17 replies to this topic

[blueprint2002]

Came across a reference to a sprint car built for Raymond Mays in 1949 or 50, fitted with a 2-litre supercharged engine delivering 320 bhp. Neither the car nor the engine is named, and I am wondering if anyone knows of it, and of its competition history.

Sorry I am unable to post an attachment, more so as it is in a pdf file, so all I can do is summarise what material I have.

The brief description refers to the rather extreme 33/67 front/rear weight distribution, intentionally arranged for the best traction. This is achieved by setting the engine well back in the frame, locating the gearbox under the driver’s seat, and bolting it directly to the worm-and-wheel “final” drive. The half-shafts from this latter have triplex sprockets at their outer ends, with chains leading forward to either wheel. The casings for these chains thus form leading arms for the IRS. A single rear brake is located right aft, at the extended end of the worm shaft, not unlike some BRMs of a few years later. Front suspension is apparently of the typical Porsche/Volkswagen trailing-arm type, though Lockheed air struts are used instead of torsion bars. The same springing medium is also used at the rear.

That chain drive seems to be a rather more sophisticated version of the arrangement used on some Trojan models of the 20s and 30s.

 

[Tim Murray]

Doug Nye has posted about this car:

I'm not sure of my evidence - I can't swear that Jim Berry's ERA Special really was derived as follows - but I have always understood the car used the frame and some body panels from the Raymond Mays chain-drive ERA hill-climb special which was built for the old queen at Bourne around 1949-1950. He used Lockheed air-strut suspension units and trailing arm IFS provided - very expensively - for the V16 BRM project, and when the Trustees like Tony Vandervell and Bernard Scott of Lucas were told of this the spaghetti really hit the fan.

The chain drive was arranged in cast chain cases which doubled-up as rear suspension leading - very important, NOT trailing - arms, the car had something like 70 rear/30 front weight distribution, and when first tested by RM and Ken Richardson the car proved an instant disaster. Its drive torque wound up the chains which raised the 'free' end of the chain-case and the corresponding rear wheel along with it. The spring then reacted, throwing the wheel back down, whereupon the suspension/drive unit on the other side would wind up. The process was self-agitating and the result was that the car would wiggle off the line like a freshly shot duck, paddling madly, wagging its tail wildly from side to side while simultaneously oscillating like a metronome sans governor around its longitudinal axis.

The project was abandoned before a) RM ended up in jail for misappropriation of BRM project hardware or b) either he or Richardson ended up in hospital. The car had been highly publicised, too, before it ran...

Some blokes just never learned...up to and including BAR/Reynard.

DCN

PS - By the way, poor Jim Berry was killed in an accident at Oulton Park, not in the ERA Special.

Without double checking I think you must be referring to the stillborn ERA Special hill-climb car which Raymond Mays had his chaps build, very foolishly using chain drive within forward-facing swinging chain chests which doubled as rear suspension locating members. I was told that when tested it took off from a standing start with first one side's chain winding-up the suspension to force the relevant road wheel down, so theoretically enhancing its traction, but then the other side's chain, then back to the first dependent upon grip achieved, so that the car 'waddled furiously' with its rear wheels in effect tramping furiously, and alternately.

It was a complete failure.

When the BRMR Trustees heard that the car had occupied BRM machine shop time, and - worse - was fitted with some of the hyper-expensive experimental Lockheed air strut suspension units intended for the (much heavier) V16 they wanted RM's guts for garters. The car's fate has always been shrouded in some mystery but I believe on balance that it was quietly broken up and forgotten...

Typical of RM, he seems to have invited the press to visit Bourne and to photograph and publicise this personal project without any prior reference to his paymasters within the British Motor Racing Research Trust.

When they reacted explosively, first questioning the provenance of some of the components used, then hearing that BRM machine-shop time had been taken up by sprint car work, the Brown Windsor soup hit the fan.

RM would have been completely bewildered by such a reaction. An only child, very much indulged ever since childhood, confident of his own self-image as a national celebrity - the aftermath of this sprint car episode had far reaching impact not only upon his self-esteem but very much moreso upon the way in which he was regarded by the BRM project's Trustees and industrialist backers. When our discussions touched upon the subject he very quickly dismissed it or digressed onto something else - e.g. "Oh Doug I must say that's a very nice shirt you are wearing, where did you buy it?" - "Errrr - my wife gets them from Marks & Sparks..."

"Oh!"

DCN

ETA: There are three photos relating to the car on page 74 of Doug’s BRM Vol 1. It looks a nice neat little car. One of the photos shows the chain casings.

[Lee Nicolle]

The car is a hillclimb special,, that is NOT to be confused with a Sprintcar that has been around in various forms since the 30s.

Apart from using other people parts and propriety this clearly was an accident waiting to happen. Does not say a lot for Mays business acumen!

Which the whole deal in hindsight was quite poor

[Tim Murray]

In the UK sprints are similar to hill climbs but held on flatter tracks. The principle is the same - one at a time against the clock.

[bradbury west]

On the Cutaways thread Marc was kind enough to post a good resolution of a cutaway drawing of this car, from a The Motor magazine in 1950.
The drawing can be found on post 15029 Dec 6 2017.
Roger Lund

[Tim Murray]

Yer tiz:

bradbury west (Roger Lund) sent me a screenshot of the Raymond Mays Sprint Special  he saved from Facebook sometime ago. It was a bit messy and damaged, but he offered
to get the shot printed as a photograph, and re-scanned it for me. I had opted to try cleaning it up.
 
Well thanks to and on behalf of Roger I am allowed to present you all...The Raymond Mays Sprint Special.......more or less the forefather of BRM

 
The rear drivetrain arrangement gave a 65/35  rear/front weight distribution, and I just love the way the chain drive in forward leading-arm formation gives independant suspension.
The rear abuttments of the chain box operating the gas strut dampers is brilliant as well.
 
There was an article on the car in Motor magazine of May 24th 1950.
 
macoran

[Steve L]

I thought Jim Berry's ERA hill climb car was based on an HAR chassis?

[Tim Murray]

This earlier thread on the Mays car also provides some info on the Jim Berry ERA Specials:

Raymond Mays’ hillclimb special

[blueprint2002]

Wow, what a response!

Thank you Tim Murray, Lee Nicolle, Bradbury West and Steve L. Mystery solved.

To return to purely technical matters, wouldn't extreme static rear weight bias be asking for trouble on a hill climb?

Adding the effects of weight transfer on acceleration, with that much power, and the upward incline, steering the front wheels couldn't have had much effect.

Not too sure about that diagnosis of the cause of the rear wheel tramping on acceleration: seems to me that chain tension would have the effect of pressing both rear wheels down, together. Perhaps the cause was elsewhere.

Anyone know if the car had a differential? Some hill climb cars didn't (Bloody Mary?).

[RogerFrench]

I can't comment on leading chain cases, but years ago I had a much-modified Honda S600 with trailing chain cases, like the RM car but upside down, if you get my meaning.
I autotested quite a lot in those days. The car was fine going forward, but in reverse it hopped around much like Doug Nye's description, except on loose surfaces where it behaved o.k. I always thought it was because the wheels on a good surface were making then losing traction alternately.
The car had a standard, open differential.

[blueprint2002]

I can't comment on leading chain cases, but years ago I had a much-modified Honda S600 with trailing chain cases, like the RM car but upside down, if you get my meaning.
I autotested quite a lot in those days. The car was fine going forward, but in reverse it hopped around much like Doug Nye's description, except on loose surfaces where it behaved o.k. I always thought it was because the wheels on a good surface were making then losing traction alternately.
The car had a standard, open differential.

Thank you for your contribution. No question about the phenomenon that was observed, just the diagnosis that still seems questionable. Anyone any ideas?

[BrmBoy]

If you scroll through here to "Mays Sprint Car" there are a few more drawings and photos.

https://www.flickr.c...157661634983314

[blueprint2002]

If you scroll through here to "Mays Sprint Car" there are a few more drawings and photos.

https://www.flickr.c...157661634983314

Thank you, BrmBoy. That is a great find!

[Charlieman]

I started to draw out the special's suspension design in order to understand the problems but it wasn't necessary. The chain case and the leading arm are the same object, so ignore concepts such as "chain wind-up".

 

There are two important things to note about leading arm suspension designs. Wheel camber angle changes directly with chassis roll angle (i.e. it is like parallel equal length wishbones). Under rear spring compression wheelbase reduces and then grows (i.e. the rear wheel moves backwards and forwards).

 

A really simple explanation of nasty behaviour occurring off the line at low speed:

All acceleration forces act through the car's centre of gravity and create squat. Squat requires that the rear spring is compressed and the rear wheel moves forwards; in order for the wheel to move forward, there has to be a forward force at the tyre contact point with the road. However transmission forces at the tyre contact point are acting backwards. The only way for the wheel to move forwards so that the car squats is that the tyre contact point slips. So one side slips first and then the other side and so on. Or the rear springs break.

 

The suspension geometry should be OK regarding camber on flat, level surfaces (e.g. an airfield runway). Any unevenness will make the squat problem more pronounced. Once off the line, problems caused by changing wheelbase will be different but horrible. Changing wheelbase/track/toe-in is an unfortunate feature of all suspension designs to a degree [edit: but this design is particularly evil]. I don't [edit: think] locked or limited slip differentials would fix the problem.

 

Roger French in his Honda with trailing arms: I think you had too much grip on sealed surfaces!

Edited by Charlieman, 23 November 2019 - 21:28.

[blueprint2002]

I started to draw out the special's suspension design in order to understand the problems but it wasn't necessary. The chain case and the leading arm are the same object, so ignore concepts such as "chain wind-up".

 

There are two important things to note about leading arm suspension designs. Wheel camber angle changes directly with chassis roll angle (i.e. it is like parallel equal length wishbones). Under rear spring compression wheelbase reduces and then grows (i.e. the rear wheel moves backwards and forwards).

 

A really simple explanation of nasty behaviour occurring off the line at low speed:

All acceleration forces act through the car's centre of gravity and create squat. Squat requires that the rear spring is compressed and the rear wheel moves forwards; in order for the wheel to move forward, there has to be a forward force at the tyre contact point with the road. However transmission forces at the tyre contact point are acting backwards. The only way for the wheel to move forwards so that the car squats is that the tyre contact point slips. So one side slips first and then the other side and so on. Or the rear springs break.

 

The suspension geometry should be OK regarding camber on flat, level surfaces (e.g. an airfield runway). Any unevenness will make the squat problem more pronounced. Once off the line, problems caused by changing wheelbase will be different but horrible. Changing wheelbase/track/toe-in is an unfortunate feature of all suspension designs to a degree [edit: but this design is particularly evil]. I don't [edit: think] locked or limited slip differentials would fix the problem.

 

Roger French in his Honda with trailing arms: I think you had too much grip on sealed surfaces!

Hate to sound pedantic but the transmission force at the tyre contact point (usually called tractive force) has to act forwards in order to accelerate the car forwards: Newton's Third Law.

[D-Type]

Hate to sound pedantic but the transmission force at the tyre contact point (usually called tractive force) has to act forwards in order to accelerate the car forwards: Newton's Third Law.

Surely where the rubber meets the road the force must act backwards. Then it will act forward at the wheel centre, the other half of the couple.

When you run it's different.  You push backwards but the force at the point of contact is forwards - action/reaction pair.

[blueprint2002]

Surely where the rubber meets the road the force must act backwards. Then it will act forward at the wheel centre, the other half of the couple.

When you run it's different.  You push backwards but the force at the point of contact is forwards - action/reaction pair.

Thank you, D-Type, that is a neat, practical, easy-to-visualise way of explaining the forces at work on the tyre, and on the car as a whole.

When power is applied, the tyre footprint does try to push the road backwards, and will do so if the surface is loose enough: hence the showers of gravel, sand, water or whatever when traction is zero.

But when the frictional force at the footprint is enough to match the applied force, the road reacts with an equal and opposite force, and it is this which accelerates the car forwards. Acting, as you have suggested, through the wheel hubs.

So that we have, in fact, all three of Newton’s Laws at work, not just the Third.

[cooper997]

3 June 1949 The Autocar's The Sport pages have this...

 

“In spite of the fact that it cannot be international until it has been run once, the Royal Scottish club’s climb at Rest-and-be-Thankful should be something sensational in the way of hill-climbs and should draw on July 9 all our best hill-climb experts, for the course is longer and more exciting than that of any other hill and the cars can be seen the whole way up. It is stated that Raymond Mays will run with, it is hoped, his new sprint car, a machine the subject of endless rumours at the last Prescott. As a matter of interest these rumours stated positively, first, that the new machine had an ERA engine in a tubular chassis with chain drive and secondly, that it was the ERA engine in one of the spare BRM tubular chassis. You can take your choice.”

 

Stephen