January 2010 Archives

I got an early start on Saturday morning with the goal of finishing the main hoop of the rollcage. The main hoop is so called as it is the first component of the rollcage and goes up and over the drivers head and stops the roof collapsing in the case of a rollover.

I probably spent a hour with Bend-Tech EZ on the verify page which allows you to pick any two points on the tubing and view the verticle, horizontal and direct dimensions between the points. I wanted the hoop as tight to the roof as possible, while having 1" of clearance between the body and tubing. The main dimension I was tweaking was the top width and overall height which are critical to getting it up close to the roof while being as wide as possible.

One tool I've found invaluable is this angle finder which shares the same radius as the bender die. It helps me visualize how the hoop is going to fit. I have a friend (Bill) who is some kind of genius (Idiot savant?) when it comes to picturing in his head what angles are required for custom parts like rollcages and header pipes, and in fact he bent up the original main hoop that was in the car previously and made my headers, but I am not so talented and have to use software and other aids.

Time to start bending. Measure and mark the tubing where Bend-Tech EZ tells you to, pull the tubing into the bender and start bending. First bend is 26 degrees, second and third bends 68 degrees and another 26 degree. Each pull on the handle bends about 5 degrees, and the tube will spring back 2 or 3 degrees. The bender has a degree wheel on it which lets you know when you are approaching the angle but don't rely on it to verify the final bend, lay the angle finder over it and take your time.

After cutting the hoop to the correct height and test fitting I can now say I am a believer in Bend-Tech EZ. The hoop fits absolutely perfectly. It could not have gone any better. It is tight up against the roof, has 1" of clearance to the doors and has enough clearance on the crossmember to allow full welding around the tube. If you have a car that nobody makes a rollcage kit for, get a bender and Bend-Tech EZ! I've run out of tubing and next I'll be designing the halo and A pillar bars. All the other bars should be straight pieces.

Clearly someone is reading this journal as I got an email asking what the hell I've been doing for the month of January and the short answer is, not much. I've been procrastinating because the next step involved making room around the tubing bender and buying tubing. But today the sun was shining so I told the boss I was taking the afternoon off to get started on the next phase of the project, the rollcage. After my enclosed trailer argued with a Semi truck, I've decided to park it and just use it for storage. I moved a bunch of stuff out to the trailer and now I've got room to swing the bender handle.

The tubing I am using is 1.625" 0.120 wall DOM tubing. It runs about $5/foot at Alro Steel. DOM stands for Drawn Over Mandrel and is a step up from welded seam tubing and is recommended for any tubing that will be bent. It starts life as welded seam tubing and is then put through an extra process (the mandrel) which ensures a consistent wall thickness. The size and wall thickness will be IHRA and NHRA legal for a full 14 point rollcage.

The bender I am using is a Protools 105 with a 6" radius die. Its a manual bender but works great for the money. I have it bolted to the floor with concrete anchors. It takes about 5 minutes to make a 90 degree bend. Don't bother with those cheap chinese hydraulic benders that push up on the tube, they will kink the tubing, trust me I know.

I am an avid viewer of Extreme 4x4 and the other PowerBlock shows, where I saw them using software called Bend-Tech Pro. The software allows you to model rollcages or entire chassis on the computer and it will calculate and print out the cut length, bend angles and bend locations of every component of your project. The EZ version is reasonably priced and is all I need for this project so I decided to give it a try.

The first task in Bend-Tech EZ is to calibrate the bender. Without going into specifics you bend up a 90 degree piece of tube, measure it, and calculate the Center Line Radius of your die. The software uses this figure to calculate how much tubing is required for each bend. Once calibrated, you select a template for the piece you are bending and provide the outside dimensions. I am starting with the main hoop as everything else is tied to it. With all the measurements insert I can see that I need 126" of tubing and have all the angles and bend locations. The verify option allows you to see the distance between any two points on the hoop which is great for double checking your work. A $5/foot for tubing I think this software will ultimately save me time and money by preventing screw ups. The following picture is my actual hoop.

Tomorrow I put the software to the test and bend up the main hoop!

Todays goal was to have the Monaro back on all 4 wheels. That meant finish welding the crossmember, frame rails and upper shock mount. I played around with the welder and some scrap to find the best heat and wire speed to get a good bead on the .056" thick box steel. Making a nice weld on the bench, and doing it while lying on the floor in tight confines are two different things but after an hour or so I had good strong welds that I can live with. I then assembled the rear housing, axles, wheels, ladder bars, shocks and rolled it all under the car and loosely bolted everything together.

Dropping the car down onto the rear wheels I can tell I am going to have to remove the inner wheel wells. I was hoping not to have to do this but it will give me more room to work and I'll fill the holes with lighter aluminum wheel wells. The wheels are sitting about 1/2" too far to the rear, but the adjustability in the ladder bars will be able to correct that. Getting the car back on its wheels was a nice milestone to hit and I can now move it around the garage on dollies. The rest of the work I can do on the lift as all the critical components are welded in place.

I spent the rest of the day unloading the Ute and moving trailers around. I wasn't able to get it started because of the cold and a weak battery. The oil looks kind of suspect too, oil isn't supposed to look like mud. But small block Chevy's grow on trees around here so I'm not concerned about the mechanics. The body is pretty straight with some problem areas. It really needs some body work and new paint, but is in good driving condition. My problem now is not enough space in the garage. Hopefully the Ute will start tomorrow and I'll be able to move it and the Torana to the front of the garage and put the Monaro up on the lift.