Thread: Narrowing the frame on my 36 truck

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I am getting ready to install a cut and shortened 8 3/4 Chrysler shur lock rear in my 36 truck. will run four bar system with Coil overs.To do so I need to narrow the back half of the frame. I have several ideas on what to do but I am looking for someone who has already done this or something similar. I will run a shortened bed and full fenders and running boards with a channelled body. I haven't seen any one do this so I am on new ground and just looking for some good advice. I was thinking of using a 2X6 .187 piece of tubing to install from one frame rail to the other right at the place where the frame gets cut and shortened. I will cut holes for drive shaft and mufflers and what ever else. Then using the cut frame rails to weld them in board to the 2x6 tubing at 36 inches apart and also do a maybe a 3 " kick up I would alsowill be using boxing plates for the cut rails. Then build a one inch square tubing to mount fenders and bed sides to. Any body have any advice. I am diffenatley this doing so I am looking for good advice.

sounds like a good plan. Might also want to figure a way to build a fixture that will hold the rear section securely while you do the cutting and fitting. When welding it together, don't try to weld it all at once as it can distort the rails and mess up the squareness of the frame. Some strong, well placed tacks and short welds on the pieces with sufficient cool time will prevent this.... Measure, Measure, Measure....Patience, Patience, Patience.

Is this a '36 Ford Pickup?

I had to narrow the rear for my 36 Chevy truck for multiple reasons. I was real lucky because the factory rails were literally angled all the way to the end of the bed from the front. I figured out where I could chop the frame off so that I could mount frame rails that would carry straight back (welded inside the existing rails...that way I could have multiple places to weld and gusset), which gave me the desired width for the tires. Ummm....I'll have to read your post again. Why are you using 2X6? Maybe I'm miss-reading but I felt like I was going over board with my 2X4 .120 wall tubing. Forgive me now.....I have a terrible attention span. My mind is an ever changing whirlwind. I'll subscribe to the thread so I can check it later.

Dave G

Oh...and by the way...listen to Dave. My shop floor is very flat...level. I thought I could get by without making a jig to hold the frame while welding. Placed some jack stands, tacked the drop arms so theyd stay in place, made some placement pins...etc..etc. Despite carefull tack welds I had a bugger of a time getting it square. Finally did though. But next time I'll be making a jig! I bet I measured that thing 10,000 times. BTW. Those little digital inclinometers are real efective for placing brackets...etc. I dont know how I got by without it. My non-digital inclonometer was off nearly a degree.....or maybe me eyeballs need adjusting.

Dave G

Edit: I re-read what you was talking about on the 2X6 tubing. You meant to use it for a crossmember. Sorry. I used a 2X3 dropped driveshaft crossmember....turned cattywhompus (upside down)....cause it worked out best for the independant rear. Then used 2 1/2 tubing under it. After all the welding was done...I cut the 2 1/2" tubing to match the angle of the drop.

Hope that helps.

Thanks guys I am screwing stantion into the floor and welding crosspieces to hold up and tack the frame to level and square, I was looking for some ideas on gussets and I see some from the pros using only 80 wall tubing that are not cross braced or gusseted, so I am looking for ideas on strengthening the weld especially where the crossmember gets welded to the rails. I don't see how I can do a fish plate at 90 degrees so I was thinking of 1/4 plate on top and bottom or is that over kill.
Some great work below on the pictures thanks for sharing.
Yes it is a 36 ford truck

Originally Posted by KOSDOS

Thanks guys I am screwing stantion into the floor and welding crosspieces to hold up and tack the frame to level and square, I was looking for some ideas on gussets and I see some from the pros using only 80 wall tubing that are not cross braced or gusseted, so I am looking for ideas on strengthening the weld especially where the crossmember gets welded to the rails. I don't see how I can do a fish plate at 90 degrees so I was thinking of 1/4 plate on top and bottom or is that over kill.
Some great work below on the pictures thanks for sharing.
Yes it is a 36 ford truck

Wish I could explain myself....I shouldve taken better pictures. On the rear rails (outboard side of rails...that mounts to the crossmember you mentioned) I left extra material and allowed it to slide inside the original (inboard side) frame rail....mating it to the boxing plates. This allowed me to drill (1/2") multiple holes in the boxing plate to plug weld to the rear rails. Gusseting should be a snap....I'd make my own if I was you. All of those little things start adding up. I was going to use some 2 1/2 round tubing split in quarters but opted for the multiple welding points instead. I feel confident I wont rip the frame in two with the ammount of power and hook-up that I might have on a track even with slicks. After all...like you said....most of these guys are using 2X3 .083 wall tubing. Thats what I used on my 69 Prostreet...but it was never intended to see much street use. After discussing this with many fabricators...I decided to go with the heavier 2X4 11 ga. for daily driving. My factory frame is 11 ga. It just made sense to match gauge thickness. The fella that won me over has been drag racing for years and said that in a daily environment he would suggest the thicker material for longevity. How much are you needing to narrow the frame? Prostreet style? Or just bigger tires? 10" rim? I found these guys ( http://autoweldchassis.com/spec.ivnu and decided to go with them. A couple of suggestionis. Make it known to them that the rails better be real close to matching....as far as the bends. Oh....and theyre not the friendliest folks on the phone but they get the job done. Best dollar spent would be to have them make a pair of full rails with the rails bent in at the rear and the rise added. I went the they're rear rails because I really wanted the factory shaped frame in the front. If I had it to do over.....I wouldve gone with the full rails with a rise built in at the front as well to get it a little lower. If your budget allows I'd go with the full rails. The idea of the 1/4" fishplate may be over kill. You'll have to ask someone with more experience than me. If your welds make good penetration a 3/16" plate should do the trick. Its all about the welds and thier placement. As far as the 90 degree fish plate like I mentioned earlier....make a concave (or is that convex...never can remember) gusset the full length (up and down) of the frame rail. Could use heavy wall rounds split in quarters to make it look as good as it functions.

Dave G

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Thank you for the suggestions. I have checked out the Autoweld stuff I am wanting to utilize what I have cause mainly I am cheap. I don't see anything wrong with the original rails that the 3/16" boxing plates won't cure. The rear frame will be 36" from the outside rails. Thanks this site and others I beleive I have the information I need now I just need to execute which takes a little longer. This Truck is Street Rod but I like the wide ass tires instead of the skinny ones everyone is using now days. I am resolute in doing it my style and not going with the main stream. Thanks KOSDOS (Dave S.)

Thanks guys. I appreciate the input. I have checked some of the stuff you and others recommended and I set to go. Now all I have to do exceute, and being that I work at one of these boob tubes 60 hours aweek my time is limited in actually working on something.