Tubular Wishbone Project

[davenport 51]

not sure off hand which pics i posted now but..

 

the red ones are by a company called PAMsport (some foreign guy caled patrice..)

the bare metal ones (beautifully tig`d) are by TRi competition

[Cameron 16]

Yeah the nicely TIG'd ones.

 

Just looked at their site, WOW they're expensive!

Made with some very exotic materials though, 25CD4S and 15CDV6 are extremely expensive but very very reliable. I made my steering column from 15CDV6 as I got the material free from work but it's normally somewhere in the region of £60 / metre for tubing.

[davenport 51]

Yeah the nicely TIG'd ones.

 

Just looked at their site, WOW they're expensive!

Made with some very exotic materials though, 25CD4S and 15CDV6 are extremely expensive but very very reliable. I made my steering column from 15CDV6 as I got the material free from work but it's normally somewhere in the region of £60 / metre for tubing.

 

 

yeah i beleive the 25CDV4S is the equivalent to UK 4130 chro-mo which requires heat treating after welding which is something i`d like to avoid if possible...

 

an ex employer (fox racing develpments) advised using CDS or T45 if weight was a major thing.... at the minute i`ve decided to just use the normal CDS stuff.. the machined parts will be in EN1A steel...

[Cameron 16]

CDS is perfectly acceptable for wishbones, to be honest all mild steels have the same Young's Modulus so all you're gaining by using the expensive stuff is ultimate tensile strength, they won't be any more rigid, just stronger.

 

You won't go wrong with CDS, but T45 would be better. They're both cheap enough and neither require any post-welding heat treatment. You'll need to research what filler wire to use though, I remember one of the guys at BTB made bike frames from T45 and found that some filler rod materials gave brittle welds.

[davenport 51]

yes.. for my trial runs on CDS i`ll be able to get away with A18 filler wire... T45 needs A31 or A32

[Rippthrough 98]

You won't go wrong with CDS, but T45 would be better. They're both cheap enough and neither require any post-welding heat treatment. You'll need to research what filler wire to use though, I remember one of the guys at BTB made bike frames from T45 and found that some filler rod materials gave brittle welds.

 

If you can get your fits close enough, braze them.

[Cameron 16]

Cool, not sure what A18 wire is though, or 31 / 32 for that matter.

[oz. 2]

A different mix of metals in the wire?

[davenport 51]

aye... its just a grading system for filler wire...

 

A18 is bog standard run-of-the-mill stuff...

 

we have about 8 or 9 different types at work for ally/stainless/stainless-to-mild....

[Cloverleaf 1]

CDS is perfectly acceptable for wishbones, to be honest all mild steels have the same Young's Modulus so all you're gaining by using the expensive stuff is ultimate tensile strength, they won't be any more rigid, just stronger.

 

You won't go wrong with CDS, but T45 would be better. They're both cheap enough and neither require any post-welding heat treatment. You'll need to research what filler wire to use though, I remember one of the guys at BTB made bike frames from T45 and found that some filler rod materials gave brittle welds.

 

If you use T45 you could use thin wall tube or smaller OD compared to CDS, saving weight.

 

I've read different things about heat treating T45, some say you don't need it, others say you need to heat it all until it's glowing red once welded and some say just TIG welding it generates enough heat to avoid the need to heat treat it.

[Rippthrough 98]

T45 is fine just welded, the heat as it cools is enough to anneal it so you don't have any real problems (provided you use a softer filler wire than the T45) 4140 chro-moly tube is another matter though.

Edited January 4, 2010 by Rippthrough

[davenport 51]

i have to agree with rippthrough.. when i was an apprentice i made MANY wishbones in T45 for LOLA sportscars.. they were never heat treated...

 

yes in using it you could probably drop down to 16swg over what i`m using but.....

 

The jig will be the same... 6m of tube is costing less than 40 quid, a 600mm chunk of EN1A solid bar is costing me £5 and i have A18 filler wire at work....

 

this is a trial run so to speak IF it works, the rear mounts and rose joints can be re-used in a lighter revision but for now its merely a "how feasable are...."

[swordfish210 20]

Ever thought about making some composite wishbones?

[Cloverleaf 1]

i have to agree with rippthrough.. when i was an apprentice i made MANY wishbones in T45 for LOLA sportscars.. they were never heat treated...

 

yes in using it you could probably drop down to 16swg over what i`m using but.....

 

The jig will be the same... 6m of tube is costing less than 40 quid, a 600mm chunk of EN1A solid bar is costing me £5 and i have A18 filler wire at work....

 

this is a trial run so to speak IF it works, the rear mounts and rose joints can be re-used in a lighter revision but for now its merely a "how feasable are...."

 

Wasn't criticism mate, just adding to what cameron said. I agree that you could always make some T45 ones in the future.

 

Most of my cage is T45 and I didn't heat treat it either (although I did TIG some of it), I was just relaying what I've read, not that I was convinced by it

[davenport 51]

another point chris made which i hadn`t thought of..

 

12swg cds is what?? 2.5mm wall.... 16swg T45 would be 1.6mm wall....

 

how resiliant to knocks / denting would the thinner wall stuff be???

 

 

 

as for composite??? i still dont trust the stuff.... its just high tech straw and toffee!! hahahahahahahaha

[Rippthrough 98]

how resiliant to knocks / denting would the thinner wall stuff be???

 

 

Not very, I'd stick with at least 2mm.

[Cloverleaf 1]

That I'm not sure I agree with, I've got some 1.6mm wall T45 and it's tough! If you're hitting something hard enough to dent it I think you'd be in trouble.

[Cameron 16]

Yeah 1.6mm tube in small diameters is pretty tough! You could clout it on the corner of a bench and only get a small dent.

You could quite happily use 16swg for a track / race car, 18swg would be even better as long as you increase the OD. That's why I was bothering with all the analysis, I could have happily made them from 14swg and they would have never broken, but it's excess weight and surely that defeats the object of tubular wishbones.

 

Re composite wishbones, it's probably not feasible for a car of this price / quality (French).

[Rippthrough 98]

That I'm not sure I agree with, I've got some 1.6mm wall T45 and it's tough! If you're hitting something hard enough to dent it I think you'd be in trouble.

 

You want to see what I did to my 1.6mm wall lower strut brace when a small rock bounced into it....

And if you're doing any rallying, you want them thicker still, we've bent 4mm wall wishbones on the buggy after hitting rocks that the tyres had dug out.

 

Fine for a track-only car though.

Edited January 4, 2010 by Rippthrough

[Cameron 16]

You want to see what I did to my 1.6mm wall lower strut brace when a big rock bounced into it....

 

What diameter was the tube though?

[Rippthrough 98]

38mm

[welshpug 1,623]

should have seen what a humpback bridge did to one of Phill's prototype 306 Lower wishbone braces!

[Cameron 16]

Ah, yeah I suppose clouting massive rocks might dent them..

 

Yours is a rally car though, a track / race car wouldn't be abusing them to the same extent.

[Rippthrough 98]

should have seen what a humpback bridge did to one of Phill's prototype 306 Lower wishbone braces!

 

 

 

Did you see that one Seans mate clouted on one of those pop-up bollard things?

[welshpug 1,623]

Ah, yeah I suppose clouting massive rocks might dent them..

 

Yours is a rally car though, a track / race car wouldn't be abusing them to the same extent.

 

wasn't on the saxo, was a Lad off the 306 forum I did some work for, over Dartmoor

 

 

 

Did you see that one Seans mate clouted on one of those pop-up bollard things?

 

 

err, I can guess!