Identifying Axle Spline

[Dave Harmison]

I'm trying to identify the axle spline on my Royale RP-21.

It's has 6 square spline teeth, not involute splines. I assume the inner part might be off something production. The inner has the markings SK9 and WP cast or forged into the rough part of the piece.

I mic'd the splines and that's where it gets confusing. The i.d. of the minor diameter is .960 and the major diameter is 1.163. That doesn't line up with anything in my Machinery Handbook or any other reference. Also, the minor diameter is the surface that is a tight fit, not the major diameter. I thought splines were usually designed to be tight on the major diameter. None of the measurements convert to anything metric, so further confusion.

Thanks.

I've never had any luck with Royale UK.

[scorp997]

Welcome to British manufacturing!
the wheel flange looks identical to my old RP16, but mine had a standard u-joint instead of a CV so that piece is similar (but different)

mine were here always a little sloppy and would need tightening on occasion. I tried to shim the ‘ride side’ of the spline to take up some slack, but it wasn’t that much. I was going to use some locktite products in the future, but car is gone now...

if you are trying to find an off the shelf replacement, you won’t find one. You may find something ‘close’ and then machine the spline and exterior diameter to fit you bearing ID.. I was going a different way by adapting Porsche 911/912 SWB (‘67) stub axles and machining VW type IV wheel flanges like the ones used on a Zink. The Porsche stubs are about 2” shorter than the typical type I Bug axles.

[Dave Harmison]

Yeah, I’m not looking for off the shelf. After racing RP-21’s since 1987 I’m running low on spares. The outer bearing surface frets and then the stub axle snaps. Normally at Pittsburgh.

I’m working on a CAD model of this part and then I figure I’ll go shopping for quotes to have them made.

[bob darcey]

Would flame spraying be an option?

[scorp997]

I’m sure you’ve reached out to Chris Shoemaker, right? Not sure if he has what you need or not. That CV part is unique to the 21 IIRC, just as the upright. The 24 uses a single double row bearing and that CV part is much deeper (also used on the later cars up through the 36)

[tlracer]

It is very likely to be a BS2059:1953 spline, bottom fitting, deep. Size is 1 1/8.

I have a copy of the relevant document - PM me your email and I'll wing it over to you!

[Dave Harmison]

Brilliant! I sent you a pm.
Thank you!

[tlracer]

Info emailed, Dave! Hope it's useful.

[Dave Harmison]

Absolutely! Really appreciate the help.

I guess I should have known, just like in threads you can have have Imperial, metric or Whitworth, in square splines you can also have SAE, metric and British!

[tlracer]

Don't get me started on screw threads, lol! The number of times I see things like...

- Using an M5 to replace 3/16" UNF
- UNF in place of BSP
- Taper threads in parallel holes (usually because the latter is worn)
- BSP in place of NPT

And then we get ISO who, having realised BSP threads are so commonly used, 'adopted' the same thread-form but changed the name. Hence 1/8" BSPP is now also called G1/8, etc. But that was parallel threads only, they also 'adopted' BSPT (taper) threads but they're called ISO 7-1...

...I need a lie down!!

[DanW]

Don't get me started on screw threads, lol! The number of times I see things like...

- Using an M5 to replace 3/16" UNF
- UNF in place of BSP
- Taper threads in parallel holes (usually because the latter is worn)
- BSP in place of NPT

And then we get ISO who, having realised BSP threads are so commonly used, 'adopted' the same thread-form but changed the name. Hence 1/8" BSPP is now also called G1/8, etc. But that was parallel threads only, they also 'adopted' BSPT (taper) threads but they're called ISO 7-1...

...I need a lie down!!

And the irony of all that is the Whitworth thread form was very good. But no, someone had to come along and try to improve on it.