1961 rambler american front suspension geometry

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   since i'm making (yet another) rear suspension for my '61 american-based roadster i wanted to see if i could do anything about matching front and rear roll centers (still working on that) but i found (sic) an online suspension calculator, and given a car and an iron pile with front suspension assemblies in it i entered the car's suspension geometry:
rambler roadster

it's kinda interesting. it's an unequal length A-arm ("double wishbone") of course but set up very conservatively (nash=conservative). the upper arm is *almost* parallel, which makes the instant centers zoom from left to right depending on ride height. (i run air springs on all four corners so i can dial this in so that both pivots of the lower arm are parallel to the road). that's what i tried to setup in the URL above.

the roll center moves all over the place with any change in lateral load! which we all know from experience. 

haven't done any poking yet to see how anything could be changed.

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tomj Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7544	Post Options Post Reply Quote tomj Report Post Thanks(0) Quote Reply Topic: 1961 rambler american front suspension geometry Posted: Apr/15/2016 at 6:28pm
	since i'm making (yet another) rear suspension for my '61 american-based roadster i wanted to see if i could do anything about matching front and rear roll centers (still working on that) but i found (sic) an online suspension calculator, and given a car and an iron pile with front suspension assemblies in it i entered the car's suspension geometry: rambler roadster it's kinda interesting. it's an unequal length A-arm ("double wishbone") of course but set up very conservatively (nash=conservative). the upper arm is almost parallel, which makes the instant centers zoom from left to right depending on ride height. (i run air springs on all four corners so i can dial this in so that both pivots of the lower arm are parallel to the road). that's what i tried to setup in the URL above. the roll center moves all over the place with any change in lateral load! which we all know from experience. haven't done any poking yet to see how anything could be changed.
	1960 Rambler Super two-door wagon, OHV auto 1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com

tomj Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7544	Post Options Post Reply Quote tomj Report Post Thanks(0) Quote Reply Posted: Apr/15/2016 at 8:19pm
	as it is, for 3 degrees of body roll the roll center/moment center moves laterally 24 inches, which is what gives ramblers that mushy understeer. if you shorten the upper arm 1" and lower the inner pivots 2", the static roll center moves from 1.8" below ground to 4" above, and for 3 degrees of body roll, the RC/MC moves only 5 inches, a heck of an improvement. though i'm unlikely to do this, it wouldn't be all that hard to do on the early americans; both upper and lower arms mount to cast or forged pivot bars, the top one of which would easily move down the outward-curving pocket. shortening the arm would be straightforward enough (not sure i'd trust my own welds on that :-) now i can go look at the suspension kits for AMX's etc and see what it is they do, and what effect it will have....
	1960 Rambler Super two-door wagon, OHV auto 1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com

farna Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19676	Post Options Post Reply Quote farna Report Post Thanks(0) Quote Reply Posted: Apr/18/2016 at 6:53am
	The early Falcon and Mustang had an issue with camber changes (the Rambler doesn't have that at least!). The upper arms were parallel with the ground. They moved the upper mounts down an inch to improve handling. They didn't change the length of the arms top or bottom (bottom is a strut rod design, limited adjustment), but may have been due to the suspension geometry of those cars. There is a kit to drop the upper pivot 1-3/4"-- it requires a wedge spacer for the upper ball joint to correct the angle. You might try the 1" drop for an easy improvement and no arm cutting. BTW -- instead of cutting the arms I'd consider making some new tubular arms. The inner bushing end would be easy enough. For the trunnion end I think I'd try flattening the tubing then drilling and tapping. Mustang II uses a bar mount upper arm -- you might consider getting the measurement off one of those then cutting at the ball joint and fabbing ends for the trunnion. Or even using a pair and lengthening/shortening as needed and ball joints and an MII spindle as well... but then steering geometry would be off, unless you also threw in rack and pinion steering. All that is getting a bit far away from the vintage feel of the car though. The 1" drop sounds like the best short term plan.
	Frank Swygert