Re: [AMC-List] Strut bushings

[Tom Jennings <tomj@xxxxxxx>]

The strut bushings get a lot of attention because they are
basically the weakest, poorest design element in the AMC
front end.

Not from a safety/failure point of view, but considering dynamic
geometry and long term stability they suck. That last part,
will it hold a #@$%%#@!! alignment more than a few months!

Upper bushings, ball joints, etc, component positions don't
displace very much as the parts wear, and they take decades to
wear enough to throw alignment off.

Crappy strut bushings compress, the lower ball joint moves
towards the back of the car, and inward; toe widens, camber
moves towards positive and caster drops.

(I suppose the one advantage is safety: Joe Shoppingmall can
drive repeatedly into a curb stone at 10mph and not crack a
lower A arm.)



On Fri, 18 Aug 2006, francis.swygert@xxxxxxxxxxxxxxxxxx wrote:

> What a time not to have my books with me!! I wouldn't say that the front
> ends were in a "state of flux" -- there were two versions of one basic
> design. There were two different strut rods and lower arms, and trunnion
> designs -- one for the small cars and one for the big. The small cars

I've not made the big survey necessary, and I don't have access
to the cars, but I know this:

Two piece bushings vs. one-piece bushings: after 1964 (65?) they
are functionally interchangable. There has been a lot of fiddling
by the OEMs and aftermarket on design, so clearly they're either
all idiots or they were attempting to address various problems,
probably longevity and alignment stability. I assume the latter
(until the 1990's when profit-at-any-cost overrode quality
concerns and they turned to the former).

Anyways the old-style one-piece has an installed steel ring that
is supposed to be swaged and spot-welded into the bracket. They
are a major PITA to install, and as Frank and I have separately
discovered, it apperars that none have been manufactured for
DECADES as my NOS set crumbled within a few days (imagine the
cost, imagine the fun). That was 5, 10 years ago for me.

One piece seems to be the original OEM design; nearly all
aftermarket are two-piece. I can see no technical reason for
the one-piece.  Any of the quality two-piece designs are just
fine, are just as or more rugged, and vastly easier to install.
No one repros this part as far as I know; good riddance to
bad rubbish.



1963-1964 suspensions: non-adjustable strut rod, upper trunnions,
lower ball joint. The strut rod is an old-fashioned part;
high-quality, forged item, it's tapered, impossible to make
adjustable except via Frank's method (cut+weld) whivch I am
not skilled enough for.  Hence my poly/rubber hybrid hack.


1965, 1966, 1967: no experience, but somewhere in here AMC
narrowed the chassis 1". The early 10, 80 chassis mutated into
the 01 chassis. The 63 classis is shockingly similar upside down
to the 70 hornet. (One of the reasons I love AMC engineering.)

68-72, small car, seems to be another class of suspension mods.

73-up, pretty much all the small cars (01's) are the same;
pretty much everything interchanges exactly (spring rates,
brakes and details excepted.)


Note that from 63 up, (I have zero knowledge of Pacers and Mats
I never worked on), all AMC suspension parts interchange or come
very close -- little design change. Even trunnion vs. ball joint,
the smallest change required was made.

Details like built-in steering stops vs. the serrated plate,
I consider BFD, since I wrench to drive, not restore.



Take 1963 and 1979 (two chassis I have a lot of experience with):
You can actually bolt on all of the lower junk from the 79 onto
the 63 car if you space the steering box and idler arm inward;
later chassis are 1" narrower.

The 1963 tie rod ends, pitman arm, steering arms, steering
knuckle are identical to later (79 at least) parts -- EXCEPT
the tapers are LARGE, vs. SMALL on newer parts.

The only difference in the lower ball joint from 1963 to 1979
is the size of the taper.

The upper insert, that contains the spring top seat and upper
arm pivot bushings, looks like it would interchange 1963 / 1979.
Welding involved. The ball joint upper A-arm **almost** fits in
the 63! (Too wide if I recall.) If the upper trunnions weren't
so damned reliable I'd consider it a worthwhile project. (Mine
now have over 300,000 miles on them.)

> used a bolt on turn stop, the big cars had the stop made into the ends
> of the strut rods. The change occurred in 67 or 68 (I think 68 models --
> this is where my books would come in handy!) -- the strut rod changed to
> an adjustable type, and the end that bolted to the lower control arm
> changed on the big cars. I think they went to a bolt on stop at this
> point also. 63-66 (or 67) should be the same, 67 (or 68) to 69 should be
> the same. 70 and later strut rods are straight for the small cars, I
> think the big cars still have a curved end to bolt to the lower control
> arm. 

I'm not sure the 70 strut rods are *actually* straight; I think
there still is a left and a right, but I could be wrong.

The various mostly small changes that happened post-65/pre-70
are the "flux" I was talking about.

> I don't know about the strut rod bushings. There does seem to be some
> experimentation with the shape of the rubber and position of the washers
> after 1970. For the most part non-adjustable strut rod bushings are one
> piece, adjustable two piece. But as John Elle indicated in another
> message, there is a one piece in the early 70s with the adjustable strut
> rod. 


I wish I had systematic access to all the parts. A full
set of parts catalogs would be a start, but I think actual
side-by-side comparison of hard parts would reveal that a lot
of different-number parts are really microscopic variations on
some one part (eg. holes for shocks, anti-roll bars, etc). Those
of us wrenching and driving would be happy to have wrong-year
parts that work :-)

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