Some engineering thoughts on the lower QD pulley bolt

[skibreeze]

It would be interesting to see if other sleds have the same issue or not as respect to the shaft being shorter than the pulley face.

 

[geo]

Very interesting thread!

Brew, I can see a loss of shear strength perpendicular to the bolt with a gap there but does that also lessen shear strength in line with the bolt? 80% loss would be a real eye-opener.
If that heavy wave washer is a little cocked it would possibly add quite a bit of perpendicular force to the head and a the heavy low amplitude vibration (like a tight track running over the drive sprockets) might just be enough force to shear any grade of 10mm bolt.
It still has to (IMO) be something simple-unique that is different with DB's sled or we'd be all shearing bolts whatever grade they are stock.

Do you feel any excessive vibration in the running boards Danbot?

Good observation Hawkster! Is that an optical illusion because of shadows? I'd like to see the same pic with a bunch of pressure on the slack side (like a tensioner or running condition). Could we have a tooth timing issue here?
The pic makes me think these belts are a lot tougher than i thought cause Danbot has a few miles.

 

[Danbot]

"If you do try the flat washer make sure it is the same OD as the original. I noticed on my pulleys that the steel insert (splines) is slightly recessed from the aluminum pulley. If you use a bigger OD washer you would be torquing on the aluminum (not good)."

From Geo's post, Just wondering if you missed it or if your not concerned about it?

I looked closely at it and my steel insert is flush with the rest of the pulley face.

 

[Danbot]

Sorry , didn't mean to change the subject but this is a really good picture . The timing of the gears and belt are off a bit , the teeth on the left are against the rotation and on the right with the rotation to the point that it is bending the lugs in to different directions and the one on the right that is engaging is pushing on the lug.

It's an illusion in this case... the belt is sitting 1/8" back from the outer edge of the pulley. My cogs fit nicely in the pulley grooves.

 

[Danbot]

Very interesting thread!

Brew, I can see a loss of shear strength perpendicular to the bolt with a gap there but does that also lessen shear strength in line with the bolt? 80% loss would be a real eye-opener.
If that heavy wave washer is a little cocked it would possibly add quite a bit of perpendicular force to the head and a the heavy low amplitude vibration (like a tight track running over the drive sprockets) might just be enough force to shear any grade of 10mm bolt.
It still has to (IMO) be something simple-unique that is different with DB's sled or we'd be all shearing bolts whatever grade they are stock.

Do you feel any excessive vibration in the running boards Danbot?

Good observation Hawkster! Is that an optical illusion because of shadows? I'd like to see the same pic with a bunch of pressure on the slack side (like a tensioner or running condition). Could we have a tooth timing issue here?
The pic makes me think these belts are a lot tougher than i thought cause Danbot has a few miles.

No excessive vibrations, no other problems of symptoms. Broke 1400 miles today, and everything seems fine. I indexed the bolt heads and washers to the pulleys... no movement yet.