Re: [Amc-list] cheap brake conversion

[Frank Swygert <farna@xxxxxxx>]

I ran Bridgestone 195/65R15 radials on 7" aluminum wheels with late model front disc brakes on my 63 American 440 (two door post sedan). Also had a sway bar adapter cobbled up and ran a late model Spirit sway bar and 15% stiffer front springs (and stiffer rear springs -- used half-leaf clamp on type "helper" springs on them). Drove it on twisty Georgia back roads like a road racer for years -- never had a failure. Engine put out around 170 hp (gross, would be around 125 hp net), and due to the long stroke pretty much fell on its face if you let it get under 45 mph (M-35 three speed auto, 3.31 gears) -- so I didn't let it drop below 45. A friend who had a very stiff 76 Trans-Am would get a little white-faced at times when we hit curves. I'd laugh and ask him what the problem was, and remind him that he knew the car would hold the road with no problems. His reply: "but it's not SUPPOSED to!!" I could probably handle those back roads better than his T/A, because it was so big an
 d stiff. The A-arms aren't a problem! 

The only stress point in that chassis is between the suspension mounting points. Over time the rails will spread due to the weight over them. There is a "K" brace from the factory, but it fastens to the lower suspension mounting bars and has slotted holes. It helps, but 40+ years takes a toll. It's easy to see if the "frame" has spread -- shouldn't be much more than 1/4" of front end alignment spacers between the bar and mounting points. I've seen these cars with 1/2" of spacers on each side...

Easiest fix is to drill two pieces of 1.5"x1.5"x1/8" angle iron to bolt on the lower suspension points in place of the K brace. Get a piece of 3/8" all thread that will run from side to side and have at least 1" on each end after it is run through a hole drilled in the angle. Place it so that it clears the oil pan, of course (near the front of the angle)! Cut a piece of 1/2" conduit or water pipe to fit precisely between the two pieces of angle. Put the pipe in, then run the all thread through and bolt in place. Of course you need to get the front end aligned first. Afterwards spacers can be put on the top suspension bar. Shops don't particularly like that, however, as the upper bar is harder to get to and will only move outward. The pipe can be shortened or washers used to lengthen it later, of course. 

Alternately, and probably better, you can drill the angle to bolt to the outside of the suspension stamping vertically. Then the rails can even be pulled in and the suspension can be aligned without moving the brace, and you should be able to leave the factory K brace in also. That's what I did on the 63. 

I wouldn't weld the angle in place due to the age and brittleness of the metal, but with modern MIG welders it might be fine. When I first noticed this no one in the area had a MIG welder (around 1980), and a shop stick welded one for me. It started disintegrating due to the heat a few months later, ruining the car. I'd asked them to gas weld it, but they decided that was too much trouble. Ruined the front end of my first 61-63 two door sedan (I think it was a 62). 

----------------------
Date: Sat, 19 Jul 2008 10:06:28 -0700
From: Tom Jennings <tomj@xxxxxxx>

That little lower A-arm system on the early Americans -- how strong is 
it?! I mean, with 8" of modern rubber tread and huge-a** brakes, could I 
stress it harmfully? 9x2 drums with skinny old pencil eraser 1960's 
tires aren't exactly like a cogged railway.

-- 
Frank Swygert
Publisher, "American Motors Cars" 
Magazine (AMC)
For all AMC enthusiasts
http://farna.home.att.net/AMC.html
(free download available!)


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