Straight axle front suspension

[LiveandLetDrive]

Quick question because I need to go to bed sometime tonight... Is there any history of "more advanced" suspension being used with solid-axle FRONT suspensions? Push/pull rods to coilovers and other such things to reduce the inherently high unsprung weight? There are plenty of examples of location linkage from all the live rear axle cars out there. What besides a truck has solid front axles these days? Any important things to get right other than low weight?

Light single seater Solo2 (autocross) car, no aero. I'm just theorizing so don't worry about rules and other such trifles...

-Chris

[Larry J-Croft]

Suggest you look at 4wd cars like Land Rovers they have solid front axles but I've no idea how they are attached.

[LiveandLetDrive]

They have large amounts of suspension travel so I think their requirements would be pretty different. I guess my chances of finding a straight axle car with single-seater-ish travel are pretty limited. I was thinking about 2 shocks toward the outside, one spring in the middle, and an anti roll bar to control all single wheel and roll movements. However I'm not sure if I'd really be saving any weight... which is my main goal here.

-Chris

[Al Weyman]

Have a look in Fred Puhns book How to Make Your Car Handle, there is something about American dirt track single seaters that use a solid axle up front. Quite a detailed cutaway drawing as I recollect.

[graham bahr]

beam axles are heavy, if you want lightweight then wishbones are the way to go

[HiRich]

I assume you mean a dead beam axle (solid bar or tube betwen wheels, but no drive facility)

There are still some vans (and I would guess SUVs) that have a traditional beam, with a pair of quarter-elliptic leaf springs. But the bending loads on the beam are large, meaning a large, heavy I-section - not just an unsprung weight but also a large envelope for it to be flapping around.

An alternative to that is the eighth-elliptical spring arrangement (I think from the Austin 7). Take half a classic leaf spring, clamp (rather than bush) it to the frame, and clamp the other end to the axle. So think like a ruler with one end pressed onto the table top, other end loose. But again, probably not worth considering.

Thirdly (and I'm going totally from memory here) didn't the Morgan sliding pillar arrangement include a beam?

I have vague recollections of someone using a beam in the early days of 500cc Formula 3. I recall something in Iota magazine, but the archives are on my currently dead other computer. It would be reasonable to assume that it was not successful.

And for trivia purposes only, Beneton and BAR tried a sort-of dead axle with their braking transfer systems. The front wheels were connected by an axle and differential. The objective was that under braking the unweighted, near locking wheel could be 'driven' by the weighted, not locking wheel. This avoided tyre damage, slightly increased ultimate braking, and added stability. But again, not what you are after.

However, for some alternatives to wishbones & coils, go back to the 500s.

You had the Coopers, using the Fiat Topolino suspension. A transverse leaf acted as the upper wishbone. Net weight penalty is minimal, and you have the benefit that the leaf is twice as stiff in roll as bump (so a smaller or eliminated roll bar).

Taking the same transverse leaf, how about using it on Macpherson struts? Very capable on some '70s Fiats.

You might consider a swing axle (though really you would expect to incorporate drive). With a lightweight car, the loads, and therefore structural weight, are promising compared to wishbones. You can then look at different spring media which could offer better weight and packaging than coils. You should take a look at (all rear, driven layouts):
- The Staride: perhaps the first ever pushrod, with single transverse coil)?
- The Trenberth (and many others): using rubber bands
- The Martin (and Mackson, etc.): where a chain (or cable) drops down from each hub to work on a single rubber tension spring mounted beneath the gearbox
Whilst you won't get the ultimate geometry with these, you may find the weight saving and lower CoG more valuable, particularly on a lightweight racer. Take a look at www.500race.org under Marques for some starter pictures. In their time, all four were very effective against more technically competent cars, so there may be something in it.

[ian.stewart]

http://www.speedwaymotors.com/xq/asp...splayGroup.htm

Torsion bars, titanium bits and all sorts of goodies are made for beam axle cars and sold by Speedway, bit of a one stop shop.

[gttouring]

i was thnkig of this myself
although i understand the advantage of wishbone front suspension and coilsprings
in a car as stiff as F1 or GT1 or LMP1 (audi's use torsion bar springs)
if they are so stiff, would a straight axle bar with a transverse leaf (like a corvette) be all that different with the correct shock/dampers?
the old sprint cars and grandprix cars did this and dirt cars do it still...
the old midget at limerock park in a Formula libre event beat them all once- it can't be that bad...

[johnny yuma]

A very small sports car the Bobbin Holden from the 60s in Australia was a fast very neat speedway -type beam front end special with a 6 cylinder 400lb
1949 iron lump up front and an angled engine running to a very off centre diff to keep the tailshaft out of the way.Great hillclimb car.

Apart from that look under American cars some as late as 1950.Did you have ball joints in mind most are kingpin.You could run coilovers,and locate the beam,hopefully a light alloy one off with steel inserts,with radius rods each side and a "panhard" type rod across.

Downside could be you come barreling into a turn ,put 2 wheels up on the ripples and instant vibrating positive camber on the front wheel doing the work !! Suppose you could still have plenty of neg camber and pos caster on either static or--and this might be a first--build in some adjustment.

[gttouring]

so stay off the kerbing then. just brush the stripes-or cut it violently

[johnny yuma]

spoken like a true speedway grub no offence -even Jack Brabham loved his speedcar with beam axle and oversteer .Even won a hillclimb in it but was disqualified for "no front brakes" by the Ruling Class.

[gttouring]

is there any merit to the ideas i had?
that is a so stiffly sprung car acts almost as if it is solid so why not make it solid (the axles that is)
other than the lack of adjust ment- if you had a pre set axle for the situation would it be so different? or would the effect of one wheel really tweak the other wher a wishbone set up this is almost eliminated (which if it is so stiff i don't see how...car lift the front up in turns all the time now-

[johnny yuma]

I googled and found Welsor-waggott a clever Super 7 type car circa1970 Australia with,as described,a steam pipe as beam BUT a clever innovation here --since it's circular a slip joint was put in the middle so caster change twisted into one side did not get to the other side.As well camber and caster adjustment was built in ,and a panhard rod.Coil sprung.Cortina discs all round.

[gttouring]

sounds- cool, i tried to goole this, bnut i got nothing..
i kept trying to correct me and say i was searching for a Welis- waggott..?

any photos, or links?

[GORDON STREETER]

Go Karts "appear" to go round corners ok !

[johnny yuma]

Originally Posted by gttouring

sounds- cool, i tried to goole this, bnut i got nothing..
i kept trying to correct me and say i was searching for a Welis- waggott..?

any photos, or links?

try googling ' Australian LS1 seldo beam axle ' it works for me ;paul

ACTUALLY THE CAR is a Welsor with assistance from Waggott Engineering.

[gttouring]

i saw a nice bulletin board talking about this..
so a front beam axle with a pivot point or hinge in the middle to give it some more give so one wheel wouldn't affect the other,
neat.
the sliding sleeve i don't get, how did this go? (the Steam pipe description fill me with dread.)

[GORDON STREETER]

Les Bellamy used to supply a kit for the E93a pops that effectively cut the beam axle in half to make IFS. He use to race one with a fair bit of success.

[johnny yuma]

a slip joint is just my interpretation based on the following-

1.Seldo refers to the fact caster change cant be transferred side to side .
2.The car was said to have a BEAM axle,which has the feature of keeping both tyres flat on the road,OR retaining any caster/camber set into it by permanent or adjustable setting.In other words there is no hinge effect in the middle
3.Imagine a pipe fitting perfectly into another with a long overlap.You could throw in some slipper bearings and lube points and have the merit of a beam axle without the vice -fact that twist given at one end will reach the other end.It may not be a big factor.I would not have thought of it ,and perhaps I'm wrong in detail anyhow-but if you think of the wide spaced upper and lower steering pivots of a typical beam axle they could twist the beam back and forth enough in a light,fast car to take precision out.

[johnny yuma]

Saw the Welsor Waggott at Wakefield Park HSRCA today.Nobody standing around with the car,but did get a good look at the front end.Tubular beam axle,has a watts linkage pivot on it,links to body,kingpin steering.Coils,single radius rod welded to beam each side rose joint at body.IT LOOKS ABSOLUTELY BASIC.No sign of the slip-joint I had imagined.

[Notso Swift]

Bizarre
THey may have as well done it properly

[johnny yuma]

Originally Posted by Notso Swift

Bizarre
THey may have as well done it properly

These cars were built 35 years ago when people improvised.We didn't go on the net and order billet this and titanium that and pay someone to put it together.