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> Street Fighter 1966 Ford Mustang, Part 15
post Aug 24 2010, 11:46 AM
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Project Street Fighter Chassisworks Rollcage Kit - Cage Dance
Project Street Fighter Gets A Strength Booster With Chassisworks' Rollcage Kit.
From the July, 2010 issue of Popular Hot Rodding
By Liz Miles
Photography by Liz Miles

A rollbar or rollcage serves two purposes: One is to accommodate the safety rules of a sanctioning body, and the second is to increase the car's rigidity. Both of these are important reasons to add the tubing, but because our '66 Mustang's primary function is a street car, improving the car is a higher priority than satisfying the tech inspection for a race. This '66 will see the track, but in an open-track non-competitive situation where a 'cage isn't required, let alone measured or inspected.

All Mustangs are of a unibody construction, meaning there isn't a separate frame assembly, but rather it's formed into the sheetmetal structure of the body. This makes it cheaper to produce and lighter overall. This also makes it susceptible to body twist, which is inherently bad for performance and for the car.

Step one is to fit the plates that the tubing will connect to the floor with. The front plates are a simple fit that sits flat on the floor up to the edge where the firewall connects.

To make this project an easier pill to swallow, we wanted something that was pre-bent, so that we'd be responsible for just cutting, fitting, and welding. We found our kit in Chris Alston's Chassisworks' catalog: It's pre-bent to fit '64-68 Mustangs and '67-68 Cougars. It's made from 1 5/8-inch HREW (hot rolled, electric welded) steel, but it is also available in DOM (drawn over mandrel) for a higher price. For our purposes, it made more sense to go with the first option. The main hoop, windshield bar, and front bars were pre-bent. The rest of the tubes needed to complete the 'cage are straight, and were provided in extra-long length with the kit. This way we've got a little freedom on how we would like it to fit. When you don't need to follow a rule book, you can tailor the fitment to your own needs. In our case, we wanted to retain the back seat unmodified, and have the front driver and passenger seats easily accessible, since above all it's a street car. To do this we would use Chassisworks' swing-out kit that allows the door bars between the main hoop and front bars to swing out.

As far as the installation goes, this is not your mom's arts and crafts project. This was an intense project that required a lot of work and patience. Since the Mustang's move to Northern California, it resides at Dominator Street Rods in Tracy. Here, the youngest of Dominator's staff, Tyler Jones, helped us out a lot. Much of this project is a two-person job; you'll need to have one person hold a couple of bars in place while the other tacks it in with a welder. The end result was much nicer than we had braced ourselves for. One thing we were concerned about was discovering how well a "pre-bent" kit would fit, and it fit pretty darn well; the problems we had were self-produced. You can expect to spend about three eight-hour days on this to get it from the shop floor, to painted and in the car, with a difficulty level of seven out of 10.

When cleaning the metal to prepare a fit for the main hoop's plates, we discovered some rust damage. Before going any further, we repaired the floor by MIG welding in a patch panel.

The place where the main hoop meets the body isn't flat, so we formed the plate to match its contours. First, we marked where the bends were in the floor onto the plate, and then bent them in a hydraulic press.

The main hoop's shape was spot-on. The only thing we had to do was fit it to the plates we just bent. The main hoop lands right on the bend on the plate, so we shaped the bottom of the tube to match it with a grinder.

The front bars go from the main hoop to the windshield along the A-pillar, and to the floor along the kick panel. These were pre-bent and only needed to be shortened and notched. The most crucial part is where the tube bends at the dash. Make sure the door closes and the dash pad doesn't get pinched.

We used a 1 5/8-inch hole saw (the same diameter as our tubing) in a mill, but you could easily use a jig with a drill press to achieve the same cut. This is called fishmouthing because the shape of the cut tube resembles a fish's open mouth.

It takes years of practice to get the notching right the first time every time, so when you're a little bit off, a sanding disc or die grinder is your best friend. Once we finished fitting the front bars, we tackwelded them onto the main hoop and the front plates.

This is our last pre-bent piece that goes between the front bars at the top bend. This tube has two slight bends in it to follow the roofline. The important thing to keep in mind for this fit is that the two ends need to be cut at exactly the same angle. For the next step, we need them liberally tacked in; we welded it about 3/4-inch on two opposing sides of the tube.

In order to weld the top of the windshield bar, we cut the tacks on the main hoop and front plates and dropped the whole assembly down.

This is what a perfect fit looks like. It may not happen every time, but the closer you can get it, the easier welding will be, and the nicer it will turn out.

Take your time for all of the welding on this project. Putting too much heat into the metal can warp it dramatically. We used a Lincoln Electric Precision TIG 375 at Dominator's shop, but a more affordable 185 would have done the trick. If you don't have access to a TIG machine or welder, a MIG welder can be used in its place.

The back bar location was totally up to us. Since being NHRA legal wasn't a big concern for this project, we decided to aim them to where the wheelhousing and package tray support meet-the strongest place short of the suspension mounting points. We made cardboard templates first, and then cut them out of metal. We shaped the bottom portion by clamping it in a vice and beating it with a hammer.

First, we fit the rear of the back bars to the plates we just tacked in and determined the angle it would sit, then set it up in the mill at that same angle since the main hoop sits exactly 90 degrees to the floor.

With the plates welded into place, it's time to weld up the rest of the 'cage. Because heat can move the bars, only weld a small part of each joint at a time. It will take hours to complete this step if you do it right. Be extremely careful with your heat where the bars are close to the headliner. Most of the time we could shield it with a piece of scrap aluminum, but we still managed to burn a couple holes in the headliner, oops. Gorilla tape anyone?

The idea is to have the rear bar look as if it were an extension of the front bar joining the main hoop at the same place. When we were happy with the fit, we tacked it in place and repeated the steps on the other side.

While the 'cage is still only tacked, we welded in all of the plates. About 90 percent of the welds were TIG, but we used a MIG welder for some of the areas where the metal was extra thin. Don't expect these welds to be the most beautiful you've done. They were the most difficult parts to weld on this 'cage because mating thin metal to thicker stock is tricky.

We left the harness bar tube for this point because it makes climbing into the back seat area a lot more difficult once it's in place. This was the only tubing piece that was 1 1/4-inch diameter. Using the same 1 5/8-inch hole saw, we cut it to fit inside the main hoop where the first bend from the base started. The ground clamp made a good holder for tack welding

The Chassisworks swing-out kit includes all of the hardware you will need to make your swing-out door bar's pin and hinge. Since the door bar should meet the main hoop someplace between your elbow and shoulder, it will make climbing over it really difficult unless you use these.

The lower part of the door bar needed an extension so that the hinged part would clear the kick panel. To find the angle we needed to fishmouth this tube, we added the front bar and door bar angle, then cut the extensions.

The door bars need to be fit and welded last because it's crucial they fit perfectly-welding the 'cage can move things around enough for them to bind. We ground down the lower inner edge of the tabs that weld to the main hoop at an angle, so it would have a nicer fit for welding. Then we tacked and welded all of the pieces together with exception to the tube on the hinged middle piece, as shown in the photos. Once that was complete, we welded the middle bar together.

It's all done! Here's our six-point rollcage that has dramatically strengthened the body. Sorry rear seat passengers-you'll need to do some climbing!

The plan was to paint the 'cage in Dupli-Color's trim black after using their gray primer. After the primer was on, we fell in love with the contrast between it and the interior and exterior colors, and decided to make the final coat Dupli-Color's medium gray general-purpose spray.

The car $3,800
Battery replace and relocation (11/08) $299
Radiator and fans (12/08) $1,398.12
Spindles, front brakes, wheels tires (1/09) $3,067.04
Trunk rehab and toolbox (2/09) $40.48
Rack-and-pinion steering, column, and wheel (4/09) $3,012
9-inch rear and brakes (5/09) $4,631.02
Rear suspension (6/09) $2,918
Front suspension (7/09) $3,034
Engine bay cleanup with engine sale (8/09) -$394.75
Smeding 427 Windsor (9/09) $9,995
Keisler five-speed swap (10/09) $4,181.55
Paint & body supplies (3/10) $1,607.85
Engine brace (6/10) $459
Rollcage (7/10) $628.95
Total: $38,677.26

Chassisworks HREW six-point 'cage kit $359
Chassisworks swing-out kit PN7030 (2) $238
Misc. welding supplies (gas/filler rod) $15
Dupli-Color primer and paint $16.95
Total: $628.95

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