 | Home > Maintenance & Modifications > Homebrew roll cages? discuss! :) |
 
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| sako243 Member Since: 08 Jul 2014 Location: Wales Posts: 1218   
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There are quite a few discussions over on lr4x4. The main set of guidelines are the "Blue book" (?) from the MSA. Which details quite thoroughly how many bends and welds should be made and where. The single biggest factor will be in the strength of the welds. Another useful resource would be pirate4x4.com where the chaps who built Ultra4 vehicles hang out, those designs take some serious impacts.
One point of nite I was initially surprised at was that they don't typically allow aluminium cages but that's because they tend not to give. I.e. you tend to have a very strong cage but if it does go it goes in a big way, whereas steel will more typically deform first. Aside from the cost advantage. With regards to material thickness etc. you can trade off again, the forums are a useful overview but I'd read the book as the definitive answer. Whilst you may not be competing in it they'll have done their research. From what I've read (and I'm by no means an expert) welded connections are preferred, as done right, they'll be the same strength as the material. Internal cages I've seen involve drilling through the tubs and bolting onto the chassis. Ed 82 Hotspur Sandringham 6x6 95 Defender 110 300Tdi |
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13th Aug 2016 5:55am |
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| GREENI Member Since: 22 Aug 2010 Location: staffs Posts: 10381 
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I've built an MSA cage before now, when I built my 80" trialler (back in the early 90's! . It's not easy, I gave up on the front and rear hoop, as I wanted it perfect, I ended up going to see a certain Drew Bowler (when he just made Comp and Trial motors) and bought front and rear hoops from him and built the rest onto it.
I'd recommend buying a tool to cut the fish mouths out as well. Buy the time you've bought all the quality gear and tubing to build one, maybe a forklift to lift it over your truck once built, you could easily have bought a Safety Devices cage...just saying  |
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13th Aug 2016 6:29am |
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| dantastic Member Since: 04 May 2010 Location: London Posts: 367
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Unless you get a mandrel bender (very expensive) those bends are very difficult to get 100% right. Good enough for a pure offroader but you're doing it on a shiney. Not to mention that the CDS pipe you will be using is a good bit more expensive than gunbarrel so you probably can't just keep trying til you get it right.
Have a look here for components. They will sell every component individually. http://www.whitbread-offroad.co.uk/flat_pack.php |
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13th Aug 2016 7:16am |
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| Laurie Member Since: 22 Feb 2008 Location: Sussex, England Posts: 2897  
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The roll cage you picture is basically a 'poser' device.
A 'proper' roll cage woul be almost all welded and contain at least one diagonal member. Borrow a copy of an ALRC Green Book (or join an ALRC Club) which will give you competition spec. cage designs for Land Rovers. Or..... http://www.land-rover-parts-shop.com/en/ui...-cages.php  |
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13th Aug 2016 10:34am |
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| agentmulder Member Since: 16 Apr 2016 Location: Outer Space Posts: 1324 
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Yeah, I agree, I don't understand how a connection that doesn't involve big bolts on mating plates would really hold up to the purpose...
I assumed welds were the go. I'm happy with a cross brace at the c-pillar, even though I'm firmly in the 'poser' camp I figure I may as well do it correctly. They'd serve well as internal mounting for jacks, extinguishers etc. - half way to a dog barrier too. Solved the bowel problem, working on the consonants... |
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13th Aug 2016 11:58am |
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| Thon Member Since: 22 Nov 2015 Location: Salisbury Plain Posts: 696
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IIRC the ALRC cage specs are significantly different to the MSA versions - from memory ALRC are built stiffer / stronger / more sturdy mountings in order to survive more frequent rolls (such as you would expect from a CCV trialer) without needing repair. The MSA versions (such as those supplied by Safety Devices) are not necessarily ALRC compliant and rely more on some level of deformation to absorb some of the impact without adversely affecting passenger safety, but would very likely need replacement. Personally I am lining up the updated Camel Trophy spec internal/external version to fit this winter. I don't like external cages because to me they shout "let's off road!" in a kind of fast show way ... but as always, each to their own as I can also see external has lots of plusses too. A "poser" version seems entirely worthless to me, but again, each to his own. |
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13th Aug 2016 1:58pm |
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| Mr Fox Member Since: 10 Sep 2011 Location: green & pleasant land Posts: 1037 
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I'm glad that someone raised the topic of how pointless a 'cage' without diagonal members is. Furthermore, glad that you'r going that route. A cross bar / diagonal can be made to work in a Defender but I'd suggest trying to get one behind the driver, in the B-pillar position. I just spent time and money ripping a cage out of another vehicle I own because the previous owner had installed a cosmetic cage into it. Considering the money he spent to do it and I spent ripping it out and replacing it, I spent the entire time wishing it had just been done correctly the first time. |
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13th Aug 2016 2:36pm |
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| couplands Member Since: 31 Aug 2011 Location: Peak District & Cornwall Posts: 1826 
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I'd be wary of too many internal parts as they are just where your head would be in the event of an accident. Plus, if your using your Defender in the lanes, the external protection will help keep the trees away from your soft roof/side panels. Just my opinion of course, but if you're having a cage for safety you need to think of these things... 
Cheers Simon |
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13th Aug 2016 8:41pm |
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| agentmulder Member Since: 16 Apr 2016 Location: Outer Space Posts: 1324
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Hi guys, thanks for the tips.
I downloaded the 2016 blue book, but I can't search for strings like 'roll cage' on my phone, got a few days of odd hours at work away from home so I'll check it proper tomorrow PM. I'm actually in NZ, and I'd rate the reasons for wanting one thusly: - Relative safety in the unlikely event I roll the vehicle. While I'm hardly a madman at the wheel, there are plenty of roadside slopes in the hills round here. On two muddy occasions now I've been one wrong decision away from going down a 's&#t your pants/no thanks!' slope. I've joined a 4WD club to learn driving skills in this regard - i.e. avoidance in the first place... - In almost equal regard - but safety wins by a nose - I get to buy a nice Miller TIG welder and hone some new skills in welding, mechanical design and fabrication.
- Cage doubles as roof rack and solid internal mounting for other stuff that is currently only half managed by stuffing under seats etc. 
- I'm a poser and I get the look I'm after. 
I certainly don't need the style where you roll over and keep going and I'm happy with the idea that it's more sacrificial (it takes the blow instead of my spine  ). Solved the bowel problem, working on the consonants... |
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13th Aug 2016 10:25pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17380 
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Bear in mind (especially when the subject of diagonal members is being discussed) that a typical competition cage is designed to allow you to turn the vehicle the right way up again and drive off, whilst a Safety Devices type cage is designed to keep you alive when the vehicle is written off.
There are many people alive today who have emerged from destroyed Landrovers relatively unscathed who would not have done so if it wasn't for an SD type, diagonal-less and bolted-together cage. Personally I see little point in making my own cage for a standard vehicle when a top-quality, commercial off-the-shelf product is available. As noted above, producing a good result with less than a CNC mandrel bender is very difficult. |
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14th Aug 2016 9:31pm |
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| George G Member Since: 02 Feb 2015 Location: Derbyshire Posts: 21
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The Fia Cross Country (Dakar vehicles) regulations are worth a look too. Can be downloaded here:
http://www.fia.com/regulation/category/100 Article 283. Minimum material requirements are also shown, but basically a 45 or 50 OD CDS with 2.5mm wall. (Sizes and wall change with material properties) Dont even consider aluminium. A cage is also only as strong as its weakest point, so keep that in mind when you decide where to bolt it to on the vehicle. If you really want to DIY build yours then find a local tube supplier and talk to them - they will have a few people they know who can bend the tube. You will struggle to do it well by hand. Most suppliers can work with just a length and an angle to make a basic shape. Just add 50mm or so to each tube end to make sure... you can always cut material away. If you are happy with just an internal then you can get away with only a few bent pieces and buy the rest in straight to keep costs down, otherwise get sketching and measuring. Many suppliers can laser cut the notches for you on the pieces from 3d cad files now and basically supply you a flatpack kit, which saves loads of time & hastle. So if you do have the luxury of knowing someone with 3D CAD software and some sparw time, then thats another option. Whichever way you do it, good luck and take your time with the welding and get it right. |
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16th Aug 2016 9:49pm |
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| roel Member Since: 08 Aug 2009 Location: Lelystad Posts: 2039  
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A Defender roof is as strong as a softtop, so I fitted a cage. I have a cage to protect me and the passengers. If I roll I would like to get out off the 90 in a good shape. The state of my 90 is off less importants. It is build from 2 written off 90's anyway.
I used a package from North off-road. You can get them completely welded or as a package that you have to weld yourself. I welded mine myself, I didn't roll yet so I don't know if my welds were as strong as I hope. I made some small changes to the North design as I want to be able te take mine off in case I need that. As I use my 90 off-road and I am not always that carefull I made a cross behind the seats too. I noticed that the middle hoop off the North cage is placed further to the rear than a lot off other cages. The good thing off that is that the cross fits straight into the middle hoop. So you don't have problems with the front seats. Click image to enlarge Click image to enlarge Click image to enlarge Roel 1984 90 2.5 na Diesel - RR V8 (1994-2001) 1997 Camel Trophy Discovery 300TDI (2001-2009) 2005 G4 Discovery III 4.4 V8 (2008-2018) It's gone but it still hurts. 2003 90 Td5 (2009-now) |
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17th Aug 2016 11:57am |
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| dave18 Member Since: 11 Jul 2015 Location: Gorleston, Great Yarmouth Posts: 497 
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My personal opinion is unless your a coded welder or weld that type of material everyday then get someone else to do the work.
Found it interesting how many different styles of cages and prices there is for the fender. and how if your not carefull you could be actually putting your self in more danger. Saw a front hoop that bolted to the roof and then to the outrigger. In roll over that would bend and possibly pin you where as with out it the windscreen frame would shatter and you might be able to get out! I keep looking at cages but have a ribber roof and dont want to get rid of it and need to physically see an internal 110CSW cage before I go and spend the dosh. |
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17th Aug 2016 6:05pm |
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| Mash Member Since: 09 Feb 2015 Location: Guernsey Posts: 1674  
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Just copy this one
https://www.ebay.co.uk/itm/302043189945
Not sure how legal the reg cover is? 90 wolf - Jasmin http://www.defender2.net/forum/topic39408.html 90 V8 - Maggie http://www.defender2.net/forum/topic42564.html 110 TD5 - Buggsy http://www.defender2.net/forum/topic59029.html 52HG25 lightweight https://www.defender2.net/forum/topic72342.html D3 Hse - Fiona Capri 2l S - Anna Think I might have a problem............ |
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17th Aug 2016 8:41pm |
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