Re: [Amc-list] American trunnion (58-63 type)

[farna@xxxxxxx]

Tom, I think you give up to easy! I repaired mine years ago. I didn't have much choice, so I got it done. Instead of a drill bit you might try a carbide cutting tool. Or a carbide tipped bit. You know, I'm probing the deep reaches of memory (I repaired my worst 63 upper trunnion about... 20 years ago??), but I seem to recall taking the trunnion to a machine shop to have that bolt drilled out becasuse of the same problem you're having. They used a drill press and carbide bit, I think. It's hard to say from 20 years ago! But I didn't have much luck with a standard drill bit. I do remember using a 9/16 bit, which is just over the size needed to thread a 5/8" hole. That gives the bolt a looer fit, leaving plenty room for grease to move around it and still enough thread to keep it in place (though the arms limit sideways movement anyway). I do know for sure I cut the arms off (cut the pin) with a hack saw. I might have used a blade for each cut (can't remember), but get a real goo
 d blad
e. Using a couple $5-6 blades just to make two cuts may sound expensive, but the alternative is a $175 or so replacement. 

I'm not sure if the camber is the same on the later models, but mounting isn't a problem. The inner bushings are different for arms that use a bolt to mount vs. the early American's mounting rod. You should be able to use the early bushings in late arms. I haven't tried it, but they appear to have the same outer diameter and profile. Should be easy to get those measurements. The mounting rod type have a larger inner diameter because the rod must be larger due to no support on one end wheras the bolt through type are supported on both sides.

Instead of going newer, try going older. The 50-55 Nash Rambler trunnion should be much cheaper and bolt on as easy (or easier) than a later model. In fact I know that the complete 50-55 front suspension will bolt right on. The steering knuckle of the earlier and later (than 58-63) suspension may have a different size/design pin on top (where it goes through the trunnion). That would be the real sticking point. 


----------------
Date: Sat, 30 Jun 2007 14:41:28 -0700
From: Tom Jennings <tomj@xxxxxxx>

Well I'm pretty much screwed. Another half dozen heat/soak cycles and it
doesn't budge. Plus I drilled a hole in the casting in the middle to get
Aerokroil in there. Did no good, and I sheared off my welded nut.

And that's on the one with enough stub that I can get a nut on it. The
other one's sheared off -- both sides -- flush with the arms.

As a last resort I tried drilling them on my 1" capacity mill. The
trunnion bolts are not much less hard than the drill bit; I didn't even
get .25" in before I cooked the bit cherry red. I may look for some
special super-hard bit but that seems desperate as a hole down the
middle of a hard, frozen bolt may not help in this case; it's so long
and no way to grip it.

Both trunnions have both arms stuck on there, which makes dealing with
them difficult. 

With a good dozen hours in them I think it's safe to say they are
unusable. With replacement costs over $700 for rebuilt used parts I have
to find another solution. (I need arms too, so it'll be even more.)

Any ideas anyone? This kinda puts the car off the road.

Does a 64-69 upper trunnion system fit, or nearly so? It appears (from
the parts catalog drawings) to have the right camber and it's probably
the same upper bearing. But I think the arms fit into the chassis like
all other 64-up cars, instead of onto that bolt-on pivot bar.


--
Frank Swygert
Publisher, "American Motors Cars" 
Magazine (AMC)
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