Hi,
Well, you asked for it.
I am extremely happy with the Corvair setup.
Why? It is dead-nuts simple to work on, you can get parts without waiting
for boats to arrive from the four corners of the globe and they are
"stout" compared to the stock piece. An no special tools required!
There are drawbacks, but nothing really bad.
Details:
First off - don't even think about welding together anything to get a
similar setup. These parts are severly stressed and I doubt that a welded
piece could take the stresses. Why worry? Well, the axle stub is not
supported by anything, so if the hub fails, you loose the wheel. This
could have disasterous results.
The bearing carrier that I have is aluminium. It's a bolt in except for
the fact that the flange is thicker (out of necessity) than the stock
forged steel piece. Therefore, you need to install longer studs in the
trailing arm for mounts. The difficulty here is that the various over the
counter sources have 1.5 inch and then 2 inch studs. You really need 1.75
inch, so get the longer ones and turn 'em down. Unless you also adapt to
disk brakes, in which case the 2 inch studs are probably adequate.
Now, changing the studs is not without issue - all the studs that I could
find are UNC on one end and UNF on the other end (we're talking automotive
suspension grade studs here). What I wound up doing is drilling out the
trailing arms for heli-coils, but I used 5/16" - 18 (e.g. UNC) into the
trailing arm (not UNF as the stock part is). I then used standard AN - 5
washers and elastic stop nuts as needed. The idea here is that it's better
to use course threads into a casting and it's better to use fine threads
in high vibration situations.
The axle stub itself is considerably larger than the stock unit.
Therefore, you need to grind some metal from the trailing arm to
accomodate the larger diameter of the stub axle (and u-joint "straps").
Basically, you widen the hole a bit at the side where the studs are into
a squared off oval. This is a trial and fit type operation with a die
grinder, maybe 1 - 2 hours per side (take your time and only remove what
you have to). Some metal needs to be removed from the "strap thingies"
that clamp down on the U-joint caps.
Note: you want to assemble the entire outer axle (stub, bearing carrier,
u-joint and outer axle "yoke") as one piece, this means that the whole
thing has to fit through the trailing arm as one. At first, it might look
like things won't fit, but they do. Key point - it's really really really
hard to torque the u-joint cap bolts with the assembly in the car owing to
low clearance around the trailing arm...
The outer axle yoke is modified TR6. A shop will "cut" the cap area to
accomodate an "inside c-clip" (as opposed to the stock outside circlip).
The only caveat here is that you need to be careful not to damage the axle
splines in the shipping/machining/shipping process. Also, finding a good
core that is not cracked might be an issue.
You _could_ use different sliding axle assemblies, the Gp 44 car uses
Mercedes 450 SL axles, but to accomodate these, you'd have to either
fabricate the flanges that mate to the differential or you'd have to
source a special u-joint that mates to the MB unit. This could be a lot of
digging... the stock axle is fine to 200+ HP.
The Corvair outer hub flange is 5 on 4.5 - this does not suit our needs,
so the hub flange needs to be drilled for the 4 on 4.5 inch pattern we
need.
Lastly, the center of the hub is a different diameter than stock, being
slightly larger (like .060 or so). SO, you need to open up the center hole
on your brake drum and (if you use steel brake drums) you might need to
open up the center of your road wheels to accomodate the bigger stub.
Alternately, if you use al-fin drums, they're "thicker" than steel so they
eat up the entire stub height, but then render your wheels to not being
hub centric - this might cause "issues", but is no big deal (you could
make a 1/8" spacer to give a locating stub if you want to.)
That's pretty much it. There are several folks that do this conversion for
a fee, I highly recommend that you seek them out and utilize thier
services, as much time went into sourcing all the parts and getting the
patterns turned into CNC code.
Note: when you are done, you have "Group 44 axles".
Figure $1200 plus or minus, depending on whether you wreck your trailing
arms or hit into some other calmaity. That's way less money than loosing
an axle/wheel in the "kink" at Road America would cost you. And you can
rebuild these babies with no special tools in the field with off the shelf
parts. That's a big win if you race.
regards,
rml
p.s. I intend to take photos of all the work that I did and publish an
installation manual for this setup as a token of gratitude to the folks
that stepped forward for this project. But I have no guesstimate as to
when that'll be done. Hopefully before the new year. I may even post all
the stuff on a web site like www.fot-racing.com. Stay tuned.
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