Projects Building a Tube Chassis for my '36 Ford Sedan

This thread is to do***ent the building of the tube ch***is that will go under my '36 Ford Sedan.

There are 125 pictures here, so the load time might be severe for guys still on dialup. For that, I apologize up front, but it cannot be helped.

I'm going to drop 10 pictures in each post and then come back and do the captions once they're all up.

Please don't post until I've got them all up. It shouldn't take more than half an hour or so to get it done.

Thank you in advance for your patience.

Here, I have started laying out the lower main frame rails on my fabrication table. As you can see, it ain't really long enough, but I was determined to get started on this project, so I forged ahead anyway.





Now the upper main rails are added, positioned via some fixtures I'd made up. At this point, it became obvious that this fab table simple was not flat, stable, or large enough to do this ch***is on, so I had to back up think about what I was going to do.





After pondering for a bit, we decided to drag in some steel from the laydown yard and build an honest to God ch***is table. Here it is all done, but before it was painted. I forgot to take pics of the painting and leveling process. Suffice to say that once it was painted, I leveled it in place using an optical survey instrument (digital theodolite).





The rest of these are the fabrication of the upper portions of the main structure. It's all tacked in place in the last of these pictures. Now we move on to support structure.

 

Here you can see that I've fleshed out the support structure in the core of the ch***is. It's now much more plain to see how the majority of the structure is laid out. Since this is not going to be a full cage type ch***is, all the rigidity has to be built in at this stage.









Here you can see the front suspension brackets tacked into place. This car is getting a short arm/long arm IFS (what the road race guys call an SLA IFS). There will be some suspension mock up pics a little farther down.







Here's a big sheet of nested brackets and gusset plates just after the CNC plasma machine was done cutting them.

 

Not so subtle plug for the business there.



One more sheet of gusset plates and brackets.



Here I'm building lower control arms. I fabricated pretty much everything in this build, except for the heims and swage tubes.









Now it's time for upper control arms. Just a small pile of parts to start with. But they come together pretty quickly.

 

Finished control arms.





I then finish welded all the major structural tube joints on the ch***is.



And then I mocked up the front suspension to make sure I hadn't made any ****-ups. I had not, so after this, it was on to finish welding the front suspension brackets. BTW, that pair of heims dangling from the upper control arm is the pickup for the front anti-roll bar (which I haven't built yet).

I also fabricated the spindles you see being used here. Their build thread can be found HERE.









Try not to think of this as "modern or high tech hot rod suspension", so much as "vintage Formula 1 suspension".

 

Next came the mul***ude of gusset plates that really give the ch***is the bulk of it's longitudinal rigidity. These side gusset plates were about 1% heavier than using 1 3/4" tube to make the lattice work, but fully 10% stiffer.















After I was happy with the gusset plates' locations, I rolled the ch***is up on its side to finish the welding all around.





Here you can see the neat little conical caps that I used on the ends of the main frame tubes. They came from A&A Mfg. When I get an ironworker bought, I will build myself some die to make them here (A&A sells them worth the money, I just like to be self sufficient if at all possible).

 

More finish welding.









At this point, all of the front suspension brackets, rear suspension brackets, and gusset plates are in and fully welded.









This is the start of the rear end housing end of the panhard rod bracket.

 

Panhard mount clamp collars before ***embly and welding.



Fully welded, but unsplit.





Panhard rod mount boss before being installed in the standoff tube.



Standoff tube and brace tube mocked up before ***embly.



Clamp collars split and mocked up in place on the rear end housing.









Here's the panhard rod mount installed on the rear end housing for final welding.

 

One more of the finish welded panhard rod bracket.



These pics show the panhard mount along with the rabbit ear mounts for the pull bar (third link).







Rear end housing mocked up with its four locating links in place. Disregard that giant hoop looking outfit in the middle of the panhard rod. It ended up interfering with the pull bar ***embly, so it had to go. It's just as well, because I forgot to take pictures when I built it. That is one instance in which my CADfu failed me miserably. The new panhard drive shaft clearance hoop is shown farther down below.









Here's the rear end with a wheel on the hub to show what that's all going to look like. The wheels are 16" x 8" with the 3/4 Ton Wide Five bolt circle.

 

More pics of the first rear suspension mockup.







These pics are of ***embly and finish welding of the floating rear brake brackets. The brackets decouple the braking forces from the rear end housing, so you can run a higher amount of anti-squat without worrying about rear wheel hop under heavy braking.

 

Finished brake floaters.



These pics are of the fabrication and ***embly of the second version of the panhard rod drive shaft clearance hoop.

Cut out on the plasma machine. Disregard that nasty dross blow on the right, my torch height control stepped on its pecker for a moment. Luckily, that ****-up didn't really hurt the part.



Cutting the upper clearance for the bolt bosses.









Flipped over, cutting steps to aid penetration with the rosette welds to come.



Turning and milling the upper bolt bosses.





Here you see all those rosette welds I was talking about before.

 

Driveshaft clearance hoop all finish welded.





Final rear suspension mockup, with brakes this time.









Here you can more clearly see how the floating brake brackets work.



Pull bar and panhard clearance hoop. That long bolt sticking into the center of the hoop is just for mockup.





Brake and panhard mount setup.

 

Everything broken down and masked for primer.















Houston, we have primer.

 

More primer (with my Dad sneaking through the background of the frame there ).











That brings us up to current, as of Monday (1-17-11).

I am going to leave the ch***is in primer for the time being, as I've still got body mounts and a roll bar to build and weld in place, and I can't decide on the color either.

The suspension parts will be getting painted satin black tomorrow, if all goes well.

More pics as progress comes.

EDIT (1-21-11): Got the suspension parts painted.







Pics of the roller to come when the paint has cured. Likely week after next.

 

OK, that's all the pictures.

I'm going to go back in and put in the captions now.

If you all want to post, it's all clear to go for it.

 

Quality work for sure...but HAMB friendly?

 

What is it with the HAMB police?

Jim Sibley built a pseudo funny car tube frame for his Chevy, and nobody batted an eye. It wasn't built to look like anything in particular (like a redo of an old design), he just built it to suit himself.

That's what I did here.

It's built for road racing or more probably autocross.

I just get tired of seeing hotrods that can only go fast in a straight line.

 

I like the use of racecar parts.

 

its obvious to anyone looking at the photos that you don't have a clue as to what your doing.... sometimes modern running gear under old cars is bad ***.....

 

she otta handle like a slot car, done alot of race car stuff myself, that panhard bar arangement is new to me though, usually a j bar, is that the newer hot ticket, i kinda see how it might be better, accept the packaging.........cool car, screw the hamb cops...

 

Thank you. I'm an oval track racer at heart. Started out on the ovals, so that's what always looks best to me.

That is my thinking as well.

The J bar offsets the rear roll center to one side, which is great for a car that only makes left hand turns, but not so great if you want to turn both directions.

The long bar puts the roll center on the centerline of the ch***is.

A watts linkage would have been better, but the packaging is even worse.

Next time perhaps.

I started out wanting to use a quick change, so the panhard had to be in front. If I'd have changed my mind on the rear end sooner, I could have moved the panhard mounts to the rear and avoided that whole clearance hoop thing. But as it happened, I was pretty much done with the tubing part of the ch***is before I made that decision, so I went with what was already built.

Such is life.

At least it's ready to accept a quick change, should I ever desire to go that route later on.

 

May I ask what grade of steel you are using, and the diameter and wall thickness?

 

I don't think it is going to be strong enough. Needs some more gussets.

 

1020 HREW, 1.75", 1.5", and 1" OD x 0.095" wall.

The gusset work is all 1018 CR 11 ga sheet.

I modeled the whole thing and did a lot of FEA work before I started the build.

And before the DOM nazis goose step in here and berate me, consider that your vaunted DOM is drawn from this exact material. The only difference is cold work . . . . which goes away when you weld it. So, DOM tubing is exactly the same strength at the weld HAZ as this material.

The only real benefit that DOM has is that it is cleaned before drawing, and the wall thickness is more uniform. DOM is more dent resistant, which comes up with the rock crawler crowd a lot, but not really that important with a road car.

Anyway, that's what I used. If a customer wants DOM and is willing to pay for it, more power to them.

However, since the material is more than strong enough for the job, and the HREW is less than 1/4th the price of DOM in the same size, that's what I went with.

Every race car I've ever driven has had a cage made from HREW, and I've been upside down in them before, to no ill effect.

You just have to be aware of the material's properties, and design accordingly.

EDIT: I don't want you to think I'm calling you a DOM nazi. I'm just trying to head them off at the p***.

There's one in every crowd.

 

thats why i was unfamilair with the long panhard versus the ja bar, my racing has been pavement oval track, and i totally agree with you on the hrew versus the dom, i have built and crashed many of cars and never had any problems using it........

 

Thank you very much.
A few follow up questions if you don't mind?

Would you still go with the same grade and diameter if lightness was important to you?

Did you use a computer program to calculate the suspension geometry, and if so which one and is it any good/ easy to work with?

Thank you also for posting all the pictures - very impressive.

 

Sorry, one more.
Would you mind saying why you chose to use plates to triangulate the frame rather than tubes?

Thanks again

 

If weight was the main consideration, I would go with the same diameters and a thinner wall in 4130 chrome moly tubing. Cost would be at least twice, probably three times that of DOM, and five or six times what the HREW cost. Plus, you must TIG or gas weld the 4130, and use the right filler rod to get all the strength potential out of it. I would probably have the entire ch***is normalized after final welding too, but that's probably just my engineering overkill kicking in.

That is not to say that this ch***is is heavy though. My Dad and I can easily pick it up ourselves. I would estimate the weight to be in the high 200# to low 300# range. I will put it on the scales before I build the roller, so I know for sure, but that's a good guess.

I designed the suspension geometry in AutoCAD using principals gleaned from many sources. Read everything you can by Carrol Smith and Steve Smith for starters, then you can move on to the others. GM Racing in combination with the SAE put out a very good (if expensive) tome on racing car vehicle dynamics which is very good, but won't be of much use to you if you don't already have an engineering background.

There are several good design aid programs out there, but I do not own any of them, so I can't really say which is the best.

I used the plates because I thought they'd look cool and they were a hell of a lot less work to build than notching all those short pieces of tubing.

I modeled the ch***is both ways to make sure I wasn't making a ****-up, and it turns out that the truss plates are actually stronger than the tubing in this kind of ***embly.

All said and done, the truss plates were ~10 LBS heavier overall than the tube truss would have been. However, they were also 10% stronger than the tube truss would have been. They also saved many hours of tube fitting work.

Another thing to consider, is that with very thin wall tubes (like 0.039" or 0.063") that are prone to failing in buckling, point loads are a bad deal, and every tube junction is a point load.

Spreading the load out over a big length like these truss plates and the big gusset plates do, will help prevent buckling failures in your structure. Thin walled tubes kink easier than thick ones, so they need all the help they can get to stay in-plane.

 

Ryan,
There are a lot of things about your design that I would have done differently but as they say "You're ****ing this cat, I am only holding the head"!!! Damn nice job! You knew what you wanted and made it! and a very nice job of it also. This is what Hot Rodding is all about, building your own ideas, anyone can take a pile of rusty junk and turn it into a bigger pile of rusty junk, not many can start with a pretty complex idea and then build it. Nice job!!

Rex

 

Thank you very much CoolHand!

 

Yeah, anyone who's raced ovals know that HREW makes a fine roll cage material.

However, the weekend road racing crowd is absolutely rife with DOM snobs.

All their sanctioning bodies require DOM and ridiculous wall thicknesses for their spec cl***es. Like 1.75" x 0.120" wall DOM steel for the main cage structure in their "Spec Miata" cl***. Let that sink in for a moment. They're racing stock Mazda Miatas (a car that weighs maybe 2,800# from the factory), with a four cylinder engine, and they spec roll cage tubing that you could set a 5,000# trophy truck on top of. Of course, that giant roll cage tubing is mated to floor pans made of 18-20 ga sheet steel using plates no thicker than 10 ga as landing pads, and nothing else. They actually limit the size of the landing pads to some very small number of square inches of area (in total). Brilliant that. Huge thick high dollar cage atop thin *** landing pads mated to super thin floor pans.

They are also aghast when they design to the strength of DOM with the cold work intact, and then find that in a hard crash, it pulls apart at the HAZ instead of just bending the whole tube.

But we're stupid and do hack work because we don't use DOM tubing in our race cars. It's idiotic. They say that a spec Miata cage should cost at least $3,500, or the guy didn't do it right. And that's not counting the car that you have to start with.

Hell, the cars I used to race, the whole damned ch***is didn't cost $2,000, and that was ready to build off of.

Totally different world over there.

Anyway, rant over.