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Discussion Starter · #1 ·
Hey People,

I'm having trouble finding out what the SFI spec for roll cages for cars in the 9's, does anyone know what size and thickness CDS tube is required and how many points the cage should be?

It's just a mess about car for the Hot Rod Drags but we still want it to safe for our goals so no gas pipe suggestions please ;-)

Cheers

Gotzy
 

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Reading the rule books will be confusing, they are often contradictory. The main tubes for a CDS drag race cage should be inch and five eighths diameter with a three mil wall. Speak to the race shops who will also sell the tube. Also speak to the drag race tech guys (Mark) for the MSA who are at the race meetings. Joining the Santa Pod Racers Club will get you a rule book. Does the car have a chassis or is it monocoque? Doing it right the first time will save money in the long run and add value to the car.
 

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Discussion Starter · #8 ·
Cheers HC

It will be a Chopped Morris Minor with a box frame, cage will be welded to the box frame and the body welded or bolted to frame, don't know yet. Not sure if we'll, or need to, weld plates to the corners where we'll weld the cage to the frame. It will have a Viva front with the front tubes and soild motor mounts connecting to the uprights. 4 bars out the back.

Pretty much picturing a smaller scaled down version of a 10 point cage like this - http://www.hotrod.com/techarticles/nhra_legal_rules_regulations_time_brackets/photo_04.html

I know it appears over kill for a RWYB car but it will be a short wheel base car and we'll also be adding nitrous next year so we could be pushing 700 hp eventually so safety is really in our minds.

Any thoughts or experience on how much tube we'd need?

Cheers

Gotzy
 

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Cheers HC

It will be a Chopped Morris Minor with a box frame, cage will be welded to the box frame and the body welded or bolted to frame, don't know yet. Not sure if we'll, or need to, weld plates to the corners where we'll weld the cage to the frame. It will have a Viva front with the front tubes and soild motor mounts connecting to the uprights. 4 bars out the back.

Pretty much picturing a smaller scaled down version of a 10 point cage like this - http://www.hotrod.com/techarticles/nhra_legal_rules_regulations_time_brackets/photo_04.html

I know it appears over kill for a RWYB car but it will be a short wheel base car and we'll also be adding nitrous next year so we could be pushing 700 hp eventually so safety is really in our minds.

Any thoughts or experience on how much tube we'd need?

Cheers

Gotzy
You will be amazed at how much tube you use. I have chassis'd and caged a good few cars and it never ceases to amaze me that even without wasteage and/or mistakes you will use at least twice as much as you think.
There are calculators out there for working it out but you need to have lots of known parameters to do that.
 

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Was thinking 8 3m lengths, what do you reckon G8RC?
I know the car is chopped but 3m lengths is going to limit your design I reckon. That's just over 9ft so doing a main hoop in one piece could be tight.
My bender adds 7" to one measurement and removes 1" form the other in a 90 deg bend. If you are doing it in CFS and not 4130 then why not buy full lengths(usually 6-7m). It will work out cheaper and most suppliers delivery prices are very reasonable.

I used over 50' of tube in this car.....

 

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didnt know you could buy cfs in 3m lenghts.
that would be very tight on youre internal loops as stated above.
just recently caged a fiat 500 and the loops were longer than 3m.

used 3 full lenghts doing that car so you should get away with 4 full lenghts.

steels cheap as chips again now so buy direct from youre local stockists
 

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Hello Gotzy

If you want I can give you Mark Norton's number, I think he has family down this way and as said before he can help you.

If you have a word with Mark after the eurofinals I will be stripping my car completely so you can have the rolling shell at his and you can take any/measurements you want along with picks. My car is tagged to 8.5 with a boxed section chassis. Once you start to build it most of it is straight forward but as previously stated there are things that have to be right and in the right place.up to 10 second pretty much anything goes.

If your at hayling on tomorrow I'll talk to you about it.
 

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Discussion Starter · #16 · (Edited)
Cheers G8RC & Nobody, important advice so thanks

Haven't made the box frame yet HC but we have 4 or 5 lengths of 80 x 40 box for it. Hopefully will get the chassis jig set-up this weekend and get the headers and box bolted to the mockup engine and put it in place and then take it from there. Rough plan is to have 2 main rails tied into the viva cross member running to the rear cross piece which the rear kick over and 4 bar brackets will be welded to. On the sides will have more box from the rear cross piece along the sills up to the A pillar then into the main rails so will have a roll cage mounting point in the 4 corners of the cabin.

Cheers Ron, that will be helpful! What do you mean about being at Hayling?
 

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Sorry thought you were sorted. I've got last years rule book here and it says a fabricated main frame should be made of at least 60 x 40 x 3mm wall. Ths covers down to 8.5 so you should be ok with what you have as long as the wall is thick enough. They measure the wall thickness with ultrasonics after construction.
 
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