Blew Belt, Sheared Primary Bolt Off, 2 XS825 Belts Gone in ~160 miles

[ClutchMaster]

Not near my shop, but here is an additional pic.

Stub Shaft Close Up

• snowcaine
• Feb 19, 2020

I ordered a stub shaft assembly and primary bolts along with some other stuff. Stub shaft assembly is on backorder until 3/31. Primary bolts are on backorder until 3/10. Do all Yamaha dealers pull parts from the same system, or can I call around to different dealers to see if they have faster lead times?

Seems like knowledgeable members are suggesting the taper may be off on the stub shaft, or the stub shaft may have moved inward. I'm thinking the best route is to just replace the entire stub shaft assembly, even if it means I'm done for the season...

Edit: deleted one of the pics. Already posted it earlier in this thread.

There’s nothing wrong with the stub shaft, oiling the taper caused your issues imo. To bend the stub shaft would be virtually impossible, it’s heat treated.
I wouldn’t hesitate to use it as long as you lap the clutch to the taper.
Your shaft probably moved in the bearing. I would press it apart and probably install a new bearing. Upon reassembly use green loctight on the inside and outside of the bearing.
The stock bolt is a 6” long 1/2”-20 bolt, it has a shoulder machined on the hex side but I don’t believe that’s necessary. My STM clutch came with a new grade 8 bolt, no shoulder.
You can find that bolt at fastenal or similar establishment.
If you oil the threads on the bolt before torquing it can be easily over tightened. I use blue loctight and torque to around 100 ft/lbs then back off, re-torque to 50.

 

[ClutchMaster]

Call a Cat dealer to see if they can have the stub shaft sooner....

I think the taper is wrong on the clutch. If your stock clutch didnt do this why would the aftermarket clutch? possible they sent you the wrong clutch?
I dont think there is any way for stub shaft to move far enough inward to cause that kind of damage.

He posted #49 that his offset was 60.8mm within spec when he first installed the Tapp, if the taper was wrong it wouldn’t have even been close. When the first belt blew it moved the shaft more than likely. Oiling a taper then pulling it together with a 1/2 fine thread bolt at 100 ft/lbs could have easily cracked the clutch hub taper imo.

 

[J & J Racing]

I have a stub shaft and a bolt is what I meant to say if you would like to get them now and replace later when the others come in

 

[74Nitro]

Not near my shop, but here is an additional pic.

Stub Shaft Close Up

• snowcaine
• Feb 19, 2020

I ordered a stub shaft assembly and primary bolts along with some other stuff. Stub shaft assembly is on backorder until 3/31. Primary bolts are on backorder until 3/10. Do all Yamaha dealers pull parts from the same system, or can I call around to different dealers to see if they have faster lead times?

Seems like knowledgeable members are suggesting the taper may be off on the stub shaft, or the stub shaft may have moved inward. I'm thinking the best route is to just replace the entire stub shaft assembly, even if it means I'm done for the season...

Edit: deleted one of the pics. Already posted it earlier in this thread.

F**k Yamaha and their backordered parts.
I could have that thing going in under a couple hours.
Pull that stub assembly out, if it has moved at all, then press it back! Get a decent mechanic or any decent welder to get what is left of that bolt out of there. This is the same bolt bolt used in Yamaha sleds for decades. Surely someone has one.
Turn the power down to 250-260, jam the stock clutches back on and RIDE!

 

[J & J Racing]

Are the stock ones that bad?
I have 2600 miles on teams @300 hp and I just changed the original belt so it didn’t eventually break.

 

[DooZ]

Are the stock ones that bad?
I have 2600 miles on teams @300 hp and I just changed the original belt so it didn’t eventually break.

As I'm sure you've been reading, there is a heightened awareness of Teams cracking moveable sheaves

 

[sideshowBob]

Are the stock ones that bad?
I have 2600 miles on teams @300 hp and I just changed the original belt so it didn’t eventually break.

I have over 1500 miles trail riding, drag racing, and towing an ice fishing sleigh on my tuned Winder.
I am running the stock Yamaha clutches with TPI rollers and Dalton tuning components. I also run an 8DN belt and have a Razor belt temp gage.
The hottest I have seen on the belt temp was on a 30 mile non stop, very high speed, run on a groomed rail bed where the belt temp was constant at 170 until I stopped and then the temp momentarily rose to 200 then began to cool...this was extreme belt punishment. Normally my belt temps are 140 - 150f
I also have a Hurricane stub shaft to quiet the rattle the stock clutches have and have had zero issues with it although after 1500 miles the primary is not as quiet as it initially was.
One benefit of the Hurricane shaft is that its a little longer and moves the primary further outboard a few mm.
I have had zero issues with the performance of my sled in all conditions with the OEM clutches.

Works for me!

 

[J & J Racing]

As I'm sure you've been reading, there is a heightened awareness of Teams cracking moveable sheaves

Yes
I always check my stuff
All oems can do this
I run a flat profile weight to Get rid of most of the low end slip in the team
72afp loaded to 92 grams
No heel but a lot of mid and tip weight
Stock primary spring

I like the zero deflection on the team and I am getting good performance out of it
I have run full STM setups too

May revisit that again?

nothing is built as well as it used to be it seems

 

[DooZ]

Yes
I always check my stuff
All oems can do this
I run a flat profile weight to Get rid of most of the low end slip in the team
72afp loaded to 92 grams
No heel but a lot of mid and tip weight
Stock primary spring

I like the zero deflection on the team and I am getting good performance out of it
I have run full STM setups too

May revisit that again?

nothing is built as well as it used to be it seems

I wish STM would make a billet moveable for the Team as they did for the older Cat primaries

 

[snowcaine]

I have a stub shaft and a bolt is what I meant to say if you would like to get them now and replace later when the others come in

PM sent. Big thanks for the offer!

 

[snowcaine]

There’s nothing wrong with the stub shaft, oiling the taper caused your issues imo. To bend the stub shaft would be virtually impossible, it’s heat treated.
I wouldn’t hesitate to use it as long as you lap the clutch to the taper.
Your shaft probably moved in the bearing. I would press it apart and probably install a new bearing. Upon reassembly use green loctight on the inside and outside of the bearing.
The stock bolt is a 6” long 1/2”-20 bolt, it has a shoulder machined on the hex side but I don’t believe that’s necessary. My STM clutch came with a new grade 8 bolt, no shoulder.
You can find that bolt at fastenal or similar establishment.
If you oil the threads on the bolt before torquing it can be easily over tightened. I use blue loctight and torque to around 100 ft/lbs then back off, re-torque to 50.
View attachment 153342

ClutchMaster, as always, thanks for the technical insight. Will be doing this and keeping my current stub shaft as a spare. Working with J&J Racing now to coordinate getting his spare stub shaft and bolt.

 

[snowcaine]

F**k Yamaha and their backordered parts.
I could have that thing going in under a couple hours.
Pull that stub assembly out, if it has moved at all, then press it back! Get a decent mechanic or any decent welder to get what is left of that bolt out of there. This is the same bolt bolt used in Yamaha sleds for decades. Surely someone has one.
Turn the power down to 250-260, jam the stock clutches back on and RIDE!

Careful 74Nitro, we're only about 6 hours apart. I'll show up with sled in tow!

 

[jonlafon1]

I have over 1500 miles trail riding, drag racing, and towing an ice fishing sleigh on my tuned Winder.
I am running the stock Yamaha clutches with TPI rollers and Dalton tuning components. I also run an 8DN belt and have a Razor belt temp gage.
The hottest I have seen on the belt temp was on a 30 mile non stop, very high speed, run on a groomed rail bed where the belt temp was constant at 170 until I stopped and then the temp momentarily rose to 200 then began to cool...this was extreme belt punishment. Normally my belt temps are 140 - 150f
I also have a Hurricane stub shaft to quiet the rattle the stock clutches have and have had zero issues with it although after 1500 miles the primary is not as quiet as it initially was.
One benefit of the Hurricane shaft is that its a little longer and moves the primary further outboard a few mm.
I have had zero issues with the performance of my sled in all conditions with the OEM clutches.

Works for me!

Good to here another member is experiencing what I have also. 3k on last xs belt. It’s now my spare. 9400 miles with stock clutches and barely any kind of roller wear or issues. I blew up two carbon belts in the first 5 hundred miles. None since. Switched to more helix angle and also did the hurricane offset tool thing. 170 is very respectable for a long 30 mile pound. I run big wide open stuff in the UP and I usually run in the 140’s. But I have been into the mid 150 ‘s on long hard pulls. Also when temps are running a bit higher outside I have noticed I run slightly warmer also. But I have not seen more then 155 with setup. I have run this set up with 3 different belts and minor adjustments on spring tension in secondary. I also played around with different secondary springs. I have run setup almost 9 k. IMO most are running slightly to much weight and or to much secondary tension. I run fairly heavy secondary but I also use a higher helix angle. I’m not a huge big end guy but I can run up into the mid to upper 120’s on speedo. Conditions dependent obviously. 270 tune.

 

[Turboflash]

Running Northern WI fire roads for lots of miles in good snow, at 80-110 MPH, I see max 160's on my XS belt w 320 PEFI tune (pump gas) on long pulls. No blown belts. Have run same XS belt for now about 1100 miles on 320 tune. Lots of long studs. I like the XS belt. Gonna change belt soon just because.

 

[NYTurbo]

Probably cause not many running that combo.

He posted #49 that his offset was 60.8mm within spec when he first installed the Tapp, if the taper was wrong it wouldn’t have even been close. When the first belt blew it moved the shaft more than likely. Oiling a taper then pulling it together with a 1/2 fine thread bolt at 100 ft/lbs could have easily cracked the clutch hub taper imo.

60.8 measured from back of primary to front of secondary on his setup may be way out of whack.