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Bone Tube
Daddylonglegs - 21/10/08 at 07:40 AM

Hi all.

Does anyone out there feel that 25mm x 2.03mm for lower bones and 20mm x 2.03mm for upper bones (seamless tube) would be not be OK?

Thoughts please.....

JB

Mr Whippy - 21/10/08 at 07:48 AM

not sure of the thinking behind using 20mm for the top, why would it need less?

I'd go for the 25mm stuff, thickness seems fine.

how about oval section, always looks nicer and resists twisting in just the right direction

[Edited on 21/10/08 by Mr Whippy]

MikeRJ - 21/10/08 at 07:59 AM

quote:
Originally posted by Mr Whippy
not sure of the thinking behind using 20mm for the top, why would it need less?


Because the upper bone is under considerably less stress than the lower one.

Mr Whippy - 21/10/08 at 08:00 AM

quote:
Originally posted by MikeRJ
quote:
Originally posted by Mr Whippy
not sure of the thinking behind using 20mm for the top, why would it need less?


Because the upper bone is under considerably less stress than the lower one.


why?

Phil.J - 21/10/08 at 08:05 AM

Because in a twin 'parallel' wishbone suspension system the lower wishbone carries 75% of the cornering loads.

[Edited on 21/10/08 by Phil.J]

Mr Whippy - 21/10/08 at 08:11 AM

quote:
Originally posted by Phil.J
Because in a twin 'parallel' wishbone suspension system the lower wishbone carries 75% of the cornering loads.

[Edited on 21/10/08 by Phil.J]


not actually trying to be awkward but why would that be? Is it due to the weight transfer?? I though it might be due to the twisting due to the coilover force not being directly over the balljoint

ahh come to think of it.. it's due to the contact point on the wheel being closer lower wishbone than the top, so it's all to do with leverage, must be needing my coffee

[Edited on 21/10/08 by Mr Whippy]

Peteff - 21/10/08 at 08:30 AM

quote:
Originally posted by Mr Whippy
not sure of the thinking behind using 20mm for the top, why would it need less?


To leave room for the shock to go through. If you use good quality tube you don't need to go large on top or bottom, stop thinking Whippy, you'll wear your brain out

Daddylonglegs - 21/10/08 at 01:58 PM

Thanks for the input guys.

For a while there I thought I'd started a popcorn moment

The only reason I was thinking of the different sizes was that's what RC did in his book (not sure if it was any different in the 2nd Edition?)

I found some CDS on eBay so just wanted people's thoughts on it.

JB

MikeRJ - 21/10/08 at 03:28 PM

quote:
Originally posted by Mr Whippy

ahh come to think of it.. it's due to the contact point on the wheel being closer lower wishbone than the top, so it's all to do with leverage, must be needing my coffee


Also the lower wishbone has the shock attached to it, and has to resist the bending forces that this imposes.

Another thing, under braking the torque applied to the upright from the caliper is trying to push the upper wishbone forward, and the lower one backwards, but the (negative) acceleration of the car is also pushing the lower wishbone back so it ends up with much more loading..

liam.mccaffrey - 21/10/08 at 03:34 PM

i used 0.75"x1/8"wall seamless for the top and bottom




top bone
top bone

Front Left Bone, whole
Front Left Bone, whole