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Let's talk primary clutch rollers

Fleecer

Fleecer

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2019 SRX
Stock 14.5mm rollers in my primary are finished after 2k miles. Have a set of 16 mm sitting in toolbox. Thinking bigger rollers may be more durable but don't want to sacrifice performance.

Ive heard mixed opinions....Some say bigger rollers slow shift and apply less belt grabbing force while others say roller size only raises rpm engagement.

For 2019 Yamaha went from 14.5 to 14.8. What are disadvantages of running big rollers?
 

less shift force and less belt grabbing down low. You could compensate by adding shims behind the spider. I haven't had the spider off the new Yamaha clutch yet but I know STM has shims for them. Not sure if they are anything special or not. Also will it need re-balanced if re-shimmed, or are the Yamaha sheaves balanced individually where it wont mater???

2019 has the same 14.5 mm rollers also.
 
KnappAttack said:
less shift force and less belt grabbing down low. You could compensate by adding shims behind the spider. I haven't had the spider off the new Yamaha clutch yet but I know STM has shims for them. Not sure if they are anything special or not. Also will it need re-balanced if re-shimmed, or are the Yamaha sheaves balanced individually where it wont mater???

2019 has the same 14.5 mm rollers also.
Click to expand...

Adding shims to increase initial primary spring force?
 
There is no advantage or disadvantage to running a different size roller. The primary rollers are a tuning component like anything else in the clutch system. In general a smaller roller will act like you have added mass to the primary weights but not exactly....
 
Unfortunately bigger roller are NOT more durable! Bushing is still slipping....:-/
Bigger roller will make the flyweight curvature act more flat and retard shift. You can compensate whit more cam angle or so
 
Fleecer said:
Stock 14.5mm rollers in my primary are finished after 2k miles. Have a set of 16 mm sitting in toolbox. Thinking bigger rollers may be more durable but don't want to sacrifice performance.

Ive heard mixed opinions....Some say bigger rollers slow shift and apply less belt grabbing force while others say roller size only raises rpm engagement.

For 2019 Yamaha went from 14.5 to 14.8. What are disadvantages of running big rollers?
Click to expand...

What is wrong with the rollers in 2k miles? They should be fine with that mileage.
 
Fleecer said:
Adding shims to increase initial primary spring force?
Click to expand...

No, not for the spring, to space the spider further from the belt and stationary sheave, it will do the same thing as changing roller size.

What the rollers do is effect the relationship on weight tuck to belt. I.E. Smaller roller is exactly like adding spider shim. Larger roller is like subtracting spider shim. To change shim you need to unscrew the spider off the clutch post and need grunt tools. More spider shim un-tucks the weight.
 
KnappAttack said:
No, not for the spring, to space the spider further from the belt and stationary sheave, it will do the same thing as changing roller size.

What the rollers do is effect the relationship on weight tuck to belt. I.E. Smaller roller is exactly like adding spider shim. Larger roller is like subtracting spider shim. To change shim you need to unscrew the spider off the clutch post and need grunt tools. More spider shim un-tucks the weight.
Click to expand...

I see, I'll try them with more helix and see what happens.
 
Maybe the fact that roller pins are not locked in place by set screw like on the Apex clutch contributes to the wear and bushing movement, it definitely adds to the clutch noise, ( try throwing a o-ring on one end see how much it quiets down) can't get em to stay though.
 
Yamaha needs a four or six arm clutch to get the roller bushing abuse under control.
 
Can't remember for sure but isn't this is the same clutch the Yamaha designed for the Vmax and SRX of the 90s. Only 140-145 hp at best and now we are putting 280-300 hp through them. Time for a different clutch for sure.
 
My stock primary rollers were hammered out quickly after installing the Hurricane Jukebox. I was way off initially on clutching(TP Orange and reverse angle helix) like many of us were early on which sure didnt help the rollers.

I installed the TP rollers, tad larger OD(14.8mm) due to thicker bushings....ran them all winter and look ok still. Will see how long they hold up.

Seems we need to find a decent primary clutch altogether. the TEAM can be the most cost effective primary to go to as its far less then a TAPP or others. Also allows for wide belts. Just not certain they hold up over time/miles? I think they are doing better then ours though.

Dan

Rollers-tn.jpg


Screen Shot 2018-11-28 at 3.59.38 PM.png
 
ROCKERDAN said:
My stock primary rollers were hammered out quickly after installing the Hurricane Jukebox. I was way off initially on clutching(TP Orange and reverse angle helix) like many of us were early on which sure didnt help the rollers.

I installed the TP rollers, tad larger OD(14.8mm) due to thicker bushings....ran them all winter and look ok still. Will see how long they hold up.

Seems we need to find a decent primary clutch altogether. the TEAM can be the most cost effective primary to go to as its far less then a TAPP or others. Also allows for wide belts. Just not certain they hold up over time/miles? I think they are doing better then ours though.

Dan

Rollers-tn.jpg


View attachment 143328
Click to expand...


I wore a set of these out last year as well with my big tune. Better than stock but still can't take the heavy weights.
 
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