Board index Flathead Power-Technical Questions, Answers, and Suggestions Big Twin Flatties Rod Races

Rod Races

Moderators: Curt!, Pa

Post Fri Nov 10, 2006 11:21 pm

Posts: 541
Location: Wa, USA
I am looking for oversize rod races for UL. Any supplier info would be appreciated.

Post Sat Nov 11, 2006 2:16 am

Posts: 630
Location: belgium
Woody, NOS.parts or J.W.Boon has +001",+002",+005",+010" oversize races in 52100 bearing steel.
Stéph

Post Sat Nov 11, 2006 9:20 am

Posts: 640
Location: Wisconsin, USA
Woody, I have used oversize races in Indian rods. I suggest you take your rods to a full service auto shop, have them magnafluxed or Xrayed for cracks and if none are present, have the race holes honed on a precision hone to round and size for .003-.005 interference fit for new races. If you have any money left when they are all fitted and done, take them, with crankpin assembly to your local Cryo guy.

Post Sat Nov 11, 2006 6:08 pm

Posts: 541
Location: Wa, USA
Thanks, guys. I had looked at NOS Parts, but I only looked at UL parts and didn't think to do a search for "rod races". They are listed in the OHV parts section. I will be taking my rods out to be magnafluxed this week and then we will see what the hone says. This will get my motor rebuild back on the front burner.

Post Tue Mar 06, 2007 9:17 pm

Posts: 541
Location: Wa, USA
amklyde, are you sure about the .003 to .005 interference fit? My builder says anything over .001 will split the rods.

Post Wed Mar 07, 2007 7:10 am

Posts: 640
Location: Wisconsin, USA
Woody, I'm sure on the spec. Harley originaly sized the rod race openings to 1.8125. OEM, Jims, and Eastern rod races are usually 1.818-1.820. Most race holes become distorted to out of round a couple of thou. In a trued hole .003 to .005 is a good fit. The races collapse considerably, the rod will not split. You may want to find an engine builder with a little more experience, I doubt he has ever rebuilt HD rods.

Post Wed Mar 07, 2007 9:40 pm

Posts: 541
Location: Wa, USA
Amklyde, thanks for the clarification. My builder has been doing this for a long time but has never used oversize races.

Post Tue Mar 13, 2007 1:53 pm

Posts: 530
Location: Ogden, Utah, USA
Amklyde: Cryo after the races are installed? Is this to equalize stress? How long should the parts sit in the liquid nitrogen? two min, couple of days? Just looking to get head around this.
Steve H

Post Wed Mar 14, 2007 6:33 am

Posts: 640
Location: Wisconsin, USA
I was going to post a link to my favorite cryo site but I don't see it on my list anymore. If you do a google search you will find a wealth of info. The racers around here swear the treatment doubles the life of engine and brake components.

Post Wed Mar 14, 2007 7:53 am

Posts: 349
Location: Champaign-Urbana, IL
Pretty good cryo explanation sheet:

http://tinyurl.com/2otdc8

Mark


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