Advantages of a roll cage
Turbo Mini Forums

I came across this comment about roll cages on minifinity

"Just to sort out this misunderstanding.

Just fitting a roll cage with its normal mounts does next to nothing for the cars rigidity. It will how ever save your life in an accident if you don't bounce your head of it.

The only time they add to the cars rigidity is when they are connected the the shell at every conceivable point. Not just the floor and rear arches."


I think "next to nothing" is a bit strong. Sure, part of the shell above where the cage is fixed can flap around just as it did before. But a cage will certinally reduce the twisting of the shell when cornering, which is what you want.

Well that's what I think, but I'd apreciate some thoughts on the subject.

Cheers

Wil

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

I'm assuming that your answer is the bottom parragraph?

A frame on it's own will definately increase rigidity - but by how much i really don't know.
I think the "at every conceivable point" is a lottle ott - or taken out of context?

I'd have thought that if the front cage was mounted to the A-Pillars at the lower dash rail, and (approx) 3/4 way up the screen, the B-pillars connected at the same heights (approx) and the rear suppports fixed to the rear arches with sturdy plates (as they should be) then it's getting on for being ideal.
Basically - If no cage was zero, and a cage even more complex than Jims was 100%, I suspect you'd be easilly to 90% with that simple mods.
Other things i would do - is add a 'floor' x-member on the front legs and main hoop, to tie the floor to the cage. That'd make the next major step, but i can't think of anything therafter that would make a 'significant' increase in structural rigidity...

Edited by turbodave16v on 11th Jan, 2006.

Well I never answered the comment on minifinity.

The bottom bit was written by me just for TM guys.

I agree with everything you say there though Dave. But my cage is fixed as 'standard' i.e. just to the floor, and I can't believe it does next to nothing.

Wil

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

as per dave, what i have found is that any cage will rigid up the car. however if the cage is welded to the shell with tabs ie down the "A" pillars, "B" pillars, floor etc. the shell becomes much stronger. this i can corroborate through seing cars rolled over. the ones without the cage welded on the points mentioned needed new shells after the crash. the ones with were ok, a few dints in the top pannel of course, but the integrity of the shell was intact !

Richie

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MikeRace, Mini13

is it tony falls who set up safety devices?
if so it was he on a video i once saw which explained how by fitting a simple 6point cage to a mk1 golf upped its torsional regidity by something like 50% ,its awhile back now [13yrs min] so my memory is not what it used to be ,but it was certainly a big increase.

carl

WWW.FORCE-RACING.CO.UK PLEASE CLICK HERE

Got to admit i can see it not adding a lot at all.

Interesting.

I guess no one knows the answer as it's probably never been measured/calculated.

All the answers above are based on engineering judgement/opinion/experiance.

The way I SEE it is that the cage is like having a 2nd roor and pillars in side the car, as it is attached to the floor in a similar way to the roof. Now we all know what happens when you cut the roof off a Mini (or any modern car). So I can see it adding a reasonable ammount, but I'd be happy to be prooved wrong.

Wil

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

In my Vauxhall (hehe) I had a full welded in rollcage, with a crisscross section in the rear and all the door bars etc. It was welded to the rear arches, and front floorpans and somewhere along the middle of the floor area too.

going round ANY corner, even light corners, if you put your fingers in between one of the roof rollcage bars and the shell, there was flexing. It wasnt that much, but on faster corners i got dan to see how much the gap between the shell and rollcage changed and it could be up to a centimeter.

The suspension was set to very very stiff though and there wasnt much suspension travel and it was seam welded everywhere so there was alot of stress on the shell.

Previous Engine: 1040cc Morespeed engine, 1275 turbo head T2 Turbo Mirage Manifolds Megajolt
Previous engine: STD metro turbo, megajolt
Drives: 399bananahp (flywheel) Honda Civic Vtec b18c4 T28 Turbo 1968 Mini

Megajolt maps to download: http://www.jamesfawcett.co.uk/cms/index.ph...&gid=3&Itemid=3

ive got a standrd 6point saftey devices roll cage with door bars in me clubman, me clubbys a solid shell good sills, good inner sills, good floor etc when its level on the ground the doors shut ok but when the fronts up on axel stands the doors dont close the same. they sort of catch a little on the latches if you know what i mean. dont know if thats relefant or not its just something ive noticed.

i believe the roll cage does improve ridgeidity loads, that way i can justify the 350 quid or so i spent on it.

im planning on getting another set of door bars and fitting one across the front botom dash area. and fitting the other across the legs that go one the rear arches, any1 ever done this?

no longer a series, but still 1.3 turbo.

strange..carl that sounds like the bottom of ya "A" pillars are rotten the bit behind the apex that the door bolts onto..........one thing you do need to consider regarding rigidity is if you have cut holes everywhere for lightness ie the cross member on the floor, or if you have removed the rear seats and havent replaced it with a brace bar. my metro was totally stiff, no flex at all, my rear seats were replaced with an aluminium sheet to cover my beam axel, the rest of the car was basically a roll cage welded intot the shell, the only part of the origional floorpan was the front footwells everything else was aluminium sheet. so once again i can confirm if the cage is fitted properly welded onto the points, and the structure of the shell is intact it will increase the stiffness...in feebs case and carl i would bet my hat i would find structural failure on their shells causing the shells to "Sagg" around the cage or the cages were not welded in the correct spots (not trying to cause offence here btw lads)

to get a propper deffinitive answer ring safety devices and ask maybe get written proff emailed ??

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MikeRace, Mini13

I think that a bolt in 6pt cage properly fitted (and emphasis on properly) does without a shadow of a doubt increase the stiffness of a car. However, by tying it into the A and B pillars, I think this would increase the benefit even more.

My track car that a lot of you have seen, has a 6 point cage installed. It also has the tags to tie it in to the pillars and roof, whoever installed it decided not to do this, but this is one of my planned jobs when I next do some major work to it.

my first turbo i cant find any rot in the areas conserned its just one of them things i fink only moves a tiny weeny bit probably a nats nudger.

no longer a series, but still 1.3 turbo.

aye nee botha lol :) just when u said, i had a shell in the past where the doors did exactly what you said, at first i thought the hinges were jiggered......wish they had been
Richie

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MikeRace, Mini13

this reminds me a bit of an old tale that submariners used to tie string across the submarine, and when they went deep the pressure would crush the hull and the string would sag...

tie tight pieces of string across the car in loads of places. LOL

and if any snap/sag then there you go.

im only being half serious btw

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

my first hill climb mini was 1971 clubman, a bit of a shed ,but road legal, i fit only a rear hoop for safety, sometimes i would take it out on a sunday marning and thrasg it aroung "Tingley Roundabout " which is J28 M62. the one you get off on for the white rose centre in leeds ,
going around this ,shall i say quickly, would see the drivers toor top open by 1/2" ,with shell twist.
i beleive when a cage manufacturer designs and builds a cage tests are done before and after to accertain its effectiveness.and the dats logged for reference.

carl

WWW.FORCE-RACING.CO.UK PLEASE CLICK HERE

I agree that the standard steering column can be a bit floppy, however I have always stayed away from messing with the mounting points, simply because in the event of a big accident, I don't want the column to be so rigid and solidly mounted that it turns into something that could seriously injure the driver.

I agree, But I'm hoping the 6 point will help me there... :) It's a racecar with an LSD. YOu really need the column to be mounted like this as the original ones WILL break.