Is there a holy grail thread for shortening lwb to swb frame
 

I have read a few different post about shortening a lwb to swb frame. I think I have seen three different ways to cut the frame. Pretty much I would be cutting out 14" out of the middle right behind the cab. What I have seen differ is on the back of the frame. I have seen cut 3" and also seen cut 6". Which? Also what is the best design to cut the frame and splice back together. I have seen just making 45 degree angle cuts and splicing back that way.

I have also seen what I call the half nazi swatstika type. Then there is the swatstika type and then cut out a diamond shape within that and weld it back in place. Kind of hard to describe. Just looking for the best design or way to cut and splice back together. Also do I need to weld in a glove or inner support plates.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

http://67-72chevytrucks.com/vboard/s...highlight=ccsb

http://67-72chevytrucks.com/vboard/s...highlight=ccsb

http://67-72chevytrucks.com/vboard/s...highlight=ccsb

http://67-72chevytrucks.com/vboard/s...highlight=ccsb

http://67-72chevytrucks.com/vboard/s...highlight=ccsb

http://73-87.com/7387garage/chassis_...lwb_to_swb.htm

here are some I've saved over time, I think the second link is my favorite.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

I'm gonna do mine soon, the "S" cut is what I plan on do'n.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

Thanks but these are all the same link except for the last one.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

Try http://www.73-87chevytrucks.com/lwb_to_swb.htm

Re: Is there a holy grail thread for shortening lwb to swb frame
 

14" between cab mount and bed mount, I think I cut off 5-6" behind, but that is easy, just a straight cut. I kinda eyeballed mine....I would do a Z cut....

Re: Is there a holy grail thread for shortening lwb to swb frame
 

I just cut one this week. 14 inches out of the center and 5 inches off the back. I've done a fair number of frame splices and have always done it the straight way, full penetration welds, and a fish plate on the inside with small fish plates on the bottom webs of the framerails. There's a lot of people on here who will disagree with my methods, but a large percentage of them have never cut a frame in their life and just repeat what they've read on the internet, so take their advice with that in mind. I learned to do it this way from an old truck mechanic as we built dump trucks.

I fit them with about a 1/16 gap between the beveled edges, tack and measure to verify that you have it all straight and aligned, then weld it up. After adding the doubler plates to the inside, I plug weld through whatever holes happen to be there on the outside of the rails also. You can cut your fish plates out of the sections of rails you removed. Most of the time I stick weld them rather than use my MIG. That's just a personal preference though. Whatever you're most comfortable with.

http://i276.photobucket.com/albums/k...d30ca4e14f.jpg

http://i276.photobucket.com/albums/k...18fd783390.jpg

http://i276.photobucket.com/albums/k...E590240FB8.jpg

http://i276.photobucket.com/albums/k...E61F6AFACA.jpg

http://i276.photobucket.com/albums/k...EAB81CA9C8.jpg

http://i276.photobucket.com/albums/k...EBE9B0AA98.jpg

Don't get too wrapped up in all the hysteria. It's not gonna break and send your careening into a bus full of nuns on their way to the orphanage, with a trailer full of puppies behind them. Worst case, you would see some cracking. Keep in mind, the bed adds a bit of a truss factor too since it's bolted in front of and behind your splices.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

Easiest and bestest way is to find a short frame and swap your stuff onto it. Saw one locally a couple of weeks ago for $150.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

Easiest is an opinion. I can shorten a chassis much quicker than going to all the swapping hassle. Plus your frame VIN will still match your can VIN.
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Re: Is there a holy grail thread for shortening lwb to swb frame
 

I agree with TX firefighter 100%. I researched and researched the "best way" and like you I came up with three different "best ways". I happen to live in the RV capitol of the world and I made it a point to look at many frames and chassis everything from class A's to big rigs extended for sleepers. Everyone I saw was straight cut and plated. If its good enough for them!

I straight cut mine. welded on a diamond plate on the inside of the frame. Then took the section I cut out, and made a outside support that I bolted on. bracing the side, top and bottom. Plus I made it where the fuel tank brackets bolt to either side of my splice. Im no engineer but Im confident It aint going anywhere.

http://i571.photobucket.com/albums/s...k/DSCF6199.jpg

http://i571.photobucket.com/albums/s...k/DSCF6200.jpg

http://i571.photobucket.com/albums/s...k/DSCF6201.jpg

http://i571.photobucket.com/albums/s...k/DSCF6207.jpg

http://i571.photobucket.com/albums/s...k/DSCF6212.jpg

http://i571.photobucket.com/albums/s...k/DSCF6213.jpg

http://i571.photobucket.com/albums/s...k/DSCF6227.jpg

Re: Is there a holy grail thread for shortening lwb to swb frame
 

I am thinking of doing this splice here. Do these measurements look right. To me it looks like you are actually moving it 20".

Re: Is there a holy grail thread for shortening lwb to swb frame
 

14" out of the front. thats a fact! How far from the cab never really concerned me. I just made sure I stayed with in the front bed bolt holes, once you get the bed off it will be pretty easy to see where you should remove those 14" The rear is not the same for everybody. I was cutting a 1 ton and only need to take of about 4". If memory serves me correct i could have taken as much as 5.5 or as little as 3.5. I believe the 1/2 ton frames are different. Do you already have the bed? if so just measure your last bed bolt hole back and transfer that number to the frame rail. Its really simple and easy to over think it.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

to answer you question. no your drawing doesnt look right. the frame is shortened 20" total 14" in the front. Find where you want to remove those 14". draw a line down the middle of that. That would be 7" either side. then make your Zcut 7" both ways.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

I didn't think that looked right. I copied it off another thread here someone elses drawing. Thanks for the info.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

And if you ever decide to sell it, you'll be selling a welded frame truck. Many buyers will shy away including myself. I've never seen anyone check the VIN stamped on top of the frame. I have a gantry crane and cab/bed dolly at my shop, I can have the whole swap done in a day with a helper, maybe quicker. Plus it gives you a chance to do any suspension work with nothing in the way before you do the swap.

But, as you said, it's an opinion.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

Frames, beds, cabs, they are too hard to come by around here. I just went up and bought one yesterday for an 86 and it was for a 73-79 and had the shock holes wallowed out and had a plate welded over one of the holes. At this point in time my best bet is to shorten the frame. Not my first choice as ideally I would like to have a 81-87 swb 4x4 factory frame. Too dang hard to come by in these parts.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

Yeah, those of us living in dry southern states tend to forget how quickly things get rusty in other parts of the country :)

Re: Is there a holy grail thread for shortening lwb to swb frame
 

If you ever bring it to nevada DMV from another state they will dam sure check that VIN on the frame. They awalys check frame vin #.

As far as shorting the frame, I did mine last summer. Straight cut , retained saddle tank mounting holes same as rhino and txfirefighter. Used piece cut out as support plating. You will also have to move the rear crossmember forward. My 85 had 8 rivets holding it in. Cut the rivets and use 3/8 bolts. Crazy thing my 85 already had the 8 holes punched in the frame for the crossmember in the forward location. I just moved it forward and bolted in.
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Re: Is there a holy grail thread for shortening lwb to swb frame
 

Where are the numbers at? I thought they were on top of the frame.

I think I am going to go ahead and do the (S)? pattern. I am looking into a shop doing it or I am going to see if my painter will let me do it at his shop. I don't have a bed yet so I hope everything goes well.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

i would definatley use a stick welder over mig while doing this, 1/8 7018

Re: Is there a holy grail thread for shortening lwb to swb frame
 

I've got a nice Miller 250 amp MIG machine, but this antique is often my go-to machine when it counts. I guess it's just a comfort level thing. A 250 amp mig with 035 wire is fully capable of jobs like this without any excuses, but I sleep better at night when I crack open a fresh box of rods and roll out my old Lincoln Tombstone

http://i276.photobucket.com/albums/k...c04c1601ae.jpg
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Re: Is there a holy grail thread for shortening lwb to swb frame
 

I use to have on just like that. Hardly ever used but when I did, it did the job well.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

When I bought it and got it home I researched the numbers on it. It was sold at Montgomery Wards back in the 50s. Here we are sixty years later and it still burns rod as reliably as it did back before most of us were even born. I wouldn't sell it for a 1000 dollars.
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Re: Is there a holy grail thread for shortening lwb to swb frame
 

same thing i have, got it from my grandpa, he had it for as long as i can remember, btw you can still get them $300 at lowes and they are exactly the same, and im the same if the metal has any wieght to it i prefer to stick it rather than use the mig, i guess it sdue to how i learned to weld(think industrial contruction)

Re: Is there a holy grail thread for shortening lwb to swb frame
 

sorry about my copy and paste skill's, here is the one I refer'd to as my favorite.

I have heard differant thing's on the rear cut, if I did'nt have the bed yet I'd hold off on that cut. it is just a cut so it would only take a few minute's once you have the bed there.

http://67-72chevytrucks.com/vboard/s...d.php?t=382503

Re: Is there a holy grail thread for shortening lwb to swb frame
 

your's look's good, what's your opinion on grind'n the weld's down on the out side ?

Re: Is there a holy grail thread for shortening lwb to swb frame
 

Nice welds.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

That's an age old debate. Too much grinding can lessen the strength of the finished product. I figured since its under the truck and out of sight I'd just leave them be.
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Re: Is there a holy grail thread for shortening lwb to swb frame
 

The new ones are somewhat different. They quit using copper windings some years back. I bought mine off craigslist and the guy had a few of them for sale. I lifted each of them and this old one is significantly heavier than the newer ones. He couldn't understand why I'd want to buy the oldest one of the bunch when he had some newer prettier ones for the same price. It's one of those times in life when things went my way. He had a row of them for sale and was asking 80 dollars per each welder.
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Re: Is there a holy grail thread for shortening lwb to swb frame
 

Okay I have a few questions about shortening the frame. When I measure am I measuring off the back of the cab? The little crossmember that is there is throwing me a curveball. If I am suppose to measure off of that then it off the lip of the crossmember of the backside of it. (See pics). Just to see where the lines would be I measured off the back of the lip.

As far as cutting the back of the frame goes. Right now I have about 10.5" from the rear of frame to the first rear crossmember. From what I have read I have to move the crossmember before cutting 3-6" off the rear frame. The issue is that the cross member is pretty much even with the rear spring hanger. I don't feel that something is right. You can see in the photos where everything is located.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

Pics of rear frame and crossmember.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

I laid a large carpenter's square up against the back of the cab and measured back 9 inches to find my cut line. Then, 14 inches beyond that to find my second cut line.

My truck being a 2wd, it has a different rear crossmember arrangement than yours. My crossmember was held into place by 6 factory rivets. Once I removed those rivets, there was a full set of factory holes located about 6 inches further forward. I just slid the crossmember forward and bolted it into those holes.

http://i276.photobucket.com/albums/k...32AD214BC6.jpg

http://i276.photobucket.com/albums/k...35828FD35C.jpg

http://i276.photobucket.com/albums/k...35724EE04A.jpg

http://i276.photobucket.com/albums/k...3562D0523A.jpg

Re: Is there a holy grail thread for shortening lwb to swb frame
 

Have you put the short bed back on it yet. Just wondering if the mount holes for the bed all lined up. I will try the carpenters square and 9" back and compare my lines to yours and go from there. As far as the rear crossmember goes it looks like mine sets where yours does now. I don't think I will have to move it. Thanks.

What made you go with the 9" off the cab? Everything I have seen is 6" in order for the frame holes to line up went mounting the bed. Just curious.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

I chose 9 inches because I read a well done thread on here where a fellow did it that way. I preferred it since that got my weld and splice area further away from the cab yet still enough room away from the spring hangers. I wanted an expanse of space that was easy to work in without having to pull the cab.

As far as the bed, yes I have it in place. Four of the bed mount holes lined right up and the rest needed drilling. I wound up doing it a different way though. I'm running a stepside bed and wanted a metal bed floor so I modified a long wide bed floor and cross members to go into my short stepside bed.

http://i276.photobucket.com/albums/k...99E755E64B.jpg
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Re: Is there a holy grail thread for shortening lwb to swb frame
 

I think that when I cut my frame I am going to cut one side one way and the other side the opposite way. I don't know if it will make any difference but my thinking is that it won't have the same exact stress points. Maybe make it that much more solid.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

this is an awesome thread!!

Re: Is there a holy grail thread for shortening lwb to swb frame
 

not a holy grail as its a sin to cut up a longbed. jesus was a carpenter.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

i know this is off topic, but i am getting ready to do a frame swap, WHERE is the vin located on the frame? i have never been able to find it on any of my trucks in the past. I have found numbers but none of them coordinate with the numbers in the vin.?

thanks in advance.

Re: Is there a holy grail thread for shortening lwb to swb frame
 

Re: Is there a holy grail thread for shortening lwb to swb frame
 

saw this a while back and its straight from GM so i guess this is the real legit way? and imo having a sleeve seems a lot stronger than a zig zag weld with a fish eye plate. I am no expert though
http://i.imgur.com/LnRO0GRl.jpg
http://i.imgur.com/zMcyxcal.jpg