Roll cage - Floor pan EVO - Mirage

Robby

New Member
Wondering if there is a major difference between the CE Mirage floor pan and the EVO 4,5,6 Lancer floor pan in the region where the main hoop would go. My question relates to whether an EVO front 4 point bolt in roll cage structure could be utilised in a Mirage with custom rear legs? The main hoop in most cars attaches in the rear corner of the rear passenger footwell - is this area significantly different?
Track day car application. Thanks in advance.
 
Suppose the next best question might be how different are hatch/coupe doors to sedan doors? Might be a good starting point to guage possible differences. Option 2 is to fabricate from scratch a roll over structure.
 
Floor pan is the same from the points your thinking of, but the roof line is completely different. Sedan roof is higher, and the front A-pillars are at a different angle and length to Mirages.
You could get a hoop for a sedan, then cut the legs and re-weld them for the height adjustment, but the rest needs to be custom made, i've been quoted around $800 for a basic rear cage from AGI roll cages.
 
T-nol, great information. My exact thinking was to approach AGI, and possibly use part of an EVO kit. If they have a jig for a Mirage even better. A four point would be enough to get started, and be fine for club level events.
I use to work for a race car fabrication work shop, but for the price AGI builds cages for, it's hardly worth while unless going for a full Tarmac spec weld in. I'd prefer bolt in front legs/dash bar/intrusion bars so the car is road legal when not doing events.
 
Cold Drawn Seemless (CDS) is around $20 to $25 per metre (around 7.5m length) and $100 freight per length to me (freight is cheaper per additional length). Cost adds up quick, and that's not formed, welded, painted/powder coated either.
 
I currently dirt autocross/rally sprint a VX LS1 powered Commodore with 300rwhp, but I stand no hope against a 1.5ltr CE Lancer Coupe that a fellow club member drives! The problem is rally tyres are limited to 15" that are max 215 wide in
 
Bond rollbars do kits for specific cars, but they are weld in cages. A weld in cage is stronger than a bolt together but it can't be removed. My cage kit cost about 1k and then it took about 40 hours to weld in then paint. Compliance with cams is easy you just download the form draw your cage and send it in. Then when you get the car logbooked they will look over the cage and check it matches your drawings.
 
Did the Bond cage kit come pre-notched Frosty7? (not that it really matters...)
I've got a good Mig so I can weld the foot plates in and I would TIG the rest. At my old work place we often use to weld in the sandwich plates for bolt in cages - with captive nuts too for ease of instalment.
Thankfully a few friends can do the log book inspection for me, and perhaps this year I may even get a bronze scruiteneering certificate if I'm not too busy building cars...
 
Bond will also do a bolt in cage if you ask for it. Peter is a very nice guy to deal with and do what he can to help you out.
 
The pipes are bent only. They all need to be notched and finished to length. You should watch some YouTube videos to see some of the red hot tips.
 
AGI didn't have a jig for one when i approached them, they would need the car for 2-3 weeks, but said for using it to make the jig, they would do the good price.
 
Cheers Frosty7 and t-nol. I had a suspicion AGI didn't have a jig based on their listings.
I'm based in Victoria so it would be easiest to fabricate my own by the looks of things - I was trying to take the easy option!
I have access to a couple of Speedwerx benders so probably best for me to DIY.
 
Yeah, thats what i figured too, i have the benders and notchers already, i just haven't found the time or motorvation to get it done, considering it's adding weight to something i've worked hard to loose a lot of weight on.
 
One trick we use to do with the main hoop was to hole saw a hole under it, then put the foot plate in place and when finally finished box the whole joint.
The holes was there so you could tack the front legs/front four point together then slide the foot plates (not yet welded in) out and drop the back of the cage down through the floor. This gave excellent access to weld the top of the hoop and the tops of the diagonal roof bars and headed bar. Then you slide it back up, put the foot plates in place and then box the whole assembly for added strength. The hole underneath would get Sikaflexed or plated to seal it up. This applies to a weld in cage. Just be careful not to melt the fuel tank which if IIRC is under the rear seat.
 
The half cage in my rage is Cams spec bolt in - 40mm main hoop, 32mm rear stays, double diagonal in the main hoop, diagonal from driver side to rear passenger stay and harness bar across bottom of rear stay. I'll have to double check those but i believe the 40mm is 2mm thick and the 32 is 2.4mm. My numbers may be wrong (my memory is vague today) but its solid, tight as hell and was great for the price. Tis a wee bit of overkill though but can you have that for a safety device?
 
You are right about the tube wall thickness. 40mm tube can have 2mm wall thickness but 1.5" (~38mm) and 1.25" (~32mm) has to have 2.4mm wall thickness. I think this is due to it having to meet 350mpa tensile strength, a few extra mm helps a lot here. Metric dies seem to be less common in fabrication shops though.
IIRC cars over 700kg's now require a main hoop to be min 1.75" (~44mm) diameter tube.
 
A great fast way to notch the pipes for me was to use a plasma cutter, the finish of the cuts doesnt matter all that much because your welds fill in all the gaps.
 
The bigger the gap to weld, the weaker the join. You want it as near to perfect as possible, the notcher gives you the proper angle of the cut to, not just the outer edge shape, but the inner edge will also be in contact all the way around.
IMO, you either do it properly or not at all, remembering it's something to save your life, not look cool by having a cage.....
 
I wouldn't recommend welding over the perrosity left by a plasma cutter. As a general rule most decent fabrication workshops won't TIG weld a gap larger than the filler rod diameter, normally about 1.6mm for roll cages.
 
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