Shortening control arms

Mythbusters shows how to split an AMC down the center. If you haven't seen it, do yourself a favor and find the video. They run a Hornet or some other AMC (I think) into a vee plow at ludicrous speed. Awesome.

When measuring the suspension on my 2wd AMC Spirit I wish I had a longer upper control arm mounted farther inward as the stock geometry is terrible. When the suspension was compressed camber would go 2 degrees positive. Without knowing the suspension pick up point measurements I’d say keep the arms as long as you can.

Is there a difference in length between a 2wd and 4wd AMC control arms? I think the lower 2wd one is already 3-4" shorter since it doesn’t angle down as far as the 4WD one.

PseudoSport I'm glad you commented.The uca are the same on both the 2wd and 4wd Amc's and attach to the body in the same location.The lca are different and unique to the 4wd.So if you had a longer uca mounted further in would mounting further in be so you can get a longer control arm?Or do you mean you would like a longer control arm and also have the balljoint moved further in toward the body?The AMC 4wd systems were designed to bolt on to 2wd bodies.AMC didn't have much money to work with.

Mounting a stock upper arm further in changed the camber curve but was still not ideal. Mounting it farther in with a longer arm would have been better but I don’t think there was enough room and I didn’t know of a stock longer arm. Also this was with the 2WD spindle which is shorter then the 4WD one. You might not even have the same issues I did.

Since the crossmember and lower control arms are wider shouldn’t you only need to shorten the lower arms and leave the uppers alone since they bolt to the body which hasn’t changes? I picture if you bolted everything up currently it would look like a stanced VW, lol.

The 4wd lower arm is different since it angles down and to the back I think where the 2wd arm is straight. You could just cut a pie section out of the shorter 2wd lower and weld it back up to get that angle. I haven’t see the two side by side so I’m not sure what else is different.

PsuedoSport The 4wd spindle is longer then the 2wd.It has the bottom balljoint installed from the bottom of the lca instead of setting on top of the lca like the 2wd.This was to make room for the axle.The crossmember isn't wider it's a lot taller to lower the lca mounting points for the taller balljoint to fit.People in the amc world often swap all the eagle stuff under the spirit body.There's even a factory version.I'm positive the uca are the same and mount the same.This leads me to believe the 4wd spindle itself is where the extra track width comes from.I can picture it sitting like a vw,funny stuff.

The 4wd lca is angled back to make room for the axle.It is also angle down at it's mounting point on the subframe.Then angles back at the other end to attach to the spindle.Check out the pics I posted in this thread earlier http://grassrootsmotorsports.com/forum/grm/suggestions-on-lowering-an-amc-eagle-needed/96220/page1/ .That'll give you a pretty good look at what I'm dealing with.I want to figure out how to make this work so I can quit driving the hornet and start the conversion.

If you don't like the arts and craft approach of the string computer, then look for a program called wishbone. Do a google search for it. I'm guessing there will still be a link to it somewhere on the internet. I think it was in a Yahoo Locost group years ago when I downloaded it. It is a virtual string computer that may help.

Most peopole seem to find that Wishbone is not as user friendly as VSusp.

Driven5 for me the VSusp is easier to use,of course I can be a bit dense.I've been looking at vintage pro amc race cars and am not finding much info.This is a street car not a race car but want it to at least handle on par with late model grocery getters.

I want to build a thin one seat mini car.  I've been debating on using a quad setup but would rather a car so it would be easier to get safety inspected to be legal on the road. 

I am looking at a classic mini front subframe with the engine, auto transmission and all the parts still on it.  I want to cut the 54 inch width wheel to wheel down to 38-42 wheel to wheel.  The subframe is approximately 24x24x24 inches.  I'm thinking of buying and cutting the control arms down or seeing if I can use go kart control arms that are shorter instead and using new struts or shocks onto the frame instead of setup of the mini with connectors in the subframe and on the body as well.  Can you suggest the best option.  I'm not a gearhead and have only looked online at the subframe so I don't know what will work best or if I could make it smaller then it is already

On another topic, I am planning to use ehub scooter motors on the rear to make it a hybrid with acceleration for the gas tank engine and electric motors. 

Driven5 said:

 

If you're not overly concerned with the quality of the suspension geometry, just build it and drive it like hot rodders have been doing for decades.

This might be your clearest answer.

Nothing better than suspension design to put you into the analysis paralysis spin cycle.

In reply to Shiver :

Again it's best to avoid shortening control arms whenever possible, primarily because longer tends to give better suspension geometry and allow for more travel. If packaging weren't a concern you'd see more cars with stupendously long control arms like you often see on purpose-built race cars:

It would be better to narrow the subframe, the main issue to look out for with this would be bump steer changes. If you're building the chassis from scratch, it's not much more work to make custom suspension arms as well, and even though suspension design looks incredibly intimidating at first, it's not terribly difficult to produce better suspension geometry than the average production car either. You can still go with production uprights and struts without having to make any major geometry compromises.