goo goo g'joob?

Just call me the eggman...

besides having 10,000% more vision than a modern car, Australian licencing would tell you to go away with the tubes going across your line of vision with the bottom 2 I am sure..




Actually I wonder if licencing in the USA will have anything against the original 2 tubes in the line of vision? - I'm sure Australia will object, hmmmm, that might decide it for me.

.

Narwhal.

to get into and out of, would having the tubes hinged at the front and lock (large overcenter clicp latch, underside) at the top be worth considering?

Hmmm good fun this rendering lark, might have another go.
Bit difficult with a touch pad though.
Thought it needed to be self energizing cheapy.

I suspect rego authorities would require padding on those tubes.

Not having seen the real thing Cheapy, I am not sure how far the body is from those bars, but in any decent shunt the head and arms move much more than most people imagine. You of course are not 'most people' ...

Are you still using the centre geared pivot on the front axle beam ?
just had a look at the Welsor thread and it doesnt look like the axle is pivoting centrally on your diagrams ?

Doh !

overlooked the 'A' frame

I quite like it Cheapracer... but can't help wondering how would it look with '70ies F1 nose in place of the small winglets/whiskers (you know, full width of the car, airfoil shaped and used to deflect the airflow from the wheels to reduce drag without having fenders; you could maybe even get away with endplates*)... If it would also turn out aerodynamically sound, you could sell it as aftermarket/upgrade option.

* and I think it could easily be done as 'bolt-on' solution (with your permission, I could deface one of those pretty pictures of yours to show what I mean)

Just give me some damn CAD drawings and ill show you some options. Even got 3ds max i can test if Inventor does not satisfy me.

Well, I couldn't wait for permissions, so I added the winglet anyways, but then decided to go a step further... I'm no fan of splitters (and believe it or not, I've seen them added to road cars!) and common type wings on road cars, I've decided to do a quick sketch showing the gist of 'my invention' i.e. BumperWing, hahaha.



And here's the way I'd do it- since if I'm to accidentaly run over somebody, I'd rather break their leg than chop ther feet off with something sharp. I'd stick the wing a bit more in front, to serve as bumper, and use thicker profile airfoil in order to use steel tube as leading edge cum bumper... One can use low density foam as a core of the winglet, or styrofoam which I believe can be, after the GRP is cured, dissolved by gasoline, leaving the hollow profile (and owner with a small quantity of byproduct*). I appologize for the sketchiness of the representation- I've neither included the means of mounting, nor properly closed GRP sections, &c...



* needles to say, this byproduct has it's own purposes, but we best not go into that...

From the Welsor thread I see you have ditched the geared lateral link and gone for an 'A' frame

I'm interested as to how you got the 'A' frame and 4 links to work .

Conventionally on a rear axle it doesn't work geometrically

At the moment for pre production cars the 'A' lateral link allows me to adjust the front roll center in minutes merely undoing the bolt and adding/subtracting spacers so I'll see what that offers first before deciding which link to use - if the FRC ends up suitably high I may even go to a simple Panhard rod.




You may have missed that the upper ball joints/upright is free to move where it wants to within the constraints of the upper radius rod's and lateral rod's arc motions. A live rear axle has fixed mounts and of course a 3rd plane(?) will rigidify the movement.

And yes I did add the 'A' lateral link to my highly professional computer drawings ...

Purple = beam lateral link (and roll centre where it meets the beam).







For those of you who understand the movement, the upper radius rods are longer/lower shorter and that's how caster is gained in bump.

I could start a whole new line ...

too many colours man

What Welsor thread is this?

Do you know the secret handshake?

The Welsor thread, a good read...

http://forums.autosport.com/index.php?showtopic=90327

Thank you Cheapy - extremely interesting. As they say - they don't build them like that anymore (which is a pity).

So, any new info/progress?

1st pre-production car is in the jig now - optimising this and that then get a run started soon and get the first box shipped to the US of Americaland.

Cheapy your lower "beam" (orange?) is over-constrained. In a situation where one wheel undergos jounce and the other rebound, the orange beam moves longitudinally towards the (red?) leading links and the (purple?) A frame wont allow that. You need a flexy beam.

Worse still, the (green?) chassis bulkhead clashes with everything else in your colour scheme.

You'll be telling him next that he can't wear yellow laces in his purple Doc Martens! You fashion police...

I don't think it's over-constrained (at least not within limits):
The (orange) beam is constrained by three points; the tip of the A-arm (purple) and the two lower longitudal arms (red)
The top joint of the upright has to be on a circle around a line trough the lower upright joint and the joint where the dark blue arm meets the beam
So as long as the upper longitudal arm from the chassis can reach this circle the design is not over-constrained

That rough drawing is taken from the real existing one that works just fine, you even just quoted this part; "You may have missed that the upper ball joints/upright is free to move where it wants to within the constraints of the upper radius rod's and lateral rod's arc motions" - the short lateral rods are not fixed to the beam, they are rose* jointed at either end and the upright is free to caster with the upper radius rod's length change (through it's arc).

The whole point of it is to allow caster differences left to right that a normal beam can not offer unless rotation is allowed for in the middle of the beam like the Welsor was (or a twist beam such as some FWD cars have at the rear).

*What's a heim joint and a rose joint? - same just originally the H.G. Heim Company Co. produced them in the USA and the Rose Bearings Co. Ltd in the UK.




Yes, so I've decided to go with mauve instead.

Cheapy your lower "beam" (orange?) is over-constrained. In a situation where one wheel undergos jounce and the other rebound, the orange beam moves longitudinally towards the (red?) leading links and the (purple?) A frame wont allow that. You need a flexy beam.

In theory - is that A-frame actually needed at all? With those leading arms steeply angled in (as they are in the drawing) wouldn't this be enough to constrain the beam to just where it has to move?

Yes, the A-frame is required. Without it the axle can move left simply by the right side of the axle moving forward and the left side of the axle moving rearward. I've done the layout work to reassure myself.

Indeed, many a lateral link would service but the A-link provides 3 advantages, RC is adjustable in seconds using only spacers, acts as a "3rd link"* and is in the middle of the beam which allows for a lighter beam as the main load is only for half the length of the beam in comparison to say a Panhard rod.

*The lower radius rods and A-link need to be mounted at different heights on the beam to stop it rolling - I actually started out with a 4 link and Panhard just for the beam then 2 more for the upper ball joints making a 7 link!

There is also a packaging layout advantage considering the whole system combined, the chassis lateral that mounts the 2 A-link pivots is already there to support the lower radius arm mounts and allows for simple chassis triangulation as shown below ..

I have no experience with location of beams and de Dions, but has slider as means of locating been used only with leaf springs (or some sort of additional was used with coil springs)? The reason I ask is that I have an oddball idea that could turn the sliding joint into ARB with adjustable roll damper...

Sorry, somehow missed your reply. My problem has nothing to do with upper anythings. If you delete everything except the orange beam and the four links that locate it to the chassis. Lift one wheel to full bump travel. Lower the other wheel to full rebound travel. The two red links locating the ends of the beam will pull the beam closer to the chassis mounting plane. The A-link on the other hand, maintains the beam at a fixed distance from the chassis mounts so - conflict - overconstrained. In reality, the beam may have sufficient flex to bend the mm or two required.

You don't seem to see it, the A-link pivot and radius rod's pivots are not on the same horizontal plane so the beam merely rolls exactly as a 3 link setup's axle rolls when one radius rod's chord length is changed while transversing through it's arc. It's not just the radius rod's that change the caster, it's also this roll that dynamically changes the lower ball joints longitudinal position relative to the car - not that theres a lot of roll as the links (A-link and lower radius rods) are very close to being the same length anyway.

Go look at some Hot Rod or Off Road vehicle's common 3 link setups.

Got it now - thanks Cheapy. Didn't realise the beam could roll.

My first iteration was a full 5 link (4 radius rods and a Panhard rod) just for the beam location, then 2 more radius rods and 2 lateral rods for upper BJ - 9 rods, 18 rod ends (Bex or Watts link 10 and 20), I thought "hmmmm ......"

So now it's 5 and A-link and 13 rod ends combined.

Leaf spring FTW!
;)

Can do great things with them, problem is public acceptance ....

The contact patch won't care what type of spring is employed, only its rate. If a leaf spring make sense from a packaging perspective I can't see any reason not to use one.

Rubber and multiple leafs have one advantage over coils and torsion bars in that they have self damping. Rubber just because it has and leaves because they rub against each other.

I always believed that was one of the Group 4 Mk2 Escorts advantages (the damping) and part of it's success, maybe not so much these days with the current damper tech - oh, and the beam axle of course!

And as they would put it in real estate business- 'location, location, location'.

Neither system is a substitute for a proper coil and damper setup.

Leafsprings have high stiction, and then tend to have friction like damping, which makes them overdamped for small motions and underdamped for large ones.

Simple rubber bushes have frequency and amplitude dependent damping, which a skilled blender can modify somewhat, independently of the rate of the bush. They do have the fantastic advanatge of no friction. Of course you can add internal mechanisms to the bush, when it is called a hydrobush, and those can get as complicated as you want. You can't get much damping out of them in road damper terms as you'll cook the rubber in no time flat, but for specific frequencies etc they are very clever.

Not if you use a single tapered leaf. Works well on light cars.
And in any case I think it's possible to ceramic coat the leaves so they don't suffer from the sticktion problem so much if you need multiples.

Which given the context of the discussion throws the baby out with the bathwater. Cheapy was saying that leafsprings provide damping, i was pointing out that it wasn't the right sort.

I would also only use them as a spring, not for location.
I can't see a problem with that.

Kind of but I was referring mainly to the Group 4 Mk2 Escort that had considerable success in it's day when dampers were fairly basic still, especially in long, rough rallies (against IRS cars) and I always considered that may have been partly due to the springs having extra damping and not solely relying on the dampers which faded rather rapidly unlike today.



As I mentioned, "maybe not so much these days with the current damper tech..."

Thought you might like to see a proper beam axle car one of less than 200 made.
Colin Chapmans first real production car, the Lotus 6.
This one is all original.
We are repairing the front stub axles and welding repairs on some of the original body panels.





Prefect E93A modified front suspension.
This one has the 100E side valve engine. Some had the older E93A engine with white metal bearings and non adjustable tappets.
I have cast new bearings for one of them.

it most certainly is not !

The gearbox is fine, trust me on that. Please.

It 'seams' there is another 'gap' in your knowledge

Possibly.
I cant say as I know of all the variations of build on the Lotus 6.
From your comment, you do.
So enlighten us.