Home built rack and pinion+ coilover build.

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gregsdart

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This is my second shot at a rack/coilover conversion. The first I did back in 1996 on my Race car, the 65 Dart in my avitar. This is a project that can be done with a torch, chalk, yardstick, grinder and a drill press. You will need an angler grinder if you want to clean it up a bit,
I am using a 71 Pinto rack, due to its' smaller dimensions than a Mustang II/later Pinto rack.
The shocks are QA1 single adjustables with 1/2 inch eyelets for mounting. They will fit into the stock shock mount on the lower control arm, and I will have to fab up a lower upper mount as they are shorter than a factory shock by one inch. That works out just right though.
The first order of business is to cut everything off the stock K that will get in the way down the road. I saved the mounting plates for the 318 mounts, as I want this unit to work with either a 318 / 360 or a 5.7 Hemi when I am ready for it.The 5.7 has mounts that are three inches further back than the 318, so I added some plate to the area that used to hold the steering sector.
In the first picture I welded a 10 x 20 x 1/4 thick steel plate to the bottom of the K.
 

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After welding on the plate, I welded gussets to the rear arms of the K frame to support them when I cut out for the rack. The spacers are one inch tall, 3/4 wide. I used a hole saw to cut through two pieces of stock to get the upper halfe of the right side mount. Carrefully mark the bolt locations, transfer to the other side, make holes!
 

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Next, after making sure the rack would fit after welding in the plates to box everything and gusset the legs to the plate, I welded the plates and gussets in place. Notice I had to cut a clearance hole in the plate for part of the rack.
 

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The rack in place, ready to go into the chassis and assemble the suspension.
 

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I trimmed up the plate some. You can't see it in this picture, but I finished welding the leading edge of the plate, plus added some other welds to make it plenty stiff and connected to all four corners.
 

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The oil pan is going to be a truck pan. I had better get to looking for a pan to put on the 318! I will post pics tommorow of the rack in place under the 5.7 in another chassis I am using for mock up.
 
Another view. I am using the stock lower control arms just as the factory built them, sans torsion bars. I did drill the end of the control arm pins for a 3/8 retaining bolt to keep the arms from ever coming off the pins. Going this route allows me to keep the rubber bushings and stock strut rods.
 

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that rack looks very narrow in relation to the LCA pin location. you worried about toe changes?

edit: fell asleep then posted... new pics were not up
 
The bump steer ought to work out fine, based on a heck of a lot of measurements I did. All I have to do now is get the proper tie rod ends set up on the small rack and then the fun of making the steering arms begins.
 
................Looks pretty good........r u bracing the top strut mount in the body somehow........kim........
Nope, other than re enforcing the arm of the K frame that the cotrol arm is on. There is a guy on Moparts that has been running his drag car that way for a long time, hangs the front real high most passes, no problems. When you consider that the rubber bushing cushions the loads put on the lowers, they should hold up fine. Ma Mopar never worried about it. If you think about it, had there been a need for a rear support, then there would be a problem with binding between the torsion bar and the socket. There isn't, and you don't see any marks from that on the hex.
 
The setup will eventually go into this car
 

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Hope you keep this thread updated. If you can, I'd like to more on how you determined "no bump steer." I'm guessing? the rack is considerably ahead? of where the original center link was?
 
Hope you keep this thread updated. If you can, I'd like to more on how you determined "no bump steer." I'm guessing? the rack is considerably ahead? of where the original center link was?

its going to depend on if the inner joint on the rack matches the LCA pivot pin. also if its level are ride height with the LBJ's. seems the toe change is going to be pretty bad though if he is pulling the wheels like the red car!
 
Getting zero bump steer means placing the outer tie rod end where ever it needs to be, and it may not wind up in perfect relation to where it needs to be for proper ackerman angle. Ackerman angle is simply the needed difference in angle between the inside tire in a turn and the outside tire in a turn. The sharper the turn combined with a shorter wheel base, the more difference there will be in angles. My race car has zero ackerman, meaning the tires stay dead parallel at all times. Makes it a real bear to push around a corner, or move it around the shop if you need to turn the front wheels. But the scrub you get when you go around a corner is liveable on a track only car, and actually is much better if the car gets sideways. The front tires don't toe out, so the front doesn't "push" and try and make the car switch ends. You wouldn't believe how fast my track car recovers from being out of shape. It snaps right back like it was on rails.
Proper Ackerman is achieved when the lower ball joint, outer tie rod end and the center of the rear axle all line up on a single line. On a front steer car, that puts the needed location out beyond the ball joint. That is why you will never see a front steer car with drum brakes. The tie rod end would be inside the brake drum! The best education on front end geometry that I can think of is in the Mopar Chassis manual. The chapter on plotting bumpsteer really explains it all very well. I hope to gert back out to the shop tomorrow and get some more things done and post some more pics. This is the front of my Racer. How many odd things do you see in this photo?
 

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Well I ain't familiar with early cars

Coil over, and no T bar so those aren't "overloads"

custom caliper mount

steering arm "up front"

non factory sleeve

Appears might be a rack looking at the inner

Is the ball joint steering arm short?

and the bump stop fell off, LOL
 
Greg, have you given thought to upper Coil-over shock mount? I am given to understand the fenders will start to spread if there is no additional bracing of the upper mount and/or no diagonal bracing on the fenders.
Bob
 
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