send me a PM

 

[STAIN]

STM angles do not match any others out there Stain but I believe you know that.

They are more aggressive on the angles than posted on the

on them if thats what's your asking. It will mess you up if you try to compare them.

Yeah, I know you can't directly compare them. Just looking for comparisons clutch to clutch, I guess.
Are you saying that a 46 STM helix will be steeper than a 46 factory Cat helix?.
I was sitting at work on a slow day and wondering what to do with my STM secondary sitting on the shelf. I have too many parts sitting around doing nothing but tying up money.
I know what works well with the stock secondary for me and was wondering what a good comparable set up would be on the STM. 46-36 seems to be a popular helix. But what angle is it really if the STM helix's are more aggressive? Maybe I will try to check it somehow.
Unfortunately, all my old A/C helix's don't seem to be viable options for the sidewinder.
In my short time using the STM secondary, I didn't really see any performance gains, just cheaper parts.

 

[DooZ]

I run the STM because I was never really impressed with the stock Cat secondary, and like you said parts are cheap for experimenting. Plus how can you go wrong with the look of billet .

 

[Srxspec]

Yeah, I know you can't directly compare them. Just looking for comparisons, I guess.
Are you saying that a 46 STM helix will be steeper than a 46 factory Cat helix?.
I was sitting at work on a slow day and wondering what to do with my STM secondary sitting on the shelf. I have too many parts sitting around doing nothing but tying up money.
I know what works well with the stock secondary for me and was wondering what a good comparable set up would be on the STM. 46-36 seems to be a popular helix. But what angle is it really if the STM helix's are more aggressive? Maybe I will try to check it somehow.
Unfortunately, all my old A/C helix's don't seem to be viable options for the sidewinder.
In my short time using the STM secondary, I didn't really see any performance gains, just cheaper parts.

I think you'll find that the STM old style CAT helix angles are very similar to the OEM CAT helix angles. It is only the STM YAMAHA Sidewinder helix angles that are much steeper. I haven't done much with a trail sled, but I would say in that 46-50 start angle and 36-40 finish angle area would be a good place to start.

 

[STAIN]

What I continue to find is that the addition of Hi-Torque rollers makes engine rpm drop. I installed a straight 35 yesterday to check over my 39-35 and also added Hi-Torque rollers. Same primary set up, same spring wrap. I lost @ 400 RPM. I had to use the clickers on my TAPP to get some of it back.
I believe that the rollers are so much smoother than stock it allows the secondary to open quicker.
I have some numbers from last year after comparing the rollers to stock in a press, like Knapp does. I will have to find them.

 

[KnappAttack]

What I continue to find is that the addition of Hi-Torque rollers makes engine rpm drop. I installed a straight 35 yesterday to check over my 39-35 and also added Hi-Torque rollers. Same primary set up, same spring wrap. I lost @ 400 RPM. I had to use the clickers on my TAPP to get some of it back.
I believe that the rollers are so much smoother than stock it allows the secondary to open quicker.
I have some numbers from last year after comparing the rollers to stock in a press, like Knapp does. I will have to find them.

Yes,
The difference in rollers is huge on the scale, and you can tell with a fresh set of Hi-Torques on the drill press scale how smooth the secondary operates, but even as they wear the pressure changes on the Hi-Torques too, but I have found them to be better than anything else out there thus far.

 

[STAIN]

The problem I have is I have run out of adjustment on my TAPP with those rollers. I can’t make it any lighter.
I may have to run the stock belt to get the rpm back up.

 

[See n blue]

A straight 42 works well.

 

[STAIN]

On a stk secondary? Or stm?
I could never run the TAPP with a stock secondary and a 42

 

[See n blue]

STM with a Tapp, green spring in the middle hole always worked the best on a 300hp tune. Found 41/37 worked best for the stk secondary at 6-3 with the b/o Dalton.

 

[STAIN]

I’m at 240 SM

 

[See n blue]

44/38 would probably work better with that tune on the stm.

 

[KnappAttack]

The problem I have is I have run out of adjustment on my TAPP with those rollers. I can’t make it any lighter.
I may have to run the stock belt to get the rpm back up.

Are you running the standard rollers in the TAPP or +1's?

FYI the original Ski-Doo rollers I find to be best no matter the size of them vs the rollers the TAPP comes with, the bushings in the OEM ski-doo rollers last much longer.