Upwards pointing wishbones

[allanallen 528 2 Cars]

17 minutes ago, Arthur said:

The failures are the ones without the head I reccon? 

Yes and ones that don’t consider the support required when moving the pivot away from the hub.
I believe I mentioned earlier that I’ve seen several pts style pins with heads fail when fitting larger spacers to correct roll centre. I’d say those failures were due to the hub not being correctly modified where the head of the pin sits and over tightening. 

[Arthur 12]

Yes. And when you triple the length from clamp to pivot, one triples the arm of the force and thus triples the force. When not supported that is. Machining the area at bolt head seems like a challenge. 

[Arthur 12]

On 6/25/2022 at 8:45 AM, allanallen said:

Yes and ones that don’t consider the support required when moving the pivot away from the hub.
I believe I mentioned earlier that I’ve seen several pts style pins with heads fail when fitting larger spacers to correct roll centre. I’d say those failures were due to the hub not being correctly modified where the head of the pin sits and over tightening. 

Did you do calculations on the cone? Even when not welding the cone to the hub, shear for will have to be overcome right? But the the pre load on the bolt should make sure the force on it at 90 degrees does not overcome the Clamping force of the setup, correct?  
 

But when preload AND shear force at operation exceeds the yield point it goes wrong so over tightening is indeed not wise. 

Edited June 27, 2022 by Arthur

[Arthur 12]

What Would you think when i would use a pin, made from 10,9 bolts with a head somewhat like this D? 

 

Edited July 1, 2022 by Arthur

[petert 588]

That’s more or less what my factory pins look like.

[wicked 103 3 Cars]

On 7/2/2022 at 12:23 AM, petert said:

That’s more or less what my factory pins look like.

What's the diameter of those pins? 16 or 18mm?

[petert 588]

I've got the spicey cough, so I can't go out and check. However, it must be Ø16, as the bearing in the wishbone is OD40, ID20 and I turned up some bushes/spacers to fine tune the wishbone angle.

[Arthur 12]

An update after some time:

 

With all your help and advise taken I decided to go for M18 10.9 bolt with a D-head and 30mm cone. I have build a wooden "car" jig and used pipes for struts at the current length of my struts base loaded. This confirms for 98% that my arms will be about 20mm/25mm longer than standard GTI ones at (my) minimum camber of about 0.5 negative. 

 

 

 

Calculation / guesstimates: / facts.

 

M18 10,9 hex bolt with 1/3 of the head machined off 

Cone made from Crmo steel. About 30 x 30 if it was a square. Smallest diameter at the ball 22 x 18. (125 mm2) (~5000kg @modest 400 yield)

95 kN (static) load ball from motorsport company. (even if dynamic was only 10% of static, should be fine) 

Tubular wishbones made from 35 x 2.5 25CRMO4 pipe, welded with crmo tig rods (700 Nm/mm2)

Nut I plan to torque at 300Nm, so about 50% of the pin/bolt is used for pre tension (600kg-ish)

No bump steer correction (yet), 206 steering rods on the shelf should 205 be too short

 

I'm pretty confident this is more then strong enough and the pre tension will never be overcome. I think I would destroy a rim far before this setup breaks. I will clean up the face of the pin even more than underneath picture. 

 

 

Edited March 1 by Arthur