Well things are rolling with the engine at last

So next thing on the list in the chassis ?

We are going to use 4130 grade 30mm chrome-moly steel - becuase it is quite light -

But im stuck on what thickness ?

0.5mm i would think would be plently thick enough - i dont want to make it too heavy but i also dont want the chassis to twist !

Anyone here done any drag racing or built tubular drag chassis ?

J

 

Anyone ?

I cant beleve that nobody has done a tubular chassis rx7 before -

Hows this

1.125"OD x .035"WT 4130 Chrome-moly steel -

It only weights 0.6KG/Meter -

So i reckon that the chassis should use about 200/300FT of tubing - that should make the chassis about 150KG's max

That plus a fibre glass chassis and engine etc the car should end up about 600/700Kgs hopefully.

 

The type of tubing really depends on the design of the chassis. If you're building a FULL tube frame to go drag racing, you will probably want to design it with a CAD program. When you've got something you like run it through ANSYS or some other stress analysis tool and you can learn which tubes are too thick (unneccesary weight) and which are too thin.
Personally I think .035" sounds too thin considering a lot of sanctioning bodies require .125".
Good luck

 

Before you go anywhere, you better have the rules book for the sanctioning body you plan to race with. Those will give you tubing sizes for chassis like the one you're building.

PaulC

 

Sounds thin to me too.

 

For a 2500 lbs road race car in Canada you have to use 1.5" x 0.095" mild tubing for the cage. Chrome moly tubing is substantially stronger, but I doubt anything less than .065" would stand up. Drag racing launches are much more stressful on a chassis than road racing is. I would also suggest ripping off your chassis design from a working car as much as possible. The less you have to seat of the pants design the better off you will be.

my $0.02
-Trent

 

If you did a tube chassis the car would be light but not very duribal so if you got into a crash you would be screwed.

 

I you want to see a tubulae chassis go to my site http://images.realride.com/cgi-bin/imageFolio.cgi and look under IMSA Rx7 project.
benny

 

I have looked into the rules a little more and have decided to use either:

1/8" O/D x .083" Wall chrome-moly steel or titanium.

I might use titanium - its lighter and will not have a fatigue problem like chrome-moly.

benny thats a nice tube chassis -

Im looking to keep the original shape of the car so that i looks as much alike an RX7 as possible.

We onwards and upwards -

Thanks for the advice - im not doing pro dragging - more run what ya brung stuff really - i may go into methanol drag racing later next year

J

 

OK, that's gotta be a typo, since your combined wall thickness would be thicker than your OD... making your tubes visible only in the 5th dimension.
Oh I get it, you decided to forgo a cage all together.

Regardless, I would avoid titanium. It's strength to weight ratio is not that much better than chromoly... certainly not enough to justify the cost. And it's more difficult to weld (properly).

 

LOL i can what i have done there !!

should be 1 1/8" O/D x .083" Wall -



J