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I switch back and forth from the stock 30" tire and 32" skat trak's. Overall the skats are 70lbs lighter than stock and the car is exactly the same between the two sets of tires rpm and power wise.
 

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I switch back and forth from the stock 30" tire and 32" skat trak's. Overall the skats are 70lbs lighter than stock and the car is exactly the same between the two sets of tires rpm and power wise.
Any changes in your clutching if so what are they? or all stock?
 

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I have been all over the place with clutching, trying to learn and get the max rpm out of it and low engagement currently I am at 3200 rpm engagement and 9300 rpm. little higher than I want to be on engagement but this setup is the only way I have got above 8400 rpm. I haven't tested this setup other than in the neighborhood so hopefully it works out

venom black green 200-280 driven spring
Bd Xtreme 36-45 ebs
Bd Xtreme 100-250 drive spring
Bd xtreme 55-71 arms weights are 3-1-0-0
 

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DynoJet has a clutch kit now available too, no info on helix cut or spring weight but in the downloads is an installation manual for reference.
View attachment 251988
I called DynoJet today inquiring about the spring rate and Helix cut. Never got an answer to either, just got. "Our kit is made for the XX, not meant to be sold individually or added to other clutch kits"
 

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Also curious. Can you post elevation, tire size, tune, and other weight in the vehicle for reference? I’m surprised you can go that heavy in weights and pull 9k or better. I have alba tune and 32s and at 6k ft need 48g or less to pull over 9k wot
We run 43 gram weights out here at 11,000 ft. elevation with the 36-45 helix and the EPI 60-200 primary spring. We also use the 200-280 secondary spring. 32" tires. Stock machines. 9500 rpm's all day long. This setup runs fantastic at high elevation. Custom weights. We also run this setup at Moab, Utah, but with 46 gram weights. Engagement is at 2400 rpm's for Moab. We are testing different custom EBS helixes at Moab.
 

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Discussion Starter · #166 ·
I just wanted to post this since there was some talk about it a while back.
I have been waiting for the AC 0646-439 (50-250) spring for months. I forgot I ordered it, it's been so long. It finally showed up and it measures the same as the 0646-467 (35-195).
The 35-195 spring is still my favorite but for some reason it is double the price.
The 50-250 spring should be a good alternative if you can find it
 

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I recently messed up my driven clutch - the retaining bolt came loose (Belleville washer no longer cupped) and the splines on the outer sheave were damaged. I know Arctic Cat changed the part number on the drive clutch when they started using a different spring, but the replacement driven clutch was exactly the same p/n as my original, so if the p/n rules are applied the same way, it is most likely identical. The original clutch kept the revs at around 8400 rpm at WOT. The new clutch lets the engine rev to 9100 rpm at WOT.

I haven't had a driven apart, so my lay-person's understanding of how the clutches combine to change ratio may not be 100% accurate. I'm wondering what would cause the difference. Is the new clutch just not fully broken in, so it does not spread as quickly/easily? I've put about 100 miles on it.

On a side note, I purchased a header (not yet installed) and ECM reflash (also not applied) from Alba during their Black Friday pricing. I had been thinking I might get away without needing the clutch kit since my shift rpm was low. I guess that is out the window now, although I suppose I could install the new outer sheave with the old driven and see if the revs drop back.
 

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I just wanted to post this since there was some talk about it a while back.
I have been waiting for the AC 0646-439 (50-250) spring for months. I forgot I ordered it, it's been so long. It finally showed up and it measures the same as the 0646-467 (35-195).
The 35-195 spring is still my favorite but for some reason it is double the price.
The 50-250 spring should be a good alternative if you can find it
I want to thank you for posting all of your results, it’s been really helpful for me. I am getting ready to try the Venom red/gold/black (810003) ......... 55-225 / 22 - 176. Was using that 35-195 spring prior and with the light tip weights that upper number was too much for it. This should give me even lower engagement too!
 

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Discussion Starter · #169 ·
I recently messed up my driven clutch - the retaining bolt came loose (Belleville washer no longer cupped) and the splines on the outer sheave were damaged. I know Arctic Cat changed the part number on the drive clutch when they started using a different spring, but the replacement driven clutch was exactly the same p/n as my original, so if the p/n rules are applied the same way, it is most likely identical. The original clutch kept the revs at around 8400 rpm at WOT. The new clutch lets the engine rev to 9100 rpm at WOT.

I haven't had a driven apart, so my lay-person's understanding of how the clutches combine to change ratio may not be 100% accurate. I'm wondering what would cause the difference. Is the new clutch just not fully broken in, so it does not spread as quickly/easily? I've put about 100 miles on it.

On a side note, I purchased a header (not yet installed) and ECM reflash (also not applied) from Alba during their Black Friday pricing. I had been thinking I might get away without needing the clutch kit since my shift rpm was low. I guess that is out the window now, although I suppose I could install the new outer sheave with the old driven and see if the revs drop back.
That's a problem with production parts. Depending on how often they are checking the tooling, and with tolerances maybe plus or minus a couple ten thousanths you could really change a clutch. Some people have buttons that are sloppy and wear out quick. I have buttons that are too tight and never wear. Some snowmobile guys have said they have several of the same spring so they can find the one that works the best.

Non of this stuff can really be considered 'identical'. That's what makes this stuff so hard. That's what makes this thread so interesting. All my testing might only apply to my exact setup. One thing different and you are on your own. That's why I wanted to do some baseline measurements so it would be easier to go the direction you think you need to go.
 

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I recently messed up my driven clutch - the retaining bolt came loose (Belleville washer no longer cupped) and the splines on the outer sheave were damaged. I know Arctic Cat changed the part number on the drive clutch when they started using a different spring, but the replacement driven clutch was exactly the same p/n as my original, so if the p/n rules are applied the same way, it is most likely identical. The original clutch kept the revs at around 8400 rpm at WOT. The new clutch lets the engine rev to 9100 rpm at WOT.

I haven't had a driven apart, so my lay-person's understanding of how the clutches combine to change ratio may not be 100% accurate. I'm wondering what would cause the difference. Is the new clutch just not fully broken in, so it does not spread as quickly/easily? I've put about 100 miles on it.

On a side note, I purchased a header (not yet installed) and ECM reflash (also not applied) from Alba during their Black Friday pricing. I had been thinking I might get away without needing the clutch kit since my shift rpm was low. I guess that is out the window now, although I suppose I could install the new outer sheave with the old driven and see if the revs drop back.
I also just got a new secondary and after reading this i am hoping it helps my rpm issue as well
 

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Discussion Starter · #172 ·
You know that saying "it runs the best right before it blows up" ?
I was saying that at every 'cold beverage' stop on our last trip to Jawbone.
The last ride was the best it ever ran, the clutch was perfect.......until it wasn't

So all this clutch work paid off.....a little.
I learned enough to know that I was fighting tight buttons the whole time, and when it finally loosened up it was AMAZING! The perfect setup, engagement right off idle, no slip at 3mph, good for rock crawling with nice engine braking, 9400rpm WOT in the desert with perfect backshift. And then.....it ate the buttons.

It seems that my clutch went from too tight to too loose in 2 trips to the desert, after 2000 miles of zero wear. This explains a lot about different results from different cars. This is why 'my setup' is different than 'your setup'. This is why clutch tuning is "black magic". You have to tune YOUR clutch.

So now I am adding the Speedwerx PTO shaft, Speedwerx buttons, and the LaRue primary cover.

Now that I know the setup I want, I'm going to see if I can make it last.
 

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While your in there with the spider pulled apart rebuilding your primary you should shim the spider with a .030 shim. We run this in Moab, Utah with severe rock crawling. Way, way lower smooth engagement with the primary spring of your choice. Try it, you will like it. This is one of the first mods we do to the primary.
 

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Crawlr, do you have a plan for balancing the clutch with the Larue cover?
 

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Discussion Starter · #175 ·
Crawlr, do you have a plan for balancing the clutch with the Larue cover?
Nope. Do you really think the little dimples they put in the stock cover are making a difference? That shitty plastic fan is more than offsetting whatever gain they might have got. The stock cover weighs almost nothing and the tiny amount they took out of it is less than nothing compared to the mass of the whole assembly. The LaRue cover adds a noticeable amount of perfectly balanced mass to the outside and eliminates the plastic fan.

I drove the hell out of it for the rest of the weekend with the buttons completely gone and everything flopping around and there was no noticeable vibration or issues, just extra noise. The balance of the primary is not an issue
 

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At 9k RPM, yes, I do.

No manufacturer adds a process to their product that doesn't yield a positive result. Balancing is even more of a cost-adder, as it takes specific equipment and extra handling compared to assembling a clutch.

The plastic fan is inherently balanced, just like the Larue cover. Equipped with the Speedwerx "thimbles", it stays centered on the clutch. Without them, not so much!
 

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Discussion Starter · #177 ·
I decided to take Winch Warrior's advice. I'm waiting for my friend to make me a .030 shim tomorrow before I put everything back together so I thought I would do a little show and tell.

Here's some of the stuff I've been playing with. Old parts, new parts, sacrificed parts, custom parts.

252765


Speedwerx was out of stock on some of the clutch tools and I didn't really want to spend another $500 anyway so I made my own. It worked great.

A couple of the rollers in the spider were pretty worn so I decided to cut apart a Wildcat X primary I had on the shelf to see if they are the same. Perfect fit!

The X buttons are also the same size but they are solid where the XX buttons have a cavity in the backside that holds a little rubber star, I guess to hold tension or absorb shock. Since I lost some of the buttons I also lost the stars and the Speedwerx buttons don't come with them. I used a gasket punch to make some rubber slugs to put in there and they seem to fit well.

252766

X button, XX buttons, Speedwerx buttons, inserts I made

I got a cheap 1 7/16 6-point deep socket off Amazon that I thought I would have to cut and extend but it was just deep enough to get the nut off. Lucky

Since I got the Speedwerx PTO shaft, I used the stock PTO as a primary holder. I welded some bolts to a plate that hold the fins, and welded that plate to the PTO shaft, and then welded the PTO to a big plate that I could park my truck on and made a spider wrench that I could put a pipe on. I figured if I was going to do it I was going to make it easy. Spider came right off
252767



Since I have the clutch off I might as well install the Speed waterpump kit that I bought a while back even though I did the Speedwerx mod and don't really need it now
 

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Speaking of buttons. The last time had my primary off, when I pressed the sheaves together, they would stay together. The spring should push them back apart right? It seems where my buttons slide up & down the "towers" is too tight. I'm thinking about hitting the "towers" with some very fine grit sand paper so the buttons can slide on them more easily & the sheaves can open/close freely as they should. Maybe this will take care of my jumpy/shuttering low rpm belt engagement?
 

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This is what I did, took a few tries and went slowly to make sure I didn't take off too much. Made other changes at the same time so impossible to say for sure what this solved for me but engagement is smoother off the line.

Speaking of buttons. The last time had my primary off, when I pressed the sheaves together, they would stay together. The spring should push them back apart right? It seems where my buttons slide up & down the "towers" is too tight. I'm thinking about hitting the "towers" with some very fine grit sand paper so the buttons can slide on them more easily & the sheaves can open/close freely as they should. Maybe this will take care of my jumpy/shuttering low rpm belt engagement?
 

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Crawlr, thanks for describing how you built your clutch holding fixture. Using the now-excess OEM PTO was a great idea!
 
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