T frame question - is this a good idea or not?

Photo didn't attach...trying again.

 

I think that I know why that frame broke. There is some condition under which the motor mount, which is near the firewall, will cause the frame to fracture. I can't remember exactly what the condition is (maybe overtightening of the bolt?) but I have read about it.

 

When you cold work metal, you increase it's fracture toughness but also decrease it's elasticity. So, if you keep bending it, it will eventually fracture... just think of a paper clip. I'm no expert on T frames but I know a little bit about the mechanics of metals.

Low carbon steel by todays standards is anything below.2%C. Medium is between .2 and .5%, the stuff standard high production connecting rods and crankshafts are made of.

 

Good point on cold working.

So, by today's standards, the T frame is medium carbon steel, correct?

 

for carbon steel yes but if its alloyed, not exactly.

 

If you know how to get a T engine to put out 75 hp, I want to hear about it!

Anyway, I could see the doubled-up T frame working. I think square tube frames end up looking like ****, real home-made. To run a four cylinder in one it would be plenty strong and probably much nicer looking than a fabbed one.

 

I've seen 2 frames used for boxing in old race cars they would slide a right and left rail into each other in an offset overlap fasion.The bottom flangeof 1 would go inside the bottom flange of the other and the top would overlap in a like manner .The outer rail on each side was usualy on the top so the weld was on the inner part of the frame toward the center of the ch***is

 

Im sorry I dragged myself into this but, you cant compare today's metals with metals that were processed during the early steel age. Becuase it was produced in such large numbers, Steel was often inconsistant and full of impur***ies. A common example is the ***anic and an even better one are the liberty ships of ww2, and I'm not talking about bad welds or rivits here. The truth of the matter, old Ford was interested in cheap and fast, and that comes at a price.

If anything, I would double them up but now you have 2x the bulk weight. Box tube sounds much better.

 

I've seen some good looking square tube frames, but not many. They look good on T-buckets. I personally don't like them on T's otherwise.

To get 75 horsepower out of a T is not easy, but doable...even with a flathead...witness Ed Winfield's flathead T engine that ran with (and even won against) the Frontys. I believe that his engine was reported to be 100 hp. I have a couple of Chevy 290 OHV heads, and will probably go that route with a conversion plate. I'm told that you can fairly easily acheive 75 horsepower with one of those on a T engine, with the hotter version of the Stipe cam.

BTW, the formula that I know for getting 100 horsepower from the 490 Chevy requires 14:1 compression.

 

If you want a box frame with a cool "model a frame" look check out this thread.... All the great aspects of a boxed frame with the look of an original model a frame!!

http://www.jalopyjournal.com/forum/showthread.php?t=87556

This is what I'm doing on my next project!

 

Hey, the frame ideas all sound sweet, but I wouldnt go with anything lower than a 4" dropped axle. You mentioned 7" dropped axles earlier. Unless you plan on runnin 19"-22 1/2" old school rims. A stock axle bows down in the center a bit and is lower than the center of the wheel (spindel). On a stock model A with 19" spokes & stock tires the spindel is 14" from the ground and the lowest point of the axle is 10". So if you run a 7" drop, the lowest point of the axle to ground would be 3" with 19's and stock tires.

So, if my figures are right, if you run say a 14" rim with "average" side wall heigth, the differance from a 19" to 14" is 5". Half of that is 2.5" which means youd have 1/2" of clearance from axle to ground (depending on how high/low the sidewall is).

Now say youre on the highway and you blow a tire off the rim, (if the 14" in half is 7" and the axle being 3" lower than that, the RIM would be 3" OFF the ground) The result is youll be iceskating on the axle and be in for one hell of a scary ride! haha!

Just something to consider when measuring axle drop/wheel size/tire size.

 

The method of sliding a left and right rail together overlapping would get you a very strong frame and you would only have to weld it every 6 inches or so with a 2-3 inch weld to make it right. Factory frames for later cars were welded in this fashion.
Add a Tbanger hooked up to a Chevy transmission or a Abanger with a V8 trans or a V8-60, a dropped T axle, Rocky Mountain brakes and you've got a speedster DeLuxe.