Clutching on the cheap

[stingray719]

Dont think you can add much more than 3 washers under that bolt.
I think 3-4 washers has the clutch sheaves hit each other.
If i remember right, to get my belt riding at the correct height in the secondary i had to pull out all 3 bolts.

OOps maybe that was not clear..sorry. I meant for each deflection bolt keep the original washer and put one everyday variety washer on for two total washer per bolt. Yes I have seen a lot of variance on belts, I changed the 8DN to a new 8DN last weekend and had to change deflection.

 

[stingray719]

I got the same washers from my dealer and had three stacked on each bolt so the sheaves were almost touching then I started the sled and ran it then checked the deflection plus how high the belt was riding and it was flush with the top of the secondary and seemed too loose,now on my other brands of sleds I've always ran my belt deflection as tight as possible without the sled wanting to creep ahead,if I grabbed the secondary I could spin the belt around the primary really easy,so it's too loose IMO

Hmmm check that belt against another for width.

 

[Kerrdog569]

Hmmm check that belt against another for width.

What's a new 8dn supposed to measure with dial calipers Bill? I have 2 new ones to measure so I'll go check

 

[Kerrdog569]

Ok just measured, both belts are the same @ 1.360

 

[NOS-PRO]

Ok just measured, both belts are the same @ 1.360

That's why... belts should be around 1.375

I have seen this far too many times now. Bought a new belt last year and it was 1.355

 

[cannondale27]

1.343 according to charts. Older 8dn is wider if can be found. 00 is old 01 is new. Look in facts sticky under clutching. Nice chart in mm though.

 

[NOS-PRO]

That's worse yet at 1.343

The belt i previously got from TA was 1.378 and is an 01 belt. Mine on the Viper is that same belt measuring at 1.374 right now. Weird........

 

[larrypolaris]

I couldn't get the belt deflection I wanted even with 3 washers,the clutch sheaves were almost touching and the belt was still sitting down or almost even with the top of the secondary,could be my belts on the long side of spec too but I sent my clutch for machining anyways to fix both issues,coil bind and belt deflection

Before I buy a belt. I would have the dealer bring out 4 or 5 belts and I measure everyone before I buy the one with the correct length.
You would be surprised on belt length/width differences right from the factory. After market belts are even worst.

Correct belt length for it's c to c is key to any snowmobile clutch system.

It's amazing how an incorrect length belt can affect the performance of a sled.

If you have any performance problems with your sled. Be sure the belt is the correct length and width before you start changing any clutch parts.

Back in my grass drag days. We used to run different length belts and brands, and compare 60 ft times and et's.

 

[TD Max]

You know I swear I read a Yamaha release (accurate or not?) stating that the new for Viper 8JP belt was supposed to be same as the 8DN only different length to accommodate the new C to C.

 

[turbo800]

Anybody run Gates belts? We've had good luck with them on our Doo's and at 1/2 the price of OEM!

 

[larrypolaris]

You know I swear I read a Yamaha release (accurate or not?) stating that the new for Viper 8JP belt was supposed to be same as the 8DN only different length to accommodate the new C to C.

Last year at one of the snowmobile shows. A Yamaha rep said the same thing. 8JP & 8DN are the same construction. Just a difference in length to accomodate
for the c to c difference.

Last season I tested both belts back to back multiple times on a mile long stretch of good hard pack snow on a lake near my house.
The 8DN did pull a couple of more mph. Engine rpms were pretty much the same for both belts.

However through out the season after I put some miles on the 8DN and the belt started to wear. I lost some rpms and I couldn't adjust the belt height
anymore because the adjusters were already maxed out.

The 8JP always worked good for me.

 

[Studroes144]

Cannondale has a few different belts he is going to be testing this year. If I remember correct he will try the 8jp, 8dn, gates and I believe 1 other belt. One thing that's been proven is the stock secondary spring will bind up in higher speeds, when running the 8dn belt and having to add the additional washers on the secondary to adjust belt ride height you are moving the secondary sheaves closer together, this allows for the secondary to travel a bit more before the spring binds..that's where the few additional mph are coming from. As for belt dust, when that spring binds, your clutches start slipping and will cause the belt dust, the 8jp just causes the binding to happen a few mph sooner. One thing that I've seen proven and have had several turbo guys tell me is that once you swap out the secondary spring the coil bind is eliminated and the 8jp works just fine. One guy supposably has 4000 miles on his original 8jp belt running a 190hp turbo kit. Looking forward to hearing cannondale's review!

 

[stingray719]

Cannondale has a few different belts he is going to be testing this year. If I remember correct he will try the 8jp, 8dn, gates and I believe 1 other belt. One thing that's been proven is the stock secondary spring will bind up in higher speeds, when running the 8dn belt and having to add the additional washers on the secondary to adjust belt ride height you are moving the secondary sheaves closer together, this allows for the secondary to travel a bit more before the spring binds..that's where the few additional mph are coming from. As for belt dust, when that spring binds, your clutches start slipping and will cause the belt dust, the 8jp just causes the binding to happen a few mph sooner. One thing that I've seen proven and have had several turbo guys tell me is that once you swap out the secondary spring the coil bind is eliminated and the 8jp works just fine. One guy supposably has 4000 miles on his original 8jp belt running a 190hp turbo kit. Looking forward to hearing cannondale's review!

Nice theory but the girlfriend babied her Viper for the first 50 miles and never got over 50mph and the clutches were full of belt dust. The soft spring, odd weights and a couple of other oddities cause issues with this clutch until fixed as you did yours. You could find a bone stock Viper and just fix the secondary and test to prove though.

 

[Studroes144]

I'm simply stating the coil bind issue and how simply swapping to the 8dn belt solves that, to a certain extent, because as seen in a recent post^^ someone stated that after some miles they still had belt dust with the 8dn

 

[Studroes144]

Last year at one of the snowmobile shows. A Yamaha rep said the same thing. 8JP & 8DN are the same construction. Just a difference in length to accomodate
for the c to c difference.

Last season I tested both belts back to back multiple times on a mile long stretch of good hard pack snow on a lake near my house.
The 8DN did pull a couple of more mph. Engine rpms were pretty much the same for both belts.

However through out the season after I put some miles on the 8DN and the belt started to wear. I lost some rpms and I couldn't adjust the belt height
anymore because the adjusters were already maxed out.

The 8JP always worked good for me.

Could you elaborate for us a bit on this? Some things we should all know to make a better judgement on your findings. Are you running a completely stock clutch setup or do you have aftermarket weights, springs, helix? What speeds were you reaching with the 8jp vs the 8dn? How many miles did you have on the 8jp belt and how many on the 8dn before you started getting the belt dust