MikeR
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| posted on 25/2/18 at 09:03 PM |
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dilemma - have I messed I up my roll bar?
So I bought a roll bar from Welderman. It's exactly what I asked for. 2 inch narrower than the chassis and very tall. I could then trim it to
the right height.
I made it two inch narrower so it had plenty of space to weld onto the mouthing plate without welding close to the edge (is o one inch each side).
I'm now thinking that was overly cautious and I should really be 5 or 10mm at most from the edge of the chassis. How close are other roll bars?
Now I would like to at some point compete .... Does that affect the decision?
So the other problem and perhaps the biggest issue is .... I messed up (I'm ill, it was cold etc etc,). I made sure my head with a helmet is
under the line from chassis front to roll bar. What I didn't do is check the bottom of the roll bar is 2 inch from my head with helmet on.
It's inch and a half.
How bar is this? Will I really fail scrutineering? Should I start again?
If I do start again it would mean I could get a 45mm roll bar. Current bar is 48mm and 2.8mm thick so a tiny bit over minimum spec.
Thoughts?
[Edited on 25/2/18 by MikeR]
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Nickp
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| posted on 25/2/18 at 09:05 PM |
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Hard to say 
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daviep
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| posted on 25/2/18 at 09:09 PM |
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Probably or you wouldn't be asking the question!
“A truly great library contains something in it to offend everyone.”
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MikeR
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| posted on 25/2/18 at 09:12 PM |
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I hit post too early 
Now edited to add the detail
[Edited on 25/2/18 by MikeR]
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jeffw
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| posted on 25/2/18 at 09:22 PM |
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Does it meet the requirements in the Bluebook (I assume this is what you are talking about from a scrutineering perspective)?
If the answer is no, it doesn't match or exceed the Bluebook then you already know the answer....
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voucht
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| posted on 25/2/18 at 09:42 PM |
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I don't know what kind of engine you have, car or bike. If it is a car engine, then if the car flips over, the front structural point is not the
front of the chassis but the font edge of the engine's head, which is much higher than the top rail of the front frame. So you have a few inches
more over your head than what you had calculated.
https://vouchtroadster.blogspot.com/
https://cafrazx550.blogspot.com/
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MikeR
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| posted on 25/2/18 at 09:54 PM |
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The engine is a crossflow. The difference in a line between the chassis and engine isn't huge - however I'm under that line from a MSA
blue book perspective. It's the head with helmet being 2 inch below the bottom of the top roll bar tube rule I'm just breaking.
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Mr Whippy
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| posted on 26/2/18 at 12:27 AM |
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Of course this all applys only if you land upsides down on a perfectly flat surface... Add in a real world bumpy one with bolders, kerbs, fences etc
and a front hoop and a fully enclosed roll cage makes much more sense.
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Theshed
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| posted on 26/2/18 at 06:30 PM |
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Lower your seat?
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MikeR
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| posted on 26/2/18 at 07:18 PM |
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So i popped into the garage earlier. I tried to figure out how much taller the roll bar would need to be. The summary is exactly the height I had it
before i cut 45mm off it. Seems i cut it to size a while ago. In my frustration / determination to do something on Friday I messed up big time.
Lowering the seat isn't an option add I'm already sitting on the floor with a homemade foam seat.
So it's new roll bar time. Now do I go for 50x2mm or 44.5x2.6mm - by my calcs 50mm is lighter by about 10%, are my calcs correct?
And yes I know I'm a Muppet.
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Mr Whippy
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| posted on 26/2/18 at 07:27 PM |
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Can you not just weld 45mm foot plates under the hoop, radius the edges 10mm...
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daviep
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| posted on 26/2/18 at 08:40 PM |
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quote:
Originally posted by MikeR
So i popped into the garage earlier. I tried to figure out how much taller the roll bar would need to be. The summary is exactly the height I had it
before i cut 45mm off it. Seems i cut it to size a while ago. In my frustration / determination to do something on Friday I messed up big time.
Lowering the seat isn't an option add I'm already sitting on the floor with a homemade foam seat.
So it's new roll bar time. Now do I go for 50x2mm or 44.5x2.6mm - by my calcs 50mm is lighter by about 10%, are my calcs correct?
And yes I know I'm a Muppet.
My calcs agree - 50mm is almost 12% lighter
Cheers
Davie
“A truly great library contains something in it to offend everyone.”
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theduck
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| posted on 27/2/18 at 07:50 AM |
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Not to be a vulture... but if the old roll bar needs a new home, I could be interested.
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Mr Whippy
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| posted on 27/2/18 at 08:04 AM |
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foam on the floor and ditch the seats 
tbh I think you've fecked up and I'd just get another bar...lesson learnt...check before cutting, bummer though
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MikeR
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| posted on 27/2/18 at 08:30 AM |
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quote:
Originally posted by theduck
Not to be a vulture... but if the old roll bar needs a new home, I could be interested.
Proper measurements to follow but it's 40 inch outside edge to outside edge, 48 cm tall (I think I can't quite remember now). 48mm od
2.8mm thick steel. CDS. With three tubes (so you can do a diagonal plus back stays).
Will be a week or two before it's available (ie I want to get it's replacement and be happy I've not messed up).
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