ford shelby upper control arm drop

[bryant]

so the standard idea of the shelby drop is to lower the the upper control arm 1" sometimes 1.5"s. occasionally the control arm is moved back 1/8th at the same time. this is popular on the 60s mustangs and other ford cars that share the same suspension architecture.

so my question is this, is their any advantage to changing the angle of the control arm?

for instance lowering the rear of the arm further than the front. ive been working on learning all the road racing/ autocross alignment suspension terms so please bare with me if i get anything wrong.
so wouldnt lowering the rear mount further for the arm increase the caster gain? now i dont have full understanding yet of the effects of caster gain but this seems to be something i see frequently offered on the newer suspension upgrades.

[Craig510]

It will add anti-dive as well. If you go more than 1" down you will need to modify your upper arms or buy aftermarket arms to avoid ball joint bind.

Maier racing sells a nice coil over kit with JRI shocks. They also have a big body Comet in the shop right now. Give them a call and they can help you out.

[bryant]

i understand the need for the ball joint angle correction. what im wondering is their more improvement to be gained by lowering the rear bolt of the control arm more than the front bolt.

what has me thinking about this is i was installing a cpp kit on a 60s la mans and the way the control arms move really change caster through the travel. the upper ball joint is actually in front of the lower at full droop and then as the suspension travels up the upper moves back and the lower moves forward. now i understand that this is 1960s suspension geometry but it did get me thinking.
when ive worked on car suspensions like mine ive noticed that the upper ball joint moves forward and back from the screw thread on the bushings. one side goes forward and the other goes back. im putting the mood problem solver bushing in to stop that and looking into replacing the rubber bushings with either polyurethane or delrin. im also going to do wedges for the ball joints.

but back to my question. is their any advantage to lowering the rear of the upper control arm further than the rear?

[CampbellshotrodsAZ]

Not sure on the geometry aspects of this, but the one thing I would wonder about is that now the UCA and corresponding lower spring mount is not parallel with the upper spring pocket. It might be small enough to be totally insignificant, but just worth mentioning.

[chevelletiger]

Call john at opentracker racing,johns a super nice guy and should answer all your questions on the early mustang suspension.
Phil

[bikefreak600]

take a look at my thread. i am going thru this with a modified cpp kit , i have several pics with specs at compressed, ride height & droop. the cpp upper arm is .5'' shorter than stock resulting in much better arm angles. i am thinking off just simplily lowering the arm .75'' & moving it back toward the rear of the car a as much as the shock tower allows to gain as much caster without using a lot of shims. i would think you would want a consistent caster setting in motion range. what you are talking about will only add caster as the suspension compresses. again this is just my understang. if you physically move the entire mounting holes towards the rear, you will gain caster throughout the entire suspension cycle.

[bikefreak600]

Not sure on the geometry aspects of this, but the one thing I would wonder about is that now the UCA and corresponding lower spring mount is not parallel with the upper spring pocket. It might be small enough to be totally insignificant, but just worth mentioning.
yes you are correct. this would put the stock spring perch at an angle, i am not sure how much it would affect the spring & shock. the only fix would to be a spherical bearing mount like a coilover or rod end uses. i would not try it with a solid mounted spring perch. the more the suspension is compressed the more it would bind the bushing OR put the spring in a bending motion etc.

[rustomatic]

If you want more caster, you're better off adjusting the upper arm (after the basic one inch drop)--Craig above figured out a way to do this cheaply (with self-applied labor and engineering skills) by adding adjustable slugs to the stock upper arms (with improved ball joints). You can also be a putz and do what I did, and achieve the same purpose: buy Total Control upper arms, so you can move the ball joint back from the vertical line that seems to define your caster (gain/decrease). Before you bother with the upper, however, you should look below. Your stock strut rods and lower control arm bushings love to create bind; the rods adjust, but create more bind in the process. Find some adjustable units that will allow you to move the lower arm forward (without constriction); combine this with an adjustable upper and viola! You get decent camber in turns, along with stability at (much) higher speeds. Use bearings for bushings, and your alignment settings won't vanish every time you hit a bump...

After this, check out what the guy at Cortex Racing did, and forget all of the above...

[GrabberGT]

....You can also be a putz and do what I did, and achieve the same purpose: buy Total Control upper arms, so you can move the ball joint back from the vertical line that seems to define your caster (gain/decrease)....

Have pics of this? I cant quite picture it.