"Clutching on the Cheap" misinformation

Mountaintech · Oct 14, 2014

Srxspec said:
A primary spring shim does not add belt pressure, it lessens it.

Adding a primary spring shim will lessen belt grab and raise your overall rpm.

Exactly!

yamaha1973 · Oct 14, 2014

Lots of good info in this thread, Im taking notes...

cannondale27 · Oct 14, 2014

8dn is only thing that stopped my belt from slipping.

stingray719 · Oct 14, 2014

Studroes144 said:
Stingray what are you referring to when u say "our setup"? Is it what you're using on your sled or nospro sled? Last I ever knew was u were running stock helix, nospro, if I remember right is using a multi angle helix. Nospro is running 8fp weights? You're running 8fs? If this is so then the similarity in your setups is that you're running primary shims, but they're also different. Do you really feel that in a drag race your personal set up with flat profile weights and stock helix well beat a set up that's using aggressive profile weights and a multi angled helix that is more aggressive they are in stock? If this were true then I'm sure every single clutch vendor would be selling primary shims. I have yet to see any.

Barry, I have made it VERY clear in my posts that the heart of this is the primary clutch spring shim. Everything else helps but the heart of this is what matters. Next, an aggressive curved profile forces a quicker upshift, shift your car too fast and see if that works. Why do you think Yamaha came out with the flat profile 8fs and put it in 4 strokes? Yamaha has long had weak secondary issues, we used to (and still do in parking lots to help people) wind the secondary way tight on a Mountain Max to make a big positive difference. Both my boosted Phazers had to get roller secondary's to work right (SRX or Mountain Max secondary, IE) because the power forced early upshift on the stock secondary and bogged them down. Have to give credit for Cannondale to getting me on that path with the Phazer secondary. Thanks Cannondale!

Look at the 8fs and 8fp weights in the picture above

. Close enough and the 8fp is MUCH cheaper and easier to get. You really should research these kind of comments before you make them. One of the well known vendors I spoke to that has not yet done a Viper kit said when I told him the Viper had 8gl weights said "that's a 2 stroke weight". Yeah look at the bump at the base that raises engine speed at take off, why do that on a torque based 4 stroke? How many of you have stock weights and hit rev limiter only on take off? Any 4 stroke weight will help here take your pick not just our recommendation.

Now for the other part, I have been doing clutches for decades and until now all I ever saw a primary clutch spring shim do is raise engagement speed and a little on top but no real performance increase other than higher engagement speed for take off. BUT this Viper clutching setup is different. One vendor I know of who has done clutches for decades is using smaller rollers with other tweaks. If I cared I could experiment with that but I do not care to waste any more riding time testing. I have what works and why spend time trying to simplify it so I can bring it here to be bashed?

As NOS-PRO has said we don't make a dime out of this in fact I just answered another private message (and am glad too). More than a few of you I have talked to via phone and discussed clutch issues in detail. Always happy to help. Barry I am going to private message you my phone number and if you have a question lets talk about it person to person as this "drama" as it was said to me in PM isn't helping anybody.

I do not have an other than professional relationship with the vendors I recommend and sometimes wonder if those attached to a vendor via job or relatives would not be better if they stated so.

Studroes144 · Oct 14, 2014

Shifting a car too fast has zero to do with snowmobile clutching, clutching is designed to shift out the clutches as fast as possible and still maintain power at a set rpm, so the fact that I'm running more aggressive weights and a more aggressive helix than anyone I've seen yet on a stock viper and pulling 9k rpm everywhere makes me feel very confident, not to mention 1800 miles on an 8jp belt that hasn't lost a bit of performance, but let's not get u started on that again. Also, that quick winding rpm on a full load take off is the best performance for the viper, if you lug it along it doesn't launch and accelerate as quickly, this was proven to me by the stalker print outs of the clutching done last winter, the fastest times my viper ever had are when it tapped the rev limiter once or twice on the take off, why do you think Evo is doing a flash to raise the rev limiter, they explained it very clearly because the viper likes the higher rpm up top and when it hits the rev limiter it kills momentum.

yamadoo · Oct 14, 2014

I appreciate the help! From both

I have used Ulmers products and advice as well as advice from Nos Pro with great satisfaction from both.

I know Terry - Nos pro - always speaks with respect for the venders and especially Ulmers shop as he has with me.

Thanks to you all sorry we have to have these issues.

Studroes144 · Oct 14, 2014

I was just informed by a very reliable source and after doing a quick search of my own found out the stock 8gl viper weight is the same weight that's been used in the nytro since 2008. My source claimed "the 8gl is in no way a 2-stroke weight, the initial hump is to increase corner to corner acceleration" sounds like it's prolly the type of weight 90% of riders are looking for.

cacsrx1 · Oct 14, 2014

First thing a lot of guys around here need to do is read Olav AAen's clutching hand book, and then read it 2 more times.

Studroes144 · Oct 14, 2014

Got it sitting right behind my toilet, browse thru it most every day lol. If u can read that book and understand it in just 2 attempts you're doing better than me! A lot of very in depth stuff in there

stingray719 · Oct 14, 2014

Studroes144 said:
I was just informed by a very reliable source and after doing a quick search of my own found out the stock 8gl viper weight is the same weight that's been used in the nytro since 2008. My source claimed "the 8gl is in no way a 2-stroke weight, the initial hump is to increase corner to corner acceleration" sounds like it's prolly the type of weight 90% of riders are looking for.

stingray719 · Oct 14, 2014

Srxspec · Oct 14, 2014

The 8GL weights came in the 2008 to 2014 FX Nytro RTX and XTX models. It came in all of those models, no matter what the track option.

The 8FP weights came in 2006 to 2010 Apex & Apex LTX (121" & 136" models).

The 8FS weights came in 2006 to 2010 Apex Mtn & Apex MTX models.

The 8FS weights also came in the 2008 to 2013 FX Nytro MTX models.

Any of the other models you listed, those weights are listed as an alternate weight, that can bolt into the clutch, it does not mean they come in those models from the factory.

Studroes144 · Oct 14, 2014

I can see why they used 8fp weights in the apex, that sled is a torque monster compared to the 1049, the 1049 in the nytro/viper gets the torquey fell because of the aggressive heel on the 8gl.

Srxspec · Oct 14, 2014

Also, how can you tell that the 8GL weight "lets the engine rev" at take off or has less belt grab, I understand, maybe in your situation out in the field you felt it was that way, but was your primary spring possibly not correct? Helix selection not correct? The Yamaha chart lists the 8FP at about 450 kgf at approximately 8mm of stroke and about 320 kgf at full stroke of 30mm. The 8GL has no numbers on it's graph, but looking at the graph, it shows that it has more of a straight up (belt grabbing) graph than the 8FP or 8FS weight at the initial.

The 8FP weight has a hump/bump at the heel as well, just before the weight engages (the roller has to go over this hump/bump right at or slightly after engagement) just like it has to on the 8GL. Now the 8GL weight is approximately .020" higher hump/bump than the 8FP weight. That hump/bump applies more initial belt grab (look at the graphs, you can see the graph spike at the beginning and then slowly go down).

If you want a flat profile weight, then you better try the 8HG!

Studroes144 · Oct 14, 2014

Allen I hope you're getting overtime for this lol

"Clutching on the Cheap" misinformation

Mountaintech

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yamaha1973

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yamadoo

Yamadoo is a snowmobile ' aholic'.

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cacsrx1

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Srxspec

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