Re: [AMC-List] Rear end change 1966 Ambassador

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

Date: Wednesday, December 13, 2006 08:48 PM
From: Anthony <f1boats@xxxxxxxxxxx>

I want to change the rear end to Ford 9 inch or something A.M.C. that
can
handle 650 HP. Has anybody made this conversion in 1966 Ambassador DPL?
-------------------

Anthony is also installing a newer model engine and trans, so that makes
things different! The entire rear suspension needs to be changed in
63-66 torque tube cars (also 56-57). Read the whole post here before
making any decisions/comments! There are other considerations I mention
on down the page.

The easiest way, and in my opinion the best way for high hp, is to build
a NASCAR style "truck arm" suspension. "Hot Rods to Hell" builds kits
for common cars, naturally no AMCs. Their G-body kit will adapt well
though. Use the spring mounts off the 63-66 axle, just drill and tap the
top of the "new" axle tubes for the 3/8" fine thread bolt and bolt them
on. Their Camaro kit shows the best pic of components, the Shoebox
(55-57 Chevy) shows the best pic of a kit installed in a frame. I
recommend the G-body kit mainly because the springs are mounted on the
axle like the Rambler. You'll have to modify the crossmember to fit
anyway. Since you already have a panhard rod that can be adapted (unbolt
the mount from the AMC rear end), you might just want to buy arms and a
crossmember. Kits run $1995 each, the arms are $220 each. The kits have
springs and a lot of other components you might not be able to use. I'd
go with the arms and a tubular crossmember. They will likely want to
know the wheelbase and width between the frame rails. What I'd do is
measure to where the crossmember bolts on, then weld ends to bolt to the
same mounts and weld a trans mount on the arm crossmember. You will want
to talk to them about that first, and make sure the mount on the trans
you're using will fit near the same place as the stock mount. You need
to get rid of the rubber mounted stock trans crossmember anyway, or at
least make solid mounts to replace the rubber ones. 
http://www.hotrodstohell.net/truckarm/truckarm_index.htm 
(use the catalog link to see individual parts, and call!!)

There are several choices for rear ends, you just need one that matches
your wheel to wheel width within about an inch. I can tell you now that
Jeep XJ axles are to wide for that body -- I ran one but had to use
3-3/4" offset 7" wheels w/205 width tires. There was BARELY enough
clearance, and if the suspension moved a lot the left tire would scrub
the edge of the fender (even after I rolled it up). It only did this
with a load in the back though (three people going to a show, with
weekend luggage and a few items for the show). You can get by with a
wider axle if you get deeper wheels. The Jaguar axle I'm using now is a
few inches wider than the stock 63-66 axle. I'm using 5.5" offset 7"
wheels, and there is plenty clearance. I can run a 215 tire, but that's
about it. There might be room for a 225 if I had a little more backset,
but 5.5" is the most you can get on a 7" wheel. I had to use a Weld Drag
Lite wheel to get that backset -- it's available in more backsets than
any other wheel, almost any in 1/4" increments (IIRC). 

Check the post on Jeep Axles for more info on those, there are some good
candidates if you don't mind redrilling hubs for the bolt pattern you
want. Ford 9", GM 12 bolt, and Chrysler 8.25" axles should all be good
for what you want to do. The Dana 44 should be also. It's said to be
good for 500 hp, but you're using a staged nitrous system to get 650 hp.
It should last since you're not putting 650 hp on it right from the
start. Ford Explorer 8.8" axle is a good choice also -- it's almost as
strong as the 9". A Dana 60 from a wide track Jeep would be the ultimate
-- those things are nearly indestructible! 

You will likely have to back-half the car to get enough rubber under
there to work with 650 hp. Otherwise you're limited to 8" wide slicks.
If you do back-half it, run the rails from the factory front ones back.
That way you tie the front and rear together ("subframe" connectors) at
the same time. The front is plenty strong, even the stock front
suspension (which is reasonably light), and even if you ran a "foreign"
big block. The old AMC V-8 is about the same size and weight as a Ford
FE or Chevy 396. The only thing I'd do in front is run a brace across
the engine at the spring towers (or just in front of them). Any of the
universal back-half kits will work. If you're going that route, you
might want to get a kit set up for a four link. That would be a bit
easier to adjust than the "truck-arm" suspension, though I still like
the simplicity and ruggedness of the truck-arm type. 

Of course with that kind of power I think any drag strip will require at
least a four point roll bar. Check track rules. I bet you'll run faster
than 9.0 seconds though (1/8 mile, 14 seconds in 1/4). The quick
reference I just glanced at
(http://www.musiccityraceway.com/rules,_regs_&_safety.htm) indicates no
roll bar needed if slower than 8.59/13.99 seconds. CHECK YOUR TRACK
THOUGH, and/or an official NHRA rule book. 

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