harleyKmodel

Hi All,
Looking for replacement axles for K & KH cams. If possible would like case hardened (60Rc) so I can use torrington bearings. Checked out Thomson & Diamond Case Shafting, but they do not carry 11/16" Dia.(.6875") 18MM (.7087")is as close as they have. Would need to have centerless ground to size. I need a min. of 28" long for two sets of cams. Any thoughts out there?
Thanks in Advance,
Rfrees1

Should be easy to buy drill rod in the size you need in whatever alloy you want (A2, D2, 01, S7, etc), heat treat to desired hardness and have finish ground to desired size. I think A2 would work well for your needs and is known for its low distortion during heat treat. S7 is also known for its low distortion during heat treat but is the softest of the drill rod alloys.

Sure you want bearings rather than bushings?

https://toolsteelservice.com/product/to ... drill-rod/

https://www.zoro.com/zoro-select-oil-ha ... ifications

https://www.paulo.com/s7-d2-a2-differen ... roperties/

The longevity of the bushing set up surely cannot be denied. Ball Bearing or Torrington being other options of course. Out of 50 or more K engines I've seen or built I would say 90% had no wear, so swapping out, line reaming, etc all uneccesary in many "cases". Surely building any engine you address the weak, worn etc parts, poor designs above all. After seeing so many perfect bushings at teardown I say H-D got that part right. Actually I see more worn stock cam axles! Sounds backwards...Axles are simply made with steel round stock. I forget what high grade steel I bought, but works great. Ends trimmed down would accept KR Ball Bearings. Less friction for the high revving KR, with Ball Crank Bearings also. Ball bearings had a relatively short life, and when they fail it can be catastrophic, compared to a Bushing. In theory, the bushing is just there to give oil molecules a place to hang out. The bearing vs bushing war continues into the roaring 20s. Ball bearing axles can be softer than Torrington since the bearing just pushes on. Torrington type would surely need precise, harder axles. With the Bushing set up you want to open up a little funnel on the top of the non thrust, case side, bushing. Correct oil. Thick. The K motor is more like a transmission with so many gears! Torrington is an amazing set up, super high loading capabilty, no center point wear like ball. If you have a Minor pit or loss on say a Trans Mainshaft it will not be effect longevity much. Oil retention slot I call them. Think of a log rolling across your lawn over a little mousehole. No effect. Still plenty of support. So bottom line, what would NASA do? Well they have gone back to Bronze Oilite Bushings for infallibility and longevity in many cases. The Launch Vehicle. Biggest truck in the world. After years of bearing maintenaince and failure the axles all ride on bushings with no maintenance except grease gun.

52K and 54 or 55 and up Inboard Cam Bushings w factory oil feeds.

Just my 2¢?
Major factor for the factory to go to Torrington: cheaper; the part may be more expensive but the machine work isn't.
I would use SAE 660 bronze bushings every time except for a race engine. The WR, KR &c. R6 inner ball bearing OD is bigger than the bushing OD so the case must be re-sized.

You can get precision ground 11/16 HSS drill blanks in 6”, 9” or 12” .

http://www.hssblanks.com/catalog/2006-D ... Blanks.pdf

That’s what I used for my KHK cam axles.

I repaired the axles on the cams in my bike. On 2 of the cams, I made 2-piece axles, and pressed them in from each end, then polished the surface for proper fit in the corresponding bushing(case or gear cover). The other 2 cams, I turned the shaft down and pressed on a steel sleeve, and turned for fitment.

I found if you press them all the way through...it galls up the shaft. You'll find some cams have a (now larger) ID in the center after you press out the old shafts. It's been about 15,000 miles (that's a lot for a '52K model) No problems.