1958 to 1963 Rambler American idler arm

06 feb 2022

More than you ever wanted to know about early Rambler American pitman arms.
More than I ever wanted to pay attention to them, but there are two systems,
and they are not interchangeable. I found out only when I installed the wrong
one by juggling parts from the pile without paying sufficient attention.

There are what I’m calling early and late systems. Late is definitely 1961
to 1963. Early may go back before 1958 but I have no data, but it is certainly
a Nash-designed part. There is a corresponding early vs late steering box and
pitman arm. The net effect is the location of the tubular steering link,
fore/aft. The early system pushes it closer to the front of the car about and
inch, and later, it runs closer to the engine.

The steering linkage wants to be exactly perpendicular to the direction of
travel. The car will “work” with wrong parts, but steering geometry (toe, and
Ackermann angle) will be wrong in turns. Given these are not generally used as
sports cars (though they do that far better than you’d ever imagine) you might not even
notice… but the car might feel funny and tire wear will increase unevenly.

Mainly though for folks who don’t do the foolishness I do, you need to know
the difference regarding idler arm bushings or replacement arms with bushings
installed.

Idler arm bushing

Year	Part	Notes	Press distance
58..60? “Early”	MEVOTECH MS404121	1.14 OD/.63 ID x2.31″. 50’s Ford, and some later AMC (79 Spirit). This part has no flange on the outer sleeve.	.953″ (61/64″) from 1958 TSM
61..63? “Late”	K3026	1.14OD/0.72 ID x 2.44″. This part has a flange on the outer sleeve.	.6875″ (11/16″) from 1963 TSM

The bushing needs to be pressed in to a fairly precise distance from the
pivot.

For far more technical information and family history compiled by the
Australian Rambler Club, refer to the idler/pitman arm document in my Documents
section.

Note that in a pinch you could install the K3026 part in the early arm; the
press-fit part size is identical, the overall length within the range of the
nut and threads, but you would need to shim the pivot with thin sheet metal.
Beer can metal would work; the steering geometry error would be immeasurably
small, the innert sleeve is fixed and does not move, the arm pivots by the
outer sleeve rotating around the inner with the intervening rubber as
“bearing”.

Early

Late

Early vs Late