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Roll Bar Bolts
mad-butcher - 28/4/03 at 07:26 PM

What size bolts do I use to hold on my standard MK roll bar.
Tony

carnut - 28/4/03 at 07:33 PM

I used 12mm and i think that anything much smaller would be unsafe

speedthing - 28/4/03 at 08:33 PM

sounds good to me

bob - 28/4/03 at 08:34 PM

I've got high tensile 8.8 and are M8,seen a couple of cars go through SVA with M8's on so i'm happy with that.

MK Goldrush - 20/9/03 at 10:37 PM

Bob - did you go straight through box section or use rivnuts to secure?

Peteff - 21/9/03 at 08:33 AM

You don't need a roll bar on for SVA but I would think twice about attaching it with rivnuts if you think it will ever be needed, especially if you are attaching anything like seatbelts to it.

yours, Pete.

spy - 21/9/03 at 03:41 PM

quote:
Originally posted by Peteff
You don't need a roll bar on for SVA but I would think twice about attaching it with rivnuts if you think it will ever be needed, especially if you are attaching anything like seatbelts to it.

yours, Pete.


Ditto re. rivnuts, Don't even think about it! Rivnuts will give absolutely no strength if (heaven forbid) you roll your car.

givemethebighammer - 27/9/03 at 12:46 PM

I've used 8 button head M10 bolts, (4 per side) . Buttons are stronger than 8.8 I think.

button saves putting covers on for SVA as well

[Edited on 27/9/03 by givemethebighammer]

Fast Westie - 17/10/03 at 12:51 PM

I don't know about the standard roll bar because if it is not braced it is as much use as a chocolate teapot. If it is a proper braced one you should use at least three high tensile M10 bolts (10.9 or 12.9) per side

givemethebighammer - 19/10/03 at 10:41 AM

Better to sleeve bolts that go through box section

Attached picture is a bit rough but basically if you are using M10 bolts, drill the holes at 13- 14mm. Insert a piece of tube to fit the hole the same width as the box section and an internal diameter of 10mm. Tube should prevent box section crushing / deforming if force is applied.

Better than rivinuts IMHO Rescued attachment sleeve.JPG
Rescued attachment sleeve.JPG

Rorty - 7/12/03 at 05:31 AM

givemethebighammer:

quote:

I've used 8 button head M10 bolts, (4 per side) . Buttons are stronger than 8.8 I think.
Careful there! "Button head" is a configuration, and has nothing to do with the fastener's strength.
I would use 12mm Class 10.9 or 1/2" Grade 8 bolts.
Yes, do use a crush tube, but it must be welded in. The area around the hole in the chassis member where the roll bar bolts up, should be deeply countersunk, so after welding and grinding flush, there's still sufficient weld present. On the reverse side, the crush tube can protrude by about 5-8mm to provide plenty of weld area.

craig1410 - 7/12/03 at 04:54 PM

Guys,
I decided to just weld my rollbar rather than bolt it. Is it sufficient to just weld around the edges of the two 4 inch square (3mm thick) plates or should I drill a few holes in the top plate and do some button welds through to the bottom plate?

Note that in case the above is unclear, I have the existing 4" square suspension turret plate and I have a plate welded to my rollbar just as if I was about to bolt them together. However I don't see the point in bolting it as I feel that a rollbar on a seven type car should be an integral and permanent part of the chassis.

I just wondered if in a rollover, the rollbar might try to cause the two plates to delaminate and this might tear the perimeter welds. Should I worry about this?

Also, in terms of rollbar strength I have just used black pipe as I couldn't easily get CDS of the right size. However, it is 48.7mm o/d by 2.8mm wall black pipe and I just wondered how this would compare for strength with either a 45mmx2.5mm or 50mmx2mm CDS rollbar as recommended? I currently don't have a diagonal brace but intend to add one, and I only have the two "cosmetic" caterham style backstays which link to the rear luggage tube top bar with some 32mm o/d x 1.6mm thick ERW tubing.
Comments welcome...I think!

Cheers,
Craig.

Staple balls - 7/12/03 at 05:37 PM

personally, i'm not keen on the idea of welds alone, i know they're stronger than the original metal (if done well) but i'm not so keen, i'll be gluing and bolting