Thread: Pinching model A frame rails at the firewall

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THE FOLLOWING RESPONSE WAS TO A GENTLEMAN FROM IRELAND, WHO WANTED TO KNOW THE PROCEDURE FOR "PINCHING" A MODEL A FRAME AT THE COWL: Hello James---Welcome to Canada---Your not intruding. I am going to assume that you still want the stock width front and rear crossmember, and that you plan on some custom body mounts.---The body mounts are an angle that set on the outside edge of the frame, so if you suck the frame in 1" per side, the outstanding leg of the angle, along with the holes in it will have to be extended by 1" to maintain the same position relative to the body. Since all of the other crossmembers will be removed except the rear crossmember and the front crossmember, you could conceivably use a boat builders clamp at the point where you want the narrowing to occur, and start tightening.---A boat clamp is a pair of castings fitted to a peice of 1" pipe. one casting is the moveable jaw, and can be slid to whatever length you need,then locked there, the other casting is attached to one end of the pipe and has a moveable jaw which is moved along parallel to the pipe with a crank mechanism and an acme thread. (I have a pair and can send you a picture if you want.) You do not say if the frame is boxed or not, (I hope not) and will structure my answer based on the assumption that it is not boxed. The big trick is to be sure that you bend each frame rail by exactly the same amount. I would set the frame up on 4 boxes about 16" high at each of the 4 corners and level it and check for squareness before I started bending anything. Use a plumb bob and a chalk line to establish a centerline on the garage floor that clearly marks the centerline of the frame on the floor. Use an oxy acetylene torch with a big cutting tip or a rosebud tip, and heat one frame rail at a time to a cherry red in a band about 2" wide exactly where you want the bend to be, before using the boat clamp. ---Be especially sure to get a lot of heat into the top and bottom flanges, as this is where the most resistance to bending will be. As soon as one frame rail is cherry red, put the boat clamp on, and start tightening untill the heated framerail moves in the required amount---It will bend very easy when heated to cherry red, and the unheated framerail will not bend. Be very carefull during this operation that you do not move the frame around on the boxes relative to the centerline, as this is your "witness mark". You will need a 24" level, and probably a carpenters square, to measure exactly how much bend is enough. Leave the boat builders clamp in place, and walk away---let everything cool for an hour. go have a beer. Then come back and remove the boat builders clamp. and repeat the heating and bending operation on the other frame rail. Measure, measure, measure, and then measure one more time to be absolutely certain that you have bent both frame rails the same amount, relative to the centerline. Walk away---leave it for an hour. Do NOT quench the heated rails with water, oil, or blasts of air. that should get it done---It wouldn't hurt, if after everything is levelled, but before you start the heating and bending, to place a 100 pound bag of sand on top of the frame rail at each corner where it is supported on the box. This will lessen the chance of inadvertantly bumping the frame with your knee and moving it away from that very important centerline, and will also ensure that the frame stays flat and level during the heating process. I would also put in a temporary support under the frame rail about 12" on either side of the zone where you are doing the heating on each frame rail, so that they don't "sag" under their own weight when heated to cherry red.---Brian (I have added this to my "how to build an early hotrod frame" post)
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And this my friends is a boat builders clamp. I inherited these from my dad. Back in the 1950's, we used to build wooden rowboats.--One a week, all summer long. These clamps were used to clamp the two sides (generally 1" x 16" pine) to the transom of the boat, untill we got it glued and screwed into place. Then came the difficult part---putting a brass woodscrew every 2" all around the perimeter of the boat to hold the plywood bottom on. On a 12 foot boat, that worked out to something like 170 screwnails, all screwed in by hand. (we had no electricity then). By the end of summer I would have a pad of callous 1/4" thick on the palm of my hand, and could arm wrestle and beat kids 3 years older than me when we went back to school in the fall!!---Anyways, they are also great for hotrod building!!----Brian

Just to add to the commentary for historical purposes, Wescott has a dimension chart for this too assuming this was meant to be pinching a deuce frame to match a Model A body; http://www.wescottsauto.com/pdf2/FR-3.pdf

Well actually, Bob, the question was about pinching a model a frame. Of course, the same process will work on a 32 frame.