Jed Copham

My shock tower was welded crooked from IFG. One control arm was at a much steaper angle when the suspension was unloaded, this and the shocks were on backwards making them bind when unloaded. Instead of realizing they were backwards, I killed the tower with my grinder. It has been bugging me ever since. The only way to fix it was to pull the cradel, cut out the old one, weld on the new one. It was also a good time to repaint it.

Endre (Andy) Bujtas

Jed had some problem with the Ryane/IFG/Shelby rear suspension.

There is a flaw in the design or the way it is assembled that could cause it to break (or at a minimum bend) under hard acceleration with high-output engines. I anticipated the problem and made the changes.

Jed's upper rear control arm connection on the Fiero upright bent when he "got on it". He now needs to either replace the pieces and implement my mods or come up with a new way. I suggested a way to use the Fiero upright to make a simpler, more exotic suspension like the Countach/Diablo or older F1 & CanAm cars, which would prevent the effects of torque steer on the suspension components. It would not be too difficult to make, but it may require the removal of the cradle. He told me this was going to be his winter project on the car. I don't have any drawings on this design, but just described to Jed the basic components and how it could be made. I don't expect a problem with mine, but if so, I'll be making drawings and implementing the new design myself. In my case, I wouldn't need to remove the cradle and could implement the design with the engine/cradle in place. I'll have to wait and see.

The revised suspension would be very similar to the real Lambo's (both Diablo & Countach), but using the Fiero upright.

This is a photo of a Diablo 6.0

The upper arm arrangement would consist of a triangular arrangement with a single adjustable transverse rod (directly over the axle & upright centerline used for camber adjustment) with 3/4 male rod ends on both sides. This will require welding a support bracket on the cradle to hold that rod end. (The photo on the right is from Jed's frame)

On the upright side, you would use the same plate that is bolted to it now, but for a slight modification. (The 3/16 plate I am talking about is in this photo, but for my suggestion, the plate is reversed to what is shown. My control arm is attached outboard of the upright. Most others have theirs attached inboard of the upright. These 2 plates would be used to afix the single transverse control arm I was talking about - in between the plates.) Spacers would be welded inside the 2 plates to center and hold that rod end in place. The bolt would hold the rod end in place and the nut would be the horizontal link bracket. The horizontal link would become the toe control link, and will do the job for torque and roll steer. This is not unlike the triangle suspension used in F1 and CanAm cars.

As for the lower control arm, you have 2 choices:

1. Use a wishbone with a lower longitudinal link. This would require a similar bracket to be welded to the cradle as with the upper arm. It would be directly in the center of the axle centerline. The wishbone would look very similar to the current upper control arm, but oriented in reverse. That is, the rod end side would be at the cradle. The other ends (using 1.5 inch tubing) would have polyurethane bushings like the current lower control arm, but attached to a new fixture bolted (or welded) to the upright. This type of wishbone will require a longitudinal link to prevent it from moving back and forth. I would recommend using swaged steel for this. A-1 Racing sells these rods. This arrangement is what was used on the Countach.

2. Use a new A-arm that does not utilize a ball joint. It would use the current chassis mount, but would have a similar mount at the upright. It wouldn't really be an A-arm, but more like an H-arm. This is what is used on the Diablos. You would make the same fixture as in option 1 above. However, in this case a longitudinal link will not be necessary since this type of H-arm will rigidly hold the upright from twisting - unlike the current balljoint arrangement. However, this design does not allow for much, if any, toe-control. Toe control would have to be built into the design or 1 end of the H-arm would have to be adjustable. The mount at the upright end could either be 3/4 rod ends or poly bushings.

In either case the lower support fixture would be the same. This design will liminate the current transverse coil-over arrangement. You can now have a single or dual coilover setup attached directly to the upright. This would give you more room above the trans in the back. You might be able to use the current upper control arm mounts on the cradle to support the shock mounts.

The new lower control arm mounting fixture would primarily consist of a ¼ flat plate with tabs to surround the current ball joint mounting boss on the upright. A bolt would replace the ball joint shaft to hold the fixture in place. At each end of the plate are the bracket tabs for the poly bushings - drilled to accept 1/2 inch bolts. Or a 1 inch tube using the current ¾ bolt if rod ends are to be used. Above it and the above the ball joint boss will be a 3/4 inch tube to allow a long 1/2 bolt to support the coil-overs at the upright end. Or you could use a threaded rod rossette welded to the tube to act as a mounting stud. This way will allow you remove 1 shock at a time instead of both together.

The general idea is that the Fiero upright can be made to work like these suspensions. And without a lot of work. It just requires a lot of measurements in order to come up with the correct control arm lengths and locations. However, my suggestions are primarily based on using the Ryane/Held-designed cradle, but any full tubular frame can be used as well. It may be difficult to implement on a stretched Fiero or a Fiero with a square subframe like that which came from CRP.

The control arms would be relatively easy to make since they are just tubes with rod ends. If one were to make them using 3/4 rod ends, then the arms could be made with 1 inch OD tubes. But you'd have to weld the fine-thread nuts onto the tube ends. Or they could be made using 1.25 inch tubes using Meziere (www.meziere.com) tube ends. They are easy - just slip them into the tube, weld them and screw in the rod end. Or you can get pre-made swaged steel rods from A1 Racing (www.a1racing.com) and work with them.

One should prototype the control arms out of wood. That should be easy to do since you can get 1 or larger inch wooden dowels at any hardware store. This way you can finalize the design and create a pattern to make the final steel arms.

Here's another set of a photos to evaluate a Maserati cradle with rear suspension.

I do have an idea for a replacement rear suspension for a stretched Fiero-based or CRP-based frame. And that one would not be difficult to make either.

It would still use the Fiero shock tower, but not for a strut. The design is similar to Maserati suspension. You would still make a plate similar to the picture I sent, but with an added piece on top to support the lower end of a coil-over shock. The upper end of the shock would use the Fiero (or similar) tower, but modified for spherical rod end. You would make tubular H-arms for the upper and lower control arms like the Maserati. The ends of the H-arms would use 1.5 inch (.090 wall) tubing to hold polyurethane bushings. With this design you could still use the stock Fiero cradle. However, this would mean a fixed toe for the rear. Gone would be the toe arm, which is instrumental in creating bump steer. No need for bump steer correction kits. The [Cavalier steering] arm on the upright that holds the toe arm ball joint could now be used for a rear sway bar link. It would be very strong and would withstand the torque of a V8.

Jed Copham

There is a problem with my rear suspension, this is an old picture so the tube is straight, after a few hard accelerations visually the plates are bent. This assembly consists of 5 pieces. 2 1/8" plates and 3 pieces of tubing. After talking with several people I think I have a plan. I am going to make the plates out of .25" flat. I will then insert a solid tube through and weld the joints. This makes the entire unit very beefy and I believe it will eliminate the problem. If I ever want more than around 350Hp I'll need to do something like Andy, but that is not my intent for this car.

You can see the old parts and the stock I am remaking these parts from. The origional side plates are 1/8" the new is 1/4". Plus I get to use my boring bar to drill a hole! This makes the bolt tube a solid bar instead of 3 spacers. I had tube stock left over after copying Andys camber adjust setup.