Gurus- I just saw Louie's great article in the VKA June magazine. Keeping the outer race between the needles and rod inner surface looks like the way to go.
I did a similar mod recently where a PP rod was honed to .688 and 19 Mac crankpin rollers fit the wristpin end nicely. I fitted side spacers like Lou did. Will the rod tolerate these rollers in direct contact with the small end's inner surface, just like the crankpin rollers at the other end?
Got this idea from old Merc outboards. The ID was only increased a few thou'
Bill
AH 58 alternate wrist pin bearing
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Bill Hermsted
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Glenn Duvall
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Re: AH 58 alternate wrist pin bearing
Bill, I haven't seen the article and can't really comment on the rollers running directly on the small end of the rod.
But I do need to pass on the importance of having properly hardened thrust washers for the end of the needles to run against.
I built a McCulloch SP 105 saw motor that is similar to the Power Products/ West Bend design with a single bearing in the small end of the rod (as opposed to the typical Mc design with two bearings pressed into the pin bosses).
I left the race in the small end of the rod and painstakingly ground the pip off of each end of the bearing needles with a Dremel. The needle length was matched as well but I don't remember the dimension.
Due to the 9/16 pin diameter, I had difficulty finding real thrust washers and instead used 9/16 "hardened" SAE washers from Fastenal. The side clearance ended up @ .018".
The needles ate through the washers after about 30 minutes run time and the debris went through the motor, essentially destroying it for all practical purposes.......
But I do need to pass on the importance of having properly hardened thrust washers for the end of the needles to run against.
I built a McCulloch SP 105 saw motor that is similar to the Power Products/ West Bend design with a single bearing in the small end of the rod (as opposed to the typical Mc design with two bearings pressed into the pin bosses).
I left the race in the small end of the rod and painstakingly ground the pip off of each end of the bearing needles with a Dremel. The needle length was matched as well but I don't remember the dimension.
Due to the 9/16 pin diameter, I had difficulty finding real thrust washers and instead used 9/16 "hardened" SAE washers from Fastenal. The side clearance ended up @ .018".
The needles ate through the washers after about 30 minutes run time and the debris went through the motor, essentially destroying it for all practical purposes.......
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Bill Hermsted
- Posts: 88
- Joined: Wed May 12, 2010 8:50 pm
- Vintage Karting items owned: 3 AH58's and 1 MC45
- User Agreement: Yes
Re: AH 58 alternate wrist pin bearing
Glenn- Thank you for a very important tip. I previously thought most any washer would do! Louie used stainless, but didn't say which type.
As you know. 300 series can not be heat treated, only work hardened. Maybe that's what Lou was thinking- that the needles would rub the washers' faces hard before eating through.
400 series can be heat treated, but only to 40 - 42 R after tempering, probably not nearly hard enough.
Sorry about your Mac. Bill
As you know. 300 series can not be heat treated, only work hardened. Maybe that's what Lou was thinking- that the needles would rub the washers' faces hard before eating through.
400 series can be heat treated, but only to 40 - 42 R after tempering, probably not nearly hard enough.
Sorry about your Mac. Bill