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8DN belt on Sidewinder

It would be rare for me to get a 1000kms out of an 8DN, and my buddy as well, when running hard.
 

Was able to get a lot of testing the past couple days. Focused on the secondary. Tried three springs and the belts. All with the 46/36 helix. The testing was done on hard pack snow. This was all short distance drag racing. Sled was set at 31 PSI. TAPP/pro4 clutching.

Black/purple - Too stiff for all belts. Ton of heat in secondary. Snapped an 8DN on second launch. I’m not sure what helix would work with that spring.....not a 46/36.

Dalton White - middle hole (standard). Had much lower secondary heat. It didn’t have any belt slip with 8jp, or XS. I used log files to confirm no belt slip.....RPM and track speed mirrored each other nicely. The 8DN slipped at any setting below hole 5 in standard, secondary temp was hotter with the 8DN. The sled was quickest with the 8JP.

EPI purple - middle hole (standard). 8DN and 8JP both had verified belt slip. Log files confirmed a flat RPM line while track speed changed +\- 10 mph, secondary ran hot too. XS had no slip on this setting. Racing the same sleds, this combo performed equal (as much as I could tell) to the 8JP with the white spring. primary was lighter by 12 grams total, cams one position higher.

My choice after testing all combos was is the 8JP with Dalton White (middle hole, standard). The sled was quick and still has decent back shift. By the way, this was exactly the way the clutch was shipped. Only belt that broke was the 8DN.
 
Last edited:
Brent68 said:
Was able to get a lot of testing the past couple days. Focused on the secondary. Tried three springs and the belts. All with the 46/36 helix. The testing was done on hard pack snow. This was all short distance drag racing. Sled was set at 31 PSI.

Black/purple - Too stiff for all belts. Ton of heat in secondary. Snapped an 8DN on second launch. I’m not sure what helix would work with that spring.....not a 46/36.

Dalton White - middle hole (standard). Had much lower secondary heat. It didn’t have any belt slip with 8jp, or XS. I used log files to confirm no belt slip.....RPM and track speed mirrored each other nicely. The 8DN slipped at any setting below hole 5 in standard, secondary temp was hotter with the 8DN. The sled was quickest with the 8JP.

EPI purple - middle hole (standard). 8DN and 8JP both had verified belt slip. Log files confirmed a flat RPM line while track speed changed +\- 10 mph, secondary ran hot too. XS had no slip on this setting. Racing the same sleds, this combo performed equal (as much as I could tell) to the 8JP with the white spring. primary was lighter by 12 grams total, cams one position higher.

My choice after testing all combos was is the 8DN with Dalton White (middle hole, standard). The sled was quick and still has decent back shift. By the way, this was exactly the way the clutch was shipped. Only belt that broke was the 8DN.
Click to expand...

Great info

Did you mean the XS was your favorite belt or the 8DN?
 
KnappAttack said:
As I recall you are only running the 240 Hurricane tune. From what I have seen, the 240 tune is very easy on belts and clutch parts. I believe you could put any belt on it and it would be happy. The clutch and belt issues arise when you turn it up and try and run the bigger tunes. We have many here running more than well over 4 and 5 thousand miles on the stock 8JP only using the 240 tune. It will run happily day after day. Its like a honey badger, it just don't give a crap what you do to it, its almost bullet proof and seems like nothing matters, even if the alignment is off you can't hurt it or do no wrong. 240 is happy, happy, happy!

But keep an eye on your drive clutch, the 8DN will grove it up on the bottom and of course you'll drop the gear ratio using it as it is longer, so will start in a lower ratio and finish in a lower ratio. Easy way to gear it down 3-4 MPH if one wants that.
Click to expand...

Why does 8DN grove it up on the bottom primary clutch? Someone have a picture?
 
Janne339 said:
Why does 8DN grove it up on the bottom primary clutch? Someone have a picture?
Click to expand...

One of the main reasons the 8DN belt is so durable is because it has a harder rubber compound then your typical belt. There are down sides to the harder compound as it will more readily slip if it gets any moisture on it and on higher mileage sleds it eventually grooves the primary clutch sheaves at the engagement area. The higher the clutch engagement rpm the more the belt slips to get the sled moving and the quicker a groove appears.
 
sideshowBob said:
One of the main reasons the 8DN belt is so durable is because it has a harder rubber compound then your typical belt. There are down sides to the harder compound as it will more readily slip if it gets any moisture on it and on higher mileage sleds it eventually grooves the primary clutch sheaves at the engagement area. The higher the clutch engagement rpm the more the belt slips to get the sled moving and the quicker a groove appears.
Click to expand...
I find that higher gearing also leads to more wear at the bottom portion of the clutch.
 
Just an update:
I am well into my third season of running an 8DN belt on my 2019 SW and have used 8DNs since the sled was new. I changed the first 8DN at somewhere around 1500 miles just because I felt it was time.
My SW has been tuned from new and has had the Hurricane Stock and Perf muffler tune bundle with Anti Lag since the start of its second season.
I have yet to visibly damage an 8DN through trail riding with numerous high speed runs, occasional snow drags, deep snow riding, two up riding, towing a sleigh ect.
I have always floated my secondary, just like all my other Yamaha sleds, since new and run a combination of Dalton and TP tuning components.
Works for me!
 
With all due respect Bob, Ill play the Devils advocate.
I was very loyal to the Yamaha 8DN, but I did explode a few on the Winder.
I switched to the Timken and haven't looked back. I think they are more gentle on the clutch surfaces also.
Sure, the 8DN is much cheaper than the Timken, but the Timken has warranty.
Will Yamaha warranty an exploded belt? Do pigs fly?
As far as float goes, IMO, manufacturers wanted a small amount of play with the secondary for one reason.
If there was no play there, when tightening the secondary bolt, the jackshaft bearing would/could be forced over.
I think it may have first been Doo, that put a step on the jackshaft for the bearing to shoulder against back in the early 2000's, eliminating float and all the spacers/washers, etc.
 
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