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Author: Subject: dilemma - have I messed I up my roll bar?
MikeR

posted on 25/2/18 at 09:03 PM Reply With Quote
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

posted on 25/2/18 at 09:05 PM Reply With Quote
Hard to say
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daviep

posted on 25/2/18 at 09:09 PM Reply With Quote
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

posted on 25/2/18 at 09:12 PM Reply With Quote
I hit post too early
Now edited to add the detail

[Edited on 25/2/18 by MikeR]

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jeffw

posted on 25/2/18 at 09:22 PM Reply With Quote
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

posted on 25/2/18 at 09:42 PM Reply With Quote
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.





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http://vouchtroadster.blogspot.se/

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MikeR

posted on 25/2/18 at 09:54 PM Reply With Quote
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

posted on 26/2/18 at 12:27 AM Reply With Quote
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

posted on 26/2/18 at 06:30 PM Reply With Quote
Lower your seat?
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MikeR

posted on 26/2/18 at 07:18 PM Reply With Quote
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

posted on 26/2/18 at 07:27 PM Reply With Quote
Can you not just weld 45mm foot plates under the hoop, radius the edges 10mm...
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daviep

posted on 26/2/18 at 08:40 PM Reply With Quote
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





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theduck

posted on 27/2/18 at 07:50 AM Reply With Quote
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

posted on 27/2/18 at 08:04 AM Reply With Quote
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

posted on 27/2/18 at 08:30 AM Reply With Quote
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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