Turbo Clutching

[Danny Dangles]

Hey Guys,

So here is a question for guys who have more experience with clutching. I have been having a little grief getting my clutching dialed in. There are a lot of factors to consider and some other niggles that I need to address but here is my setup, what I am seeing and what I would like to see. Hopefully you can help with the latter.

Riding Elevation: 6-7k feet
12 Pro HM Turbo @ 7psi with 50av/50pump
Primary Spring: 150/310
Weights:MTX 71+2+2
Secondary Spring:Stock Polaris 155/222
Secondary Setting: HM5 (custom helix)
Track:Stock

I am seeing a boost spike due to the track not hooking up initially (overwhelmed) then for the first few seconds of pulling I am seeing desired rpm (8150-8250) but when kept on the clamp for more than a few seconds RPM tapers off (boost levels to desired level) sometimes only pulling 7800rpm.

Speaking with HM they say with the stock track clutching can be difficult to control the initial spin (avoid rev limiter) followed by maintaining desired rpm. They seem to think my secondary spring is overwhelmed by my primary. Thus on the longer pulls the belt is riding lower on the secondary causing the low rpm (my words.) In your opinion is my thinking correct? I have a blk/purp (160/240) secondary spring ready to go in there (it was but was changed out on recommendation by someone.) Will the stiffer spring control the extra power on the secondary better and keep the belt riding higher and rpms up?

All this will be thrown out the window as I will be going to a CE 2.5 anyhow but I have friends who are running this setup as well.

Thx

 

[briand]

Riding Elevation: 6-7k feet
12 Pro HM Turbo @ 7psi with 50av/50pump
Primary Spring: 150/310
Weights:MTX 71+2+2
Secondary Spring:Stock Polaris 155/222
Secondary Setting: HM5 (custom helix)
Track:Stock

I never had good luck with the 155-222 secondary spring with my boondocker turbo at 8 pounds# The best spring that I found was the one boondocker sent me in the kit which was a 180-260 black yellow team spring. Helps keep the rpm in check. I also went to a team silver primary spring which is a 160-340 . Don't know what the angles of the HM5 helix is but found the 44-48.46 helix worked very well also.
Its possible you may need to drop of 2 grams in the tip of your MTX weights first and see if this helps you out before you go out and try all these changes. It could help also.

 

[Spaarky]

Don't know what the angles of the HM5 helix is but found the 44-48.46 helix worked very well also.

I think that HM helix is in the same ball park. Its a reverse helix of some sort.

 

[briand]

Another thing Danny is if you already have the black purple try it first and see if this helps. Maybe all you need is the black purple 160-240. Also another thing to try is taking 2 grams out of the tip and put 3 grams in mid hole or just try with 2 grams mid then go from there.

 

[gus bohne]

shim spider out .060. makes a world of difference with those weights.

you will have better control of initial over rev without adding more mass to weight. do the shim and it will level out..

 

[Danny Dangles]

Another thing Danny is if you already have the black purple try it first and see if this helps. Maybe all you need is the black purple 160-240. Also another thing to try is taking 2 grams out of the tip and put 3 grams in mid hole or just try with 2 grams mid then go from there.

I will for sure throw the blk/purple back in there, I think it will make a big difference. By Mid you are referring to the heel? I would for certain over-rev removing that much weight from my tip. Great thing is there are 4 people I know with this setup so we get a pretty good idea of what is working.

 

[Danny Dangles]

shim spider out .060. makes a world of difference with those weights.

you will have better control of initial over rev without adding more mass to weight. do the shim and it will level out..

Sorry shimming the spider out would give me .060 of belt to sheave clearance? What is the reason and or advantage of this?

I enjoy learning about this stuff so any input is appreciated.

 

[briand]

I will for sure throw the blk/purple back in there, I think it will make a big difference. By Mid you are referring to the heel? I would for certain over-rev removing that much weight from my tip. Great thing is there are 4 people I know with this setup so we get a pretty good idea of what is working.

When you say over reving are you talking about bottom end overreving like you have now or top end over reving by removing 2 grams from the tip?

I would try the spring. I think this will help to maintain your peak rpm but with the weight setup as 2 grams mid and 2 grams tip I feel that you will still have over rev in the bottom end. My thinking was just changing the weights distribution a little. Like maybe from 2 mid 2 tip to a 3 or 4 gram mid and 1or 0 gram in the tip. what this would do is shift harder in the bottom end keeping the revs down here and let it rev out in the top end. but only try this if you don't get the change your were looking for with the spring change. Until you try the spring it is hard to give advice on how to setup the weights. I am thinking along the lines of that 155-222 spring is just to weak in the top end for a turbo setup and you are slipping the belt some and pulling down rpm. are your clutches hot after a pull and or hot belt and or black smudge marks on the clutches? this is a indication that your slipping more then you should be.

I never like the 155-222 spring when I ran it stock cause I thought I had too much belt and clutch heat. Ran the black purple and loved it.

 

[Spaarky]

I believe the black/purple is what's in mine. I don't know if it's a coincidence or not, but mind has always went to the rpm and locked in. My helix, gearing, primary set up is way different than yours though.

 

[Danny Dangles]

When you say over reving are you talking about bottom end overreving like you have now or top end over reving by removing 2 grams from the tip?

I would try the spring. I think this will help to maintain your peak rpm but with the weight setup as 2 grams mid and 2 grams tip I feel that you will still have over rev in the bottom end. My thinking was just changing the weights distribution a little. Like maybe from 2 mid 2 tip to a 3 or 4 gram mid and 1or 0 gram in the tip. what this would do is shift harder in the bottom end keeping the revs down here and let it rev out in the top end. but only try this if you don't get the change your were looking for with the spring change. Until you try the spring it is hard to give advice on how to setup the weights. I am thinking along the lines of that 155-222 spring is just to weak in the top end for a turbo setup and you are slipping the belt some and pulling down rpm. are your clutches hot after a pull and or hot belt and or black smudge marks on the clutches? this is a indication that your slipping more then you should be.

I never like the 155-222 spring when I ran it stock cause I thought I had too much belt and clutch heat. Ran the black purple and loved it.

I appreciate the advice and you maybe right, this is something I have considered before. The primary has always looked great but now that you mention it I have seen slight smudging an inch or so down on the secondary. I will for sure run the blk/purp before making anymore primary changes.

The reason I don't want to make those changes to the primary is HM recommends 71-2-2 with the stock track and 71-1-2 with the CE 2.5 I am installing. As well similar setups locally are running 2-2, I have their logs to prove it is working.

 

[philsummers21]

Stock secondary spring is your biggest problem with your setup. Switch it out with the 160-240 I prefer the 280 finish and it's what I'm running. Rest of clutching seems fine. Hard to say with an unknown helix tho. That's why I hate clutching with a "special" helix

Sent from my galaxy note3 via tapatalk

 

[briand]

The reason I don't want to make those changes to the primary is HM recommends 71-2-2 with the stock track and 71-1-2 with the CE 2.5 I am installing. As well similar setups locally are running 2-2, I have their logs to prove it is working.

ahh ok, then just try the spring. you can always fine tune the weights later if its needs it.

 

[Danny Dangles]

Thanks guys, I was just more asking if my train of thought was correct. I will try this next week hopefully and be sure to post if the problem was solved or not.

 

[gus bohne]

shimming the spider sets roller to weight start position and does NOT change belt clearance. shimming the sheave is different than shimming the spider.

 

[briand]

Thanks guys, I was just more asking if my train of thought was correct. I will try this next week hopefully and be sure to post if the problem was solved or not.

yes i think your train of thought is correct. Please keep us posted on your results.

 

[Danny Dangles]

shimming the spider sets roller to weight start position and does NOT change belt clearance. shimming the sheave is different than shimming the spider.

Ok thank you for the clarification. I will try one thing at a time, well thats a lie, I will change the track and try the blk/purple and hopefully only fine tuning from there.

Thx again guys

 

[die hard poo]

shimming the spider sets roller to weight start position and does NOT change belt clearance. shimming the sheave is different than shimming the spider.

I guess I am not following you here. If you add or remove shims from behind the spider, you directly affect the belt to sheave clearance. This is because like you kinda stated, the roller on the spider has now moved either closer or farther away from the stationary sheave(since the roller is on the spider). Then if your weights are the same, the movable sheave will either be closer or farther away from the stationary sheave there by opening or closing the belt to sheave clearance.

I personally like a tight belt to sheave clearance. You can also change this gap by weight thickness or profile, belt width by different manufacturers, and lastly spider shim adjustment.

As far as your problem Danny, it sounds like to me like too light of a sec. spring. And with the MTX weights you don't have quite as much fine tuning with that weight. If you get a weight that has three hole adjustment you can tune your weight more precisely.

 

[gus bohne]

there are 2 sizes of shim washer, narr ow od is to move spider independently from sheave.
large od allows sheave movement independent of spider.

for 30 yrs Ive been moving spiders around to teach folks how to tune clutches. it can be done as a combined move or independent move.. its up to the person doing the work and their knowedge.

this is how I get .020 belt to sheave and ANY roller to weight setting I choose.
JUST changing tuck on a weight like the mds has an effect on belt sheave clearance but has NO EFECT on shift force..do you know why??

because the roller never moved ,, only the sheave moved away as the weight dropped IN deeper. engagment rpm will rise but shift will be unaffected.

the old aeen book would explain this for you..
Its really invaluable to NOT read that book if you own a turbo..imho

 

[Danny Dangles]

the old aeen book would explain this for you..
Its really invaluable to NOT read that book if you own a turbo..imho

I am coming to this realization.....

 

[Danny Dangles]

As far as your problem Danny, it sounds like to me like too light of a sec. spring. And with the MTX weights you don't have quite as much fine tuning with that weight. If you get a weight that has three hole adjustment you can tune your weight more precisely.

I will try to do one thing at a time, first thing is to get the sled to pull and hold rpm's better before fine tuning with three hole weights. If I do go that route, what do you recommend? Changing weight manufacturers is going to obviously change the ramp profile. HM provided these weights I would assume for their profile, is this something I want to start playing with?

Thx