JoelP
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| posted on 23/8/05 at 09:19 PM |
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fancy wishbones
for a new project im thinking of starting soon, i want to set the bones up as show in the attached diagram. They will be rosejointed, and i guess the
two legs will have to be joined by rod ends too. The reason i want to do this is its easier to mount the bones to the chassis, and it gives more
adjustability (castor, specifically).
Does anyone have any experience or pictures of this done please? I need inspiration. 
'twill also have pushrod suspension and an antiroll bar
[Edited on 23/8/05 by JoelP]
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Dusty
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| posted on 23/8/05 at 09:44 PM |
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Main snag is the axis of rotation of the inner ends of the wishbones should be on the same line and parallel to the centre line of the car or the
castor and wheelbase vary with each bounce. Bit too adjustable.
 
Rescued attachment wish.jpg
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JoelP
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| posted on 23/8/05 at 09:47 PM |
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it'll be quite stiff, plus the extra length of the 'trailing' arm minimizes the amount it pulls the other arm off course.
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gazza285
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| posted on 23/8/05 at 09:52 PM |
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Its called a compression strut and has been used on a few road cars as well as race cars. As usual I can't find any decent photos but
here's one on a Datsun Z240.
Formula 1 used a similar wishbone set up for years, but on the top rear link. Look at almost any car from the DFV era and you'll see the radius
arm.
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dnmalc
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| posted on 23/8/05 at 10:11 PM |
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Joel if you are going for bones that are a bit different have you thought about putting some anti dive into the front I have about 5 degrees in my
build but its still early days so I do not yet know how effective it will be
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JoelP
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| posted on 23/8/05 at 10:17 PM |
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doing this, you could make adjustable antidive by adding in a few brackets for the rearmost legs good point.
My main problem is how to prevent the arms twisting, and how to mount the ball joints.
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gazza285
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| posted on 23/8/05 at 10:24 PM |
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Here is a better picture.
There should not be any twisting moment on the wishbones.
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Avoneer
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| posted on 23/8/05 at 10:40 PM |
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Hi Joel,
How about finishing the one car!
Then using those 50 odd motorbike engines for an aeroplane,
And then opening a Ford Sierra Spares warehouse,
Then building another car!
Pat 
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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Kissy
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| posted on 24/8/05 at 06:05 AM |
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Looking at tha diagram it would appear you won't be going round tight corners!
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JoelP
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| posted on 24/8/05 at 07:33 AM |
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quote:
Originally posted by Kissy
Looking at tha diagram it would appear you won't be going round tight corners!
that occured to me last night in bed! I guess it needs to be closer to the setup in gazzas picture. Cheers for the input everyone (even pat!), all
food for thought.
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NS Dev
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| posted on 24/8/05 at 07:50 AM |
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sorry about the huge pic, but I have this setup on the front of the grasser.
Yes, it does slightly compromise steering lock............but.......I still have about 75 degrees!!!!!!
see my avatar........if you need more lock than that then something is wrong.
 
grasser 3
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JoelP
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| posted on 24/8/05 at 08:04 AM |
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useful pic that one, cheers
Looking through your archive, is the lower bone a normal one? is it just the upper one thats in two pieces?
What hubs does it use? Im thinking of using cortinas to start with so that i can upgrade to the raceleda ones once finished.
Do you every adjust the upper bone to change castor, or have you done it this way primarily to send loads into the chassis better?
cheers
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NS Dev
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| posted on 24/8/05 at 08:16 AM |
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I was going to have both wishbones adjustable, but mounting the shocker made that tricky on the lower one so that one is non-adjustable. It is still
the same design (i.e. long compression leg and short transverse leg) but is one-piece.
Yes, I use the compression link on the top 'bone to set the castor, in fact the castor is "skewed" to assist the car on right hand
turns (autograss is r/h oval).
You can easily adjust castor and camber with this setup, though as has been mentioned, it is also easy to set everything wrong (only took me two
meetings to get it handling right though, about 10 mins racing, no practice allowed in grassing)
The uprights are cortina, and the balljoints are transit ones (same as locost upper one) used top and bottom both sides (car is quite light, you can
pick it up at the front!!)
The steering arms are modded to get quicker steering and more ackerman but otherwise std cortina uprights.
The rose joints are all 5/8"x5/8" cheapo "Carborace" ones from Rally Design.
The compression links are mounted on single shear stubs. These are EN8 bright bar, turned to a "top hat" type fitting, then drilled and
tapped M8 in the outer end for a retaining bolt and washer to hold on and clamp the joint, and then the inner end of the fittings were accurately sawn
off at the correct angle to weld onto the chassis rails. Didn't like the single shear idea but they have proved excellent. Have hit things hard
enough to knock chunks out of the alloys in the pic and the mounts are fine.
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JoelP
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| posted on 24/8/05 at 08:34 AM |
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i noticed the single shear bolts, but didnt question it cos i guess the proofs in the pudding!
oh yeah, is the lower taper naturally the same as the transit rod end, or does it need reaming? cheers
[Edited on 24/8/05 by JoelP]
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NS Dev
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| posted on 24/8/05 at 09:00 AM |
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I'm sure the tapers are the same top and bottom, but I'll double check the ones on the 7 when I get home, I know I haven't modded
those!!
The bolts are not in single shear on the compression struts, the welded on stubs are, the bolts just retain and stop the joints rotating.
see crap drawing below that I just did in paint, the red blobs are weld and the threads on the rose joint are pointing the wrong way but you get the
idea!
 
susp1
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DorsetStrider
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| posted on 24/8/05 at 09:15 AM |
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I'm sure you've already thought about this but just in case you haven't (we all overlook the obvious till it's too late)
looking at the diagrams it doesn't look like you are leaving yourself much room for the wheel under steering.
It looks fine when you turn right but when you turn left aren't you going to foul the trailing suspension arm?
Who the f**K tightened this up!
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britishtrident
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| posted on 24/8/05 at 09:35 AM |
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Here is one Eric Broadley preared earlier :-)
62 Lola F1 car
This Layout was used by a few chassis designer in thr 60s and 70s
The only major downside of this layout is the strut part of the wishbone can punch back into the cockpit as a resut of an impact -- err quite nasty
!
[Edited on 24/8/05 by britishtrident]
 
Rescued attachment Flola.jpg
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NS Dev
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| posted on 24/8/05 at 10:51 AM |
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quote:
Originally posted by DorsetStrider
I'm sure you've already thought about this but just in case you haven't (we all overlook the obvious till it's too late)
looking at the diagrams it doesn't look like you are leaving yourself much room for the wheel under steering.
It looks fine when you turn right but when you turn left aren't you going to foul the trailing suspension arm?
err? the arms are the same both sides! They obstruct both sides equally, I have around 75 degrees of lock to the right and left. The arm on the rhs
obstructs turning right and the left vice versa.
Makes no difference though, any more lock (with the increased ackerman) and the steering arms on the "inside" upright go over centre with
the top and bottom balljoints though and the steering would cease to work anyway!!
Car's been racing for 2 1/2 years now with no probs.
[Edited on 24/8/05 by NS Dev]
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NS Dev
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| posted on 24/8/05 at 10:53 AM |
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quote:
Originally posted by britishtrident
Here is one Eric Broadley preared earlier :-)
62 Lola F1 car
This Layout was used by a few chassis designer in thr 60s and 70s
The only major downside of this layout is the strut part of the wishbone can punch back into the cockpit as a resut of an impact -- err quite nasty
!
[Edited on 24/8/05 by britishtrident]
Yes, that worried me too, I just hope that should the worst happen, the upper arm will go over the top of the chassis rail and the lower one under the
lower one, then they would both miss my legs!?? (hope it doesn't come to that though, have hit a few things fairly hard now and nothing at the
front has even moved yet, let along broken!)
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Peteff
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| posted on 24/8/05 at 12:36 PM |
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Race wishbones nowadays have a cross piece in to prevent them going through the cockpit sides.
 
Rescued attachment Flola.jpg
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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stevebubs
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| posted on 24/8/05 at 05:08 PM |
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The original Sylva lower wishbone setup on the Fury used Mk II Escort Track Control Arms with Compression strut....
http://www.cantcatchme.net/galleries/2003/stoneleigh.html
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JoelP
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| posted on 28/8/05 at 04:18 PM |
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saw this today, beautiful and working well on a racecar. Imagine it with a pushrod.
 
Rescued attachment bonessmall.jpg
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tweek
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| posted on 29/8/05 at 12:57 AM |
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well as long as you dont need to do any three point turns you'll be grand! 
Im guessing this is trackday only stuff your planning though!
"oh dear..." said god,
"I hadn't thought of that"
and promptly vanishes in a puff of logic
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MikeR
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| posted on 29/8/05 at 01:17 PM |
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See NS Dev's post. I've seen him move his grasser onto the trailer - its got plenty of lock. Its all relative. Put your road car on full
lock and see what angle you've got. Design your car to have something similar to that and i bet you still get a decent amount of
rear-ward-ability with the rear wishbone.
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JoelP
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| posted on 29/8/05 at 01:31 PM |
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its basically a compromise, i believe it will be easy to set it up with enough lock and still get away with a good angle on the rear bone leg. Im
thinking of using 25x2mm for the front part, and 19x2mm for the rear bit, as the shocker doesnt press on it directly. It will also use a transit
draglink bottom and top, i think it will easily be strong enough as its a bec dedicated chassis. People have used astra balljoints in the past, which
arent designed for that loading either. Still waiting for someone to confirm that cortina/raceleda hubs have the same taper top and bottom!
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