Clutch test - new info

[stingray719]

Bought another Viper today and did a fresh out of the box real world test.

2014 XTX Viper just out of crate, Myself, the shop owner, and his mechanic ride it. It is what we expected from a new Viper.

I put a 3 millimeter shim in the primary clutch under the primary spring and change the belt from the Viper 8jp belt to a Nytro 8dn belt (belt change was so I do not get belt dust in my clutch, and is unlikely it had any performance effect) ONLY CHANGE IS BOOSTING SPRING RATE WITH A 3 MM SHIM.

WOW, what a difference. Sled with stock setup spun the track a little, with shim it left big black marks for about a full car length and more. Not only did the shop owner marvel at the change we drew a crowd of around 7 or 8 people watching the test.

Now, of course you can do better than this in fact I have a 30-143 primary I am going to test so I can not use any shims. Or you can buy an Ulmer or Hartman kit. But for those that do not buy any vendor kits this seems to be the answer. This is a follow on from the clutch setup last winter, just felt I wanted to do a fresh test without any other modifications from stock to be certain of our testing.

Questions welcome but please don't bash something you have not tried, my patience for that is a little thin from last year......I post this for your benefit not mine.

 

[TestMaster]

So by raising the spring rate have you have raised the engagement speed?

Do you attribute the enhanced performance to the belt, the engagement speed or a combination of both?

Will the stock belt have a similar change? Or???

Love that you can do this, don't believe my dealer is interested in doing this kind of testing, I think the mountain dealers are more used to experimentation unless the flat landers race then...

 

[stingray719]

So by raising the spring rate have you have raised the engagement speed?

Do you attribute the enhanced performance to the belt, the engagement speed or a combination of both?

Will the stock belt have a similar change? Or???

Love that you can do this, don't believe my dealer is interested in doing this kind of testing, I think the mountain dealers are more used to experimentation unless the flat landers race then...

Myself and NOS-PRO did extensive testing last winter and found the secret seemed to be very high spring pressure, I just wanted a virgin test to prove it. Engagement speed is now at 4100 after shims added, our other sled works even better with spring change and engagement speed of 3200. The test with original 8jp would probably been the same as it was a new belt but those 8jp shed so much belt dust I didn't want to have to clean it out so I changed the belt. Our other Viper that has flat profile 8fs weights and a grn/wht/grn with 2mm shim is even noticeably better yet. But my goal here was to take a sled out of the crate and do ONLY one change to pinpoint the big issue with this clutch. By that I mean you can always find a little here and there clutch tuning, I was interested in pinpointing the really BIG issue that needs fixed before you hit other tuning. I would assume Ulmer and Hartman have already fixed there kits so buying one of those is an option also for those that buy clutch kits.

I have bought a orange/silver/orange spring and intend to try to dial this in without the use of spacers, but that is not what this thread is about

Also, there are countless ways to tune a clutch so my way is by no means the only way. Some tune from secondary forward but I like tuning from primary back, doesn't matter if you get it to work as you wish. So far this has worked for everyone that has tried it and if you try it and it does not please post data as I would be very interested in knowing why.

 

[stingray719]

So by raising the spring rate have you have raised the engagement speed?

Do you attribute the enhanced performance to the belt, the engagement speed or a combination of both?

Will the stock belt have a similar change? Or???

Love that you can do this, don't believe my dealer is interested in doing this kind of testing, I think the mountain dealers are more used to experimentation unless the flat landers race then...

Oh, one other thing. NOS-PRO is a flatlander and helped test and dial this in....this is not a mountain setting its a base clutch issue. Figured you knew that but wanted to add that so others wouldn't be confused.

 

[Studroes144]

Have you tried an orange pink orange primary spring? That's what I have in my D&D kit and I believe that is the stiffest spring yammi offers.

 

[weasel33]

At 4300 rpm does that want to rip your arms off at take off or can it be made more linear from take off. I guess what Im asking is it smooth clutch engagement at 4300 rpm. Thanks

 

[stingray719]

At 4300 rpm does that want to rip your arms off at take off or can it be made more linear from take off. I guess what Im asking is it smooth clutch engagement at 4300 rpm. Thanks

Not smooth at all, a di

Have you tried an orange pink orange primary spring? That's what I have in my D&D kit and I believe that is the stiffest spring yammi offers.

I bought the wrong spring, bought a short one...have to buy the right one now...lol. orange/pink/orange is the same as grn/wt/grn on finishing rate, just diff on engagement speed. I think the orange/silver/orange is going to be the right spring.
orange/pink/orange = 30kg preload (engagement speed) and 137 finishing rate (shift rate)
green/white/green= 45kg preload and 136 finishing rate
orange/silver/orange= 35kg preload and 143 finishing rate.

 

[Studroes144]

Just took another look at the spring charts and by the looks of it and what you've already tried I'd say with the orange silver orange you are prolly on the right track. In a perfect world that spring should treat you real good.. Unfortunately we know how the perfect world treats us when it comes to snowmobiles lol I can't remember now if we tried the o-s-o in mine or not but likely came up with the orange pink orange because of the aftermarket weights. Might be a good spring for me to try out tho this fall once the turbo is on and hopefully making a bunch more power! Best of luck and I'm very jealous you have any type of snow to ride on..what I wouldn't give for a 2' snow storm right now!

 

[YamahaTim]

Just took another look at the spring charts and by the looks of it and what you've already tried I'd say with the orange silver orange you are prolly on the right track. In a perfect world that spring should treat you real good.. Unfortunately we know how the perfect world treats us when it comes to snowmobiles lol I can't remember now if we tried the o-s-o in mine or not but likely came up with the orange pink orange because of the aftermarket weights. Might be a good spring for me to try out tho this fall once the turbo is on and hopefully making a bunch more power! Best of luck and I'm very jealous you have any type of snow to ride on..what I wouldn't give for a 2' snow storm right now!

Lol...I'm with ya there! Can't wait for snow!!

 

[viperjeff]

2 feet would be good 4 feet would be better lol

 

[stingray719]

Just did an online search and found 2 companys that sell spacers (primary clutch shims) that are larger than Yamaha ones. As I do not see them on the vendor list here I am not going to name them but 4mm shims to 8mm shims are available.

 

[TestMaster]

Message Tom and ask him if it's OK. Tell him why, perhaps he knows of an advertiser who has them, if not, he may let you provide the source in this thread. Never hurts to ask!

 

[stingray719]

Message Tom and ask him if it's OK. Tell him why, perhaps he knows of an advertiser who has them, if not, he may let you provide the source in this thread. Never hurts to ask!

Vendor is not an advertiser here so I am not going to advertise for him, but shims are available if you look. I have some on the way and my orange/silver/orange spring came in today so I hope to test it this weekend on the side street (wish me luck on getting caught) lol.

 

[TestMaster]

Know how you feel X3. Friend and I had a 64 GTO with a 427 Chevy with tunnel ram & dual 780 Holley double pumpers. Until we had a starter hand wound by a local expert we put a new starter in every weekend. 12.5:1 compression will do that! Had a rock crusher trans with a Borg & Beck 4300 lb. double diaphragm clutch. Spinning a 4:56 rear end.

One seat, battery in trunk, and green metal flake. Used to shake the houses when we started it while tuning it at home. Used to make test runs (200-300 ft) on the street in front of the house almost weekly on the East Side of Detroit. That would have been 1970-71.

Things were simpler then, never had the police show, all the neighborhood kids came out to watch the mayhem! Oh yea, and a couple of the parents. Open headers really woke things up!

 

[MrSled]

If you can get a part number Yamaha may have them as well at any dealer. Do you know if Pioneer has them?? He might be able to get them if you call them if they are not listed on his site.