Tubular Wishbone Project

[Rippthrough 98]

Didn't bust the welding though :smugbastardsmiley:

[Cloverleaf 1]

Yeah, as you've said, it all depends on the intended use and if you want them to survive crashes

[Cameron 16]

Well I've always been told that you want to make the wishbone break before the mounting bracket (subframe) does. It's way easier to replace a wishbone than it is to straighten out a bent bracket / subframe / chassis!

[Rippthrough 98]

There's a sacrificial pin in mine, that way the pin busts if I whack a kerb hard and all I have to do is replace the pin (and probably the wheel...)

[oz. 2]

Well I've always been told that you want to make the wishbone break before the mounting bracket (subframe) does. It's way easier to replace a wishbone than it is to straighten out a bent bracket / subframe / chassis!

 

That must be why a wishbone on a mates ford fiesta bent. Caught out on wet leaves in a tescos car park apparently. Wheel had some nice kerbing but only cosmetic damage

[swordfish210 20]

I only brougt up the topic of composites in wishbones as i've been reading up on it for the past month for uni work. Some of the loads they can withstand are pretty impressive and the theoretical infinate lifespan due to the fatigue resistance is quite appealing. Although then getting written off by a single stonechip isn't

 

Cost is obviously a pretty big issue.....a really really big issue Would be good to see a 205 with composite suspension components. though.

[EdCherry 34 1 Cars]

When we had a look at Force India mark they actually use carbon covers over the wishbone. Strong enough to take some abuse from stones, and provide the aerodyanmic shape (similar to the spectrums bones) while the inner material was actually doing all the work.

[Mandic 0]

Bit of an OT, but does anyone know where to get tubes made from 25CrMo4 material? Need them for custom subframe.

 

Thanks!

 

Cheers

 

Ziga

[Rippthrough 98]

When we had a look at Force India mark they actually use carbon covers over the wishbone. Strong enough to take some abuse from stones, and provide the aerodyanmic shape (similar to the spectrums bones) while the inner material was actually doing all the work.

 

Actually now you mention that we use thin 0.6mm ally panels to cover the bottom of the damper to stop adjuster damage where it bolts to the wishbone - as that way they can bend and absorb the energy all they like without being critical, might be an idea if you want to use the thinnest tube you can.

[swordfish210 20]

Yeah but the real F1 teams Imbed the wishbones with a certain amount of kevlar to resist damage. The still write them off with the tiniest chip though as they will never pass the rigourous QC checks they do on them, ultrasound pictures and high intensity listening devices.

[EdCherry 34 1 Cars]

Real F1 teams aye? There 7 post rig was pretty impressive, gets better data than other considering its mounted direct to the hubs where the model the tyres later for sim's. Maybe they don't have the budget to win at everything but certainly had a good car.

 

Sorry for going offtopic cam!

[swordfish210 20]

Someone left their sense of humour at the door.

[EdCherry 34 1 Cars]

My sense of humour is querky, you should know that by now.

[Cameron 16]

 

I don't mind the off topic, it's still relevant!

 

I think the only thing you're going to encounter on track that may damage the wishbones are high kerbs, and they're probably going to put a dent in a wishbone however thick you make the material (within reason). But then if there's one high enough to clout the wishbone then you're probably going to smash the entire underside of the car against it too!

[welshpug 1,658]

with a 205 and a 306 definitely, but a 106 hangs its wishbones under the line of the shell as there is no subframe.

[EdCherry 34 1 Cars]

You will encounter a bit of debris on the track, we have small car park like ding's on our wishbones but some of them have done a good 2, maybe 3 seasons without being bent/damaged/replaced. I think you should just start by making a simple design, with simple material's and evolve it once you've done your first.

Edited January 5, 2010 by EdCherry

[swordfish210 20]

Hmm, clobbering a wishbone on a kerb, now theres a nasty thought

[davenport 51]

cameron- may i ask if you decided on a "safe" sized rod end using your posh computer program??

 

i was going to use 5/8th UNF on the inboard fitting

 

and

 

7/8th UNF on the position under the hub

 

the more i look at other companies i keep feeling i may (as usual) have over engineered and should really be looking at 3/4UNF...

 

 

what did your pretty coloured drawings determine????????

 

 

 

 

edit: that wasn`t a sacastic comment BTW i have respect for anyone who can do stuff like that... to me.. they are just pretty colours hahaha

Edited January 7, 2010 by davenport

[davenport 51]

sorry to keep adding gumpf to your thread but i`ve spent ages trying to find rose jointed wishbone details and have finally spotted these on Egay:

 

http://cgi.ebay.co.uk/Peugeot-205-Rally-Ca...106198001r34853

 

under hub rod end - 3/4UNF

[Cameron 16]

Why are you using imperial threads? You'd surely have a lot more choice with metric.

 

I think (don't hold me to it) I was going to use 16mm for the outer, then 12mm front and 10mm back for the inners. Basically the standard 205 bolt sizes for the inner and then 16mm outer, all heavy duty ones though as they are made from stronger material.

 

The pretty drawings showed that the forces at the rear 10mm rod end would cause a failure, but this was down to the Y-shaped design. Making them A-shaped would put the rod end in compression rather than shear, which would significantly reduce the peak stress. I never got round to modelling this though.

 

I think (when I pick this back up) I'm going to use spherical bearings for the inners rather than rod-ends, I've learned a lot this year that tells me a rod end is far from ideal. This also keeps the packaging around the ARB nice and tight.

Edited January 7, 2010 by Cameron

[welshpug 1,658]

they look close to what Compbrake sell at £245, though they may actually fit with an Anti roll bar..

 

 

 

Edited January 7, 2010 by welshpug

[Dazza 4]

they look close to what Compbrake sell at £245, though they may actually fit with an Anti roll bar..

 

 

 

 

 

Waw those are expensive by comparison to the CB items ....I wonder if you get the coil-over struts to in that price ..

Edited January 7, 2010 by Dazza

[Rippthrough 98]

Why are you using imperial threads? You'd surely have a lot more choice with metric.

 

 

I think (when I pick this back up) I'm going to use spherical bearings for the inners rather than rod-ends, I've learned a lot this year that tells me a rod end is far from ideal. This also keeps the packaging around the ARB nice and tight.

 

 

Imperial rod ends are cheaper and more widely available, american market drives that, personally I have imperial sized bodies and balls ground with a metric bore - nearly as cheap as imperial ends and ease of use with Metric bolts.

You can see why I had using rod ends on the outers and prefer a ball joint or spherical bearing then?

[EdCherry 34 1 Cars]

Americans is why you use imperial... same thing with stuff like NAS bolts, you CAN get them in metric... if you want to pay 3 times the price of the imperial equivalent/similar.

[davenport 51]

as mentioned cost is the main factor for using imperial....

 

another very good reason is i only have UNF taps (this is what comes from working on OLD race cars + bikes) lol