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Wishbone material
sammy - 30/3/07 at 09:04 PM

Finally reached the stage where I can start to look at making the wishbones for my Rover V8 locost.

I've got some 3mm wall tube (21mm inner diameter, 27mm outer) so should be strong but it's not seamless. (Very heavy compared to 19mm 16swg tube!)

Question is will it be suitable for making the wishbones?
It's quite heavy tube, will the extra weight cause any handling problems?

Cheers
Sammy

t.j. - 30/3/07 at 09:13 PM

I'm using 3 mm pipe 25 mm dia.

The unsprungweight will rise but if you fit alloy wheels this is compensated.
So no worries there.

I'm using a Ford DOHC, and I don't know what the RV8 weights. But i personal think it is really strong enough

Grtz

JoelP - 30/3/07 at 09:23 PM

that would be fine, more than infact. 2mm would be strong in my books, and 1.5mm adequate if designed well. All IMHO.

violentblue - 30/3/07 at 09:28 PM

I was considering doing this for my suspension as well, using larger diameter than what is called for, both front and rear IRS.

I'm thinking 1 1/4" or 1 1/2" regular seemed tube, but a little heavier walled
I figured it'd be fine, but I'd like to hear from someone who's done it.

mark chandler - 30/3/07 at 09:45 PM

It depends on where you place the shock, if its pointing towards the ball joint centre, ie not using the bone as a lever you can go thinner. The book design is very bad in this respect as the bone becomes a pivot point 2/3rds along its length.

Also on the weight of the car, yours will be relatively haevy with a RV8 up front.

That said, the tube you propose will handle most things and the extra wieght across its length will not affect much.

Regards Mark

Regards Mark

JB - 31/3/07 at 04:45 AM

The tube dimensions you mention should be fine if the grade of steel is suitable for welding and you design the wishbones correctly.

However the suspension is such a critical part of a car I would never compromise on design or quality of materials and components.

907 - 31/3/07 at 05:39 AM

quote:
Originally posted by sammy
Finally reached the stage where I can start to look at making the wishbones for my Rover V8 locost.

I've got some 3mm wall tube (21mm inner diameter, 27mm outer) so should be strong but it's not seamless. (Very heavy compared to 19mm 16swg tube!)

Question is will it be suitable for making the wishbones?
It's quite heavy tube, will the extra weight cause any handling problems?

Cheers
Sammy




Hi Sammy

Sounds like you have 3/4" NB, the pipe that takes an NPT or BSP thread.

IMHO this would be more than adequate, in fact slightly overkill.

My own w/b's are stainless and my bottom rear is made of this size.
Top rear, and top & bottom front, I made from 1/2" NB which is 22.2mm ( 7/8" ) o/d x 2mm wall.

Again, just my opinion, but I do think w/b's can look too flimsy or beefy.
You've got to strike a balance between strength and looks.


I had to smile the other day when reading the thread on powder coating wish bones.
Maybe stainless is not so expensive after all.
A quick rub down with a Scotch pad is the only finish required.


Atb

Paul G

blueshift - 31/3/07 at 09:18 AM

There have been many discussions about this before, and some stress analysis done etc..

The conclusion others came to and I agreed with was that book standard 3/4" 16ga tube is a bit light, but 1" 16ga is a lot stronger. That's what I'm using for my wishbones.

I think 3mm wall is somewhat overkill, I don't know of any kit manufacturers using anything as beefy as that. Having said that you probably won't notice much difference, it'll still be the best handling car you've ever driven

procomp - 31/3/07 at 10:16 AM

Hi also consider that if the wishbones are to strong. If you ever do happen to hit a kerb/object then it may well mean that you have removed the chassis saving weak link .

Its easier to replase a pair of wishbones than repair a bent chassis if it comes to the crunch.

cheers matt