My TP frame is 1.5 x 3" rails but most other manufacturers use the 2x3" rails. Do you think the weaker frame could contribute to some of the steering issues and body cracks that some people experience? I was thinking along the lines that the frame is flexing enough to induce changes in the suspension and steering geometry.
My TP frame is 1.5 x 3" rails but most other manufacturers use the 2x3" rails. Do you think the weaker frame could contribute to some of the steering issues and body cracks that some people experience? I was thinking along the lines that the frame is flexing enough to induce changes in the suspension and steering geometry.
I chose the 1 1/2"x3"x3/16" because it looks more proportional to the size of the body. I've had NO flexing or cracks in close to 20,000 miles. One thing that I did though, was to install a "K" member to minimize flexing that you can easily get with a simple "ladder" type frame. Check the attached picture.
I like that wishbone locator Jim. When I was working on my m/cyl I noticed that where the fiberglass trans cover is attached to the floor I have some cracks as well. I'm not sure if it is the bumpy roads here, poor quality build or too much power and things are twisting too much. The floor area is not very large and that is all that is attached to the frame. If the frame twists so does everything else and of course fiberglass is not structural or very strong when it comes to twisting.
WRONG, they are welded to the sides of the main frame rails. You may have seen it that way as the cross member and K member are 1 1/2"x1 1/2"x3/16" tube that are welded flush with the bottom of the main rails. Sorry for the confusion of the pictures.
I agree think 1-1/2 x3' 3/16" like Jim has is more than adequate. If you look at what a original T or A frame is, the 3/16" rect tube is much stronger. What is more important is to brace the frame with crossmembers and diagonals. This will keep the frame more rigid and less resistant to flex/rack, etc. Lots of guys go with 1/4", but this is not needed in my opinion. I used 2x3x3/16:
My TP frame is 1.5 x 3" rails but most other manufacturers use the 2x3" rails. Do you think the weaker frame could contribute to some of the steering issues and body cracks that some people experience? I was thinking along the lines that the frame is flexing enough to induce changes in the suspension and steering geometry.
If you look at EX JUNKs frame....he has it tied in really well from the rear of the trans to the rear end, while the front is tied in at the front. A really good strong frame. BenTs frame....well it'd survive a Boss 429 attack.....not much is gonna bend it.
Alot of poeple don't realize, you want SOME flex in a frame! If its too rigid, as the road will have a hammering effect on suspension attachment points, you want a slight give so the frame won't develop stress cracks.
Too thin and it'll crack out from flex. Too stiff and you'll flex right beside your attachment points, leading to stress cracks and such. Usually right beside the weld....
Your frame needs to absorb twists and flexes....but just a little.
Too much and your ride will suffer also....no enough, the suspension will be like a noodle
1.5 x 3 tubing is good....its just in how its braced, how its welded, and how things attach to it. Small blocks and medium horse cars are ok. I would not want to put a 650 Horse Blown Hemi Stroker in there....unless its done right.
There is some nice frames there. The reason I started this thread is last time I was under my car I noticed that where the trans tunnel is fiberglassed to the floor it looked like it was cracking.
18 ga. I had to make the in 3 pieces and weld them together to get the length as our brake and shear is only 4'. They have a 3" leg on the top and are rolled at the bottom for a softer look.
1.5x3 or 2x3, either one....1/8th or 10 ga. is marginal, 3/16 is good, if you have a monster to contain or your building a heavier car, 1/4 is the choice. If you use less bracing the 1/4 is a good choice.
With std. bracing, a regular frame, 3/16 is plenty strong for most anything....
1.5x3 or 2x3, either one....1/8th or 10 ga. is marginal, 3/16 is good, if you have a monster to contain or your building a heavier car, 1/4 is the choice. If you use less bracing the 1/4 is a good choice.
With std. bracing, a regular frame, 3/16 is plenty strong for most anything....
What he said. Torsional rigidity is a function of the vertical section, a 2X4 is over three times as rigid as a 2X2. Bigger section is far better than wall thickness, all other things being equal. BUT. Keep in mind the frame is only as good as the welds. Up to 1/8" (3.2mm) full penetration without much in the way of joint prep is fairly easy to achieve. Full penetration means no stress riser in the unfused root area. Once you get to 1/4" (6.4mm) a vee type prep is essential. And keep weight in mind, weight is the enemy of performance. Double the wall thickness, double the weight, one reason we love buckets is, they go like a raped ape, and thats because they weigh less.
Talking about weight of tubing.
3x1.5x .188 tube is 5.07 lbs per foot
3x2x.125 tube is 3.98 lbs per foot
3x2x.188 tube is 5.75 lbs per foot
4x2x.188 tube is 7.04 lbs per foot
You can build a bucket frame with 20 foot stick and have some left over.
18 ga. I had to make the in 3 pieces and weld them together to get the length as our brake and shear is only 4'. They have a 3" leg on the top and are rolled at the bottom for a softer look.
It is true that it is used in drag racing but it performs fine on the street also. The primary reason in my choosing the wishbone over a panhard bar was that I liked the way the rear travels up and down in a perfectly vertical path rather than the parallelogram type of path with a panhard bar. Plus, there is a problem finding a proper place under my car to fit a really long panhard bar. Remember, the longer the panhard, the closer you get to the never attainable "true" vertical path of the wishbone. IMHO
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