If you were to build a new frame, what would you change? (1 Viewer)

[Ramination]

I am embarking on a build that has already escalated further than expected. Ha! This rig is being built as an offroad toy as opposed to a restoration so I had planned on chopping the frame in the rear and boxing in the entire frame where it wasn't from the factory. Plus, I plan to stretch the body and frame to get a little more room out back, so going in I'd planned to chop the frame in the middle and do a whole new rear BUT as I stripped the frame completely it became obvious that the front would need A LOT of work - it is very rusty.

Between all the work that'd need to be done and the fact that I'm squeezing a small block in the engine bay and one ton axles w/4 link rear and 3 link front I think I'd be better off building a new frame - faster, stronger, easier (maybe?) and more accommodating to the equipment I plan to run than reusing/rebuilding the old frame, especially considering I'd only really be reusing the front section.

What I've come up with so far is using 2"x5"x0.250" rect tube for the main rails on bottom and 2"x4" at not yet determined thickness for the front and rear parts of the frame.

I plan to maintain the stock geometry in regards to the way the frame rails flair out from front to rear right after the motor, though I don't know if I will maintain the distances between the frame rails in front and rear. The front I am considering going a little wider (paying mind to the fact that the firewall/tub will limit how far I can go but I figure any little bit will help to squeeze a V8 and links up there). On the rear I may not go as wide - it seems like a lot of the (silly) Jeep guys have to notch out the frame to keep the coilovers from hitting the tire or frame.

Is there anything I am missing in regards to widening the frame at the front or narrowing the rear? I don't plan to go crazy, maybe an inch or two at each end. Aside from body mounts (which I can accommodate for with new tub floor and stretch), what am I not seeing? Anyway, I *think* I have this part under control but input is welcome.

For those who have put one tons, linked suspension, coilovers and V8s in their 40s, are there any dimensions of the frame you had to change or would change if you were to do it over again? Some things I have bouncing around in my head as potential unknowns at this time are:
- Crossmember locations
- Distance from centerline of main frame rail to centerline of the frame rail around engine area.
- Material thickness on frame rails
- Anything in relation to how to make it easier to tie full cage into frame
- Considering I am doing full cage which will sandwich body and mount to frame, how many of the old body mount positions should I plan to maintain - this is important to me because A LOT of my tub will be new metal
- ANYTHING ELSE?!?!?!

 

[White Stripe]

I think 3/4 of the frame is good for most mods. I would stretch it to make it a fj43. Also where the frame comes up for the rear axle, I would just extend that rather than curving back down so that you can have more room for stretched wheelbase and flex.

 

[Ramination]

Yea my plan is to go straight back on the rear as you mentioned. Easier and functional, perfect.

I'll have to look up the specs on FJ43 length, I am planning on going somwhere between 12-18" at this point.

Thanks

 

[White Stripe]

Yea my plan is to go straight back on the rear as you mentioned. Easier and functional, perfect.

I'll have to look up the specs on FJ43 length, I am planning on going somwhere between 12-18" at this point.

Thanks

You do have to move the rear wheel opening back on the fj43 tub so u don't have overhang, doing this makes for a great wheelbase for a crawler, nice interior space, and look sweet. A guy on pirate built a wicked blue fj43 crawler. U can buy 3/4 and 1/2 fj43 tubs to adapt to a fj40.

 

[Swenny186]

Does Aqualu make a better starting point for you, to save you some of the fabrication work?

Land Cruiser Frames

 

[Mieser]

1/4" thick material is VERY thick for a frame....and heavy. You are likely going to want to plate the miters also which is going to start really adding up the weight and making the frame very thick.

As the material thickness increases on box tube you also have a much larger corner radius. On 2" wide tube you end up with a very short 'flat' on the tube which can make fabrication of certain things a pain in the rear.

If you're buying material anyways. I would hunt for stronger A513 tubing and reduce wall thickness down to 3/16 depending on wheelbase.
The height of the box section makes more of a difference than wall thickness in a lot of applications. If the wheelbase is going to be 110ish I would think about using a 6" tall belly section and tucking it tighter to the floor and hat channels to get a little of the clearance back.

Sounds like a fun project!

 

[Ramination]

Does Aqualu make a better starting point for you, to save you some of the fabrication work?

Land Cruiser Frames

I don't think they technically make a frame and/or body for my year (64) although considering the work in about to embark on it would surely be easier to modify that as opposed to building new - or easier yet just buy body AND frame new from them - gee why waste all my time! Haha! Regardless of all that, yes it would be a better start point but I am not going to do it any ways. Money is the main reason, second is that won't be nearly as good of a story in the end...

Thanks for the link though, definitely some fine looking work.

1/4" thick material is VERY thick for a frame....and heavy. You are likely going to want to plate the miters also which is going to start really adding up the weight and making the frame very thick.

As the material thickness increases on box tube you also have a much larger corner radius. On 2" wide tube you end up with a very short 'flat' on the tube which can make fabrication of certain things a pain in the rear.

If you're buying material anyways. I would hunt for stronger A513 tubing and reduce wall thickness down to 3/16 depending on wheelbase.
The height of the box section makes more of a difference than wall thickness in a lot of applications. If the wheelbase is going to be 110ish I would think about using a 6" tall belly section and tucking it tighter to the floor and hat channels to get a little of the clearance back.

Sounds like a fun project!

Awesome, thank you very much for the feedback. And yes I do plan to plate the miters, was planning on using a sheet of 3/16" but that may be too much?

I will be starting a build thread once I have more to share than a rusted shell of an FJ.

Thanks again

 

[Mieser]

Awesome, thank you very much for the feedback. And yes I do plan to plate the miters, was planning on using a sheet of 3/16" but that may be too much?

Thanks again

yes, 1/4" frame with 3/16" gussets would be into overkill range in my opinion.

If you are going to use it really hard I would do a 3/16 tube with a 1/8 gussets. If you where going to drive it like a semi normal person without 500hp and 40" tires, I wouldn't hesitate building the frame out of 1/8" good quality tube with 1/8" gussets. Most oem box frames are about that thick in material that is maybe 50kpsi. Thinner material is also going to be easier to fabricate and weld reducing input time.

It's not a land cruiser, but here is my old flat fender....



I built a new frame for it about 4+ years ago. It is all 2x4x1/8 box with 1/8 gussets. I've run it pretty hard over the last few years with no issues including two Ultimate Adventure trips with 4WOR magazine. The only frame damage, which is actually rear bumper damage, was from basically sliding the entire car down a big muddy cliff backwards onto a pointy rock in the middle of the vertical span of the rear bumper....probably about a dozen times. It dented a little bit.

For a longer wheelbase and more weight I would increase the beam weight in the belly section to 6" tall tubing if the wheelbase is going to be 110" or so and 5000lbs of vehicle weight. If the bottom of the belly tube is going to be exposed, you might add a strip of material over the bottom ( or the belly skidplate ) to help with long term wear and dent resistance. Adding thickness to the top and bottom of the tube with some strapping will also greatly increase beam strength.

Cheers.

 

[Ramination]

Oh my gosh, that is YOU? I love your Flatty!

Anyhow, thanks for the advice, noted in detail. I do anticipate being around 110" wheelbase, but only 37s and a lot less than 500hp, for a while anyways.

 

[Mieser]

Oh my gosh, that is YOU? I love your Flatty!

Anyhow, thanks for the advice, noted in detail. I do anticipate being around 110" wheelbase, but only 37s and a lot less than 500hp, for a while anyways.

Thank you, yes that is me and mine.