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Author: Subject: MNR and Their Infeasibly Large Roll-Bars
scootz

posted on 9/8/13 at 09:34 AM Reply With Quote
MNR and Their Infeasibly Large Roll-Bars

For me, the MNR is one of the prettier kits... until they go and put those flipping great scaffolding pieces on the back of them!

I know that they're thinking about our safety, but why do they have to be SO much taller than all the other manufacturers?

And then there's this monstrosity... a really nice car with a full cage that can touch the sky! Why oh why? Surely a full cage can be lower than that???


LINKY





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Slimy38

posted on 9/8/13 at 09:38 AM Reply With Quote
That's bonkers, I know it's good practise to have it a little above a helmeted head but you could fit a hairmet under that.

For the non-scrubs fans, this is a hairmet...

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loggyboy

posted on 9/8/13 at 09:39 AM Reply With Quote
That doesnt even look like its made from the correct diameter to make it suitably strong. Coupled with the leverage the height would give the ground if it was struck at speed it would look like it would just fold up!

I can only hope to assume this was just a customer who wanted (insisted) on somthing so fuggly and functionally less safe.





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MikeRJ

posted on 9/8/13 at 09:44 AM Reply With Quote
quote:
Originally posted by scootz
For me, the MNR is one of the prettier kits... until they go and put those flipping great scaffolding pieces on the back of them!

I know that they're thinking about our safety, but why do they have to be SO much taller than all the other manufacturers?

And then there's this monstrosity... a really nice car with a full cage that can touch the sky! Why oh why? Surely a full cage can be lower than that???


LINKY


Perhaps that one was built by a very tall person?

I agree that big cages really spoil the looks of a 7, not an issue for a track car but I doubt I'd choose to have a full cage for a road car.

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loggyboy

posted on 9/8/13 at 09:46 AM Reply With Quote
quote:
Originally posted by MikeRJ
Perhaps that one was built by a very tall person?

I agree that big cages really spoil the looks of a 7, not an issue for a track car but I doubt I'd choose to have a full cage for a road car.


I did. on I do plan to use it on track, but 90% will be road use. Ignoring the roll over protection, it does and strengh to the cockpit for other impacts.





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sdh2903

posted on 9/8/13 at 09:47 AM Reply With Quote
There's a few Mnrs kicking around with tall cages on so I dont think it's a customer one off.

If you look at the roadrunner sr2 I think that looks like a lower sleeker option which looks much better.

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loggyboy

posted on 9/8/13 at 09:48 AM Reply With Quote
quote:
Originally posted by sdh2903
There's a few Mnrs kicking around with tall cages on so I dont think it's a customer one off.



If you read the advert, is says it is!





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wylliezx9r

posted on 9/8/13 at 09:52 AM Reply With Quote
quote:
Originally posted by scootz
For me, the MNR is one of the prettier kits... until they go and put those flipping great scaffolding pieces on the back of them!

I know that they're thinking about our safety, but why do they have to be SO much taller than all the other manufacturers?

And then there's this monstrosity... a really nice car with a full cage that can touch the sky! Why oh why? Surely a full cage can be lower than that???


LINKY


The ad says the original owner was 6ft8 hence the height of the cage. The tube diameter does seem too small, overall it just doesn't look right





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iank

posted on 9/8/13 at 09:53 AM Reply With Quote
Procomp goes high at the back and low at the front. Looks much better to my eye. Of course with an approved cage rather than a blue book MSA drawing complaint cage you can do that kind of thing and still race.



More detailed:
http://www.procomp.co.uk/newimages/detailed_illustrations/n50.jpg





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sdh2903

posted on 9/8/13 at 09:55 AM Reply With Quote
Yes but I guess it's a standard option from mnr because there are a few knocking about.
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loggyboy

posted on 9/8/13 at 09:56 AM Reply With Quote
quote:
Originally posted by iank
Procomp goes high at the back and low at the front. Looks much better to my eye. Of course with an approved cage rather than a blue book MSA drawing complaint cage you can do that kind of thing and still race.



Thats how mine is too, which I was slightly disapointed with as I wanted mine slightly taller at the front, but RAW didnt quite finish it as my designs. Fortunately its grown on me now.







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coozer

posted on 9/8/13 at 10:02 AM Reply With Quote
At MNR when you order a kit, Chris sits you on a chair and measures you from seat base to top of head, then the roll bar height is worked out to ensure you dont drag your nut along the ground if you flip over..

Its all about safety.





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FuryRebuild

posted on 9/8/13 at 10:15 AM Reply With Quote
The blue-book states that you have to set the cage height at 50mm above the height of the drivers helmet, and in such a way that any forward tubes must go forward without a bend to the highest hard point on the chassis. That is the safety zone that is protected if you go on to your lid.

There are rules about crossing the tubes at the back of the cage to support it, as well as the size of the plates and the tube to plate mounting rules,

IIRC, the book even talks about what good welding should look like on the cage, and advises you to walk away from bird-shit.





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Not Anumber

posted on 9/8/13 at 10:39 AM Reply With Quote
Frankly i think all this metalwork seriously detracts from the looks of a 7.

Roll over bars and cages are safe and sensible for racing and track use but I think Lotus got the looks pretty much spot on with the road going series 2 and series 3 Super 7 which had no rollover bar and looked much more elgant and purposeful for it.

For a road car there is no requirement to have a roll over bar, it's not compulsory, it's not an MOT requirement so why on earth bother with the ugly scafolding. It just looks like health and safety gone mad.






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RichardK

posted on 9/8/13 at 11:15 AM Reply With Quote
Saying nothing





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iank

posted on 9/8/13 at 11:30 AM Reply With Quote
quote:
Originally posted by Not Anumber
Frankly i think all this metalwork seriously detracts from the looks of a 7.

Roll over bars and cages are safe and sensible for racing and track use but I think Lotus got the looks pretty much spot on with the road going series 2 and series 3 Super 7 which had no rollover bar and looked much more elgant and purposeful for it.

For a road car there is no requirement to have a roll over bar, it's not compulsory, it's not an MOT requirement so why on earth bother with the ugly scafolding. It just looks like health and safety gone mad.


Maybe people want to avoid ending their days in a wheelchair being fed with a tube and having someone wipe their arse for them?





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FuryRebuild

posted on 9/8/13 at 11:33 AM Reply With Quote
Also, find out what quality the steel is. I went for T45, quite expensive and difficult to bend, but great to weld.

I know from my grass-tracking mates that the rules state mild steel cages only, even though they would (if allowed) fit T45 steel cages at the same wall thickness. T45 is way more strong than mild steel, so for these guys it would mean a weight saving for similar if not more strength.





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Mr Whippy

posted on 9/8/13 at 11:42 AM Reply With Quote
quote:
Originally posted by iank
quote:
Originally posted by Not Anumber
Frankly i think all this metalwork seriously detracts from the looks of a 7.

Roll over bars and cages are safe and sensible for racing and track use but I think Lotus got the looks pretty much spot on with the road going series 2 and series 3 Super 7 which had no rollover bar and looked much more elgant and purposeful for it.

For a road car there is no requirement to have a roll over bar, it's not compulsory, it's not an MOT requirement so why on earth bother with the ugly scafolding. It just looks like health and safety gone mad.


Maybe people want to avoid ending their days in a wheelchair being fed with a tube and having someone wipe their arse for them?


Yeah I think common sense says since cars crash on the road and many land on their roof something that prevents you needing to support a 700kg car on your head would be a good idea, required by an MOT or not. But then you can just live in hope or denial

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PhillipM

posted on 9/8/13 at 12:11 PM Reply With Quote
quote:
Originally posted by FuryRebuild
Also, find out what quality the steel is. I went for T45, quite expensive and difficult to bend, but great to weld.

I know from my grass-tracking mates that the rules state mild steel cages only, even though they would (if allowed) fit T45 steel cages at the same wall thickness. T45 is way more strong than mild steel, so for these guys it would mean a weight saving for similar if not more strength.


Our entire frame is T45, not cheap though!

Some of these cages look downright scary, what's with all the random bends in the middle of the tubes?!
A cage is only strong as a triangulated structure, same as a chassis, so sticking extra bends in and making it a nice, easily foldable parallelogram is not exact the best idea...

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sdh2903

posted on 9/8/13 at 12:13 PM Reply With Quote
I don't think this thread was debating the need for safety I think we are all grown up to accept rollover protection is a neccessity. It was more about design and 'packaging' to suit the design of the 7, there are many ways to design a safe car without it looking like the car had crashed into a local scaffolding yard.
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FuryRebuild

posted on 9/8/13 at 12:17 PM Reply With Quote
£50 a metre trade I was paying, not including the 3 hours time it took us to measure, cut and bend just to get the hoop right.

Saying that, you put an off it in the vice and smack it with a two pound lumper and you can tell the difference, once your hand stops vibrating.

It's the best you can do. Mandated for NASCAR if I'm right. It also needs the right rod for welding properly. Mild rods leave the weld pool too brittle.

quote:
Originally posted by PhillipM
quote:
Originally posted by FuryRebuild
Alsoq, find out what quality the steel is. I went for T45, quite expensive and difficult to bend, but great to weld.

I know from my grass-tracking mates that the rules state mild steel cages only, even though they would (if allowed) fit T45 steel cages at the same wall thickness. T45 is way more strong than mild steel, so for these guys it would mean a weight saving for similar if not more strength.


Our entire frame is T45, not cheap though!

Some of these cages look downright scary, what's with all the random bends in the middle of the tubes?!
A cage is only strong as a triangulated structure, same as a chassis, so sticking extra bends in and making it a nice, easily foldable parallelogram is not exact the best idea...






When all you have is a hammer, everything around you is a nail.

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loggyboy

posted on 9/8/13 at 12:31 PM Reply With Quote
quote:
Originally posted by PhillipM
Our entire frame is T45, not cheap though!
Some of these cages look downright scary, what's with all the random bends in the middle of the tubes?!
A cage is only strong as a triangulated structure, same as a chassis, so sticking extra bends in and making it a nice, easily foldable parallelogram is not exact the best idea...


A triange will still collapse on impact if the force is enough. Traingles are great for transmitting intended forces, but a crash can happen at pretty much any angle and any speed and lots of force, so as long as the bends arent in the key structure (front and rear roll bar) they arent as disasterous as you may think.





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scootz

posted on 9/8/13 at 12:31 PM Reply With Quote
Oops... missed the part about the cage being made for a 6'8" driver. My bad!

That said, the general sentiment regarding the 'normal' height of an MNR's roll-over protection still stands... they're feckin huge and often spoil the looks of their cars!





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dave107

posted on 9/8/13 at 12:53 PM Reply With Quote
Well mines fine only about 3inch above my head.
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PhillipM

posted on 9/8/13 at 12:58 PM Reply With Quote
quote:
Originally posted by loggyboy
A triange will still collapse on impact if the force is enough. Traingles are great for transmitting intended forces, but a crash can happen at pretty much any angle and any speed and lots of force, so as long as the bends arent in the key structure (front and rear roll bar) they arent as disasterous as you may think.


I'll take a roll cage that transmits forces away from me over one that folds at the joints like a hinge any day of the week. Even if part of it bends or kinks from an impact, if the rest is properly triangulated everywhere it will still prevent the cage folding and transmit force away from the damaged area.

[Edited on 9/8/13 by PhillipM]

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