TECH: Making a LWB to a SWB - cutting a '55 - '59 Chevy Truck Frame

TECH: Making a LWB to a SWB 1955 to 1959 Chevy Pick up

This tech shows how to cut a long wheel base (LWB) frame to a short wheel base (SWB), in this case a 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/chevyresto/56071.htm

for confirmation, I have a 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 inches from the rear frame horns.

This is the patient going under the knife.

 

These were the measurement points on the frame I needed, plus wheel base numbers, mostly all other measurements were taken off the manuals and Ruben's 56.

 

I removed the bed, rear axle, leveled out the frame with jackstands and a jack, this pic was taken right before I placed large jackstand at the rear

After some research this seemed to be 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.

 

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.

 

Great post more pics please. And what about the bed? This needs to be in tech library.

 

Separated everything apart again, I cleaned up the cuts, beveled the edges for welding, made these 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 yet, 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.

Next installment the bed……..

 

Thanks Hot Rod Ron

Its pretty straight forward procedure, I am planning to do the bed after I come back from vacation, a week maybe, its probably easier to just buy a SWB bed, but where is the fun in that,,,besides the bed I have now is in alot better shape than some of the ones I have seen.

 

I totally agree and will look forward of more post. To make it easy just post on this thread of the whole build of your truck. What are you other plans for the truck?

 

This is great. I just had a '65 Chevy LWB Fleetside given to me, and I'd like to shorten it, but didn't know where to begin. Now I do. Thanks!

 

Excellent tech article. I know you can either replace the bed or shorten the original.

Keep posting these stories. Way cool.

 

Thanks arkiehotrods,
Merry Christmas..... this should help you out
http://67-72chevytrucks.com/vboard/showthread.php?t=123624

 

Hey HRR,
I plan just to keep this thread going, I have a camaro clip ready to go, this is an all original truck, so I have a solid start.

Still got my paws in this thing (53 Olds) so the truck will be an on and off project, but I am stoked I got it started, it seems like an easier project.

Here are some build threads of my Olds,,,4 door to a 2 door conversion
http://www.jalopyjournal.com/forum/showthread.php?t=41987

Hey RGV,
I am a La Joya native, I'll be down in the valley for Christmas. Moved about 7 years ago.

 

Why not just find a short wheelbase truck? I have just been in the US for three months and couldn't find the long 59 truck that I wanted.

 

I knew this question would come up, it always does, why not just buy a 2 door instead of cutting up a 4 door, why not just buy a short wheel base....depending in the region you live in just "finding" a short wheel base frame is not that simple. Some people will not part out trucks, so why buy another whole truck? there are several other reasons; cost, ease of procedure, truck is kept in tact, learnign process, being able to write up tech posts on the HAMB, etc.

Besides, wheres the fun in just buying everything.

 

Great thread. If anybody is leery of this frame shortening method, start peeking under trucks you see with standard cabs and 10-14ft flatbeds. This is exactly how most dually flatbeds are lengthened, and they see far more abuse than any hot rod.

 

Very cool, this is just what I was looking for

 

Awesome post!

 

Exactly, even the Chevy manual:

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

has pages on how and where the 1 ton frames are extended, by how much and what types of filler plates were used to strengthen them, of course the standard procdure is to extend them for work purposes, not shorten them for fun.

I love me too.

 

Nice job, I have been thinking of doing the same to the F-truck. You had the same idea I did with stepping the cut. I may get to mine one of these days.

 

Then what would you do with this one? It looks like the thing this ugly duck needs to me ..............Theres always one in every crowd, this time its you 97.............or wait, maybe its me (just kidding)
I done a 56 ford like this. Its much easier and less expensive than trying to change motor, trans,cab etc. etc. on to a short bed frame and its using what you already have

 

exactly

 

Nice job! There are a TON of long bed trucks out there that are Cherry builders... but just have that ugly ass long bed on them...

If you're going to put a Camaro clip under one of those Chevies... I always thought it would be eazy to just move the body mounts rearward (drill out rivits and then weld them back on further back on the frame)... then you'd just whack the frame off in the front and graft your Camaro clip on! Instand short bed, and a slam-o-ram with one of the best front suspension swaps for these trucks!

Sam

 

Here are some of the SWB measurements from my friend Ruben's 56 Chevy truck.

What i did was compare my LWB measurements and used that to know how much to cut.

 

awsome thread lots of good tech.

 

Please place on the Tech Month Tech List.

 

Great post.

 

Here is an update of the SWB conversion: Cutting the Bed

I made sure the bed was square on the jack stands, because the bed frame rails were not too helpful because the bolts had rotted off.

Once it was square, I reinforced the bed with scrap angle iron and rectangular tubing, this is very important to make sure the bed stays square and does not flop on you when you cut it.

Removed the bed steps.

 

Once square, I started the measurements, I used the measurements from my buddy’s truck to cut the bed. I took measurements from his bottom front stake pocket to the fender and used that as a guide to measure upwards on mine, remember the fender is not straight at the bed side, it bulges forward, so you need to take the measurement of the bottom fender to stake pocket of the SWB, THEN take that and subtract it from the LWB front of the stake pocket to the back. I know it does not make sense, hopefully the pics help.

Once measurements are made, the front bed panel is bolted off

The bed stake pockets spot welds are drilled out, with a little persuasion, chiseled apart

Now you have a bed without the front panel and bed stake pockets.

 

The cutting begins.

I measured and cut did both sides. The drivers side had a spare tire mount, I just removed that.

I cheated a bit, I did not fold the edge in when the panel bolts onto the pockets, banging on the bed side to make that L shaped edge was going to be problematic, so I cut the edge and ended up welding it to the bed pocket.

I welded in the drilled out spot welds to the bed side

I bolted everything back together.

 

The rear portion of the bed was a doozy.

I reinforced the bed right behind the tailgate, removed the tailgate and started measuring. On the rear, cut the entire rear section of the bed right where the spot weld lip is at and just slid it forward.

Separating the sections separately was going to take too much time and probably going to cause more damage than good.

I didn’t take as many pics as I should have but you can see where I cut, slid forward, clamped and welded. I left a 2 inch lip inside the bed that slid over the stake pocket and welded that in.