Structural question on my dragster frame...

In the drawing above, what is the purpose of the red bar?

I have a conflict with that bar at mid-span that I am trying to solve and I'm having trouble getting my head around what it's for so I can design a workaround.

As I look at the structure of the car, the purpose of the x-braces in the bays next to it are obvious, and if this one went from corner to corner I would understand it too. The thing I don't understand is since it doesn't go corner to corner, and is only braced against the top rail, it really doesn't seem to stiffen that bay very much. It just creates a rigid triangle out to where it meets the top rail, leaving the bottom bar and the front portion of the top rail to flex independent of it. And since the engine is stiffening that bay, I can't figure out why is it there at all.

Help.

-Brian

 

I cant tell by the drawing if the valve covers have spark plugs in them or not but if its a hemi and the bar went corner to corner it would hit the oil pump.

 

oil pump is likely.....

I had to move those bars on a car that was converted from a fontana to a chrysler style block. The debate was then "do we do both sides or just the left?". I did both the left and the right but only someone as experienced as bob meyer could offer an opinion if it would have mattered.

g'day,
Bryce

 

Yeah, it's a hemi setup. The bar would definitely conflict with the oil pump if it went all the way to the upper corner. The other side is the same way though. Also, I'm pretty sure this tube is a common layout on dragsters.

Bryce, where did you reposition the bars to?

-Brian

 

I wouldn't worry so much about that bar as I would want more side bars in the driver area.

 

bar placement

I moved the left bar to clear the oil pump, but left the right bar go from corner to corner,it did not affect anything.

 

I could see that bar being useful (and necessary) if the front plate rested in that area. Other than that, I would say the bar is a problem. As you mentioned, it actually causes a flexpoint in the top rail that will eventually begin to crack.

 

my ta/d does not have that tube there,,dave

 

Who was the chassis builder? May want to call them and see what they recommend or suggest.

 

So that bay is just the upper and lower bars on yours?

-Brian

 

bar

It may depend on the class sticker you want to put on the car. Every one of my alky cars have had that bar. And I have had 3 ,You really need to find out the SFI spec on that. You can call them and ask. I have done that before. Also, doesn't the rule book show something in the back? Don

 

Don, I went and dug out my 2.5c SFI spec, which is what I've been following for this car (6.0-7.49). It doesn't show anything in front or behind the cage, except the axle mounts. I'ts pretty much just the cage they are concerned with. I also looked at the IHRA rulebook for 2011 and it doesn't show anything there either. For the most part it looks like I'm on my own from a rules standpoint. I just don't want to snap the thing in half.

-Brian

 

Chassis

Call J ED Horton 1-864-338-9942 . He built my car that was set up for a chevy and we later made a move from a chevy to a hemi. The bar was a problem only if you had to take the oil pump off with motor in the car. I had about a 1/8 in clearance. We talked about taking it out but never did. Give him a call he will get you in right direction and save you alot of this " I dont know mess" GOD BLESS, Clayton Reeves

 

call Brad Hadman.he or his wife will answer he is great to talk to his wife is also very smart on all this stuff..Dave