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Rear suspension advice
Jon Ison - 5/1/06 at 08:01 PM

I'll try and explain with the help of a very poor picture........

Would this work ? Imagine the scribble in the picture is a lower rear wishbone, the red X looking down is where I am thinking of mounting the rear shocker........

If you can make sense of it the side view shows how I am thinking of fixing it, two brackets fully welded full length of the wishbone arm roughly the shape shown, the mounting hole would be around 40mm above the upper surface of the wishbone.........

Thoughts please........

Will it work ?

Could the wishbone be a better design than drawn and still pick up where required ?

Am I putting too much load into a small area ?

How could I spread the load better ?

All thoughts and idea's welcome.

Thnx J.


JoelP - 5/1/06 at 08:21 PM

are all three legs fixed perminantly together, or is there a rosejoint involved to allow rear toe adjustment? This will affect how strong it is. If you can spread the load between two legs it would be easier, and obviously keep the joint as far out as you can. Also, i think the top of the bracket/triangle should probably be curved, to ease the loads at its end.

Or, you could increase the diameter or wall thickness of the rear leg to make up strength, if you are concerned!

im going to draw a little diagram of the bones im putting on the car i have on paper at the minute. brb

[Edited on 5/1/06 by JoelP]


JoelP - 5/1/06 at 08:31 PM

ok, bones in black, rosejoints in red, chassis bars in mauve. The top set is the bottom bone, the bottom set is the top bone. Three points on the hub, 5 to the car, toe adjustent via the lower back leg, camber by the top leg, all acceleration being directed forward down the front legs, which are attached to the bottom of the roll bar, which in turn comes all the way to the bottom to offer some side impact protection.

Suspension will be via pullrods off the top arm, to allow the joint to get closer to the pivot, to reduce bending in the arm.

Does that make sense?

picture below... *rolls eyes*

[Edited on 5/1/06 by JoelP]


JoelP - 5/1/06 at 08:31 PM

ah yes, a picture... Rescued attachment bones.JPG
Rescued attachment bones.JPG


Jon Ison - 5/1/06 at 08:32 PM

there are 4 rose joints, two too chassis, two too upright.


two too two too, sound like a tutu


JoelP - 5/1/06 at 08:33 PM

desmond tutu?!

so would it be possible to weld a plate between the two legs? would help spread the load a bit, unless thats what you plan and ive completely missed the point!


JonBowden - 5/1/06 at 08:37 PM

Looks like the sort of set-up on an old single seater eg the 1963 legrand mk 1
I'm pretty sure you will find more examples if you look at the pictures at this sight http://www.atspeedimages.com/


JonBowden - 5/1/06 at 08:40 PM

is this the sort of thing you mean? (this is a lotus 18) Rescued attachment 18j791pn.jpg
Rescued attachment 18j791pn.jpg


JoelP - 5/1/06 at 08:41 PM

yes, but with parallel lower bones so, if you wanted, you could change the wheelbase without changing toe.


Jon Ison - 5/1/06 at 09:48 PM

Come on guys, is it any good ?

dont be shy.


gazza285 - 5/1/06 at 10:39 PM

quote:
Originally posted by Jon Ison
Will it work ?




Yes.


JoelP - 5/1/06 at 10:46 PM

IMHO, yes, but it depends on the tube size you are using. If i was doing it, id use 25x2mm tube, seamless if you are feeling posh , and make sure the suspension mounts less than a tenth of the way down the tube, to minimise bending.

The bracket itself, id add a taper, use 3mm plates each side, and put a small piece between them to stop them 'falling over' so to speak.

You appreciate few of us can offer more than opinions though. Thats how id do it, if someone turns up with proper figures they might agree or disagree.


Mix - 6/1/06 at 07:12 AM

Is it an option / have you considered mounting the shock directly onto the upright?

Re the design of the bone, which way is forward?

Mick


Jon Ison - 6/1/06 at 03:58 PM

I cant really mount on the upright do too bodywork and drive shaft restraints.

Does no one have an opinion ? If it was a "bent bone" we where talking about manufactured by a "kit manufacturer" there would be 100 replies by now ??


gazza285 - 6/1/06 at 05:19 PM

Loads of racecars have the shock mounted there, including the Lotus 49. What's the worst that can happen (again).


JonBowden - 10/1/06 at 07:06 PM

John, this picture might give you some confidence / inspiration (I think this is what you have in mind)

http://www.atspeedimages.com/...
Chevron B15 rear suspension

I can't post the image since it is big and the site has clear copyright notices