Forum: HoseHeads Sprint Car General Forum (go)
Moderators: dirtonly  /  dmantx  /  hosehead

Considering the recent post concerning xxx chassis and parts, there quality and price vs domestic builders, the photo of the Lucas Wolfe cars front end being ripped apart and other post stating that the chrome tubing is breaking just beyond the welds, regardless of who builds them. Here's something to think about.

The last racecar I built was in 1982, a 100" modified with a similar design as the sprint chassis of today, not a down tube but a standard type 4 bar car. That chassis and previous ones I built were all constructed of 1018 mild steel tubing, .120 & .90 wall. This material was quite common during this time even in sprint cars. The welding procedure required no pre or post heat or annealing. In accidents, nothing would break, it bent, absorbing energy. Todays chassis are considered to be disposable anyway so why not. Actually I think more 1018 chassis could and would be repaired than tossed.

Why not go back to this technology and material today? It's cheaper, much more forgiving and much easier to fabricate and weld, therefor labor cost is cheaper. As I remember, the primary reason for going to the use of 4130 was weight savings. Now with minimum weight rules, wouldn't it make since to have that extra weight incorporated in the chassis rather than bolted on? After all, it is considered sprung weight, meaning distribution of the weight shouldn't be a big factor.

Just though I would throw this out there as a possible way to save money. Am I being too old school and haven't keep up with the times?,....maybe but it seems logical to me.

When I owned my muffer shop, I had an employee of my tubing supplier selling AK (aluminum killed) exaust tubing out the back door to the local stock car racers.

This was a tubing made especially for bending.

Dirt cheap, thank God, nobody I know of was killed in this deal.

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This makes a lot of sense to me, why not?

correct, the cars are tearing apart but the cages are not. The tearing apart absorbs energy but the cgae will not bead. Would you want your cage bending enough to make the drivers head the first thing to absorb a 2nd or 3rd impact?

jonesy, I understand your concern but bending also absorbs energy and the bending would happen, in the example of a frontal accident, from bumper to torque tubes, side rails, braces etc before affecting the cage. In a rare instance, what if the cage was the first to receive the impact, as being t-boned by the front end of another car, wouldn't you rather have it bend than break off? I wouldn't even suggest using the process and materials as explaned in my above post if I thought it would be less safe than what the present application is. Perhaps someone with present day experience will comment and explain why this wouldn't be practical today. My position is that if a sprint car is required by rules to weigh, lets say 1,400 pounds and we all know that with the use of all the lightweight componets available today, one can and has been built weighing less than 1,000, why not use heavier wall, larger diameter mild steel tubing for the chassis construction?

Your right on target! Many years ago in the KCMO area we built one of the first tubular frame cars and foud the mild steel tubing was much better for racing with its bend factor instead of break. and you didn't have to heat treat it. Some of the old is still good Take care and enjoy the races.

If welded properly and the proper grade of Chromoly (normalized) it will bend and not break. It's still about weight. No racer buys something heavier if lighter is available for twice the price. The lightest car I ever heard of was Joey Saldana before weight rules. It was under 1100 with no driver and had every peice of titanium that money can buy. Add a 215 lb. driver and iron 360 and very little titanium and I'm lucky to weigh under 1540 with a 1475 lb. minimum weight rule. So even a budget racer like me would rather save 50 lbs. with a chromoly frame.

May it because I haven't welded anything in a long time. But back in the late 80' my dad built some mini sprint chassis that we raced and I don't remember doing any pre or post heating annealing, and I think we where using 4310 chromoly tubing? He just welded them using a TIG. Those cars where wrecked several time and we never had any tubing break, although the tubing bent a few times. Now I know our cars didn't go anywhere near as fast as a 410.

Can anyone explain the reason to pre or post heat.

Sprint57 hit the nail on the head. Why chromoly? ...~50 lbs a frame, that's why.

Thicker wall DOM would be almost as strong, but bend more before breaking, be way cheaper, be much easier to weld properly, a frame would last ten times as long before flexing out, plus its a lot easier to straighten...

But its also ~30% heavier, that's the catch.

I'm pretty sure a lot of series like Nascar use mild steel chassis.

 
 
 
They don't even know how to spell sprint car 
much less chromoly...http://www.ycmco.com