Upright cast-in-lug examples anyone?

[MP4/4]

Hi,

I am at the point in the bachelor thesis where I need to think about the actual design of the upright.
All basic parameters are set.

The problem I have is that lug means so many things translated to german.

As I was reading Allan Staniforth "Competition Car Suspension" for ideas, on page 83, he talks about
"...uprights with cast in lugs to which can be bolted two horizontal alloy plates."
Unfortunatly I can't imagine how this looks like.

I'd like to incorporate this idea into my design, so the guys can dial out bump steer, change the
Ackermann angles and check different steering ratios.
As this is a new team, I welcome the possibility to change a lot of parameters on the car, when
everything is finished, to fully test and tune the car.

I can imagine the plates he is talking about and changing the attachment point
of the steering arms to them to adjust bump steer.

But what does he means by lugs?

Does anyone have a picture of such an assembly?

Best regards,
Alex

[Z]

MP4/4,

And indeed "lugs" can mean many things even in English. From my dictionary the word stems from the Norwegian "lugge" = "to pull by the hair".

The most fitting English meanings for your usage are;
1. "to carry or drag (something heavy) with great effort",
2. "a projecting piece by which something is connected, supported, or lifted",
3. (from informal Scottish) "an ear" (derived from "to pull by the ear...").

So picture your upright in side-view as a "Y" shaped structure. The axle passes through the crux (centre-cross) of the Y. Bottom-wishbone-outer-BJ connects to the bottom of the Y.

The two top points of the Y are biggish lumps of metal (ie. "lugs" or "ears") with, perhaps, vertical holes drilled in them. The "two horizontal alloy plates" are bolted to these "lugs" with two (or more) vertical bolts.

Hope that makes sense. Maybe someone can post a picture...?

Z

[MP4/4]

Hi Z,

thanks for the explanation.

I can sort of picture it, sort of.

I would like to know how the alloy plates are attached to the lugs, so I can change
the parameters.

If somebody could post a picture of such an upright,
this would be quiet helpful!

Alex

[Z]

Alex,

This one has a single machined "horizontal plate" that is bolted to the upright's two "lugs" with two vertical bolts.
http://img.photobucket.com/albums/v626/nsmikle/upright05front.jpg

This one has a "horizontal channel section" bolted to the upright with 4 (?) horizontal bolts.
http://www.pilbeamracing.co.uk/photos/general/lotus_front_upright.jpg

The important point is that the "horizontal plates" are "change parts". To change the Castor or Ackermann you must change this part (ie. remove the old one, and fit a new, different, one).

More pictures, anyone...???

Z

[MP4/4]

Hi Z,

thanks again.

Basically, when you change this plate you could practically move the upper ball joint further to the back, to increase positive castor.

You don't drill 2 more holes in the existing plate/upright because that would influence compliance. That's why you use these plates.

I'll use a design like that, with additional shims to change camber.

An idea that comes up is to fit long holes in the second pictures upright, so I can change the height of the upper ball joint.
The steering arm, in this case, should have an own plate or better being directly attached to the upright.

Advanced rigidity analyses would come into place, due to the additional long holes.

I'll probably go along to offer them 2 additional plates to play with without the long holes.

Alex

[MP4/4]

During the research, I found a thread on the locost forum with a lot of pictures of different upright solutions.

http://www.locostusa.com/forums/viewtopic.php?f=5&t=12384

Maybe this can also help others.

[Z]

... I found a thread on the locost forum ...

http://www.locostusa.com/forums/viewtopic.php?f=5&t=12384

Yes, the old-fart is a cynical, critical, old curmudgeon, but there is not a single upright on that Locost thread that I would consider remotely acceptable. Most are downright atrocious, bordering on criminally negligent (ie. too weak, or too heavy, or usually both!).

If you students want to see good examples of efficient structural design, then please get out of your classrooms and take a walk in any forest, and look at how the trees grow. Or, more appropriately in this case, go and look in the bone-yards out the back of any abattoir.

Inefficient designs in Nature are soon identified ... and deleted.

Z