5-lug conversion question

[jsteele22]

Hi All,

Short Form :

Will '69-'73 hubs + stub axles fit in a 914-4 trailing arm, with stock 914-4 rear wheel bearings ?


More Detail :

I'm thinking of switching over to VW bus (type 2) axles/CVs as part of a subaru engine/tranny swap, mainly because they're cheap, strong, and readily available. I've got a machinist friend who is willing to "help me" make the adapters neccesary : inner CV to Suby transmission, outer CV to stub axle. In particular, I'm thinking of welding the outer adapter to the stub axle so there are no hidden bolts to wrooy about.

At the same time, I'm thinking of going to a 5-bolt wheel pattern. So what I was thinking was that instead of drilling out a weak (1972+) or rare (pre-1972) 914-4 hub, I'd just use a 911 hub from '69-'73 and also the stub axles to match. I could do the welding/machining of the stub axle adapter and have things ready to go before any disassembly of the 914.

Based on reading the 5-lug conversion tech notes, it sounds like it should work. But the first note specifies a '69-'71 hub, whereas the second note (about swapping rear bearings) specifies '69-'73. Is there anything different about '72 and '72 hubs, or is this a typo ?
Also, what is the diameter of the 911 stub axle flange ? Will it fit inside the 914 trailing arm ?

Finally, I just R&R'd my rear wheel bearings less than 2000 miles ago. Any chance of getting the hubs out without destroying them ?

Thanks,

Jeff

[BigD9146gt]

Jeff,

-Don't bother welding, that WILL be a weak point. Most parts in the drive train are heat treated... and welding will change it. The bolts have worked for how many years by now?
-The bolt-on adapters will work fine, just like the ones Renegade makes. I've installed these on GPR's 914-6 with a 3.2 Carrera engine... they work just fine.
-Just re-drill your hubs for the 5 lug. Don't spend the time or money on the 911 hubs. If you find them for a good deal, you got lucky. Again, the re-drilled hubs work fine. How many people on this board (excluding hear-say) have you talked too that have broken a re-drilled 914 hub. I can't count how many I've re-drilled for V8 customers and others with 3.0+ engines.
-Buy new bearings.

Good luck with your project, the scuby engine will be awesome!
Cheers, Don.

[Dave at Pelican Parts]

The only ones I know of that have broken were ones that were very poorly done in the first place. I would be nervous about trying to tap the holes in the hub--the threads are stress risers and there ain't much metal there to hold the thread--but with press-in studs done by a good machinist you should be just fine.

--DD

[trojanman]

when's the big swap jeff?
is your car going to be running with us on the 20th?

[jsteele22]

Okay, both replies are real helpful.

On the outer sides, I feel a little better about using press-in studs. (Psychologically, its a little scary to think the wheels are held on just by a press-fit, but as long as I'm not the first to try it....)

Buying new bearings SUX. Just thought I'd say that. Now I feel better.

Don, I have heard about at least one person (at 914club.com) having trouble with the bolts that hold the adapter to the stub axle. This was not the PP conversion kit, but a DIY adapter plate. He then welded it on, and claims that it works fine - and he's a racer. I am a little concerned about the heat treating issue, though. The shop I have access to does have an oven; is it possible to re-treat the part after welding ?

OTOH, if I go with the bolt-on solution, what kind of bolts should I use to hold the adapter to the stub axle ? The normal CV bolts are way too long. Is there any way to get the proper bolts, without having to buy the complete ($$$) conversion kit ?

[jsteele22]

Originally posted by trojanman
when's the big swap jeff?
is your car going to be running with us on the 20th?

Hi Greg,

I don't think I'll start the swap -- actually removing stuff from the car -- until I have everything ready to go. That will be well into summer, at the earliest. And my current engine probably isn't up to any hard driving -- I think the valves might be stretching. But it's tempting to go down and watch. My big concern is having the car driveable for RRC.

Cheers,
Jeff

[Eric_Shea]

instead of drilling out a weak (1972+) or rare (pre-1972) 914-4 hub, I'd just use a 911 hub from '69-'73 and also the stub axles to match.

Hmmmm. Weak 1972+ hub? You've got to do a bit more research. We've been drilling and welding ring bosses on these hubs for a while now. Even the ones that are spot faced to 3mm are not weak. The ring boses bring the height back up to that of the original 914 boss (11mm). That's 'only' for stud engagement frankly. I've "NEVER" seen a properly drilled hub fail and "many" people are out racing on them now.

I'm with the Damp-One, the only failure I've seen in photos is some moron who drilled them with a drill and didn't spot face the hub on the backside. That's 1 picture...

Also... For the record, "I do not like the 'rare' early hub." The bosses are only about 5mm tall and a later hub with proper ring bosses is much stronger I would say. I have one if someone wants to give me stupid money for it (only 1 sorry). Talk amongst yourselves.

You can go whacky with it and get a pair of $200 911 hubs and then find the $600 stub axles to make them work or you can spend $145 and bolt them right on.

XXOO

E.

[jsteele22]

Thanks, Eric. My impression that the later hubs were weak came from the Pelican tech note. Now I know otherwise. And I didn't know about the idea of welding the ring bosses on.

BTW, what's the deal with welding onto hardened components : do you do any heat treatment afterwards ? My guess (based on 0 experience) would be that since the studs are fairly far from the axis, the forces are much lower and its not as big a concern as stuff close to the shaft.

And watch those XXOO's, baby. Someone might find out.

[jsteele22]

Oh, BTW, about the press-in studs : I had misunderstood how they work. I thought they pressed in from the front; I feel a lot better seeing that there's something to keep 'em from pulling out !