33 replies to this topic

[Ray Bell]

...locate the front 'axle' laterally?

I have a bunch of photos of it, courtesy of Paul Hamilton, but none of them seem to show any means of lateral location. No sliding pegs (that I could be sure of), no Watts Links, no Panhard bars.

Anyone had a close enough look to work it out?

[macoran]

Interesting question Ray.

I happened to be looking at Ultimatecarpage.com and was studying this pic.
http://www.ultimatec...m=5&carnum=1456

Seems like the front suspension is running through a "box" section welded into/against the chassis.

[Ray Bell]

That's right, it runs through that 'box'...

But what locates the axle laterally?

[macoran]

What intriques me is that the steering trackrod slides through the foremost upper suspension
tubes, so I would presume total movement to be minimal.The said suspension tubes would have to
"swing" at both ends of the steering rack
Any "hinge" type components visble on your Hamilton photos visble Ray ?
Would you be allowed to post a pic ?

[Ray Bell]

The rack is actually a part of the 'axle'... with the pinion bouncing up and down according to the vagaries of the surface of the road and a flexibility built into the steering column that allows this to happen...

That is a pair of universal joints and a sliding spline, I believe. This is also not fully covered in the pics.

But the rack is:



Yes, Paul did say I could use the pics here. And no 'hinge' components, at least as far as I understand what you mean.

[Bonde]

From the pics on Ultimate Car Page it appears that the rear axle beam is located laterally by a low-mounted A-frame arrangement, so I suspect the front may be similarly located. Having a 'floating' rack on a beam axle is not unique to the 58 - I believe some clubmans had that arrangement (Welsor?), as did Hurtubise's dinosaur 'Herc' Indy roadster.

Any chance of seing more pics of the 58 "nude", Ray? [one day when I get old I'd love to find the time to do a cutaway drawing of the 58, a wonderfully different but nice looking car. I love the wedge theme].

[macoran]

I think the "claw" like thing on the right should be the telltale when we are looking for lateral location. I would presume it is welded to the tubes with slotwelds on the inside, I think it looks like a casting, and presume that somewhere near where the steering shaft comes through it there should be a rotation/pivot point.
That would indicate it not to be a full De Dion arrangement, but a solid axle with a central pivot. This central pivot seconding as a lateral location point.

[Paul Hamilton]

Ray, you should have a closer look at all of the photos I gave you. The clue is in the shot taken from above the battery in front of the front bulkhead which shows the two lateral links which locate the front axle beam. They run from each side of the top of the tub down to a pair of longditudinal links which join up to the front axle beam. Its all pretty complex but when you draw it up it should work OK to allow the front axle free vertical movement under the control of the trailing arms but without any lateral movement at all. I don't know just where the roll centre would be but it should be adjustable to some extent anyway by changing the length of the lateral locating links.

[Ray Bell]

I looked at that one, Paul, but as I was looking for something familiar, like a Watts Linkage, I couldn't see what the purpose of this piece was... nor could I see in any of the internal pics how it hooked up through that front wall...

Does it move? How does it work?

[macoran]

It seems that this shot would affirm my theory that it is a centrally pivoting axle construction.
But I can't see how the two tubes entering the bulkhead meet up with/ join the rest of the front axle "spaceframe". And, of course still not sure how the rear pivots without causing the steering to tighten up terribly.
Also seems there would be "zero" dive under braking.......?

[Paul Hamilton]

I could not see the mounting for the longditudinal locating links on the fabricated axle beam and my photos did not capture that either (they were taken 'blind' through openings in the tub). However, I think its pretty simple to work out how it all works and the axle beam certainly does not pivot in the centre.

As I see it the two longditudinal links would have spherical joints where they locate on the beam and would effectively be an 'A' frame providing lateral axle beam location through the forward mounting you can see joining the two diagonal links which run up to the top corners of the tub. Those links have spherical joints at both ends so, although the combination of the 'A' frame and the diagonal links provides totally effective lateral location for the axle beam, there is no interference with the freedom of the beam to move a little longditudinally as it moves up and down on an arc determined by the trailing links.

The geometry is all pretty simple and effective as you would expect from ACBC in his heyday even though a bit complex in execution. It should never be labled a De Dion system as it is nothing more that a beam front axle with the De Dion description properly restricted to the rear suspension.

[Ray Bell]

Ah yes, I understand it now! Thanks Paul...

That piece outside the chassis is able to move in concert with the fore and aft movement (as minimal as that might be) of the axle... then there's some kind of A-frame attaching that to the axle.

Like you say, neat and ACBC at his peak.

[Bonde]

A-frames at both ends it is then, but with fore-aft articulated anchors to enable the longitudinal locating links to do their work unrestricted. As far as I can work out off hand, roll centre locations will be at the apexes of the A-frames. The front roll centre appears to be just over the floor of the tub.

The 58 is such an interesting car isn't it? (And IMO a very handsome one, too). It is also interesting to note the complexity of the truss design required for a beam axle designed not to be loaded in bending, in contrast to, say, the bent-by-the-kingpins tubular beam of a typical USAC roadster. It's not surprising that beam axles never caught on in mid-engined single seaters - it's not that difficult to find a good compromise between camber change in roll and heave with the standard double wishbone arrangement, especially when using very long links and very little travel as done these days. I suppose the beam axle (assuming it were possible to keep the unsprung mass down to double wishbone levels) could work well enough on a perfectly smooth track...but it just seems such a complex installation, so why would one bother?

PS: Any chance of more 58 pictures?

[Ray Bell]

What do you think, Paul?

On the subject of how worthwhile the beam axle would be, maybe we should ask our resident expert on the subject, David Seldon?

[Pat Clarke]

Quote Ray B "Like you say, neat and ACBC at his peak".

You must be joking Ray.
Like you, I was interested to see the 58 at Eastern Creek, more from technical curiosity than from thoughts of what might have been.
But, unnecessary, weighty, difficult to package with obtuse load paths and an almost impossibility to adjust to track requirements. No wonder it disappeared without trace!
I think more ACBC on acid than ACBC at his peak!
Okay, I won't speak ill of the dead, maybe he was just having a migraine headache.
Seriously, he no doubt thought it was something he needed to explore. He did that, found out what he wanted to know and scrapped the car...But it rose from the dead!
The man must be turning in his grave that we are critiquing a mistake that he thought was dead and buried.

Regards
Pat

[David Beard]

Originally posted by Bonde


PS: Any chance of more 58 pictures?

As seen at Oulton Park a few years ago...

[Ray Bell]

Originally posted by Pat Clarke
You must be joking Ray.
Like you, I was interested to see the 58 at Eastern Creek, more from technical curiosity than from thoughts of what might have been.
But, unnecessary, weighty, difficult to package with obtuse load paths and an almost impossibility to adjust to track requirements. No wonder it disappeared without trace!

Patrice... please...

I was speaking purely of the method of lateral location.

As to the merits of the suspension, I gather we don't know how it ever performed... or would have performed... anyway, do we?

Was it comprehensively tested?

Was it tested at all?

[Bonde]

Cheers David!

Beautiful, clean wedge shape, except for those front spring/damper outriggers, horrendously complex suspension.

Certainly the rear uprights appear to be from the Lotus Components component bank - I suppose the front ones are as well?

According to Hodges' "A-Z", the 57 was the F2 car, whereas the 58 was an evolution (or the same chassis in fact?) with a DFW engine. So the one we're seing here must be a 57, or what? Am I correct in assuming only one chassis was built?

[macoran]

Originally posted by David Beard


As seen at Oulton Park a few years ago...

Seems like the rest of the lateral locating diagional, and attachment to the fabricated front axle beam is visible here.


Thanks for the pics David...... apologies for the abuse.

Love the rear end treatment.......one of very few Formula cars with (semi)- enclosing rear end bodywork,
Ensign N173(von Opel) Fittipaldi FD01

[Ray Bell]

Originally posted by macoran
Seems like the rest of the lateral locating diagional, and attachment to the fabricated front axle beam is visible here.....

No, not at all... just the longitudinal location, the steering, the anti-roll bar and the frame of the axle itself.

As for the engine cover, apparently it didn't run often enough for that to be discarded...

[Pat Clarke]

Quote Ray B...

I was speaking purely of the method of lateral location.

As to the merits of the suspension, I gather we don't know how it ever performed... or would have performed... anyway, do we?

Ray,
I love your fond view of odd things past (I share it), but I really believe the reason for this odd thing being in the past is that the design was fundamentally flawed.

The 'horns' on the monocoque were probably most of the (undamped) springing.
The 4 parallel trailing links would have imparted torsion to the front axle in cornering.
The slight fore/aft motion in the axle when controlled by the training links meant there was a bending force fed into the axle.
The front brake torque, the strongest force in the car, loadpath is offset and reacted directly into the rack housing before the trailing arms can do their thing.

The steering rack in the front axle structure added to unsprung weight and had to bind when the above mentioned forces were fed through the structure.

Sorry, but every way I look at it I think it is horrible! Far to many compromises to keep the tyre presented square to the road, when the proven double wishbone solution worked well, and has continued to work well (I exclude current F1 here) in the 35 odd years since.

Note, I dont have anything like the same feelings about the rear suspension.

The whole thing reminds me of Ron Tauranac's words when we first saw a FSAE car with a DeDion axle.

"I made that mistake once......50 years ago"!
'nuff said.

Pat

[Charles Helps]

Originally posted by Bonde
Cheers David!

...

According to Hodges' "A-Z", the 57 was the F2 car, whereas the 58 was an evolution (or the same chassis in fact?) with a DFW engine. So the one we're seing here must be a 57, or what? Am I correct in assuming only one chassis was built?

According to DCN's The Story of Lotus 1961 - 1971 (pub 1972)
"LOTUS 57 - Formula 1 De Dion-axled car which completed design stage but was never built.

LOTUS 58 - Formula 2 experimental De Dion-axled car which was completed and tested but quickly shelved. Said also to have run with 3 litre Cosworth-Ford engine installed (see above). One-off."

slightly OT: Any thoughts now about whether it ran with the DFV and, more to the point, how it handled? (DCN wrote "... covered a considerable test mileage. ...all its drivers thought it handled marvellously, it was so predictable")

[David Beard]

Originally posted by Pat Clarke
Quote Ray B...

The 'horns' on the monocoque were probably most of the (undamped) springing.

Pat

Until they eventually and inevitably parted company with the tub, of course!

[Pat Clarke]

Giggling here David

And no doubt ACBC would have planned that to happen just as the car passed under the chequered flag

I was also considering the effect of gyroscopic precession in the front axle, but rather than get technical at this time of year, allow me to tell you all about the time I 'discovered' gyroscopic precession.

At about the same time as the 58 was built I was working for Yamaha. A group of us decided to enter a 250 motocross bike in a 6 hour short circuit (US readers read 'Flat Track' but with left and right turns) race.

We lowered the bike, fitted road wheels and a front disc brake and the result was a nimble and fast bike for the application.

Our race strategy was simple. Take the bike out and race it until it ran out of gas, put it on reserve and then pit to change over to the next rider (There were 5 of us). I seem to recall a tank lasted about half an hour.

The day was hot, and as the oil lifted through the clay, the track became incredibly sticky. There was a long fast left hand sweeper out the back of the track where I was leaning over so far my butt and elbow was contacting the track. Then as I put the power back on the front wheel would come up and the bike could be balanced with countersteer. I thought this was intriguing (daydreaming...always my shortfall when racing!).
I noticed one of my workmates taking pictures at this corner, and decided that next lap, I would really pitch the bike in sideways and get the front wheel way up for him to get a good picture.

All went to plan, the bike felt like it was at about 45 degrees with the front wheel a foot up in the air and steered way into the slide. I thought I would stop the front wheel for the picture so the spokes would be sharp in the shot, and I remember, like it was yesterday, thinking 'This might not be such a good idea' as my finger squeezed the front brake lever.

One nanosecond later I woke in the ambulance with concussion, a broken collar bone and separated tendons in my knee as well as acres of gravel rash and a ruined helmet and leathers!

That was my practical demonstration of the effects of Gyroscopic Precession (or the lack of it).

And the photographer was so shocked at the suddenness of the crash, he forgot to release the shutter

And a Happy and prosperous New Year to all here, especially the TNF badge holders.

Pat

Edit...to add the GP story

[Paul Hamilton]

Pat, while the verdict of history certainly does tell us that the 58 was not a success story I cannot agree with your critical analysis of the front suspension geometry which appears to be fundamentaly the same as the rear. Provided the trailing links are equal in length and parallel as they appear to be, roll movement would NOT impart the twisting loads on the axle beam which you suggest.

My first experience of this form of beam axle locating geometry was a hard lesson with my Turner prod sports car in around 1969. When repairing the results of a major altercation with the Warwick Farm pit counter I determined that the rear trailing links, while of equal length were not parallel. By correcting that design error I was able to totally eliminate the previous rather violent oversteer characteristics of the car as once the locating arms were parallel the rear axle housing was no longer required to perform as a rather oversized anti roll bar in the manner you suggest the front axle of the 58 would work. After adding a more scientific form of roll resistance to the rear of the car the Turner became a rather sweet handling well balanced little car with which I had quite considerable success.

I do agree with you that the 58's unsprung weight would have created issues and the front spring mount horns are certainly rather nasty but we should be kinder to ACBC's memory when we look at the suspension locating geometry which I think he got pretty right. He had done that once or twice before after all!! I have never asked Malcolm Ricketts the reason for the 58's failure but will do so when next in contact with him. I do seem to recall some period commentry about the undesireable impacts of gyroscopic forces generated within the front axle beam.

[Pat Clarke]

Hi Paul

quote...but we should be kinder to ACBC's memory when we look at the suspension locating geometry which I think he got pretty right. He had done that once or twice before after all!!

Please understand I am not being disrespectful to Colin Chapman. He was a hero of my youth and I loved his inventiveness and innovation, though that respect did fade a little as I became more aware of the sometimes human cost of that I and I.
Brought home with more than a tinge of sadness when I walked out into the country at Hockenheim in August......A very introspective walk back to the Sachshaus!

I mentioned in an earlier post that I thought the reason for the existence of this car was to practically evaluate the worth of beam/DeDion axles, and I am sure the testing showed that it was a blind alley, and so the car was scrapped without ever having been seen in public.

Think about what the next Lotus F2 car was? the 59 was almost a lesson in humility after the avantgarde 57/58. A 'reality check' is the term used today, and history has shown that the 59 and its sub models were very successful cars.

All in all, it is very interesting to review things past with the wisdom of hindsight and a delightful way to while away some holiday hours. Normally I am too busy to come here, but when I do, I certainly have fun.
Pat

PS. There is a fundamental difference between the front and rear suspensions. The front end steers =)

[Dave Wright]

Hopefully on-topic, this is what Chapman had to say about the suspension in an interview in Road and Track

Bulmer: It is fairly well-known that you have been experi­menting for some time with a car with quite different suspension-in fact with beam or the equivalent at both front and back. Can you say how this is shaping

Chapman: Well, it's still very experimental-we've been run­ning it on and off when we've had the time this year. In places it behaves incredibly well but we rather clouded the issue by deciding to build a Formula 2 car initially simply because we had Formula 2 engines to spare. The initial response was tremendous-we went out and ran so much quicker than we'd ever run before the first time out that it was unbelievable but then we tried it on faster circuits and found that really the car was a bit too big-we were gaining on the turns but losing on maximum speed and this clouded the issue for a bit.

Bulmer: Was it a consequence of the type of suspension?

Chapman: No, it's a very big car because we'd designed it to be capable of taking the Formula 1 engine and also it has the wedge shape. But we had such a frantic season building and rebuilding team cars that we've only just got back to normal development on the beam axle car. We've now put a Formula 1 engine in it and we're doing a test program on that but we've only just started so I can't tell any more really.

Bulmer: Have you tried it on a really bumpy surface?

Chapman: Oh yes, well we've run it at Snetterton which is as bumpy as most and it behaved very well.

Bulmer: No steering problems?

Chapman: No. The thing that I was really worried about was the steering problem and it just hasn't appeared at all. The biggest problem is roll because we've got very low roll centers -we tried to run it without anti-roll bars but the roll was enough to use up too much of the suspension travel. We've only got about 6 in. of suspension travel at the front-we made a mistake there. And when Firestone changed all their tire diameters we lost another inch because of ground clearance.

Bulmer: You've got the old beam axle problem of an effective spring base which is much narrower than the track.

Chapman: Yes, and we've also got a very high pitch oscilla­tion on it, very high; even though we're running fairly high spring rates, we're still getting far too much pitch.

Bulmer: Have you got the springing harder at the front than at the back?

Chapman: No, we're running at frequencies of about 100/105 laden or something like that which is different from a year ago -we had it all very soft then but we've still got too much roll and so we're just putting anti-roll bars on now.

Bulmer: I can't see any disadvantage in that really.

Chapman: No, well we were trying to get away without them. So then we tried to cut the roll down by raising the roll center and that definitely reduced the cornering power so we've now gone back to the low roll center with roll bars. It sounds easy but in fact with the particular configuration of the car it's not very easy to put them on-it's the old, old story: we should have designed them in in the first place. So we're cobbling some on at the moment and then we'll see how it goes.

[Pat Clarke]

Thanks for that Dave, an interesting read. Now that you have posted it, I have a dim memory of reading the article, and it whetted my appetite for more at the time.
But, there was no more! In the cut throat business of racing, had the beam axle car had the benefits Colin Chapman claimed, then it WOULD have been raced.
Instead, it was dismantled and the parts put away in the attic or someplace, only to be revived and restored for all us old fogies to disseminate at length while we digest our Christmas pud.
And I, for one, am loving it =]

Are there any more stillborn radical racers out there for us to cogitate over?

Regards
Pat

[Ray Bell]

Yeah, there is...

You can read about it in the Welsor thread.

[David Beard]

Originally posted by Dave Wright

Chapman: ..................only got about 6 in. of suspension travel at the front-we made a mistake there.

Was off road racing of some sort envisaged?

[kayemod]

Originally posted by David Beard


Was off road racing of some sort envisaged?

Maybe The Great Man meant three inches on each side, six inches in total.

[Dave Wright]

This was the era when cars had suspensions In the same interview Chapman says they increased the suspension travel on the Lotus 49 from 6.75-7.00" to 8.25-8.75" for the 49B.

[David Beard]

Originally posted by Dave Wright
This was the era when cars had suspensions In the same interview Chapman says they increased the suspension travel on the Lotus 49 from 6.75-7.00" to 8.25-8.75" for the 49B.

I know suspension actually used to be suspension... but these numbers have me astonished

[Bonde]

Interesting thread!

I suppose some of all that suspension travel of yore was in droop. Looking at '60s and '70s single seaters in action (not least over the 'yumps' of the old Nordschleife) they appeared to have gobs of droop, whereas nowadays we use virtually none at all. What really was the main factor that made all that travel disappear - developments in tyres, increased aero download, razing of the tracks? I recall the ground effect cars of c. 1980 being rock-hard due to downforce levels and ground clearance/pitch sensitivity, but the trend in decrease in suspension travel seemed to have set in somewhat earlier - the very early 1970s is when noses of cars last appeared to be rising skywards by half-feet during acceleration. I have the impression that Southgate's Shadow DN5 was one of the last cars with massive, visible suspension travel.

Re. the 58/57:

Had the beam axle(s) had real merit, the 72 would surely have sported them. But by then ACBC was all into 4WD (63; another blind alley) and inboard brakes (imagine the complexity and bulk of a front truss beam axle with inboard brakes! The wedge theme, in a slightly moderated form, seems to be all that passed on from the 57 to the 72.

Although the 58 doesn't appear big to me, it probably was compared with contemporary F2 cars - and the rather steep wedge with a high tail-mounted radiator and a maze of suspension bits out in the airstream couldn't have helped its straight line speed. The back end of the 58 car looks very draggy to me, but I could be wrong.

I agree with Paul Hamilton that the execution of the truss beam longitudinal, lateral and rotational (brake torque) location was about as sound as it could be from a geometric standpoint, but I also agree with Pat Clarke that some of the load path offsets on the chassis are very nasty, not least the'orrible spring 'horns' and the pick-up 'ears' for the trailing links - it looks like a test hack adorned with afterthoughts - which is exactly what it was by ACBC's own admission! I do, however, find it difficult to see how the steering rack would pick up brake torque loads, as the (albeit unusually short) 'track rod' link is spherically jointed at each end and thus really won't pick up any load except in its own direction, which is normal to the brake torque reaction; remove the track rod, and the triangular truss will still be be able to react brake torque from the upright to the trailing links through the outer truss members. Toe will, of course, be affected due to steering offset (I suspect the car uses standard Lotus Components front uprights) as on an IFS car, but that is reacted in the axis of the rack and usually symmetrically balanced, so not really an issue.

What surprises me about the structural design of the 57/58 (apart from the nasty cantilevered bits mentioned previously) is why they didn't use a tubular front truss subframe to pick up all the articulation points for the front axle - the stressed skin structure actually used looks difficult to make, difficult to feed point loads into and difficult to access the interior of (the 72's accessible front 'subframe' seems much more sensible, and more or less copied on the Tyrrell 005 and BRM P201). They might also have done themselves a favour by going with some push- or pull-rod system for the front springs in order to widen the spring base, get the desired rate characteristic and to avoid the nasty horns. The again, 20-20 hindsight is always a good thing!

Now, for other stillborn radical cars, there's always the thread about the 1969-70 BRM wing car, for instance...