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

[NYTurbo]

Probably cause not many running that combo.

 

[sideshowBob]

The old Cat 1100 Suzi Turbo had a 35mm taper and the our Yamahas have always used a 30mm taper. If the clutch has the 35mm taper it would never seat on the stub shaft and would just move in on taper until it bottomed out on something...kind of looks like what happened here.

 

[race24x]

I run a Razorback
it is nice to compare your changes

I have never heard of anyone running a finish as low as you. To each their own though.
Island
I would run a 46 36 or 46 38

Can someone do a quick explaination of the angles and finish and better or worse. What is trail and what is ice racing loose snow etc.

 

[snowcaine]

NYTurbo, I asked this question about 2 months ago on another post about the TAPP/PRO4 combo WITHOUT any response ( or measurement ) other than my own. Maybe no one that bought this combo has the technical tools ( 2 straight edges and a caliper ) to do this difficult job. Everyone saw the inconsistent measurements with the stock setup to try and get the offset right, this combo shouldn't be any different.

Islandracing, sorry I never saw your question. I measured 60.8 mm offset with the TAPP/Pro 4 combo when I first installed it. I have the service manual and followed the instructions for measuring it, and I also reviewed this site for what others found worked best (albeit on stock clutch setups). After I blew the first belt, I (foolishly) didn't re-measure the offset. When I torqued the initial 108 ft-lbs, it felt like it was taking quite a while to seat and reach torque. I of course backed it off completely and re-torqued to 45 ft-lbs (yes I know spec is 43 ft-lbs).

I also added a thin coat of oil to the stub shaft before reinstalling the primary after I blew the first belt. After discussions with others, I realize this was probably a significant mistake and could have contributed to the failure. I'm sharing so others don't make the same mistake.

 

[snowcaine]

Oh boy,
That clutch looking like its obviously not seating properly on the shaft and hitting the housing. The question is why? They can't all be like that or we'd be seeing many more with the same type of issues.

And that is why the bolt broke too, the clutch was spinning on the shaft and just kept tightening itself up till it broke and launched the clutch into the belly pan spinning till it stopped.

That clutch is no longer usable, and did it also damage the secondary beyond use?

Mr. Knapp, the secondary appears undamaged, but I haven't pulled it yet. It only has some black marks on the sheaves. I'm shipping the TAPP to Dave at Powder Lites today so he can refurbish it and hopefully give me some insight into why things went south as they did.

 

[ClutchMaster]

Islandracing, sorry I never saw your question. I measured 60.8 mm offset with the TAPP/Pro 4 combo when I first installed it. I have the service manual and followed the instructions for measuring it, and I also reviewed this site for what others found worked best (albeit on stock clutch setups). After I blew the first belt, I (foolishly) didn't re-measure the offset. When I torqued the initial 108 ft-lbs, it felt like it was taking quite a while to seat and reach torque. I of course backed it off completely and re-torqued to 45 ft-lbs (yes I know spec is 43 ft-lbs).

I also added a thin coat of oil to the stub shaft before reinstalling the primary after I blew the first belt. After discussions with others, I realize this was probably a significant mistake and could have contributed to the failure. I'm sharing so others don't make the same mistake.

The oil was a big mistake, if the shaft was dry it would have galling on the taper and likely would not have popped off. When the belt blew, the stub moved inward, clutch hit the engine and popped the taper, clutch spun and broke the bolt, clutch flew off

 

[snowcaine]

Didn’t look like the clutch spun on the stub shaft, is there any galling on the stub? It looks like that it was very hot. Belt blew and clutches slammed together releasing the taper? Did you torque it to 100 ft/lbs release, then retorque to 48 ft/lbs?

ClutchMaster, I definitely torqued it to spec. No question. I carry a 1/2" torque wrench in the trailer. Torqued it to 108 ft-lbs, backed off, then 45 ft-lbs (I know 43 ft-lbs is true spect). I'm sure I screwed something up, but it definitely wasn't failing to torque it correctly. I mentioned in another post on this thread that I put a light film of oil on the stub shaft, and while I was torquing the primary, it seemed to take quite a while to hit 108 ft-lbs. I now believe putting a light film of oil on the stub shaft was error. What do you think?

Edit: thanks I see you posted before I did.

 

[74Nitro]

The oil was a big mistake, if the shaft was dry it would have galling on the taper and likely would not have popped off. When the belt blew, the stub moved inward, clutch hit the engine and popped the taper, clutch spun and broke the bolt, clutch flew off

Yes, do not use oil or any lubricant.

 

[ClutchMaster]

Oil on the taper could have cracked the clutch taper also.

 

[ClutchMaster]

The old Cat 1100 Suzi Turbo had a 35mm taper and the our Yamahas have always used a 30mm taper. If the clutch has the 35mm taper it would never seat on the stub shaft and would just move in on taper until it bottomed out on something...kind of looks like what happened here.

That’s a great analogy but I’m thinking he cracked the taper with oil, it pulled onto the taper so far it hit the shoulder and stopped?

 

[sledding rocks]

I just installed my Tapp at 55lb torque as recommended by arctic specs and speaking with tomcat , I checked all my clearances behind clutch , looks good , I'm wondering why Yamaha specs r different when torquing the clutch ? seems like its over kill .

 

[STAIN]

any better pictures of the taper on the clutch? can you measure the diameter? compare that taper to the stock unit?
it almost seems like the application was wrong, as Sideshow said.......

 

[snowcaine]

any better pictures of the taper on the clutch? can you measure the diameter? compare that taper to the stock unit?
it almost seems like the application was wrong, as Sideshow said.......

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.

 

[STAIN]

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

Seems like knowledgeable members are suggesting the taper may be off on the stub shaft

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.

 

[J & J Racing]

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.

I have both items
Just replace them when yours comes