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

[jitteryguy]

Originally Posted by Tx Firefighter

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.



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.

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

[Duster]

Originally Posted by Tx Firefighter

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.













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.

Nice welds.

[Tx Firefighter]

Originally Posted by jitteryguy

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

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.
Posted via Mobile Device

[Tx Firefighter]

Originally Posted by meatwagon83

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)

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.
Posted via Mobile Device

[rs74]

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.

[rs74]

Pics of rear frame and crossmember.

[Tx Firefighter]

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.

[rs74]

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.

[Tx Firefighter]

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.


Posted via Mobile Device

[rs74]

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.

[made2drag]

this is an awesome thread!!

[nekkidhillbilly]

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

[izzy_Britton]

Originally Posted by Tx Firefighter

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.
Posted via Mobile Device

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.

[LostMy65]

https://youtu.be/6o2k6QoERio

[StarDust]

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

[LostMy65]

Found the full pdf
http://www.google.com/url?q=http://w...lDZS3LdKeKIubw

[jjzepplin]

Originally Posted by StarDust

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

This is how I was going to do it AND you can use the piece you cut out for the sleeve with a little modification. Then I found a frame on CL and it saved me a bunch of time. Here in FL they don't check the frame VIN. And as long as the frame is not stolen - Why would it even matter?

[wraprail]

Originally Posted by jjzepplin

Here in FL they don't check the frame VIN. And as long as the frame is not stolen - Why would it even matter?

It matters. If the frame vin doesn't match your title then you would need some kind of paper work for the frame

As for location, on my 74 it was right on top toward the front underhood area.
They only check it here if it's coming from out of state.

[daddyjeep]

I'm a little late to the party here, but I will add my opinions and experience as well. I was sold on the "Z" cut while researching mine and at the last minute decided to do a simpler 45 degree cut. I read somewhere a post from a guy that worked for a company that built wreckers. He stated that the "Z" cut gave them the most problems with longevity. He had two frames come back with cracks coming off of the corners of the "Z". Not real big problems, but problems none the less. The 45 degree cut was a middle ground between the straight cut and the "Z". It gives you a little more weld surface. Feel free to check out my build. I documented my steps pretty well.

[N2TRUX]

Originally Posted by daddyjeep

I'm a little late to the party here, but I will add my opinions and experience as well. I was sold on the "Z" cut while researching mine and at the last minute decided to do a simpler 45 degree cut. I read somewhere a post from a guy that worked for a company that built wreckers. He stated that the "Z" cut gave them the most problems with longevity. He had two frames come back with cracks coming off of the corners of the "Z". Not real big problems, but problems none the less. The 45 degree cut was a middle ground between the straight cut and the "Z". It gives you a little more weld surface. Feel free to check out my build. I documented my steps pretty well.

My guess is those Z cuts that came back were not drilled at the corners. There plenty of opinions on what is best, but my experience has taught me that surface area is important. The straight cut or 45 angle might be just fine, but I would sleep better know my frame had a Z cut.

[KQQL IT]

Originally Posted by N2TRUX

My guess is those Z cuts that came back were not drilled at the corners. There plenty of opinions on what is best, but my experience has taught me that surface area is important. The straight cut or 45 angle might be just fine, but I would sleep better know my frame had a Z cut.

Diesel trucks are stretched and shortened straight with a glove, wouldn't bother me a bit without a Z or even a 45° if I get around to cutting my crewcab it will be straight with a glove several inches either side.