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roll cage start open to advice (not 56k friendly)


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I didn't mean to get you worried about your actual welds, since well I can't really inspect them and pictures can be misleading when trying to evaluate the look of a weld.

 

I also thought you would have cut the rear bars, the ones that run from the main hoop to the rear floor and have them notched to fit around the strut brace. What you have is better than nothing, but would tie the chassis together better for it to be fitted with the bars intersecting on the same plane. At this point, it would take a bit of work to change, and unless you start building 4 digit HP and running deep single digits, or serious road racing/auto-x, I would just leave it as is.

 

thanks alot i figure to do it right the first time hp can be added times could drop but re welding sucks.

 

Has anyone ever mounted there seats to the cage here if so whats the best way to do this pics would be great

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I don't know about anyone here, but I know a lot of Super Street and Outlaw 10.5 cars have the seats mounted this way.

 

How you would go about maiing the actual mounts depends on the seat itself and how it's mounting pads are designed.

 

In most cases there will be bars running between a rear crossmember, and a front crossmember or front frame rail. There will also be rocker bars. Between these bars side to side, there will be more bars added, usually of a smaller diameter, that have plates welded to them for mounting points of the seat(s).

 

Another variation on this is to build or bend bars rather that run from door bar to door bar, down from one side under the seat up over the tranny tunnel, down again on the other side under the other seat and then back up to the other side's lower door bar. I'm not a fan of this design, because all the bends in the bars make for weak points, and requires large diameter bars to have the same strength. I also haven't seen this very often, probably due to difficulty of building (bending) such a support, and would also think safety concerns keep this one from being used more often.

 

Another variation is to use a bar that is a hoop attached to the lower door or rocker bar, and runs around the perimeter of the seat, with smaller bars used to attach plates under the seat mounting points. Usually there will be crossmembers attached to the hoop to help strengthen the mounting scheme, by tieing both sides of the car together. A variation I've seen of this is one that is not a hoop, but attaches to a lower door bar or rocker bar and then attaches to a rear crossmember. All the rest is the same though, smaller bars and plates, and crossmembers.

 

Done right and with proper planning this is a safer way to attach the seat, since the floor pan can easily buckle in a roll over or side impact, heck even in a front or rear impact the floor could buckle. This would mean the seat moves, where as the seat belt attachment points don't, bad situation no matter how you look at it. I dealy the seat would stay in the same location relative to the cage and more importantly the seat belt attachment points so that the occupant is held where they were pre-impact.

 

Also depending on the type of seat being used an upper attachment point will be used, usually attached to the seat belt bar, and has a flat plate that is then bolted to the back of the seat. I see this on aluminium seats.

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would something like this work? be legal? I have see it before I think its what you were talking about but I'm not sure. The seat needs to stay low in the cab so the bars will also hit the floor and go with it to the tunnel. Sorry about the crude drawing but here it is

seatmounts.jpg

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Holy ♥♥♥♥. I dont even want to imagine how much that cage weighs LOL. Thats gotta be like 200lbs worth of steel!

I dont think its that much its only about 4 sticks of dom by the time Im done itll be close to 220lbs but well worth the weight. I have yet to tie the seats in and build the door bars but it will hapen soon very soon. and the weight will just mean more hp to the ground Im planning to have this car in the low 10s so any added strength is well worth it.

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I looked at your cage and saw that a lot isn't tied directly into the main section very well. Back protection isn't as necessary as you're building it, so I made a few modifications to your design to what I think would make it lighter and possibly more rigid.

Red is deletion and blue is addition.

the X you made while a good idea, isn't really needed. If you took that out, and instead, from the center bar on the outsides, made diagonals that mounted to the transmission tunnel I think it would help make the car more rigid overall, since it makes the rollcage tie directly into that central point.

Also, for the rear, I'm not really sure where your mounting point is. Is it just the body? You don't have to worry about the rear of the car. In an accident, the car will be toast. You want more focus on the driver than the car. Instead of having it extend so far back without really tying into the strut towers, it doesn't make the car overall stronger (in my opinion)

BUT if you were to take those 2 bars, and weld them to the strut bar you have, that would in my opinion, make it stronger as a whole, The two bars you have tying at the center I think is a good idea though. The single center bar between the two, not such a good idea. The best thing to do I think would be to find some way to tie your differential directly into your cage by somehow finding a way to bring the cage to the diff, and making some sort of custom solid bracket for it. That will reduce the twisting action of the diff to basically none, and should help with transfering torque (Not 100% sure on that, but when we put the roll bar into my dad's bug, it tied directly to the transmission frame horns, and his car was able to take off so much faster, that the first time out, his car red lit by over 1 tenth. He had to do a lot of re-adjusting to his car because it was able to put down the power so much harder)

I'm not a fabricator and have never built a cage, but I do love engineering. this is just my opinion on things, and I'm not really sure if I'm correct on my assumptions.

cage_thumb.JPG

cage2_thumb.JPG

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I looked at your cage and saw that a lot isn't tied directly into the main section very well. Back protection isn't as necessary as you're building it, so I made a few modifications to your design to what I think would make it lighter and possibly more rigid.

Red is deletion and blue is addition.

the X you made while a good idea, isn't really needed. If you took that out, and instead, from the center bar on the outsides, made diagonals that mounted to the transmission tunnel I think it would help make the car more rigid overall, since it makes the rollcage tie directly into that central point.

Also, for the rear, I'm not really sure where your mounting point is. Is it just the body? You don't have to worry about the rear of the car. In an accident, the car will be toast. You want more focus on the driver than the car. Instead of having it extend so far back without really tying into the strut towers, it doesn't make the car overall stronger (in my opinion)

BUT if you were to take those 2 bars, and weld them to the strut bar you have, that would in my opinion, make it stronger as a whole, The two bars you have tying at the center I think is a good idea though. The single center bar between the two, not such a good idea. The best thing to do I think would be to find some way to tie your differential directly into your cage by somehow finding a way to bring the cage to the diff, and making some sort of custom solid bracket for it. That will reduce the twisting action of the diff to basically none, and should help with transfering torque (Not 100% sure on that, but when we put the roll bar into my dad's bug, it tied directly to the transmission frame horns, and his car was able to take off so much faster, that the first time out, his car red lit by over 1 tenth. He had to do a lot of re-adjusting to his car because it was able to put down the power so much harder)

I'm not a fabricator and have never built a cage, but I do love engineering. this is just my opinion on things, and I'm not really sure if I'm correct on my assumptions.

i was told by a local builder that the x needs to be within 18" of the floor and he did a basic layout for me on the center hoop but i am always willing to take suggestions ill run these by him and see if he thinks i should change it up

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  • 2 weeks later...
Holy ♥♥♥♥. I dont even want to imagine how much that cage weighs LOL. Thats gotta be like 200lbs worth of steel!

 

I was thinking the same thing ! But as you wrote if its not a problem for you good job !

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All racing org. have VERY specific rules on cages design, materal, size, and welding method used to be legal. Check with them for there rules, you may have to change or start over in not correct......

 

 

QFT!

 

I don't know of any organization that allows grinding of the welds.

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None of the sanctioning bodies that I'm aware of, allow grinding of the welds.

 

On the door bar that you started how are you going to weld the underside of those joints and the portion next to the lower door jam?

ill reweld them then so the weld is visible not a big deal. Im going to have to weld them in very awkward angles lol its not going to be fun but yea it can be done.

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ill reweld them then so the weld is visible not a big deal. Im going to have to weld them in very awkward angles lol its not going to be fun but yea it can be done.
Not to freak you all out i never ground the welds except on the gussets thats all so ill v/notch them at the seams and re weld
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  • 8 months later...
I dont think its that much its only about 4 sticks of dom by the time Im done itll be close to 220lbs but well worth the weight. I have yet to tie the seats in and build the door bars but it will hapen soon very soon. and the weight will just mean more hp to the ground Im planning to have this car in the low 10s so any added strength is well worth it.

 

when you think about it, thats pretty much like giving a friend a ride, or a large spouse. i wouldnt be too concerned about it either. the rigidity is going to make a difference when you are shifting weight for corner entry or perhaps a drift if thats what youre in to. after im done installing all the parts i have on order i think the next thing would be a cage. but i wonder, does anyone have a set of plans? like blueprints or something that i could base mine off of? i saw that jegs sells pre bent kits but thats like $250+ id rather go to home depot and get some pipe. i have access to a bender and i know a little how to use it so i then all i have to does is weld them shits into place and ill be set. so if anyone is scrambling for their file cabinet or garage door looking for their old plans right now i have a 73 s30. thanks a bunch :o

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when you think about it, thats pretty much like giving a friend a ride, or a large spouse. i wouldnt be too concerned about it either. the rigidity is going to make a difference when you are shifting weight for corner entry or perhaps a drift if thats what youre in to. after im done installing all the parts i have on order i think the next thing would be a cage. but i wonder, does anyone have a set of plans? like blueprints or something that i could base mine off of? i saw that jegs sells pre bent kits but thats like $250+ id rather go to home depot and get some pipe. i have access to a bender and i know a little how to use it so i then all i have to does is weld them shits into place and ill be set. so if anyone is scrambling for their file cabinet or garage door looking for their old plans right now i have a 73 s30. thanks a bunch :o

yea about this I couldnt find this pipe at home depot I had to go to a metal shop

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