33 GTR Broken front wheel knuckle

[MBS206]

11 minutes ago, R32 TT said:

Well I'll start by saying I'm not an engineer.

I am going to go with the KiwiCNC ones.  They are made of 7050 alloy have good fillets and radius.  The material alone is in the order of double the strength and fatigue resistance -

Those bolts, once torqued correctly place most of the load at the flat face of the mating surface - the 'stretch' you're talking about through torqueing them up would be far more than the extra stretch 'load' placed on them from a steering input or bump. (in my opinion) so I doubt they would flinch.    - but again "not an engineer".     

But again, the engineers said your cast aluminium would be fine based on the load that would be stretching that section. Same load stretching the bolts in a flex (not the twist), with a much smaller cross sectional area than the original part you've broken. It's why you'd need to be using higher strength bolts, but that's just making up for the strength you lose with less area...

[GTSBoy]

22 minutes ago, MBS206 said:

But again, the engineers said your cast aluminium would be fine based on the load that would be stretching that section. Same load stretching the bolts in a flex (not the twist), with a much smaller cross sectional area than the original part you've broken. It's why you'd need to be using higher strength bolts, but that's just making up for the strength you lose with less area...

Hmm. Perhaps not the same engineers.

The OE Nissan engineers did not forsee a future with spacers pushing the tie rod force application further away from the steering arm and creating that torque. The failures are happening since the advent of those things, and some 30 years after they designed the uprights. So latent casting deficiencies, 30+ yrs of wear and tear, + unexpected usage could quite easily = unforeseen failure.

Meanwhile, the engineers who are designing the billet CNC or fabricated uprights are also designing, for the same parts makers, the correction tie rod ends. And they are designing and building these with motorsport (or, at the very least, the meth addled antics of drifters) in mind. So I would hope (in fact, I would expect) that their design work included the offset of that steering force.

Doesn't mean that it is not totally valid to ask the question of them, before committing $$.

[MBS206]

1 hour ago, GTSBoy said:

Hmm. Perhaps not the same engineers.

The OE Nissan engineers did not forsee a future with spacers pushing the tie rod force application further away from the steering arm and creating that torque. The failures are happening since the advent of those things, and some 30 years after they designed the uprights. So latent casting deficiencies, 30+ yrs of wear and tear, + unexpected usage could quite easily = unforeseen failure.

Meanwhile, the engineers who are designing the billet CNC or fabricated uprights are also designing, for the same parts makers, the correction tie rod ends. And they are designing and building these with motorsport (or, at the very least, the meth addled antics of drifters) in mind. So I would hope (in fact, I would expect) that their design work included the offset of that steering force.

Doesn't mean that it is not totally valid to ask the question of them, before committing $$.

Let's be honest, most of the people designing parts like the above, aren't engineers.

Sometimes they come from disciplines that gives them more qualitative feel for design than quantitive, however, plenty of them have just picked up a license to Fusion and started making things.

And that's the honest part about the majority of these guys making parts like that, they don't have huge R&D teams and heaps of time or experience working out the numbers on it.

Shit, most smaller teams that do have real engineers still roll with "yeah, it should be okay, and does the job, let's make them and just see"...

 

The smaller guys like KiwiCNC, aren't the likes of Bosch etc with proper engineering procedures, and oversights, and sign off. As such, it's why they can produce a product to market a lot quicker, but it always comes back to, question it all.

 

I'm still not a fan of that bolt on piece. Why not just machine it all in one go? With the right design it's possible. The only reason I can see is if they want different heights/length for the tie rod to bolt to. And if they have the cncs themselves,they can easily offer that exact feature, and just machine it all in one go. 

[GTSBoy]

38 minutes ago, MBS206 said:

I'm still not a fan of that bolt on piece.

There's plenty of OEM steering arms that are bolted on. Not in the same fashion/orientation as that one, to be sure, but still. Examples of what I'm thinking of would use holes like the ones that have the downward facing studs on the GTR uprights (down the bottom end, under the driveshaft opening, near the lower balljoint) and bolt a steering arm on using only 2 bolts that would be somewhat similarly in shear as these you're complainig about. I reckon old Holdens did that, and I've never seen a broken one of those.

[R32 TT]

Well - they have arrived.  And they are easy on the eye to put it mildly...

These only have three bolts - but for a start there is a key that fits with vacuum like precision..  And as you can see by my ruler, the interface is large..  

I listened to a podcast on HP Academy about Dan (KiwiCNC) and I'm more than comfortable he knows what he is doing.

R35 Bearing assembly should arrive later today so can mock that up for a look.

Can't wait to get these on and get some brake pressure logging too.

Edited 2 hours ago by R32 TT