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Slander

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I am in the planning stages to build a new frame aft of my cab mount on my 1st gen Tacoma. It's plated, has a bunch of rust holes and in general is a rusty flakey shit show, it will be easier to start fresh back there. I'm thinking 2x3 3/16, I built my front frame section out of this when I did my sas and it's been working great. The plan is to build new rails and most likely run the factory bed as everytime I think tube bed I just go back to running the factory bed so I can haul shit, probably will have some sort of roll bar back there as a foundation of a future cage. I'm also looking at raising the fuel tank and keeping it on leafs for now.

A few questions: I probably need some flex in the frame, is 3/16 over kill for a fully boxed rear frame? Can I step it down to .120?
I will probably have at least 3 crossmembers back there, is this a situation where triangulation isn't always better? I was kidding around the idea of just an "x" right where the factory spare tire would have went.
I will have factory frame sections running from the rear cab mount to the forward cab mount, roughly 4.5ft as that's all good metal.
 

rockota

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I am in the planning stages to build a new frame aft of my cab mount on my 1st gen Tacoma. It's plated, has a bunch of rust holes and in general is a rusty flakey shit show, it will be easier to start fresh back there. I'm thinking 2x3 3/16, I built my front frame section out of this when I did my sas and it's been working great. The plan is to build new rails and most likely run the factory bed as everytime I think tube bed I just go back to running the factory bed so I can haul shit, probably will have some sort of roll bar back there as a foundation of a future cage. I'm also looking at raising the fuel tank and keeping it on leafs for now.

A few questions: I probably need some flex in the frame, is 3/16 over kill for a fully boxed rear frame? Can I step it down to .120?
I will probably have at least 3 crossmembers back there, is this a situation where triangulation isn't always better? I was kidding around the idea of just an "x" right where the factory spare tire would have went.
I will have factory frame sections running from the rear cab mount to the forward cab mount, roughly 4.5ft as that's all good metal.

If you only back-half, you'll have plenty of flex under the cab to cause cracks and rip the skins...

so you'll be good.
 

chaplinfj60

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i did 3/16 back in 2015 i would not even worry about it. lots of people do it. it will be fine and plus it will out live the rest of the frame. gives you solid mounting points for anything you need also.

cheers
20160206_104639.jpg
20160101_154945.jpg
20160227_163101.jpg
 

rockota

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If you only back-half, you'll have plenty of flex under the cab to cause cracks and rip the skins...

so you'll be good.

And this was both sarcasm and fact. If you're going to go through the effort of building the front 1/2 and now back 1/2... just replace everything under the cab. That's where you'll see a lot of flex... And if wheeled hard enough, you'll likely see cracks at the body mounts....
 

Slander

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And this was both sarcasm and fact. If you're going to go through the effort of building the front 1/2 and now back 1/2... just replace everything under the cab. That's where you'll see a lot of flex... And if wheeled hard enough, you'll likely see cracks at the body mounts....
Are you talking cracks on the frame side or body side? Shouldn't my 20yr old shitty rubber body mounts be eating up that flex? (Sarcastic and partly serious question there)
 

rockota

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Are you talking cracks on the frame side or body side? Shouldn't my 20yr old shitty rubber body mounts be eating up that flex? (Sarcastic and partly serious question there)

you'll be transferring the flex that used to go across the entire frame... to a ~4' section in the middle. 01Tundra did similar... he ended up with cracks.


I think if you're going to go any stiffer than stock, you might just as well replace the section under the cab. Probably won't take any more work than what you're already starting on. And you'll get rid of any residual rust/rot.

or by my frame... with everything attached. :flipoff2:
 

Slander

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you'll be transferring the flex that used to go across the entire frame... to a ~4' section in the middle. 01Tundra did similar... he ended up with cracks.


I think if you're going to go any stiffer than stock, you might just as well replace the section under the cab. Probably won't take any more work than what you're already starting on. And you'll get rid of any residual rust/rot.

or by my frame... with everything attached. :flipoff2:
I can get a new frame built for under $3k, so $3k for your inoperable truck!!:flipoff2:

Keep the info coming, my goal is to fix this POS as quickly as possible and not cause too many serious down stream effects. As nice as a full frame swap would be, knowing me that would be a year long project, but if that's the most logical way to go then so be it.
 
Last edited:

Slander

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i did 3/16 back in 2015 i would not even worry about it. lots of people do it. it will be fine and plus it will out live the rest of the frame. gives you solid mounting points for anything you need also.

cheers
20160206_104639.jpg
20160101_154945.jpg
20160227_163101.jpg
How many more crossmembers did you toss in the back when it rolled out?
 

rockota

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I can get a new frame built for under $3k, so $3k for your inoperable truck!!:flipoff2:

Keep the info coming, my goal is to fix this POS as quickly as possible and not cause too many serious down stream effects. As nice as a full frame swap would be, knowing me that would be a year long project, but if that's the most logical way to go then so be it.
you're missing a significant digit in your offer. :flipoff2:

you'll be able to back 1/2 faster...

But it'll ultimately take you more time when you have to go back and fix it...
 

chaplinfj60

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a bunch, but because i needed them for shock mounts or tool box mounts or what ever. i made adjustable shock mounts too 2x2 square to the rescue. lol

zoom in on the first pic i even made a cross member the the center bar of cage goes down to out of 2x2 1/4 wall square. i went thru so many changes and the tubing did not care, just cut off, grind smooth and redo. thats another thing that was nice
 

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Slander

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you're missing a significant digit in your offer. :flipoff2:

you'll be able to back 1/2 faster...

But it'll ultimately take you more time when you have to go back and fix it...
I stand by my offer as I saw it personally in non action:flipoff2:

I really enjoy using the truck and hate working on it, so I don't want to be chasing issues all around.

chaplinfj60 thanks for those pics!!
 

chaplinfj60

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i would do .120 wall now, hindsight being what it is. especially now considering steel is 3 times as high as it was a year ago or even less than a year.
 

YotaAtieToo

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I did 2x4x120 for my rear frame on my 4runner.

I think it worked perfectly, the frame was 2.25x4 where I tied in, so it made it easy. Never saw any cracking body or frame. I'd do it again.
 

Oddball

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A stock frame is made of two C channels, roughly 1/8th thick, welded together to form a box. But they new it wasn't good enough, so they added an extra layer in key places. If you know what to look for, you can see where rust jacking between those layers bulges the frame.
 

bdkw1

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2x4x.120 is plenty if you are caging it. Some gussets where in key spots where high load things attach and it will live a long time.
 

YotaAtieToo

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A stock frame is made of two C channels, roughly 1/8th thick, welded together to form a box. But they new it wasn't good enough, so they added an extra layer in key places. If you know what to look for, you can see where rust jacking between those layers bulges the frame.

I think you're being generous on the thickness. I'm not too familiar with taco frames, but my understanding is that they are more flimsy than previous generation pickups. The frames on my 90 4runner was more like 0.100 wall out side and 0.080 inside. :laughing:

2x4x120 box as a structure is more than strong enough for a frame. A stock samurai frame is 2x4x065 or something ridiculous, and although they are lighter they seem to hold up extremely well, even with bigger parts and tires added. But as mentioned, you need to take care in your method of joining it with the stock frame.

Most focus on fish plates, but adding material to the top and bottom is just as, or more important. A structural I beam is a good example, as well as the 2 C channels on the stock frame. Carl jantz had a sweet thread about this and where to more material was critical or not.

One downside to 120 wall is that it's can easily dent where it's exposed to rocks. Once that happens, it can be a huge weak point. With the last 2 points, I've always thought that adding a piece of 1/8" flatbar to the bottom of the frame would be a good idea. 1 piece that runs under the stock frame and onto the new frame would be ideal.
 

bdkw1

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I think you're being generous on the thickness. I'm not too familiar with taco frames, but my understanding is that they are more flimsy than previous generation pickups. The frames on my 90 4runner was more like 0.100 wall out side and 0.080 inside. :laughing:

2x4x120 box as a structure is more than strong enough for a frame. A stock samurai frame is 2x4x065 or something ridiculous, and although they are lighter they seem to hold up extremely well, even with bigger parts and tires added. But as mentioned, you need to take care in your method of joining it with the stock frame.

Most focus on fish plates, but adding material to the top and bottom is just as, or more important. A structural I beam is a good example, as well as the 2 C channels on the stock frame. Carl jantz had a sweet thread about this and where to more material was critical or not.

One downside to 120 wall is that it's can easily dent where it's exposed to rocks. Once that happens, it can be a huge weak point. With the last 2 points, I've always thought that adding a piece of 1/8" flatbar to the bottom of the frame would be a good idea. 1 piece that runs under the stock frame and onto the new frame would be ideal.

Hey, Samurai's are a beefy .095. It's really odd that all the tubing on them is imperial sized.
 

Slander

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Slander what dimension is the frame where you plan to splice? I'd try to match that atleast in height. Should be closer to 5" tall under the cab, I think?
Rear most body mount. I would pie cut it a bit like I did for my front frame chop if it didn't fit. There's a shop by me that makes mandrel bent custom frame rails, I'll.probably pay a visit to them and see what they can bend up for me.
 

YotaAtieToo

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Rear most body mount. I would pie cut it a bit like I did for my front frame chop if it didn't fit. There's a shop by me that makes mandrel bent custom frame rails, I'll.probably pay a visit to them and see what they can bend up for me.

A mandrel bent piece of 2x4x120 would be the tits.

I wonder if you could chop the old frame off and take it to them?
 

rockota

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Rear most body mount. I would pie cut it a bit like I did for my front frame chop if it didn't fit. There's a shop by me that makes mandrel bent custom frame rails, I'll.probably pay a visit to them and see what they can bend up for me.
If you’re going that far….

Do the entire frame…. Dammit
 

Slander

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A mandrel bent piece of 2x4x120 would be the tits.

I wonder if you could chop the old frame off and take it to them?
I would drive my POS there and get some consultations.

The shop is SSchassisworx. LowDown used them to build the frame for his 4runner build.
 
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