Re: [AMC-List] Mustang front end

["Swygert, Francis G MSgt 436 CES/CECM" <Francis.Swygert3@xxxxxxxxxxxx>]

Date: Tuesday, October 31, 2006 01:57 PM
From: russ hathaway <russh97309@xxxxxxxxx>

Dave; AMC "borrowed" a lot of the front end ideas from
Fomoco when they went away from trunnions in 1970. The
biggest diff would be in placing the spring high on
the top arm. I would cut out the whole shock tower
assy from a 70s and up Rebel or Hornet donor and fool
around with that, see if your 62 matchs up pretty
good.
-----------------------------------------

ONE MORE TIME!!! 
The trunnion suspension for the big cars IS NOT the same as the
American! The upper trunnion for the big cars is a very simple, really
foolproof and trouble free design. The later model American/Javelin/AMX
trunnion is troublesome after 10+ years of service as it was designed to
not be lubricated. It's great for 10 years/100K miles, and will last
that long, but after 20 years it's pretty much toast. NOT SO for the big
car trunnion! There is little stress on the upper trunnion and they
RARELY wear out as long as it's kept somewhat greased. Since there's
little stress on the part it's pretty forgiving as long as it's
lubricated every few years. 

It's also easy to install air bags or a coil over shock on this
suspension with some simple fabrication. A coil over can be used in
place of the shock or in place of the spring. Both locations require a
little fab work. The later ball joint suspension is much heavier and no
better. 

On 62 and later big cars the lower trunnion has already been replaced
with a ball joint and single arm/strut rod -- it pretty much IS a MII
type design. The lower trunnion COULD be troublesome if abused --
meaning hardly ever greased over a long period of time. I've only had
one car out of six that had a lower trunnion come apart, and all were
well used (over 80K miles) when I got them. You're not doing yourself
any favors by deleting the upper trunnion on a 62-69
Classic/Rebel/Ambassador. The 58-63 American uses an unusual trunnion,
but it can be fixed much easier than replaced with something else. 

If brakes are a concern, there are several options -- in order of
fabrication work required:
1) Use a set of 79-83 Concord/Spirit/Pacer front discs. Bolts right on,
and Speedway has a braided banjo hose kit for $40 that fits both the
early and late caliper. 
2) Aerolite makes a complete hub/caliper/rotor kit for the Javelin and
AMX that bolts right on. Price is around $1200 last I heard. 
3) The Mustang II hub is supposed to fit the AMC small car/pre 67 big
car six cylinder spindle (I believe the bigger spindle is for 67-78 V-8
big cars, maybe all), but I haven't verified it. This allows use of a
Mustang II hub and rotor, but the caliper bracket will need to be
modified or shimmed to center the caliper and/or use an aftermarket
caliper. Be aware thath the offset for the MII hub is 1/2" to 3/4"
further out than the AMC hub, so the track will be 1" to 1-1/2" wider.
In most cases this won't be a problem.
4) Use an AMC drum brake hub with the drum removed and an aftermarket
hat type rotor. A mount will need to be made for an aftermarket caliper
or the AMC caliper mount used with stock calipers or an adapter.
Speedway sells several mounting kits for older Fords that used a bolt on
spindle that could be adapted to the AMC spindle, and they sell weld on
mounts for rear brakes that could be used for adapters or the basis for
a fabricated caliper mount. As long as you use 3/8" cold rolled plate a
caliper mount can be made easy enough. 
5) Finally, do you really need discs? I once mounted 64 Classic front
drums on a 61 American. The Classic drums were 1/2" wider than the
American's and used a slightly larger wheel cylinder. I think both were
the same diameter, but I could be wrong about how much bigger (and how)
the 64 Classic brakes were (both were six cylinder cars). The end result
was that you'd think the American had discs on it -- stopping power
improved dramatically. If you have access to a parts car with bigger
drums, that might be all the improvement you need. 

I've modified many AMCs, and I don't mind taking something that doesn't
work well, is hard to replace, or hard to find parts for out on a
modified driver. The upper trunnion just doesn't fit the bill. It can be
hard to find, but is easy to change and lasts forever if taken care of
-- even the 64-69 American/Jav/AMX replacements (made with urethane
instead of the original synthetic rubber, or bronze bushings). The
trunnion suspensions are generally lighter as well. It's more work and
trouble to replace than to repair, but people still insist on going to
great lengths to replace them! 

The MII is popular, but that is mostly for older cars with straight
axles or early independent suspensions that still use king pins, are
difficult to work on, and most are hard to get parts for. Only recently
have MII kits become available for cars like early Mustangs. I believe
that's more the kit manufacturers trying to expand their markets, but
may be racers/pro street builders just looking for something cost
effective and "pretty" -- for racers easy to adjust to track conditions
and find replacements parts for. Of course if you're restoring there is
no choice but to keep original. 


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