Making a LWB into a SWB - shortening a '55-'59 Chevy Truck Frame & Bed

[53choptop]

Its been a while since I posted, I have mostly lurked and learned. So thought my next post would be a good one. BTW I used glock35ipsc tech post on shortening a '68 LWB as a reference, measurements are different, but his great pics and description helped out alot to get the jist of the task. Thanks glock35ipsc.

This tech shows how to shorten a long wheel base (LWB) frame to a short wheel base (SWB), in this case my 1957 Chevy. This is a 3600 model with a wheelbase of 123.25 inches the SWB 55-59 Chevy have a 114 inch wheelbase.

All the measurements I got off frame dimension manuals online:

http://chevy.oldcarmanualproject.com...esto/56071.htm

for confirmation, I have my friend-Ruben with a 1956 Chevy SWB that measured his truck frame for me at specific rivet points, cab mounts, rear axle centerline etc.

To make a LWB to a SWB, 9.25 inches needs to be removed from the center of the frame and 5 (I need to look at my notes again but I think its 5) inches from the rear frame horns.

This is the patient going under the knife.

[53choptop]

There were several measurement points on the frame and bed I needed, plus wheel base numbers, mostly all other measurements were taken off the manuals and Ruben's 56. I will use these to "cut and paste"

[53choptop]

I removed the bed, rear axle, leveled out the frame with jackstands and a jack. I tried to keep everything level, you dont really have to becasue your cuts will be made using measurements and not levels.

After researching this site and other sites on the web, this is the best way to cut the frame. It distributed the stress and makes the welds stronger. The total measurement is are 18.5 inches from the rear cab mount, this goes all the way to the first rivet on the center crossmember, which needed to be removed.

The shaded portions are what will be removed, I cut 9.25 inches from the bottom 3 inches of the frame and another 9.25 inches from the top 3 inches of the frame on both sides.

[53choptop]

After the cuts were made on both sides, I joined the frame together, re-measured the wheelbase, reference points from the SWB measurements I got from the manuals and my friends truck, re-measured and re-re-measured just to make sure.

Since I removed a rivet from the front of the center crossmember, the crossmember helped in aligning the 2 pieces together; the rear portion of the frame slid into the front portion.

I used a ratcheting tow strap to tighten the frame together, I clamped the frame at critical point on the cuts, top to bottom, inside frame and clamped it all down.

Measured again....everything good.

[53choptop]

An important part of the whole process is making sure your wheel base is right on. I made a mistake of not taking into account the rear end centerline. It was a faded soapstone line, it took me a while to confirm and get the rear end center line again. Make sure you mark everything down. In this picture, you can barely see it, but that black line on the frame right above the rear end center line saved my butt. After I tightened everything down with the strap the wheelbase was right on e .... 114 inches.

[53choptop]

Separated everything apart again, I cleaned up the cuts, beveled the edges for welding, made plates out of 1/4 inch steel (its a 12x6 "diamond" shape) to weld inside of the frame for strength, put everything back together, clamped, tightened and re-measured one last time.

I installed the rear axle, wheels and re-measured the wheelbase now at 114 inches. I don't have pics of the rear frame cut, but all I will do is just measure from the back of the spring mount to the end of the frame and cut the end off that extends beyond the SWB frame measurements.

[nuke1]

very nicely done, i also did a shortened frame on a 58

[53choptop]

Thanks nuke1, I was checking your build threads...really cool too. I see you've done a few lwb shortenings. I also see I am not the only one working in a limited space garage, I like how you arranged the 68 to fit in one end of the garage while you work on it and other things

[entourageguy]

Nice info on an often asked question.
I think the mods should make this a sticky on this forum.

[JML55]

Nice work man, i like the mods. I didn't shorten my frame its already swb but i made short box side from a 7 foot box too.

[nuke1]

Originally Posted by 53choptop

Thanks nuke1, I was checking your build threads...really cool too. I see you've done a few lwb shortenings. I also see I am not the only one working in a limited space garage, I like how you arranged the 68 to fit in one end of the garage while you work on it and other things

thanks for the praise, i do what i can in the amount of space i have, you know what i meen. As for the arranging of the truck, i had to find more room, if only i had and extra.........

James

[DennyB]

Great post James!

[53choptop]

Thanks guys, I am attaching a few more pics of the measurements I used from my buddy Rubens truck for reference. This is probably the most important part of the project.

[53choptop]

Last 2

[kttrucks]

Very nice! Looks like you've got a very solid truck to work on.

Good Job.

KT.

[53choptop]

Thanks,

BTW anybody have one of those No Limit Engineering tech videos "Camaro clip in a 55-59 Chevy" they no longer need? Looking to buy one on the cheap.

[JANJ]

i have a 56 3200 i would like to shorten -- i am in dallas area -- if i brought it to you - being in no hurry - could you do it ?? -- approx cost ???

[53choptop]

Sorry JanJ, I don't do work for others. Thanks for the offer though.

[ChuckDriver]

Thanks for all the great info!! Very nice work too!!

[dan76]

Thanks for the detailed post. Did you do any plug welds or did you rely upon the 1/4" plate as reinforcements?

[53choptop]

don't really understand what you mean by plugging the welds, but the 1/4 inch plate plus the step cut is enough, even some of the factory manuals I have seen show this is the way it should be done when shortening a frame.

[RCbowtie69]

nice job, cool !!!!

[hotrodjoe1952]

very nice mods man, i enjoy good craftsmanship and detail...i am working on my own truck and the frame and bed need to be shorten and your post has given me the direction i need to go...thanks.

[brooksinc1976]

Subscribed. Like the info I just got ----->





for------->

I am sure Ill have some questions if your still on here

[thotfulspot]

That's some hard-core fabrication. The previous owner shortened the frame on mine and I'm cheating by buying a Mar-K box and will adjust the frame as needed. I've got a Porterbuilt suspension ready to be installed. The rear notch and dropmember should make it easier to make adjustments on the frame.

I really wish I was doing the fabrication on mine. I've done all the rest of my projects including another '57 when I was in college. Due to an accident the right side of my body is pieced back together. Instead on a never ending project in the garage, she made me get a shop to do the work while I watch from the sidelines. At least I'm playing project manager and handling all the part purchasing and making the decisions on what is being done. It was supposed to be a birthday present for me this fall. Maybe next year.