New guy here, and another roll cage design question. I'm fabbing a cage for my friend in his 87 Civic AutoX car, and I'm wondering what is best for attaching bars to the rear shock towers. Should we build a box section around the tower or weld to the tower? Here's some pics, please feel free to add your comment about the design. Nothing is welded yet, so we can change anything that is glaringly wrong.
http://www.redpepperracing.com/gallery/cage_build
I'm also curious about the bar behind the seat, should we move it so it isn't directly behind the seat? We have a nice, bent harness bar at a good height, but I am wondering if the diagonal bar behind the seat is to much in the path of the drivers head. Should the bars to the rear line up with the bars that are eventually going to the front. The cage is being built to conform to the specs of the road racing classes run up here, so there's no issues there, I just want to build the best, safest cage possible.

Thanks

D.

 

Nice fit up on the tubing. I am guessing that the rear diagonals just need the tubes rotated for proper fit up. My preference would be to move the top of the diagonal in the main hoop over to the right more. The NASA CCR allows the top to be within 12" of the corner. Not sure about the SCCA GCR but I think it is the same.

 

yeah, the rears are just sitting there, they are just some bars left over from another car, we haven't notched them yet. So you think we should move the diag. bar away from the drivers head more? What about the mounting of the rear bars to the shock tower?

D.

 

Well can you build a 3 sided box around them. like 1/2 of a cube rember to leave an opening that fits over the current shock opening over the shock. this is just incase you want to add camber plates later the plates will be bolted straight to your roll cage...
Im not all that familar with the ITA cage rules.. can you weld a cross bar between your shock towers? If so are you going to and are you going to put a threaded "load" adjustment in it?

Well I see that you are setting up a new racecar.... If you would like a some what sponsor.. You run my stickers on the 4 corners of the car and one on each side of the trailer and registar on my new site I will give you 5% off anything in the store.. Just for running my logos. I already sell every thing for a verry low price. like a set of 2 Sparco FIA REV seats with Comp brackets for $889.99 a pair.
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The Gforce suits are "jobber" as well.

Well let me know what you think. Its a simple deal... You run my logos I give you 5% off anything till you peal my stickers.

Hope this helps
Ralph

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SPECTORracing &raquo;</TD></TR><TR><TD CLASS="quote">this is just incase you want to add camber plates later the plates will be bolted straight to your roll cage... </TD></TR></TABLE>

Uh, this is for the rear. Cant weld to the front shock towers...

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">If so are you going to and are you going to put a threaded "load" adjustment in it?</TD></TR></TABLE>

Why?

 

SPECTORacing, thanks for the offer. It's actually my car that is being built. I may take you up on the offer, you have a few things that i will need. We are located in Canada, so we are building to the CASC ruleset for cages. The main difference is that you are allowed to go through the firewall to the front shock tower, which if I do it, will not allow me to run ECHC, not that it was really in the cards to begin with.

It is currently a Solo 1/Solo 2 car, but I hope to step up to road racing in the next few years, so I figured we'd build the car now since we have the tools.

We ended up leaving the diagonal on the main hoop where it is. When I'm in the seat, there is a foot of clearance from my head to the cage, and I'd have to go through the seat to hit it anyway. If it's that bad, I'm not sure the position of the bar would matter...

There are updated pics in the link mentioned above, btw.

Thanks for the advice!

 

Well Im sorry I read the post wrong what can i say it was LATE...
I was talking about the front instead of the back. but you could put that setup on the rear. ...

the threaded cross beam would allow you to pre-stress the cage. that And i dont know if he has independent rear suspention with half shafts.. (like S2k, and others)
then he could be using rear camber if he wanted to. He could also benifit from tieing the shock towers together with a welded bar. but if he is tig welding its some times hard to get the proper pre-stress on the cage. and its always nice to be able to change that anyway. its like an adjustable shock tower brace just REALY BEEFY...

As far as the "why" question.. well im not sure that you want to know the physics or metalurgy be hind that but. if you would like to talk about this further I can answer your more specific questions toll free 888.833.RACE

I guess it all depends on if he is going to more of the Prototype side of the house or if he just wants to race a specific class.

Any way... what the hey its just my thoughts and opinions.. those are prob not worth 2 cents...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SPECTORracing &raquo;</TD></TR><TR><TD CLASS="quote">Well Im sorry I read the post wrong what can i say it was LATE...
I was talking about the front instead of the back. but you could put that setup on the rear. ...

the threaded cross beam would allow you to pre-stress the cage. that And i dont know if he has independent rear suspention with half shafts.. (like S2k, and others)
then he could be using rear camber if he wanted to. He could also benifit from tieing the shock towers together with a welded bar. but if he is tig welding its some times hard to get the proper pre-stress on the cage. and its always nice to be able to change that anyway. its like an adjustable shock tower brace just REALY BEEFY...
</TD></TR></TABLE>

Nope, it's a solid rear axle, so there isn't much to gain by going to that trouble, I don't think. We will be putting in a cross brace between the towers, but it doesn't do all that much on these cars. Our question is, do we go tower to tower, or down tube to down tube, just before the tower?

 

So other than welding, the back is pretty much done, is there anything we should add to the back? We have added a bar that continues along the same plane as the harness bar to the pass. side of the hoop. Is it worth an X? or is that just added weight? The car, before cage weighed approx 1650lbs. minus driver.

 

No suggestions? As mentioned, we added a horizontal bar that continues the harness bar, and the cage (well, roll bar at this point) is fully welded now. More pics here: http://www.redpepperracing.com/gallery/rpr-cb-day4 if anyone cares to look.

Thanks guys.
Tom

 

i'd say the rear of the cage is just fine and doesnt need an X. the trusses should act in compression and tension, so an extra cross truss is redundant. i like the fact you put a lower crossbeam in the main hoop. it should add a lot more rigidity. are you going to add a forward hoop? if its for autox and solo, i dont think youll need to at all.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Masta &raquo;</TD></TR><TR><TD CLASS="quote"> I'm wondering what is best for attaching bars to the rear shock towers.</TD></TR></TABLE>

control arm pickup points are what you want to brace , its not a Macpherson struted car.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Masta &raquo;</TD></TR><TR><TD CLASS="quote">Should we build a box section around the tower ? </TD></TR></TABLE>

no.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Masta &raquo;</TD></TR><TR><TD CLASS="quote">or weld to the tower? </TD></TR></TABLE>

you should attach to plates welded to the car.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Masta &raquo;</TD></TR><TR><TD CLASS="quote"> Nothing is welded yet, so we can change anything that is glaringly wrong.
</TD></TR></TABLE>

its not bad , no need to X the back , two triangles dont flex anymore than four triangles do.

 

Thanks for the feedback guys, this is mainly an AutoX car, with some Solo 1 planned. A forward cage is planned, but we're going to leave it for now and focus on the motor project

Thanks H-T

D.