Stub Shaft

[cannondale27]

Ok couple of things to note:

1. As I mentioned above, the only two stub shaft assemblies I've ever seen are the one I removed from my machine and the new one I unboxed from Yamaha. Both had a gap as shown in post #20 above. I intend to buy another assembly to toss on the shelf. When I get it, I'm very interested to see what kind of gap it has. If knowledgeable people like Cannondale say it should sit flush with no gap, then I'd trust that when disassembling/reassembling!

2. What I mentioned in post #28 regarding a concave slope inward from the outside portion of the bearing to the center of the bearing is shown with the following pictures. On my old stub shaft assembly, there is a 1.17 mm inward slope from the outside of the bearing seal to the inner portion of the bearing seal, and it is visually obvious in person. On my new stub shaft assembly, that surface is visually flat (I didn't measure it before I installed it, but it was visually flat).

Surface To Outer Part Of Seal

• snowcaine
• Mar 30, 2020

Surface To Inner Part Of Seal

• snowcaine
• Mar 30, 2020

3. For what it's worth, on my old stub shaft assembly, there is a 0.011" gap between the stub shaft collar and the bearing seating surface. I didn't measure the new one, but when I get my shelf unit, I'll measure that one to compare.

Distance From Stub Shaft Collar To Bearing Seating Surface

• snowcaine
• Mar 30, 2020

Are you sure you don't have the two pics mixed up? The second pic sure looks like bearing is seated. First one it does not. If you have a feeler guage take note of how far it goes in. Each corner of the bearing and the housing has either a radius or chamfer so a picture really can't be trusted to show whether it's seated. I think you made it the right call replacing it since the seal was pushed in surely. Probably crushed the cage and could have failed.

 

[snowcaine]

Are you sure you don't have the two pics mixed up? The second pic sure looks like bearing is seated. First one it does not. If you have a feeler guage take note of how far it goes in. Each corner of the bearing and the housing has either a radius or chamfer so a picture really can't be trusted to show whether it's seated. I think you made it the right call replacing it since the seal was pushed in surely. Probably crushed the cage and could have failed.

Cannondale, pics are definitely not mixed up. You can tell by the pics below (specifically, the wear marks/ring on the shaft) that the pic in post #20 of the old stub shaft is definitely the old stub shaft. The gap distance on the old stub shaft is 0.032". Didn't measure the new one because I didn't know this was a thing. I have my dad's '20 in my trailer. REAL tempted to pop his primary off and see what it looks/measures like. He hasn't blown a belt and only has ~150 miles!

Old And New Stub Shaft Side-by-Side Comparison

• snowcaine
• Mar 18, 2020

Stub Shaft Close Up

• snowcaine
• Feb 19, 2020

 

[1nc 2000]

Will the stub shaft bottom out on the crank inducing side load on the crank?
I have not had mine out, it only is in .004" compared to a new stub shaft assy.

 

[sideshowBob]

In your pics you can see the bearing retention ring is definitely lower on the new one compared to the old one which means the bearing is seated either deeper on the stub shaft and/or deeper into the retention ring so your primary clutch will now sit further out away from the engine.

 

[Turboflash]

I would like to mention again, I use slime instead of grease. its quick and doesn't require thread tape. a blast of air cleans it up after. also, another reason for people to quit pulling the clutch all the time. the one on my nytro has never been off. 25127 miles. used a set of weights, maybe 3 or 4 belts and that's it. I do plan to do stub bearings this year, just figure they are on borrowed time at this point.

What is the "slime" you refer to? Is it something you can buy or is it your own concoction? Grease makes a mess for sure.

 

[Turboflash]

Could someone please post size of that bearing? Is should be on side of bearing or seal. I want to get a better one than what comes in it. Thanks.

 

[Hammer70]

Could someone please post size of that bearing? Is should be on side of bearing or seal. I want to get a better one than what comes in it. Thanks.

If my memory serves me right it’s koyo Japan bearing and is a good bearing Imo

 

[sideshowBob]

Koyo Bearing quality seems fine
Pictures worth 1000 words

 

[Turboflash]

Thanks much. Koyo is good. It's Japan bearing not China.

 

[sideshowBob]

Thanks much. Koyo is good. It's Japan bearing not China.

Yes it says right on it made in Japan

 

[Turboflash]

Yeah, after I thought about it again, I shudda known cuz this is Yamaha DNA part NOT Cat/Textron DNA. No wonder it's a good quality part.

 

[4strokes]

any parts store anywhere. or tractor supply or walmart...tire sealant

 

[snowcaine]

In your pics you can see the bearing retention ring is definitely lower on the new one compared to the old one which means the bearing is seated either deeper on the stub shaft and/or deeper into the retention ring so your primary clutch will now sit further out away from the engine.

Interesting. I'm at ~60.5mm offset right now with the new stub shaft assembly (TAPP/stock secondary). It seems if my bearing was seated against the housing my offset would drop by that distance, which seems to be 1-1.5mm. That would take me down to 59-59.5mm offset, which is where I should be! This is BS I expect when I order a stub shaft assembly it would come from Yam drop-in bolt-on ready! Guess not. I just ordered another one though. Will update with pics/measurements when it comes in.

 

[KnappAttack]

Why would you order up another one? Just push it apart, clean up, put green loctite on it an push it together. They need loctite as to not move anyway.

Factory assembly does not come with loctite and one belt blow and it slides in anyway.

 

[sideshowBob]

Hey would you order up another one? Just push it apart, clean up, put green loctite on it an push it together. They need loctite as to not move anyway.

Factory assembly does not come with loctite and one belt blow and it slides in anyway.

I agree...set the new one up properly with green Loctite and then you know its done right