Chassis

chassis

Frame

The stock bugeye is a unibody design, so building a chassis was no trivial task. Uni-body cars flex, causing suspension geometry problems and if the car isn't going straight off the line, it isn't as fast as it could be. By building a steel tube chassis, body stress is reduced; weight is transferred more evenly to the rear where you want it.

The entire chassis and suspension is custom and newly built. The frame uses 2x3”x.083 rectangular mild steel tubing to make the frame stronger yet lighter than a stock frame on almost any modern American V8 powered car. The frame is reinforced with 1¾ x .134 square rectangular mild steel tubing triangulated to form an incredibility ridged design. The frame rails are 12” apart at the front widen to the full width of the car at the cockpit to offer side protection and than narrow in the rear to support the wide tubs and narrowed rear end. All joints are mig welded.

Fortunately I live in a new house and my garage floor is completely level and has no cracks. I built a jig on the floor to lay out the frame, I used a steel cutting blade in a skill saw to cut each frame piece. I than measured and adjusted side to side, front to back top to bottom and most importantly diagonally until the frame sat in the jig 100% square from all dimensions. After that my trusty mig welder came out and I tack welded each joint, measured once more, and than welded up every joint.

The basic frame was now complete and ready to be mounted to the body. As this was originally a unibody design, cutting the floor pan would have resulted in some nasty effects to the body, there would be nothing supporting the body and it would simply twist into a contorted mess.

Instead of cutting the body off of the floor pan, I installed the new frame in the following order: First I slid the new frame under the old unibody, second I tack welded it to key supporting locations, third I cut out the floor pan fourth completed welding the new frame to the body, finally I cut and welded in new floor pans.

It is important to make sure that your loaded center of gravity is as near the center of the car as possible. With two passengers, this car is dead on. With a driver only, the weight distribution is about 60% front 40% rear, this is because of the short wheel base and the big heavy engine up front, an aluminum frame would have resulted in a lighter car and a slightly better weight distribution, naturally a smaller (lighter) engine would have the same effect.

Rear Suspension

The rear suspension was a challenge at first, because of the short wheelbase and the car’s low 5” height (bottom of frame to ground), a four link or a ladder bar would have serious problems with ground clearance and front mounting location. If I were building a strip only car it wouldn’t matter, but this is a street show rod and it needed more ground clearance than a ladder bar or four link would allow. I discovered a system made by Jegs called a Jegster street/strip bars. Jegster street/strip bars. It is linked in the back by brackets welded to the ford 8” rear axle housing connected by a four-link system to a solid rectangular bar that swings from brackets welded to the frame by the transmission cross member. It looks like it was built to fit this application and it offers incredible ground clearance. It also has a feature that allows it to be adjusted for street so it corners like a four link or for strip use so it is ridged like a ladder bar. While this is one of those small car compromises, I don’t feel it is a compromise at all, I would consider using the system on a larger car as well. I am using Koni coil over. coil over shocks in the back and the entire system works quite well.

Front Suspension

Here is a step by step roadmap to building a very cool all polished stainless steel IFS using tubular upper and lower A arms, and coil over shocks and very big 11” disk brakes with 4 piston calipers.

Several years ago I built a complete 2x3 steel tube frame. If you are starting with a stock unibody sprite you will need to fabricate the entire frame from scratch to support the new IFS. If you are planning a V8 conversion you will need this anyway to support the weight and torque. The stock unibody chassis is completely insufficient.

I had Fat Man Fabrications build cross member and shock towers to my specifications and than I simply welded them to the newly modified frame. All geometry is based on Mustang II.

The upper and lower control arms are all polished stainless steel. The shocks are Alden polished coil over, the rack (which has been narrowed) is Mustang II the tie rod ends are polished stainless, the spindles have a 2 inch drop. Brakes are Wilwood with drilled and slotted rotors, polished hubs and 4 piston calipers. The steering column is stainless steel from Flaming River In the end it looks great, supports the weight of the V8 and performs like a new vehicle, a huge change from the stock lever shocks, 6” single piston brakes and single control arm front end.

Tips and Tricks

Welding

I have seen very strong welds that look ugly and I have seen weak welds that look neat. Welding is NOT a compromise between looks and strength, both need to be accomplished. When you start with a clean surface free of paint, rust and oil and your welder is set to the correct heat and speed, its all about practice and technique. Anyone can learn to join two pieces of steel, but a strong weld with a nice appearance is an art that takes practice. If you don’t have experience welding or if you can’t take the time to learn to do it right, I would suggest that you farm it out to someone. You can always drop a new engine in after the car is completed, but you don’t want to be fooling with the welded joints.



   © Copyright 2007. kenvoss.com Last update July 2009