Fitting A Safety Devices Roll Cage

[Pugnut 9 1 Cars]

Right, i've bought a second hand safety devices 6 point bolt in cage which was fitted to another car too far back and welded , the guy removed it and fitted an OMP instead.

 

The cage is basically new but has had the base plates chopped off and the main hoop is about 30mm short of reaching the floor.

 

My plan is to extent the main hoop down by fitting a sleeve over the main hoop at both sides to extend them down .I'm going to make it so its still a bolt in cage .

 

a few questions!

 

 

1,with the rear 4 mounts having no plates i can play with height ,so can i set the height of the main to fit snug onto the rooflining (sunroof model). the fact that with the cage fitted in the car at the moment the rearmost bars are sitting hard against the boot floor (these have been chopped so it must be a bloody tight fit normally)

 

2, anyone got any measurements of the A pillar to the point of the dash? i need to know if i'm in the right place

 

3, Anyone know where i can get the correct tubing to slip neatly over the main hoop for an extension? Cant source any locally without going to machine shop to get some turned. 45mm OD , so something with a 45mm ID .

 

4,the car is on 4 axlestands at the moment with no windscreen so i'm in real danger of welding a cage into a twisted shell . Any tips for getting it sitting straight ? I've got a reasonably level garage floor and with the use of 'wooden shims' i've got the car sitting level . I've used a spirit level and the boot floor is level as well as the underside of the front subframe. i've also measure at the 4 corners of the car and these about 2mm maximum difference left to right. Have i done enough?

 

5,I realise that this will null and void the certification of the cage which wont affect me but can it be recertified at all?

 

 

I made some cardboard templates after finding what they should look like on Mattcony's guide.Then i nipped down to the local agricultural engineers and for a tenner they whipped me up some plates and a bag of 10mm bolts/nuts.

some more pics

pic1

pic2

pic3

 

any advice/tips/criticism welcome

 

cheers Al

[Phil 0]

I would think the only safe(ish) way to do this is to make a slightly thinner sleve to fit inside the original bar which contains the mounting foot, but also around the bottom of this there should be a 30mm or so ring of tubing in the same diameter as the original cage. Therefore the downward force in the event of a roll is not taken by a weld on the inner sleve but it presses on the thicker ring of metal. The inner sleve is simply to provide lateral support.

[mbayley77 0]

Well a piece of tube 1 7/8" x 18swg (1.25mm) will give you the correct size to slip over your existing tube. but am thinking that 1.25mm thick wall is not exactly super strong in the event of an accident.

 

Alternatively you could go for 50mm x 2mm tube leaving a 1mm clearnce around the existing tube (0.5mm each side) you could then weld this to the flat plates and also to the existing tube of the cage. This should get back some of the strength and rigidity.

 

i agree with the other comment of a spacer piece being used internally to lessen any stresses on the weld in the event of an accident.

 

shouldnt be that much of a headache though.

[Dj_mini 7]

You could drill two or three holes in the sleve where the two tubes overlap and puddle weld them up to gain extra strength so dont rely on the weld around the top of the sleve.

[Pugnut 9 1 Cars]

i got some 60mm od pipe 4mm thick! I have cut and shut it to neatly fit the tube.I managed to weld the tube inside as well as out so its should be quite strong as it is but i think i might try to fit a smaller dia tube as you guys say . belt'n'braces

 

I ran out of gas 10 min before the shop shuts and i'm 15 mins away, bloody typical.

 

 

[Pugnut 9 1 Cars]

are foot plates bolted down with M10 or 12 bolts ? (17 or 19mm spanner)

 

cheers Al

[jonah 1]

1. Yeah that sounds about right. I've kept the roof lining in my car and the cage is wedged tight up against it.

 

3. Try Metal Supermarkets (www.metalsupermarkets.co.uk), they will deliver if there isn't a store near you.

 

4. That should be fine... a straightforward cage doesn't offer much resistance against front to rear twist anyway.

 

5. Not sure, I guess it would count as a custom cage installation so it would have to meet the technical regs in the blue book to pass scrutineering, but I don't know how you go about getting it examined.

 

(and your last question) M10 were the bolts suppied with my cage, 17mm heads.

 

The extension you've put on looks nice and strong, but I would have thought it would be easier to extend it with the same diameter tubing. Grind a chamfer about 45degrees on the outer edge of each tube, going nearly as deep as the wall thickness, so that when you butt the tubes up you have a deep V groove all the way around. Then just do a fillet weld all the way round to fill in the groove. I've used this to join two round pieces together before and found it really easy (even with my very limited welding skills!) to get a neat and very strong join. You can then grind it back to a smooth surface so you'll barely even see the seam. Might not be quite as strong as the original tubing, but the loads it'll take there will be mainly compressive, so IMO there's very very little chance of the seam cracking if the welding is good.

[Pugnut 9 1 Cars]

Thanks Jonah.

 

I was toying with the idea of keeping the new part the same diameter but what swung it for me was that with the larger diameter i could slip it over the existing tube , assemble the rollgage in the car with the plates in place then just slide the new piece down and tack it in place.

 

Been at it this afternoon , i've had the cage in and out of the car god knows how many times now but i've started getting somewhere .

 

I've modified the rear plates so there not so much fill welding to do :

 

base plate welded in and Footplate for the main hoop all bolted in , i can just tack on the tube once the cage is bolted in the car (again ) :

 

finished off the main hoop:

 

cheers Al

[Gavin Waddell 18]

thats a lovely weld you got going on the base plate

[Pugnut 9 1 Cars]

why thank you

 

i took a pic of the best bit

 

its all in and bolted up at the moment , i think it looks pretty much like how the proper one should .Just a lick of paint required .

 

cheers AL