Secondary Clutch/8DN made easy

[TD Max]

I think what he's saying is that the drawing is elementary belt deflection setup or belt deflection for dummies. It is only a quick visual part of the proper and thorough way to set it up and assumes that the belt length and c to c are perfect. Good enough to get it out the door and down the trail and to satisfy 99% of the people, but a true racer or HP junkie seldom stops there.


I seem to recall Kerrdog setting his up like this (bolts out and visibly correct) but having more actual deflection than he wanted.

 

[Srxspec]

So you are saying this document is wrong?

View attachment 99781

Yes, I will tell you, due to manufacturing tolerances, that that is not the correct way to set belt deflection!

 

[stingray719]

Yes, I will tell you, due to manufacturing tolerances, that that is not the correct way to set belt deflection!

Wow, just wow.

 

[Studroes144]

Someone correct me if I'm wrong, but isn't "belt deflection" what Allen is describing about using a straight edge to measure the slack in the belt? Also, the 3 bolts on the back of the secondary, isn't the sole purpose of those to adjust the ride height of the belt in the secondary? Sure if you're deflection is close and you need to add shims to the secondary to get proper belt height it can kill 2 birds with 1 stone, but even if u have a belt that has 2 inches of sag in the deflection it can still be set right in the secondary using the shims to get proper ride height..but that doesn't mean the clutches are setup properly. I haven't seen a viper with an 8dn belt so I have no idea what the deflection looks like, but certainly for as simple of a task as it is to check, I'm sure a few guys could easily check theirs and report back with what the deflection measurement is. On a side note I was at My dealers today and talking with one of the mechanics he said that at the yamaha school they discussed the belt issues. He said that indeed the 8dn has a different compound making it a stronger belt. He also said that yamaha made an 8dn length belt but used the 8jp compound and tested it and it did not hold up, but they're still choosing to use the 8jp belt on the vipers because of the center to center clutch measurements. Just thought it would be some neat info for u folks. Now you can atleast know that yamaha is well aware of what's going on and is doing I'm sure more testing than any of us have done in regards to belts and clutches. They're continuing to use the 8jp for reason, whatever it is, we can only guess..but yamaha is well aware of what's going on

 

[sxr70001]

I think what Allen is saying is proper deflection is measured by how much slack is in the belt. Not where it rides in the secondary, even though most of us are aware of both methods. Whatever floats your boat, we don't need to be so sensitive here.

 

[stingray719]

I think what Allen is saying is proper deflection is measured by how much slack is in the belt. Not where it rides in the secondary, even though most of us are aware of both methods. Whatever floats your boat, we don't need to be so sensitive here.

Agreed, if your parts are good and in spec either way gets the same result. The tiff was when someone said one was not correct, which should have been phrased as one is more concise.

 

[cannondale27]

On my SRX I used to set deflection just so the track rolled on the stand on its own. Phazer does it also. The Viper doesn't roll easily. Working on that but I think those stupid bumps on track are part of problem.

 

[arctic viper]

The tiff was when someone said one was not correct.........NOT WRONG., big difference.

 

[cannondale27]

The main point of this thread is to explain where the shims are! That's originally why it was started and stickied. I thought. Yes there are many out there who don't know. More than one has thought the alignment shims are what you change. Reason this is new even to old Yamaha users is belt deflection didn't change much with stock clutching till 3000 mi or more. Now we notice it at 500 with stock sleds. We used to just change the belt rather than mess with the adjustment because we felt it had served well and make it a spare. If perfect belt deflection is needed for either clutch kit to work maybe two separate threads should be made so a helpful thread doesn't get clustered with opinions on a thing that has never been a issue.

 

[NOS-PRO]

Someone correct me if I'm wrong, but isn't "belt deflection" what Allen is describing about using a straight edge to measure the slack in the belt? Also, the 3 bolts on the back of the secondary, isn't the sole purpose of those to adjust the ride height of the belt in the secondary? Sure if you're deflection is close and you need to add shims to the secondary to get proper belt height it can kill 2 birds with 1 stone, but even if u have a belt that has 2 inches of sag in the deflection it can still be set right in the secondary using the shims to get proper ride height..but that doesn't mean the clutches are setup properly. I haven't seen a viper with an 8dn belt so I have no idea what the deflection looks like, but certainly for as simple of a task as it is to check, I'm sure a few guys could easily check theirs and report back with what the deflection measurement is. On a side note I was at My dealers today and talking with one of the mechanics he said that at the yamaha school they discussed the belt issues. He said that indeed the 8dn has a different compound making it a stronger belt. He also said that yamaha made an 8dn length belt but used the 8jp compound and tested it and it did not hold up, but they're still choosing to use the 8jp belt on the vipers because of the center to center clutch measurements. Just thought it would be some neat info for u folks. Now you can atleast know that yamaha is well aware of what's going on and is doing I'm sure more testing than any of us have done in regards to belts and clutches. They're continuing to use the 8jp for reason, whatever it is, we can only guess..but yamaha is well aware of what's going on

Thank you for this info Barry, the compound is different between belts.

 

[titanrcr]

Very surprising to me that Yamaha would ship out these sleds with clutch calibration that would have the secondary spring go into coil bind while the primary is still shifting. I'm sure the new Viper belt would hold up just fine without this issue. Once the secondary stops movement during the upshift the primary is continuing to shift causing all the varying RPM issues, blown belts, etc. A problem I see with running the 8DN belt is that the longer belt wont allow the sled to get into the correct or intended final drive ratio. The 8DN is just a bandaid at this point. Yamaha better step it up and get the calibration staightened out.

 

[larrypolaris]

On my SRX I used to set deflection just so the track rolled on the stand on its own. Phazer does it also. The Viper doesn't roll easily. Working on that but I think those stupid bumps on track are part of problem.

Same here. I my drag and trail sleds. I set the belt(warm belt) where the track rolls on the jack stand. But not too tight then you get belt squeal.
Key is you need to do this on a belt at operating temps. A cold belt and you get a different result.

 

[titanrcr]

Same here. I my drag and trail sleds. I set the belt(warm belt) where the track rolls on the jack stand. But not too tight then you get belt squeal.
Key is you need to do this on a belt at operating temps. A cold belt and you get a different result.

I've been doing the same for years, really the best way to set belt deflection. I also run external belt deflection adjusters on all my sleds. Been using them for about 15 years.

 

[nherbst454]

I've been doing the same for years, really the best way to set belt deflection. I also run external belt deflection adjusters on all my sleds. Been using them for about 15 years.

Are you using the Goodwin Performance adjuster? It's the only one I've found that seems to be for the Yamaha clutches. I just called and he said he would have to look into whether or not they work with the new Vipers as he wasn't sure if they've had to add washers to the jackshaft or not.

 

[titanrcr]

Are you using the Goodwin Performance adjuster? It's the only one I've found that seems to be for the Yamaha clutches. I just called and he said he would have to look into whether or not they work with the new Vipers as he wasn't sure if they've had to add washers to the jackshaft or not.

I have purchased them from Bender and Hauck in the past. I think they both still have them and yes they should work just fine with a viper, same clutch for years.