Secondary Clutch/8DN made easy

[TD Max]

Lots of "I heard" going around I am afraid. The 8DN and for that matter most belts are built to some pretty loose standards and you may find some rather large variance. As I said before one of our Viper needed extra washers and one did not. I would like anybody that ran out of adjustment with a healthy belt within accepted belt tolerance to please post though as I would really like to know if that can become an issue. I tried all 6 of my 8DN for fit so I would know what I could use and although they varied greatly none of them could not be set correctly. But, as I said above lets see if that might be the case and if so was it one clutch built out of tolerance or will most do it.

Lots of "I did" here. How many people have stated that they just took out the bolts because at the shim height necessary they were no longer doing anything?

The reason for doing a secondary "trim" is so that you have the ABILITY to make up for the variances of belt thickness, c to c distance etc.

I'm not saying your 8DN mod is not a good one. I'm saying take it all the way for a touchdown rather than fumbling in the red zone. I know it's not cheap, but it's right...

But then again what's cheaper than eliminating coil bind in the secondary spring and using the belt that came with the sled? I'll be interested to see how this plays out.

 

[wavemaster]

40-46 helix or 46-40?

Can you tell by the markings?

 

[Studroes144]

Yes that would be 46/40. Initial part of the helix is more aggressive then levels out as the clutches shift out more. Fast shift out bottom to mid range for that grunt feel

 

[cacsrx1]

Im pretty sure he wouldn't sell you a 40/46.....

 

[cacsrx1]

Get out your angle finder......there used to be a LOT of differences in helix angles and at what point in the shift curve the angle actually changed. My point being one vendors 46/40 could be a lot different than another vendors 46/40.

 

[wavemaster]

Yes that would be 46/40. Initial part of the helix is more aggressive then levels out as the clutches shift out more. Fast shift out bottom to mid range for that grunt feel

Sweet.

My plan it to do a 10-20 mile hot supper beat in, then dump the oil and get on the mods, then test. So it will be bone stock for the first ride then she will be changing. Hopefully I can get the break-in ride in before the annual Christmas trip. It is close every year with the trails "opening" on Dec. 15th. Sometimes we do the shakeout in a field just to see if we forgot anything prior to the trip up north. We do bring the portable lift and propane heater for the trailer so it isn't too bad working on them up north but nothing beats the shop.

 

[stingray719]

Sweet.

My plan it to do a 10-20 mile hot supper beat in, then dump the oil and get on the mods, then test. So it will be bone stock for the first ride then she will be changing. Hopefully I can get the break-in ride in before the annual Christmas trip. It is close every year with the trails "opening" on Dec. 15th. Sometimes we do the shakeout in a field just to see if we forgot anything prior to the trip up north. We do bring the portable lift and propane heater for the trailer so it isn't too bad working on them up north but nothing beats the shop.

Viper changes a lot during break in, at least ours did. 0 to 50mph pretty sad, 50 to 200 miles a lot more power, at about 400 miles it really started to wake up. My point is it takes a bit for this sled to wake up.

 

[Studroes144]

Break it in hard! Lol better not go too into depth on that cuz everyone has different views on it..for mine I did a few heat cycles, then put maybe 5 miles just toolin around a bit then it was to the open field and I was holdin it wide open! She's ran awesome every day. Doing mods step by step is beat as you get to see what mods do what, but ultimately it's a pain in the butt since with every mod you do you're prolly going to have to adjust clutching to account for the added power, if you don't then chances are whatever change u made wasn't worth it. I actually enjoy more going from a stock machine right to the finished product in 1 shot, the initial "oh my goodness" factor when you get on it for the first time makes it all more worth it.

 

[Studroes144]

Viper changes a lot during break in, at least ours did. 0 to 50mph pretty sad, 50 to 200 miles a lot more power, at about 400 miles it really started to wake up. My point is it takes a bit for this sled to wake up.

This is very true. I noticed mine start to come alive after 50 or so miles, and again at around 400 or so miles I had to add weight to the primary to keep it off the rev limiter.

 

[shagman]

View attachment 99771

Can you tell by the markings?

That is a 46/40 Dalton helix, the same one i run. I ran it with the sled stock and now i'm running it with the turbo.

 

[shagman]

This is very true. I noticed mine start to come alive after 50 or so miles, and again at around 400 or so miles I had to add weight to the primary to keep it off the rev limiter.

I had to keep adding weight all the way to 3000 miles and it was hitting the limiter again at 3300 mile when i parked it in the spring.

 

[NOS-PRO]

But then again what's cheaper than eliminating coil bind in the secondary spring and using the belt that came with the sled? I'll be interested to see how this plays out.

TD - The spring will bind no matter what belt you use. The problem is the White and Pink (Stock) spring diameter are too thick. When compressed there is not enough room in the secondary. Only way to eliminate the problem is machine the helix or secondary, or cheap way is put washers under the helix.

 

[Srxspec]

A lot of confusion I am seeing in private messages so I thought I would try to clarify here. Don't get me wrong I don't mind private messages but more people get the info this way.

1. Secondary clutch shims.
a. Shims required for 8DN belt. This is different from other shims like helix shims or center shims.

On the back of the secondary clutch are 3 small bolts. (first pic below one bolt removed) They push in and hold the secondary apart to adjust belt deflection in the closed or stopped position (that is in simple terms the belt slack or tightness). Yes I know why so archaic of a method for belt deflection. Anyways those of you that rode Yamaha very long know these bolts get beat up and shorten and you have to replace them when the deflection changes usually noticed by belt squealing and sled trying to creep at idle. So new bolts if the belt rides too high over the sheave, and add washers if the belt rides too low.

View attachment 99753

So when you install an 8DN belt you need to check deflection. When the ribs just stick above the sheave you are correct. This in my opinion is not an exact science so a little leeway is ok here as long as it is close (disclaimer: close is relative term though) The pic below is close to what I consider proper belt deflection, maybe a hair high. (not going to adjust it a hair for this pic...lol)

View attachment 99755

So when you add an 8DN belt you may need to add another washer to this bolt to space apart the sheaves for proper belt deflection and getting the 8DN to the deflection shown above. Here is a bolt and everyday garden variety of washer added for most 8DN installs (NOTE: some 8DN go on and do not need any adjustment) Obviously same size washer set on all 3 bolts. You can also have machining done instead of washer but it is not necessary.

View attachment 99756

You still have secondary off, wrap belt around sheave and check deflection. Reinstall when correct.

NOTE!!!!!!!!!!! Belts have a lot of difference even when new, check deflection when changing belts even the same size belts.








2. Helix shims
a. Helix shims are for reducing the secondary coil spring bind. The best way is to have your secondary or helix machined to get rid of coil bind but if you choose instead to shim the helix (this is usually used to test whether coil bind is affecting you to decide if you wish to machine your parts) this is how. NOTE: this is not the recommended long term solution to coil bind.

Remove Helix and put 3 washers all the same size on the studs as shown below and bolt helix back on. Test and decide if you wish to machine your secondary or helix and THEN REMOVE WASHERS as this is not the recommended way and put here only to remove confusion about the different secondary shims being discussed.

View attachment 99757

Using the method of visually checking how far out of the secondary your belt rides, is not correct for setting belt deflection, due to the tolerances in belt length and center to center length (probably not much tolerance in center to center distance on most of the 4 stroke Yamaha motor sleds).

The truly proper way to do it is by using a straight edge/flat edge and checking deflection. If you laid a flat edge on top of the belt from the center of your secondary to the center of your primary and pushed down on the belt roughly in the middle you should have no more than 1-1/4" of movement when pushing down on it. Your sled will have the best possible belt deflection using this method (no matter if the belt is a little longer or shorter).

The only springs you will experience coil bind with is the Yamaha pink (stock) or Yamaha white secondary spring. It has to do with the # of coils and wire diameter of the spring. You can shim the helix up, but this may cause your shift RPM to change as you are changing the spacing of the helix buttons on the helix ramp. Ulmer Racing has a spring that will not coil bind available for those that would like to upgrade (also comes in our clutch kits).

 

[stingray719]

Using the method of visually checking how far out of the secondary your belt rides, is not correct for setting belt deflection, due to the tolerances in belt length and center to center length (probably not much tolerance in center to center distance on most of the 4 stroke Yamaha motor sleds).

The truly proper way to do it is by using a straight edge/flat edge and checking deflection. If you laid a flat edge on top of the belt from the center of your secondary to the center of your primary and pushed down on the belt roughly in the middle you should have no more than 1-1/4" of movement when pushing down on it. Your sled will have the best possible belt deflection using this method (no matter if the belt is a little longer or shorter).

The only springs you will experience coil bind with is the Yamaha pink (stock) or Yamaha white secondary spring. It has to do with the # of coils and wire diameter of the spring. You can shim the helix up, but this may cause your shift RPM to change as you are changing the spacing of the helix buttons on the helix ramp. Ulmer Racing has a spring that will not coil bind available for those that would like to upgrade (also comes in our clutch kits).

Used to have a guy in the shop way back then that would spout numbers for "correct" way to do things. Then we would have him measure ours and it was the same....lol... Now I didn't say you were wrong, you just said another way to achieve the same thing I said and added I was not correct. Walk over to any Viper you have in the shop with an 8DN riding in the sheave as per my pic and measure your way and see if it has no more movement than 1-1/4" movement. You made a statement that said I was not correct lets see, I will trust your word on the measurement above.

 

[stingray719]

Using the method of visually checking how far out of the secondary your belt rides, is not correct for setting belt deflection, due to the tolerances in belt length and center to center length (probably not much tolerance in center to center distance on most of the 4 stroke Yamaha motor sleds).

The truly proper way to do it is by using a straight edge/flat edge and checking deflection. If you laid a flat edge on top of the belt from the center of your secondary to the center of your primary and pushed down on the belt roughly in the middle you should have no more than 1-1/4" of movement when pushing down on it. Your sled will have the best possible belt deflection using this method (no matter if the belt is a little longer or shorter).

The only springs you will experience coil bind with is the Yamaha pink (stock) or Yamaha white secondary spring. It has to do with the # of coils and wire diameter of the spring. You can shim the helix up, but this may cause your shift RPM to change as you are changing the spacing of the helix buttons on the helix ramp. Ulmer Racing has a spring that will not coil bind available for those that would like to upgrade (also comes in our clutch kits).

So you are saying this document is wrong?