67 replies to this topic

[cnrandall]

If you are retaining roady ride heights then changing uprights will make fcuk all difference. Only real + will be provision for bigger brake callipers. There is very much a tipping point when it comes to ride hight, drop below it and you will get instability, above it you're cool. Clearly Mike won't find 10 secs a lap by bolting on different upright, in fact I would suggest he would find nothing. But, without wanting to confuse, if you put Jamie's car on stock upright it would loose a good amount of lap time because the whole car is optimised around the ride height and he has spent a considerable amount of time putting a proper aero setup on that car with help from mssr. mcBeath. On Mike's priority list I would suggest that different hubs are relatively low down although going to bigger tyres would give speed and that might need the uprights to work.

[JimmyJamJerusalem]

I went into this thinking they were developing a new hub for the VX. After seeing the cost of the Nitron hubs you have Chris I've never considered them. Now I see that theyre fairly reasonably priced on EP It's got my interest.......

[Winstar]

What is the fatigue preformance of the Ali used for a road/track I seem to remember the Nitron ones used 7075 which has a farly low fatigue resistance/strength.

7075 is the right stuff to use, the issue is you have to design them with the properties of the material in mind.

let me put it this way, I have run them on cars for over 8 years now, with zero fatigue issues, yes we have had some broken, but every time this had involved contact usually with a concrete wall first.

speaking personally, I would not get into a car and give it death of I had *ANY* concern over a single part of it, I have no wish to maim/kill myself.

Yes I realise the importance of designing to the material*, however 7000 series Ali has a very high strength to density but lot lower ratio of high cycle fatigue strngth to yield (~30%) to other Ali grades which means that it's great for application like motorsport or aerospace where life of componets is short and are regually inspected but shoudn't be treated as a fit and forget part on a road car. However the EP hub do look alot more robust of a design than the Niitron ones.

To one of the earlier point this is why it's not used by OEM's on road car as if you designing for fatigue like then steel has a similar yeild but a high cycle fatigue 66% of yeild meaning that it negates a lot of weight saving for an increase in cost, and OEM's will do anything to save even pence.

*my background is FEA and CFD analysis

[Scuffers]

Quite right, however, fatigue is the fall out of flex, if your not flexing it, then your not fatigueing it. The point in the upright design is to prevent flex in the first place (or limit it to the point of irrelevance more accuratly)

[Goosenka]

Forgive me Scuffers just wanted to know whilst reading this as to who you are? I am sure everyone else knows but I generally miss the boat. Assuming you are a Time Attack involved person?

[JohnTurbo]

Oh... I was pretty sure he was a plucky cartoon dog-come-superhero. You mean its a MAN?!

[Goosenka]

Oh... I was pretty sure he was a plucky cartoon dog-come-superhero. You mean its a MAN?!

Could well be. I love a mystery

[Mike (Cliffie)]

Scuffers is one of the best X220/Elise chassis engineers currently who works with Lotus and Elise Parts on design, development and testing of chassis components. He knows what he is talking about for sure. Agreed, a set of GT uprights in isolation will make little difference to my car or my lap times and would need to be a part of a complete rethink from the chassis outwards.