Another build thread? Yep, my track-style T

[J. Robinson]

Brickman: The frame is of my own design, as is the one under my coupe. Chassis design and fabrication is one of my favorite parts of building hotrods. There are at least 18 or 19 of my one-off frames running around under various street rods. All of them are built from rectangular tubing. That's why I wanted to do one from round tubing - something different and a new challenge for me.

EG: You are correct... up to a point. Any type of dipping (like galvanizing) or plating process can cause nitrogen embrittlement of the base metal and therefore cause big problems related to metal fatigue, crystalized welds, etc. You can use galvanized in a non-stress area, but I would not use it on the chassis, especially any part of the suspension or steering.

[J. Robinson]

Final assembly on rhe front radius rods is done by welding the previously fabricated pieces together. To accomplish this, and get them both the same, it is necessary to have a simple jig. I took a piece of scrap 1/2" plywood and laid the pieces on it with the rod ends screwed all the way in to protect the threads from welding slag. (Later I will reassemble them with jam nuts before installing them.) I use a 6" o.c. spread between holes on the front. The overall length from back hole to the front holes is 39 1/2". (Radius rods can be fabricated at any length according to your application. Generally, though, the longer the better.) Once I got everything lined up so it looks right, I marked where the rod end bolts need to be and removed the pieces. After checking everything with a tape measure, I drilled the three holes in the plywood and drove some old 1/2" bolts through from the back side. I put the radius rod pieces back on the finished jig, lined them up, and commenced welding. I started by tacking the pieces together on one side, then lifted the assembly off, turned it over, put it back on the jig and welded the second side completely. After the first assembly was welded, I put some marks on the plywood with a sharpie pen so I could line up the second set of pieces the same way and repeated the process.

[Itoldyouso]

One engine you might consider is the 3 liter Chevy engines that Mercruiser, Volvo Penta, and OMC have been using for years in boats. They are super little engines, I think of 181 cubic inch displacement, and a machine shop guy told me circle track racers use these with I think 327 pistons and some head work, and crank out good numbers.

I bought one for $ 200 for just such a project as you are doing, but finally got tired of it laying around, so I put it on Ebay and sold it. Nice part is, it has a regular Chevy bellhousing bolt pattern, and I understand 6 cylinder Chevy flexplates and things go right on it.

I didn't research it really deeply, but I planned on yanking off the watercooled exhaust/intake manifold and fabbing up a tube intake and exhaust setup.

These are all over the place, and pretty cheap too. Being that you live here in Florida, you know how many boats we have here.


Don

[firebird77clone]

Ok, so inquiring minds want to know:

What IS DOM tubing? What makes for 'good' tubing, and how do I know? Where do I get it?

I have been kicking around the idea of building a tube chassy for a while now, and before I get my feet wet, I wanna know the water is safe.

[Dave Severson]

You are correct in every aspect on moly tubing. I became sold on it dating back to my sprint car days.... Yes, it's tougher to work with, yes, it's way more money, but it's light and strong and I have a TIG!!! For street chassis use, I tend to add an X here and a gusset there to limit the flex a bit, but then I guess it also depends on your definition of streetable, my definition is quite loose!!!! Heck, I don't know....maybe I'm just some kind of moly snob or something. On one of our sprinters we didn't even bother with paint, just a purple scoth-brite pad and a couple coats of clear... We were trying to save weight, ended up with a really great looking frame!!!!

[Henry Rifle]

EG:

DOM tubing: http://www.steeltubeinstitute.org/domprocesses.htm is made by Drawing it Over a Mandrel. The process makes a very strong, uniform (OD, ID and wall thickness) tubing with excelent strength and a nice finish.

I actually prefer mild steel tubing because I am more confident with my welding ability on that stock. Since I'm not building race cars, I'm not that worried about a little extra weight.

Dave,

What kind of rod do you use on moly?

[J. Robinson]

Good idea, Don. We have two marinas right here in Titusville and a couple of boat dealers. I will check around and see what's available.

EG: DOM is the designation for "Drawn Over Mandrel". It means that the tubing, as it's manufactured, is drawn over a set of rolling dies that squeeze the tubing and make the diameter consistent throughout. The process also slightly work-hardens the tubing which makes it a little more rigid and it flattens the seam in the tubing making it almost invisible. DOM tubing is sometimes called "seamless" tubing, but that really is a misnomer because all tubing has a seam somewhere. Ordinary mild steel tubing is just formed, welded, and scarfed (has the slag scraped off the seam). Depending on the accuracy and condition of the forming dies, it may vary several thousandths of an inch in diameter and roundness.

I don't know about your part of the country. The best thing to do would be to call around some steel suppliers and see if they can get what you want. I can get flat steel and square or rectangular tubing delivered right to my door from several suppliers here, but if I want round tubing I have to order it and go get it (one of the reasons I am using black iron).

[Dave Severson]

Dave,

What kind of rod do you use on moly?

I've used ER80 in the past, now the Lincoln rep has me playing with stainless 312. The big trick with moly (or any alloy for that matter) is to use as little filler as possible, which means spending even more time fitting. Friend of mine teaches welding at a Vo-Tech, mostly I use the filler he tells me to buy!!! The guy is so good with any kind of welder it almost makes ya sick!!!!! Worst part is, now my eyes are getting bad enough that it's time to turn the welding over to somebody else.....

For DOM I've had good luck with the non coated .035 high tensile strenth wire.... Can't for the life of me remember the number on it..... The guy on the Lincoln truck does though!!!!

[J. Robinson]

Ah, Dave, I'm jealous. I wish I had a TIG machine. They make such pretty welds... The ends of my radius rods would look so much neater.

Hey, at least you clearcoated the frame. The top fuel guys are so weight concious that they don't paint their frames except for the part of the roll cage you can see!

[bluestang67]

ER80 and 312 then dom hey there's a rookie here talk nice Actually i looked up dom ,welding rod and wire i just ask all the pros like here.

[J. Robinson]

Duh! I forgot to show the finished radius rods... Here they are with the jam nuts installed. I will set these aside, now, while I prepare the '65 Ford Econoline front axle and fabricate the "batwings".

Front axle preparation begins with torching off the edges of the spring pads and grinding the edges smooth. Also, since some of it is visible on the finished car, I want the top side of the axle to be smooth. A little extra time spent grinding the forging marks off now will save a lot of headaches later when all the brackets are welded in place.

For you beginners out there, these old beam axles are made of very dense forged steel, not cast iron. Grinding on them does not damage them. Actually, metalurgically speaking, grinding off the forge marks removes stress risers which could actually strengthen the axle!

[Hotrod46]

I'm in the same boat as J Robinson, no one around here stocks DOM. And they're not really excited about ordering it. If it's not black pipe or hot-rolled sheet you're pretty much out of luck!

I used "seamless" SCH80 1/2" pipe for the 4-bars on my car. The SCH80 stuff has an ID that can be tapped for 5/8 fine thread. The stress calculations are better than most people would think. I think the poly bushings in the ends would fail long before the rod does.

If you need small pieces of 4130 CM, I've ordered from these people.
http://www.aircraftspruce.com/

They stock a lot of unusual stuff.

[Itoldyouso]

Boy, you are going to have to back to school after Spring Break to GET A REST !!!

Your T is coming together fast. I like the idea of the Econoline front axle setup........you get good brakes and readily available replacement parts. Radius rods came out looking like store bought, nice job.


Don

[J. Robinson]

Shoot! I've already been back at work for a week...

I have used Econoline axles before; they work pretty well. The brakes aren't terribly large in diameter, but are wide. For drum brakes, they work pretty well.

OK, on with the show... In order to attach the radius rods to the axle, I need a set of "batwings". I start by making a pattern from poster board and then duplicate it in steel using 1/4" x 3" flat stock. I cut the pieces so they have 45 degree angles on both ends, deburr them, and then clamp them together with vise-grips to do the drilling and grinding. This assures that the pieces will be identical.

After the holes are drilled, corners rounded off, and the edges all ground to match, I remove the vise-grips and separate the pieces. The notches for the axle are marked, cut with a torch, and the slag ground off. Then I bolt the pieces together and grind the notches to final shape so that they match. The batwings and radius rods are now ready for installation.

[firebird77clone]

apples and oranges here:

would there be any advantage to me digging up an econoline 65 axle for my 36 chevy master sedan, compared to using the original? Same set up.

Thanks, and also thanks for the quick replys to my tubing querries.