Rear upright bearing loading - vintage FF

[scorp997]

I was hoping to harness the knowledge of the group here to see if an idea I am looking at is feasible.

i am looking at redesigning my stub axles on my Royale to accept CVs on the outer axle (inner joint is already a CV). Here is a little background:
make: Royale RP16 FF
upright material: magnesium
inside bearing: 6208 (80x40x18)
outside bearing: 6208 (80x40x18)
bearing spacer: 35mm

my plan is to use Porsche 911 (SWB version) stub axle (30mm dia) with a machined adapter to accept the same 6208 (80x40x18) inside bearing and a machined/splined wheel hub/flange that would fit a 6010 (80x50x16) outside bearing. Changing the outside bearing will allow me to increase the splined section wall thickness and make the flange stronger. This setup will be similar to the Zink design but with larger diameter bearings and the wheel flange pressed into the bore of the bearing instead of pressed against it.

my question is will this new bearing in the outside location be strong enough for a vintage FF loads? I do know this bearing has lower load ratings (about 10% static and 30% dynamic), but I believe the original bearings were oversized to begin with and treaded tires have a lot of sidewall deflection.

how do these bearing sizes compare with newer axle designs? Nearly all modern axles use cartridge double row angular contact bearings so maybe a direct comparison isn’t practical.

Hope someone has some experience with this and can offer some guidance.
thanks

[Rick Kirchner]

My RP 14 has been wrecked for a long time, and the one recently available here will not be much help since it's a drum brake rear. But the FSVs were required to use VW parts.

Your uprights should be able to take VW type 3 bearings and stub axles. I seem to remember buying some new uprights from royale and the bearings pushed out - they had not been machined for this big-ass circlip that is standard on volkswagons.

I think if you dig around in a junkyard you'll find the necessary stub axles from a VW TY 3 or 4. IIRC there's a four-bolt plate that retains the outer bearing, and the circlip for the inner one, and there's probably a spacer in-between, or perhaps shoulders on the stub, been too long.....

Hot VWs magazine is a good source for specialty VW shops that might offer some advice - and have the parts!

Charlie Schmidt might remember more.

[scorp997]

Thanks Rick
i know the early SVs used VW parts, but the RP14 used a different upright than the FF models. While they were geometrical similar, the bearings were sized for VW (62x30x16) and the upper mounting arms were cast with the “I” beam cross section 90deg to the FF. one of my goals here is to not modify the original upright, and to not have to source another set.

I did do a little more bearing research and it looks like the bearing used in the VW (and SVs) have less load ratings than the bearings I’m proposing so I may be OK. I’m still open for comments though

[scorp997]

Some additional images to help describe my design.

comparison between the VW axle type 1/3 (longer) and the Porsche axle (approx 2” shorter). CVs and splines are same (later 911s use larger CVs)

Drawings of upright bearing section. Staggered sized bearings on left, original sized bearings on right

I have considered using VW type3 wheel splined hub flanges as Zink originally did, but the castings are somewhat thin and aftermarket part quality are suspect. Another option (beyond billet machining) I have considered is to use EMPI rear disc brake rotors and cut the bell off (I have inboard brakes). I believe the flange thickness is greater than the type3 flanges and aren’t stepped (thinned) to accept a drum. They also come in un-drilled versions so I can keep my pattern and don’t cost much. Any experience on material quality from EMPI? Maybe R Pare looked into this option when producing the Zink replacements? I have a local Bug shop nearby so I may be able to look at them in person.

[Charlie Schmidt]

The supervee setup was straight off the street car T3, bearings, stub axles, spacer, even the halfshaft and CV
AFAIK the same stuff as an IRS bug

I'd think you need the spacer between the bearings to control end float

the Titan Mk6 in my garage uses 6208 + 6209 bearings

[scorp997]

Thanks, I do have a spacer between the bearings as part of the design and was part of the original Royale setup. Most SVs did use the entire axle/bearing/shaft from a type1 or 3 (as dictated by rules), the earliest ones had rear drums while laters allowed discs.

I thought the Mk6 had different sized bearings but wasn’t sure.

if I had access to the RP9~RP14 SuperVee uprights I would go that route. I’m sure the parts would be much more expensive than I’d like to spend.

[Rick Kirchner]

I'm racing at Willow Springs this weekend and there are a couple of -16s here. I was unaware of the difference in rear uprights but when you see them in person they are quite different.

You might drop a note to Alan Cornock in the UK, see if he has any NOS laying around, can't remember who the US rep is now after Kleinpeter passed. When I bought some from him in 87 or so they were only $300 each.

I bought some because the uprights on my car were fabricated monstrosities. However, they don't look that hard to make - three pieces of aluminum bar stock for the ends, a large piece of round stock in the middle to turn the bearing holders, and a bunch of 1/4" plate to tie all of it together.

With enough time I could dig them out of the sea van and take pics.

[Steve Davis]

FWIW, Royale USA is alive and kicking, though I don't know anything else..
https://royaleracingllc.com

Steve

[Charlie Schmidt]

there are no more 14 uprights

I got the last 3 Alan had

my car had crappy aluminum ones, really bad castings that folded if you looked at them wrong
nobody, including Alan had any idea where they came from

[scorp997]

Thanks for all of the responses.

here are a couple images that may show the differences between the RP3/16 uprights and the RP9/11/14. Geometrically similar could work as a complete swap, but I won’t be going there. I will work on getting my hands on some type3 hubs and look at this some more, I have the time..

RP3 image (RP16 same except inboard brakes and inner CV)

My spare uprights being repaired (I believe the RH upright is a Titan Mk6)


RP14 (LH upright shows the reversed “I” beam construction, and RH indicates the bolt on bearing housing next to drum backing plate)