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205_sunderland

Building Bottom Arms With Rose Joints - If We All Chip In Money Saved

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B1ack_Mi16

Hi!

 

About my bottom arms, the test of the pics are done with a 1500kg braking charge.

 

Un saludo.

 

Ok, good to know, is it then 1500kg each side, or 1500kg both sides, so you have applied ~15kN or ~7.5kN to the wishbone in the analysis?

 

I've been doing some FE analysis myself and think I used whole cars weight on one front wheel combined with 1.5 in friction factor (sadly I'm an engineer and I always seem to wanna use huge safety factors on anything I do :)). That will be about ~12.5kN on each wishbone in my case.

 

Only thing I'm little bit unsure about is if you hit a hole in the road or such, how much extra does it need to take compared to pure braking.

Anyway in real life probably maximum 65% of total weight will be on one of the front tires while braking so it should be a good margin I believe.

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B1ack_Mi16

I'd be concerned about 16mm rod ends tbh, I was going to use these to make tubular wishbones a while back and on road tyres they're fine, but semi's / slicks could bring them close to failing under braking.. if you trail-braked into a kerbed chicane it's probable you'd bend one.

 

You are concerned about using M16 on the outer or on the inner joints (I suppose outers)?

 

I was thinking about making some arms myself and for the outer ones I was figuring out that M18 or preferably M20 would be the safest, at least if they are wound out a little bit to adjust camber...

 

Anyway my problem with trying to calculate this type of setup is that it is hard to know which of the inner ones that will take most of the shear force from the braking. If fabricated a little bit out of perfect tolerance I would think it is hard to know whether the front or rear one actually will take the shear force, but anyway, if it starts to bend a tiny amount the lesser loaded one will step in so it might not be much of a problem in real world.

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Cameron

Bas - that's more like it! :D

 

My concern was that a 16mm rod end used for the BBJ could get close to it's elastic limit under heavy braking (i.e. bend!) since the threads are the major weak point. If your guy has done his sums, which I guess he has to spec a lighter duty rod end to the norm, then good work to him! However, if I were making these components for a large variety of applications - race / road / rally cars all of different weights and setups, then I would be very uncomfortable cutting it fine on the spec of the rod end - I guess that was the point I was trying to make.

Edited by Cameron

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205_sunderland

sadly this is all on hold an the moment until i get some money but ill keep you posted :)

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Bas

Bas - that's more like it! :D

 

My concern was that a 16mm rod end used for the BBJ could get close to it's elastic limit under heavy braking (i.e. bend!) since the threads are the major weak point. If your guy has done his sums, which I guess he has to spec a lighter duty rod end to the norm, then good work to him! However, if I were making these components for a large variety of applications - race / road / rally cars all of different weights and setups, then I would be very uncomfortable cutting it fine on the spec of the rod end - I guess that was the point I was trying to make.

 

 

Ok point taken. :) I think you're right with a rally car in mind.

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lahondal

Hi!

 

Sorry for reflooding, but I sell my sets of wishbones at 190GBP a pair.

 

Thanks!.

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Francesco

As i mentioned before:

 

The 205 GTi Turbo 16 (350 HP 420 Nm) of Eelko Kleibeuker is racing DNRT (Dutch National Racing Team) with these Bottom Arms.

 

If 16mm rod ends can hold 350 HP and 420 Nm (on a Peugeot 205 GTi Turbo 16 that is doing RL (Real Live) races) without any problems I'm sure 16mm is strong enough.

 

Why are you concerned Cameron?

 

I use the same ones as Bas and Eelko on my 205. And if they can handle this abuse.....

 

post-11728-0-24562100-1352334032_thumb.jpg

 

I don't think you have to worry about the strenght. I have tested it ;). They survived this and i still use them. (car and driver where ok after this little mistake).

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