, works for me
Whats the recomended wall thickness of the tube for the roll bar? I bought one off ebay and it looks a tad thin..
Mine is 3.25mm (1/8", works for me
I saw them on ebay --- thought it looked a bit too much like exhaust tube.
I suspect the seller has posted on the forum but only to advertise under the name ARA RACING, the fabrication quality of the other bits advertised
looked fine but I am not sure how much Locost car building experience he really has.
I think the blue book (RAC guide) says it should be x mm for y tube. I've done a deal with a mate for some x+.5mm tube.........
worked out for the total lot at something like 10kg extra - but for the protection it brings i think its worth it.
(i did quote x and y but wasn't sure and didnt' want to get it wrong)
I think it is 2mm wall for 50mm diameter and 2.5mm wall for 45mm diameter and it must be seamless. I think you would also need to provide proof of the
material used if asked and for motorsport you need some inspection holes drilled in it for wall thickness measurement. Oh, and you also need to ensure
that you don't get any significant ovality when bending. There is a spec for this also which I think is something like the minor diameter at the
bend must be no less than 90% of the major diameter.
Usual disclaimers, check for yourself in the MSA manual.
Hope this helps,
Craig.
For road use any peice of metal will do (legally) as long as SVA don't catch thier ball on an edge etc.
for road use no metal will do legally - its not a requirement!
the minimum we use on our cars is 1 3/4 17 g t45 or 1 3/4 14g cds
we use this even on all road cars as we work on the theory better to be safe than sorry ( after all this is the only protection you have if you turn
the car over ) also has the added bonus of extra rigidity for the rear shock mounts / rear of the car
In the US, for the weight catagory of a Locost, I believe the SCCA requires 1.5", 0.125" wall tubing.
Forget passing SVA and worry about your head, it's just plain good sense to have one.
quote:
Originally posted by MikeR
I think the blue book (RAC guide) says it should be x mm for y tube. I've done a deal with a mate for some x+.5mm tube.........
worked out for the total lot at something like 10kg extra - but for the protection it brings i think its worth it.
(i did quote x and y but wasn't sure and didnt' want to get it wrong)
I've used 50mm dia 3mm wall for the roll bar and back braced it with the same.
I'm rather attached to my head.
Standing under it's own steam
[Edited on 8/3/05 by andyharding]
The roll bar i got looks to me like it is made of exhaust tube.. I got it cos it was cheap.. Not from ARA racing i must add all his stuff looks very good.. Il make the decision to use it when the time comes. Dont think iwill..
quote:
Originally posted by NS Dev
quote:
Originally posted by MikeR
I've done a deal with a mate for some x+.5mm tube.........
Would that be me then!?
Just checked the weights, the RAC spec min, 45 x 2.5 (or imperial equiv) is 2.62 Kg/m and the 45 x 3.2 is 3.3 kg/m. If you (over) estimate thr qty of tube needed at 4m, (incl backstays) then its only 2.7 Kg heavier than the RAC tube would be. The total rollbar will weigh around 10 Kg.
[Edited on 8/3/05 by NS Dev]
even happier now. Should be getting round to the roll bar really
soon 
So the 54mm *5.4mm i've used could be classed as overkill.
ATB Dan.
[Edited on 8/3/05 by scutter]
quote:
Originally posted by andyharding
I've used 50mm dia 3mm wall for the roll bar and back braced it with the same.
I'm rather attached to my head.
Standing under it's own steam
[Edited on 8/3/05 by andyharding]
A roll bar is no stronger then the tubing it's attached to. If the car rolls and the small supporting tubes collapse, a big roll-bar won't
work. In the picture, the forward mounts look fine since they're triangulated and paneled. Are the rear-most bottom mounts also triangulated
and paneled? Hard to see.
From a geometry standpoint, having such steeply angled rear supports greatly diminish how well they strengthen the main hoop from bending over
backwards.
Of course in a 7, there's simply no where to go with those rear braces. While they don't hurt any, their effectiveness greatly depends how
well the rear paneling stiffens up those lower rear mounting points.
[Edited on 3/8/05 by kb58]
I'd advise you to be careful and not go overboard on the wall thickness of the rollbar as I think that there is a requirement for the chassis
plate onto which the rollbar attaches to be thicker than the bar itself to avoid punch-through. This may be an MSA requirement rather than a general
requirement but I'm sure I've read it somewhere...
My rollbar is 48mm x 3.2mm wall and I have doubled up the 3mm turret plates to give me 6mm for this reason.
I agree with the comments that the rollbar may not be the weakest link, especially when talking about backstays, and would expect tubes W1 and W2 to
take a battering in a rollover situation. Note that W1 and W2 are specified as 3/4" in the book which is what I used but they really should be at
least 1" and ideally 1"x2" if you are going to use proper MSA spec backstays. My own backstays are Caterham style and are made from
38mm x 16swg tubing, attaching to the rear luggage tubes. They will add some strength to the rollbar but are mainly cosmetic and to help support the
backend of the chassis in the absence of sturdier W1 and W2 tubes.
Cheers,
Craig.
Page 53 of the second edition book, start of the text on the page goes and I quote
'Cut tubes W1 and W2 fron 1in (25mm) RHS to fit, as shown in drawing, and fully weld in place'
The size of tube is wrong compared to cutting lists/diagrams. I used 1" any way, because I want a good strong chassis, light weight is second on
my list as its a road car.
Yes I remember seeing the contradictory specification for W1 and W2 after I had already built the chassis from the cutting list... I would imagine
that most folk would go by the cutting list unless the contradiction was pointed out in advance. Even the McSorley plans which I switched to after
setting out the base-rails specifies 3/4" for these tubes.
However, I am not at all concerned at this as my chassis is all built from 2mm thick steel instead of 1.6mm which pretty much makes up for the smaller
tubing (not quite but very nearly). Also, the rollbar and backstays will add a fair bit of strength.
Cheers,
Craig.
How are people attaching the roll hoops to the suspension mounting plates, welding them directly on top?
Mike,
I welded a second suspension plate on top of the original one to make the material thickness up to 6mm. I seam welded this all round and did a few
plug welds to attach the plates to each other in the middle as well. I then welded the rollbar onto the top of the plates.
HTH,
Craig.
quote:
Originally posted by craig1410
Yes I remember seeing the contradictory specification for W1 and W2 after I had already built the chassis from the cutting list... I would imagine that most folk would go by the cutting list unless the contradiction was pointed out in advance. Even the McSorley plans which I switched to after setting out the base-rails specifies 3/4" for these tubes.
However, I am not at all concerned at this as my chassis is all built from 2mm thick steel instead of 1.6mm which pretty much makes up for the smaller tubing (not quite but very nearly). Also, the rollbar and backstays will add a fair bit of strength.
Cheers,
Craig.