Race-Track.com Renegade Buildup

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Installment Number four: You should have a bare frame now.

    The main hoop sits in the frame rails.
Now that you have removed the frame from under the body and you rolled back into your garage; you are ready to prep the frame for the cage install. You should have all the dirt, rust and barnacles removed from the entire frame. The time you took to do this will pay off from now on. It is easy to see why frame preparation, it takes a lot of time to do it correctly, can make the difference in how your racecar will perform week after week. I have said this before and I say it again, the motor makes it go, but the chassis makes it go fast. You must weld all the original factory seams. The chassis on this car was not meant to be under a racecar off the assembly line. It is up to you to make the chassis as strong as possible within the rule book (plus or minus a few gray areas). The picture below details the frame after cleaning and wire brushing. Air was blown through the frame rails to clean the dirt out before welding and overall painting. The use of a high gloss 
enamel will not only aid in appearance but also allow you to spot any stress cracks in welds or see fluids such as engine oil and brake fluid leaks that you could develop while racing. Don't try fooling yourself into thinking that no one cares about a small oil leak. Just watch how fast that "black" flag comes out for you if you don't. Finding the source early on could just save you a win.  You can also take time to examine the frame for any possible damage. The thing to look for is rust and poor repair work that may have been done on the frame by a local garage. I might suggest you take a few photos of the bare frame.

 The frame is brushed, welded and painted.

The chassis can be lifted up and the frame rolled out from under the passenger compartment. You can take a few minutes to blow out all the dirt and road gravel that has accumulated in the rails over time.

 String the center section to check square.
Let us prepare the center section of the frame for the main hoop. You may use the dimensions shown below. Remember that the driver height and leg length will factor into this measurement. I suggest you add one inch for a 6 foot driver. Add the difference only at the (A) measurement. This will set the cage rearward and allow more head room from behind for the seat arrangement. Use a template (1 3/4) and spray paint the frame where the hoop and bars will be cut into the rail. You must center the starter hole (3/16) over the paint mark and drill. Insert a pop-rivet and tighten down (do not "pop"). The stem will be used for stringing the car to check roll cage square. Now measure diagonal across the 2 sides. If they are the same you are in square.  If not you either measured wrong or the center section of your frame is out of shape The rail measurement from the window bar center (the pop-rivet stem) to the mail hoop center must be 42 3/4 inches.

We HIGHLY recommend the use of a professional chassis builder. However, in the racing communtiy, there are many of us that would like to "Do it myself". The following is an illustration of how you might install a "Do it yourself" kit from CSC.
Keep in mind that the door bars are the same sizefrom top to bottom and therefore the 41 inches inside to inside must remain vertical from the bar to hoop bottom to top.  Note:  Gary is  
setting the door bar to check an angle to the frame rail. He will do the same from top to bottom after the main hoop and the window bars have been set and tacked. No final welds should be made at this time. I used a 1 3/4 hole saw to cut the frame rails. You should notice that on a GM frame the rail will be cut into the notch. Your main hoop and window bars should pass down through the rail to the floor. You will add strength to this area during the final weld after the body is back on the frame.
A note about cage kits: Not all are the same, however by NASCAR mandate they must be 1 3/4 - .095 mild steel tubing.  Check your track for local rules. The CSC cage kits come bent and notched. If you have equipment to do just that there is no reason for you to be reading this article. The CSC kit is recommended by racers because of it's ease of install and, when built correctly, great safety integrity. Don't fool yourself safety is first and last on your racecar "to do" list.  
 "We cannot emphasize enough how important this stage is."

 From the A-frame ball joint grease fitting.

 The cage must pass through the frame rails.

Frame Dimensions: 1978-1980 Monte Carlo (mid size GM) 
Driver: 5 foot 6 inches tall with average leg length.
(A) 30 inches from the upper A-frame grease fitting to window bar.
(MARK) and add 1 3/4 inches for the pipe dimension. Total = 31 3/4 inches from A-frame.
(B) 41 inches inside measurement between window bar and main hoop.
(MARK) and for the main hoop dimension. Total = 72 3/4 inches from A-frame. Now add 1 3/4 inch.
(C) Mark this 12 1/4 inch dimension from inside to inside for later use. 

Next Time: More cage development and we mount the rear end under the car.
Disclaimer: The article here was written as reference for novice builders of the RENEGADE division racer only. 
No guarantee of success is implied. Racing can be a dangerous sport and safety must be the number one priority of any builder.

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© 2002

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