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Wishbone angles?
caprixpak - 8/12/12 at 03:09 PM

Hi all, I'm building a full spaceframe mk2 capri using rallydesigns locost wishbone kit. I've been trying to research the best angles to mount them. Has anyone tried mounting them so the top slopes 4degrees from the wheelside and the bottom 4 degrees sloping uphill from wheel to chassis. (inward converging) I thought this would give a raised forward rollcentre but also produce too much negative camber as the suspension moves. If this is daft ill have to do flat bottom arms but am limited by the travel of the transit drag links so can't really angle the tops which gives a really low forward rollcentre. Any input on this would be great as I have been dwelling on this for ages and just want to get on with build as it's going well. Cheers.

designer - 8/12/12 at 03:34 PM

If you are using these wishbones you have to use the same geometry as the Locost. Hit and miss ain't gonna work!

You will have to make a small mounting frame to fix on the bodyshell and carry the suspension.

caprixpak - 8/12/12 at 03:43 PM

Might be easier, there's no shell left, so mounting them onto spaceframe, shell just a roof and sides. Might have go with this geometry and change it if rubbish but if someone has tried it then it would save me the hassle, cheers.

maccmike - 8/12/12 at 04:59 PM

upload picys

tilly819 - 8/12/12 at 06:06 PM

quote:
Originally posted by designer
If you are using these wishbones you have to use the same geometry as the Locost.


I dont often disagree with what you say but this is complete tosh!

By using a set of pre-made wishbones you are constrained to the length of the arms however you can still mount them at other angles to create different geometry, RC locations camber curves etc.

Beware of the maximum articulation of the ball joints however this must be a consideration when designing.

At there bare minimum make a model of your proposed design and measure the angles of the wheel in bump, droop and roll and make sure they are at least sensible, it may also be worth making the chassis mounts adjustable so you can alter the position of the inboard pivots if your design does not work out perfectly.

I highly recomend doing A LOT of reading on the subject before you commit to anything.

As designer said "Hit and Miss aint gonna work"

Tilly

caprixpak - 8/12/12 at 06:22 PM

I have made some full scale drawings and followed the arc of the wishbone. I have read a few books and done some research. The only problem I see is with the camber changes during travel. I think I'll do it this way, it's a track only car. Not much to look at right now, main cage done moving out front now. Has an atlas axle with watts linkage so rear rollcentre fixed to Centre of diff. Using a volvo 5 cylinder engine. Is basically a locost with a body plonked on top.

designer - 8/12/12 at 07:00 PM

quote:

I dont often disagree with what you say but this is complete tosh!


Don't understand. He has bought wishbones designed for a certain geometry, so the easiest way is to use the geometry they are designed for. With a bit of sorting this geometry can be made to work, why bother messing to create something else, far away from a well sortable baseline.

britishtrident - 8/12/12 at 08:03 PM

Apparently some brands of Transit drag links allow more articulation than others

See if you can find some front end pictures of the ex-works Capri that Douglas Niven put a Boss V8 in or some of Gerry Marshall's or Bill Dryden's Firenzas.