Trying The 8DN BELT

[YamahaTim]

Did some belt testing yesterday. Viper belt vs a 8DN belt. Both belts were new and both were broke in with about 20 miles on them.

Added washers to the 8DN for good belt deflection.

The Viper belt measured 1123mm. The 8DN measured 1131mm.

Tested on a approx 1/4 mile long icy river bed with fresh snow on top packed down from other sled traffic.
Not the best for top speed but smooth and flat.

Both belts performed about the same.

Top end was showing in the low 90 mph range at the end of each run. I ran multiple runs back to back in both directions on both belts.

The engine was spinning between 8900-9050 RPMs on the runs for both belts.

My sled is stock with a Hauck clutch kit. 1830 miles on the sled.
The same Hauck clutch kit I had on my Nytro but I changed the weight to work on the Viper.
I installed the Hauck clutch kit at around 350 miles on the sled.

The new Viper belt I tested yesterday the width measured 1.340". The original Viper I took off belt measured 1.315".

I had the original belt on since day one.
The original belt I took off had about 1760 miles on it. Over all it looked good. Just wore 0.025".

FYI on my findings.

That's good info. Thanks.

It's weird that your performance dint Change, and you rpm didn't change. It was like night and day difference for me.

Did you check clutch temp after the runs?

Which belt are you going to use?

I forgot my lazer temp light. But I did touch both clutches after each run on both belts.
The primary was warm to the touch with both belts.
The seconday was hot. Not super hot, but hotter then the primary. And basically felt the same with both belts.

I plan on running the 8DN. I marked my primary with a marker and the 8DN ran higher on the primary.

I think in the long run the 8DN will pull more mph.

It's all good! A lot of testing, it's kind of fun ain't it. I did all that too. Except with the stock belt my clutches felt way hotter. I could hold my hand on the 8DN but not the 8 JP. No way! I have not done the marker test yet. And I should, because then I would know for sure if I need a different clutch set up. But I just want to ride ride ride! So maybe I'll let the experts do that and I'll get the kit from Allen. Sucks but the warm weather is coming! So I'm going to go the rest of the week! I am trying to get as many miles as possible! So far the belt is holding up way better! So I'm happy with that!

 

[NOS-PRO]

To all, in my post a week ago, a new Viper belt will be close to an 8DN, I proved that also. It's when a Viper belt gets burnt and starts to slip is when times, speeds and rpm's go haywire.

 

[mewaschuk]

my experience, threw in an 8dn and had to REMOVE shims to get the secondary right. which makes more since the 8dn is wider, no. loss ~600rpm top end with all else equal.

 

[kritter5150]

well that didnt last long. 150 miles. belt exploded. second belt to go. one was the viper belt. that lasted 1500 miles. nytro belt lasted 150 miles. now what??

Try a gates g-force belt !
Part # 40g4313

OMG give up! Ulmer is using 8dn, Hartman is testing 8dn, I say it works and countless others and still you are trying to say it does not. Now not everybody knows how to identify a "Technical Wizard In Training" aka TWIT so please people do your research before you believe a TWIT and not someone who actually tests things. Call your favorite clutching expert and ASK, all that I deal with will take the time to talk to you and explain things if you have questions. But there time is valuable so please ask just the questions you need answers to and not "how does a clutch work"...lol.

i did not say it didnt work. i was basically asking why my belts are breaking. obviously something other than the belts is not working properly

Kritter that response was not meant for you. I answered you in another post.



hey no problem. we re all here for the same reasons. we all love snowmobiling and we just want to solve any issues or help others with theirs.


Thanks!

 

[YamahaTim]

Thats what this site is for to give ideas and help people!

 

[09nytro]

well that didnt last long. 150 miles. belt exploded. second belt to go. one was the viper belt. that lasted 1500 miles. nytro belt lasted 150 miles. now what??

Try a gates g-force belt !
Part # 40g4313

Also check your offset , it should be 20mm , take a straightedge from front of primary clutch to the back edge of the secondary then on front edge of secondary you should have 20mm make sure your clutch is pushed all the way in on bearing on jack shaft .

I thought it was the same as previous Yamaha's- 15mm +/-1.5???

That's what the manual says .... But then again what do I know ....

 

[cannondale27]

Put 8dn on tonight. Riding sled to work for belt breaking then will test tomorrow after work. Can't wait to see what all the excitements about!

 

[TJ-R]

had to REMOVE shims to get the secondary right. which makes more since the 8dn is wider,

I agree, and don't understand the logic of adding a shim. It appears to me that the shims holds the stop screws out further and therefore the more shim the closer the two halves of the secondary become. If the belt is wider or taller would you not want the spacing to be wider or maybe equal if you are looking to get the belt to ride higher?

By the way the stock shim measured .040" (1mm) thick. Standard 6mm washers that I have measured .055" thick. Point being that if adding washers check them and make sure they are the same thickness as well as determine how much you are adding.

 

[cannondale27]

The belt is longer than stock so raising the belt height gives you proper belt deflection. You raise the belt by adding washers to the screws.

 

[TJ-R]

The belt is longer than stock so raising the belt height gives you proper belt deflection. You raise the belt by adding washers to the screws.

That makes sense to me. Thank you for clearing that up. Look forward to hear how the 8dn works out for you.

I ordered one for this past weekend and got a totally different part sent to me... so haven't tried the 8dn yet. My stock belt is squealing and slipping alot at 650 miles. I might just try it with the washers if I don't get an 8dn.

 

[Apex1958]

Time for my 2 cents well I took a vernier caliper measured the two belts and difference found I believe is the manufacturing tolerance; they are the same except for the length and the fins on the top. My dealer also tested them on the dyno and got 2 hp more with the 8dn only after he put three washers total to raise the belt height in the second dairy. After seeing my belt with 1400 miles on it and the piss poor shape it was in he thinks the compound of the viper belt Sucks. I started losing MPH after 500 miles on the belt, I put a new viper one on and I hit 87 MPH and it pulls like a freight train. Next I am going to loosen up the chain case at 500 Miles my dealer adjusted it and turned it out ¼ turn, now Yamaha says 1 ½ turns. I am hoping that it’s two tight and I will pick up some MPH because I can hear it making a wining noise that was real bad at 500 miles but now at 1500 miles it’s still there but not as bad. I had this sled at 95 MPH when it had 450 miles on it since then things have been going south for the top end. I had a Yamaha Rep. tell me that this sled is a 90 MPH sled and look at what the trubo guys are getting 105 to 110. SO FOR ME THIS SLED IS GOING DOWN THE ROAD AND IT IS NOT EXCEPTABLE THAT ANY 600CC WILL GO BY ME LIKE I AM STANDING STILL AT TOP END!!!! If you don’t care about top end then this sled is great and from 0 to 85 MPH pulls like hell and I am very happy with that after I put the new belt on. I WILL BE CHANGING TO THE 8DN FOR L0NGEVITY REASONS. NOS-PRO you 100% RIGHT.

 

[NOS-PRO]

Time for my 2 cents well I took a vernier caliper measured the two belts and difference found I believe is the manufacturing tolerance; they are the same except for the length and the fins on the top. My dealer also tested them on the dyno and got 2 hp more with the 8dn only after he put three washers total to raise the belt height in the second dairy. After seeing my belt with 1400 miles on it and the piss poor shape it was in he thinks the compound of the viper belt Sucks. I started losing MPH after 500 miles on the belt, I put a new viper one on and I hit 87 MPH and it pulls like a freight train. Next I am going to loosen up the chain case at 500 Miles my dealer adjusted it and turned it out ¼ turn, now Yamaha says 1 ½ turns. I am hoping that it’s two tight and I will pick up some MPH because I can hear it making a wining noise that was real bad at 500 miles but now at 1500 miles it’s still there but not as bad. I had this sled at 95 MPH when it had 450 miles on it since then things have been going south for the top end. I had a Yamaha Rep. tell me that this sled is a 90 MPH sled and look at what the trubo guys are getting 105 to 110. SO FOR ME THIS SLED IS GOING DOWN THE ROAD AND IT IS NOT EXCEPTABLE THAT ANY 600CC WILL GO BY ME LIKE I AM STANDING STILL AT TOP END!!!! If you don’t care about top end then this sled is great and from 0 to 85 MPH pulls like hell and I am very happy with that after I put the new belt on. I WILL BE CHANGING TO THE 8DN FOR L0NGEVITY REASONS. NOS-PRO you 100% RIGHT.

Thanks Apex1958!

Totally agree, the Viper belt compound is horrible and the belt is used up within 400 miles. Cool that the dyno even shows an increase of hpr with the 8DN

 

[09NytroRTX]

I am not familier at all with clutching.. That being said there has been a lot of people with awesome details of doing an oil change with arrow's pointing how to remove hood etc. Anyway we could get something like that for making the proper adjustments to make the 8DN belt work for the viper? I know all sleds are different so it won't be the same for all but if we could get something as to where to add washer's or shims that would help me out a great deal. If not no big deal just thought I would check and see. Thanks in advance.

 

[NOS-PRO]

I know there are quite a few posts for the Viper changing over to the 8DN belt, but it actually is the same for yamaha secondary clutching (Maybe the Phazer is different)

Here it goes:

There are 3 bolts on the rear side (opposite side of the helix) of the secondary clutch. These 3 bolts are a specific length and control the spacing between the sheaves of the secondary where the belt rides. There are washers that come from the factory (1 under each bolt head).

When your belt is new or squealing at idle :
With your clutching exposed, lock the brake/parking brake and remove belt. Take correct size socket and remove secondary bolt (watch what shims come out and this is exactly how it needs to go back together). Once the bolt and spacers are removed, remove secondary from jack shaft making sure the shims (if any) remain on the jackshaft. Locate the (3) 8mm bolts and remove each washer under all 3 bolts. The bolts without the washer will go into the clutch more to separate the sheaves making the belt distance shorter bewteen clutches curing the squealing problem. Tighten all 3 bolts without the washers, but keep the washers. re-install secondary per torque settings and install belt.

Too much belt deflection or changing a viper from the stock belt to an 8DN belt :
Use the same procedure to remove belt and secondary in the previous paragraph. Instead of taking the washers out, find 3 washers from a local hardware store or a Yamaha dealer. Add 1 washer to each bolt and re-install. (your setup should be 2 washers under each bolt head). If the washers are different sizes, the clutch will not engage properly and/or vibration will occur. Adding a washer brings the sheaves together more making the 8DN belt ride up n the secondary thus making belt deflection correct.

Having an extra set of washers from Yamaha is the ticket, but I tell peole as long as they are the same size (I check mine with a Caliper) you should be all good.

 

[BETHEVIPER]

Has anyone changed the center to center to be correct?
Just making the secondary narrower to take up the extra length is not going to fix everything. If the belt is longer, and you make it ride up on the secondary further, this means, it will bottom out the primary first, making the sled slower overall. The other thing running a belt long for the center to center is you are gearing the sled down, so I have no doubt that the sled pulls better, even if the rpms are off. We are talking about 4-6mm different center to center depending on belt variation between the two belts. That is alot when dealing with clutching.
I wish I had one of these sled here and time to fix it. The belt may work better but not without a correct center to center or overdrive in the primary to get back what the lower gear ratio and the clutch bottoming out took away from your gain in a better quality belt. Not to mention, when you lower the gear ratio(make the secondary larger diameter) your changing the effect of the helix and spring on that belt. This changes how the primary will react to these new loads.

To really put this theory to the test, assemble your clutches with no springs, use a warm belt(bends easier) around your clutches, you can tell somewhat close, how your belt will be when the clutches shift out. I say close because under load, the primary will get closer.

can someone measure center to center and see if they can loosen the motor up and how close they can come to the correct distance of 268.5?

Sorry if I seem ranty, I just think many are missing an important piece of this pie. If I am wrong, great, that just means I have learned something.

Someone donate me a viper