[JESSE_at_TLT]

Wanted to share some pictures of this 4-seater truggy that we're building right now down at Pacific Fabrication. All started with an FJ80 that had been rolled; the owner decided to build a trail-rig instead of sending it to the junkyard. The original plan was to build a simple rollcage around the stock floorpan and firewall, and then wheel the piss out of it. But it's turned into something a lot closer to a race-quality cage/chassis. Anyway, this is what it looks like right now.

 

[JESSE_at_TLT]

First thing we did was remove the stock shocks and springs, then leveled the chassis with the suspension at full compression. Removed the stock bumpstops and did some light clearancing in order to get a little bit more bump-travel, but Toyota did such a good job with the suspension design and packaging on these trucks that we were able to get the axles all the way up to the point where they were touching the bottom of the framerails (front-and-rear) without much trouble at all. So we're going to stick with the stock suspension linkage for now. There's no room to improve on it up front without starting over from scratch, and that would kind of defeat the whole point. In the rear, we're probably going to leave the stock four-link and panhard bar too, mostly so we can keep gas tank in the stock location (remember, it's a 4-seater). The front suspension cycles about 13" of vertical wheel-travel and the rear is closer to 15".

 

[JESSE_at_TLT]

After leveling the chassis, I spent the better part of a day taking all kinds of measurements. Lots of them. Then turned several pages of notes into some some simple 2D sketches. Had to know what I was working with before I could start designing anything. This vehicle had been in a wreck, and rolled, but it was still remarkably straight considering what it had been through. There are lots of different ways to do things, but I like to design in layers. The dimensions that I took from the chassis were the first layer; the foundation. Have gotten in the habit of making notes next to most of the dimensions, indicating whether dimensions are rough, or verified, or need to be finalized, or whatever. Just including some of this kind of information because I like getting to see how other people work. Almost always pick up some good tips/tricks.

 

[JESSE_at_TLT]

Funny thing about this project is that it's something I have wanted to build for a long time. Actually purchased a rolled 4Runner back in 2004 and started designing a roll cage for it, but the owner ditched the project before it ever really got started. So I was pretty excited when this FJ80 rolled into the shop. After a few conversations with the owner and the other guys at pacfab, we had a pretty clear idea of what we wanted to build, so I started layering 2D and 3D sketches on top of the chassis dimensions. Really just a simple game of connect-the-dots.

Currently doing all of my design work in SolidWorks, and use Weldments to lay-out chassis tubes. Using Weldments is a lot better than sweeping tubes along sketch-paths, but when it comes time to actually start bending and notching tubes I have to spend a bunch of time taking measurements. Also have a copy of BendtechPRO, and it's much better in that regard; just spits out all the dimensions that I have to take manually in SolidWorks. But the SolidWorks interface is a lot better, and it's obviously a lot more powerful program. Best thing to do would probably be to pony-up for Bendtech's SolidWorks plug-in, then I'd have the best of both worlds.

Spent a little more time revising the CAD models and tightening-up the dimensions after meeting with the customer to have him sign-off on the basic design. The engine-cage tube work is still just conceptual. Won't know exactly how that's going to go until we get into it.

 

[JESSE_at_TLT]

Most of the dimensions were determined by the location of things like the firewall and the floorpan and the framerails and the axles and the drivetrain, etc. So it was essential to build around full-compression. Almost impossible to take a good picture of the front suspension at full-stuff because it's so tight. But I was really impressed. Have never seen another production vehicle with that kind of clearance, everything so perfectly packaged.

 

[JESSE_at_TLT]

The first task once the build actually started was to cut the floorpan and firewall to the rough size and shape that we were planning on building around. Had to position the B-pillar crossmember in order to do that, as that was going to be the zero-point for the whole chassis (2x3" x 3/16" wall tubing). Notched the framerails to allow it to be mounted low enough that the floorpan can sit right on top of it. We also pre-notched that crossmember for the rocker-panel tubes before welding it into place. Then started hacking-up the rocker-panels and A-pillars.

 

[JESSE_at_TLT]

After cutting the floorpan down, we set what was left of the cab down onto the chassis, squared everything up, then laid-in the rocker-panel tubes and started erecting the B-pillar. We used those tie-down straps to pull the cab down/back tight against the B-pillar crossmember while we tack-welded everything.

 

[JESSE_at_TLT]

Employed a few more tie-downs to square-up the bottom half of the B-pillar. Floating the first few tubes is always the trickiest parts.

 

[JESSE_at_TLT]

There are very few bends in this chassis, and it would seem that might make it easier to build, but that hasn't been my experience. Have found floating straight tubes in space to be quite a bit more difficult than erecting bent hoops. In order to assemble the top half of the B-pillar, we cut cut and notched all the tubes, then pre-assembled the top half of the B-pillar, using some short tubes in the corners, then cutting them out after fitting the top half of the B-pillar to the chassis and welding-in some temporary corner braces. Then we bent-up the B-to-C-pillar hoop and slipped it into position. Sorry, didn't get any pics of that...

 

[JESSE_at_TLT]

Here is a picture of a tube being notched on the chassis. The JMR bother is great for that. In this case, we just found it easier to float this particular tube using temporary support tubes that we welded into place, then notching it afterwards. Setting the height, and keeping it level, and keeping it square to the rest of the chassis was difficult enough. Notching afterwards only meant that we didn't have to worry about the rotation and keeping the tube perfectly centered.

 

[JESSE_at_TLT]

Started picking up momentum once we got some of the perimeter tubework done. Used a straight tube to set the width at the top of the A-pillars, then cut it out and replaced it with the bent windshield tube. That's one of the only tubes we actually had to fit twice. Was a super-tricky notch and I blew it the first time. The tube that's in there now doesn't have the gap that you can see in these pics.

 

[JESSE_at_TLT]

Fitting all the triangulating tubework in the back half of the chassis went pretty quickly too. Working from CAD models and taking the time to ensure that we held reasonably good tolerances, this was all paint-by-numbers.

 

[JESSE_at_TLT]

Went through several different designs for the door-bracing, and this is what we ended up with. Started by fitting horizontal tubes from the A-pillar directly to the B-pillar. We were never planning on leaving them like this, it was just the easiest way to keep everything square. Once we had the vertical A-pillar tubes tacked into place, we were able to cut those horizontal tubes down to length, and re-use the tubing to make the diagonal crossbracing.

 

[JESSE_at_TLT]

Then we moved on to the front-end. Cross-bracing the radiator support and building the front bumper / winch-deck. All these sheet metal parts were cut on pacfab's in-house CNC plasma table. It's been really great having access to all of the top-notch equipment in their shop.

 

[JESSE_at_TLT]

Welded a temporary crossmember to the radiator support to help locate the fenders, then removed the temporary support after tacking all the tubes into place.

 

[JESSE_at_TLT]

With most of the tubework out of the way, it was time to turn our attention to the suspension. We used the plasma torch to remove all the stock coil and shock mounting bracketry. Andrew gave me a hand grinding-down the welds on the frontend and it's all smoothed-out now, ready to start working on the coil over mounts...

 

[JESSE_at_TLT]

This is how the rear coil over mounts went together. Designed the shock mounts in SolidWorks knowing that we would have to mock-up the shocks and cycle the suspension in order to determine final placement. Was really just a matter of figuring out where the would sit side-to-side, mostly depending on clearances on articulation.

 

[JESSE_at_TLT]

...and that pretty much brings us up-to-date. Will try to update this thread regularly through the rest of the build.

 

[Blase]

Very cool. Keep up the good work.

 

[TBItoy]

Firewall buggy FTW!!:grinpimp:

I hope he's keeping the Heat and A/C working too!

I dig the firewall buggy approach for a simple trail rig