Got a Mustang II front end on the drag car,,, I need some really good tech, build, an conversion notes here. Control arms have been replaced, coil over shocks, Not stock pivot points on control arm mounting. Did some searching on the net an can't find a good site for info. Getting too many critics on this, control arms level or tilted ball joint up, tilted ball joint down. Any an all info would be appreciated!
You are taking on an engineering nightmare. I can tell you that for the best roll control and handling you need to have the control arm geometry set so that if you drew a line from the two spindle connections through the oposite side of the car it should come together at or below ground level. I would have to get my notes out on chassis design to be more specific than that. You never want them parallel. The angle depends on many other things - I would never attempt to do one without a kit and instructions. I wish you the best!
Two trips a day in and out of a trailer and multiple trips at high speed, under maximum acceleration. You need to be sure that you can control the car at over 100MPH with full throttle and coasting at high speed. It is just as important to you as it is to the auto-cross racer. The geometry is different but you do need to get it right. I would recommend looking at some books by Petersen Publishing, SA Design, and HP Books to see if they have any information on what you are attempting. The used to have a paperbound book on chassis mods for drag racing but it has been ten years or more since I took any classes on that stuff. Check your local Community Colleges and Tech schools to see if they have any classes. If nothing else it will get you some contacts that you can use for information.
Mavman, more of a home made installation. Car was suppose to run 8 seconds, cant confirm that. Upper control arm bracket mounted to frame rail, bottom does not have full cross over cross member, just brackets off bottom rail enough to mount lower control arm. Will have to get some pic's to help explain. Pivot points are not factory spacing. Lower control arm looks like it will angle down to ball joint
Since the mustang II uses unequal length control arms, you can get by with having them level, since compression will still give a negative chamber increase. However, it also gives negative chamber under droop, which isn't the worst thing on a drag car. It'll make the wheels up landings a little more controlable. Paul is talking about instant centers and how they relate to the center of gravity. Here is a pretty decent illustration of how to find your instant centers and resultant roll center. The closer the roll center is to the center of gravity, the better. If you place the roll center ABOVE the CG, then the car will actually lean into a corner. Most of the time, space constraints won't allow that. You also need to look at when your tie rods and rack are going to mount to eliminate bump steer, which can be very much bad in a drag car. Then you need to look at the side of the car and determine how much caster you want in the spindle. Caster makes the vehicle more stable, and uses the weight of the car to "center" the wheels or make them return to center from a turn. Every car's front wheels turn on pivots attached to the suspension. Caster is the angle of the imaginary line drawn through the pivots. It's measured in degrees relative to vertical. If the top pivot point is behind the lower pivot point so the caster angle slopes backward like on a bicycle (as viewed from the side), the caster is positive. If the angle slopes forward (which it never does), the caster is negative. These articles are VERY informative... You can also design some anti-dive into your suspension, but be careful not to mess up the caster when you do. (I'm starting to get lazy. If you google anti-dive it'll give lots of useful info) http://www.sportcompactcarweb.com/tech/0507_sccp_making_it_stick_part_2/guidelines.html
Does a drag racer want posative or negative camber on the wheels? (top or bottom of the tire out further) I would think that lots of caster was in order to help keep it in a straight line but I have little experience with drag car set up.
Trick question. Keep in mind that on most M2 IFS setups that camber will change as the front end is lifted. At rest it may have zero camber. As the front end rises, camber will go positive slightly. That's where a strut front suspension comes in. Struts won't allow the camber to increase a significant amount--at least not nearly as much as an A-Arm setup will. You want as much caster as you can get. I run 0 camber at rest 1/16" toe in, and 9 deg caster. Even driving out of some pretty hairy wheelstands it is very smooth. Many times I can't even feel the transition from air and track. But remember, I am using a factory M2 crossmember with mounts. A friend of ours has a setup like you are describing. The upper arm mounts are welded to the frame. The lower mounts are also welded--and there is no crossmember. It's pretty "rigged" but it works. The only downside is that the rack on his Maverick is mounted out on the front crossmember under the radiator. When it lifts the wheels, you can literally see the tires change the toe. It looks bad, but he says he can't feel it. I would guess that there is as much as 2-4 inches of bump steer.
