schedule 40 tubing

[26Troadster]

ok folks i need some backup. i got a cuz back home i was talking to over the holiday. says he going to build a t bucket, i asked what metal he was using to build the frame with and he says 2" and 2 1/2" schedule 40 tubing. i asked if it was a space frame and was told no. he thinks one 2 1/2" frame rail each side with 2" cross members. i told him that wasn't a good choice. let's see what yall have to say and then maybe he will believe somebody.

 

[Tripper]

Just my quick reaction... what's the wheel base (114"?) & what power plant? I guess you probably could but would I... nope! I think wall thickness on 2 1/2" is less than 1/4"!

BoB

 

[Old Iron]

Absolutely no way

 

[bob w]

2 1/2" schedule 40 steel pipe is 2 7/8" in diameter and has a wall thickness of .203". The cross section is 6 1/2". Many short wheelbase T Bucket kit frames (90") were built with 1 1/2" by 3" rectangular tubing with a wall thickness of .125". That' a cross section of 4.5".
A 2" by 3" rectangular frame would have a cross section of 6".
So it appears that the pipe is strong enough.
The remaining question is frame flex. I don't know if a length of 2 1/2" pipe would flex more that an equal length of 2" by 3" rectangular tubing.
We built my son's '27 roadster with a 115" wheelbase out of 1 1/2" by 3" rectangular tubing and it has gone many miles.
I'd use the pipe assuming it is steel and use some smaller diameter tubing to add some trusswork in the high stress areas. It'll be harder to build but might be more unique visually.

 

[26Troadster]

thanks for the reply's. he wants a sm block chebby and a short wheel base of around 100" i myself wouldn't do it even with a 4 banger. my frame on the roadster i'm trying to build is 2"x3"x.125" and i'm thinking it's to lite. i'm trying to get him to read this and have been trying to get him to join us here, so who knows.

 

[Old Iron]

2" x 3" x 1/8" is too light, it allows the chassis to be springy.
A friend of mine built a bobber pickup with that and it has a goofy feeling to it. ( at least to me)

 

[Sam_Fear]

Using this calculator for comparisons:
https://www.engineering.com/calculators/beams.htm#tube

Your 1/8" 2x3 is going to be slightly more springy than his 2-1/2" schedule 40. all else being equal. 2" is a no-go.

 

[26Troadster]

Thats why i have been dragging my feet on my roadster. I talked to him and now he's going with box tube. Thanks fella's.

 

[Tripper]

Thats why i have been dragging my feet on my roadster. I talked to him and now he's going with box tube. Thanks fella's.

Good decision IMO! [cl

A friend of mine built a bobber pickup with that and it has a goofy feeling to it. ( at least to me)

I've felt that before & I didn't care for it. Very strange feeling!

BoB

 

[Burgerman]

What would you guys use here or recommend [S
[P

 

[bruno]

2x4 3/16 rectangular tubing.

 

[kenny c]

I used 2x4 .120 wall with an X member of the same material. It seem very ridged with no flex or twist but I haven't driven it yet.

 

[rustybeercan]

What would you guys use here or recommend [S
[P

2”x3” 3/16” is good for nearly application IMO!

Beercan

 

[26Troadster]

i went with the 2"x3"x.120" wall from info in one of the t bucket books. when i build the next frame for the roadster it will be 2"x3"x.250" wall as i like big blocks and have a heavy foot. i'm gonna use the frame i built to go under a rambler with a cage so it should be ok.

 

[bob w]

I have a back half kit from Chris Alston Chassisworks in my Anglia. The frame rails are 2" by 3" by .083" wall. Shows you how thick the pros think the frame needs to be when incorporating a roll cage. Wall thickness is not the best or most effective way to gain stiffness. It is a good way to provide tapped holes in the frame. And, in a T Bucket the weight penalty really doesn't matter. In fact, heavier is probably better to keep a T Bucket on the road at high speed.