This issue we have a story on understanding (and varying) gearing, based primarily on changing tyre diameter. The prompt for the story was the availability of a wide variety of on-line calculators that allow you to very easily correlate road speed with selected gear and engine rpm, and to see how overall gearing changes can be made by changing diff ratio or tyre size.

And there’s nothing at all wrong with those calculators – in fact, it’s easy to spend a few hours trialling all sorts of different combinations of numbers!

However, when looking at making major reductions to tyre rolling diameter, there is a trap that I wasn’t aware of.

And the trap?

Load index!

Load index is the rating given to a tyre that describes the maximum weight that should act through that tyre. The rating is indicated by a number that correlates to a vertical load (in kg or pounds). So for example, a tyre with a load rating of 89 has a maximum load of 580kg per tyre. (And at what tyre pressure does that apply? Again this is an area that most people don’t think about, but that load applies only at a specified inflation pressure – often 36 psi.) Load index tables can easily be found by a web search.

And what governs load index? Most references talk about the strength of the tyre (ie how many layers of steel reinforcement are used, for example) but in fact it also depends to a large extent on the volume of air trapped within the tyre.

And, as you go smaller in rolling diameter, that volume decreases!

Thus, changing gearing by reducing tyre diameter may be difficult if the load index of the smaller diameter tyre has decreased a great amount.

The minimum load index is a legal requirement as stated on the tyre placard. For example, my little Honda Insight, with 165/65 14 tyres, requires a minimum load index of 79 (or 78 in some markets). A load index of 79 means the tyres can cope with 437kg per tyre. That seems really high for this small car – the highest static load the Honda tyres would ever have to deal with is about 330kg – but that’s what the placard says.

If I wished to lower the gearing, changing the wheel size to 13 inch and going with 165/55 tyres (which would give about 10 per cent lower gearing) sounds good – until you realise that the load index of such tyres is only 70, or 335kg. A load index of 335kg is some 23 per cent lower than legal!

In fact, I found it impossible to find a tyre with a legal load index that gave a smaller rolling diameter on the Honda. To go further, I also found it hard to find any cars where these small tyres would be legal, their load indices being so low.

So if you’re thinking of reducing the volume of air inside the tyre (eg a by using a lower profile but keeping the same width, or a combination of smaller wheels and smaller tyres), check the load index of the available tyres first.

It’s honestly not an area I’d ever given much thought to.

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Earlier this year I published my 15th book.

Now that might sound impressive, but you can do the same.

Yes, you!

How? Read on…

My first book, 21st Century Performance, was published in a very traditional manner in 2001. A print magazine publisher (who I’d done quite a lot of work for) suggested to me that he’d be interested in a book on car engines. I asked if that could be broadened to all things car performance, and he agreed.

I put a huge amount of work into the book – not just its content, but also working with its graphic designer. The production quality turned out to be excellent – the photo reproduction (off quality 35mm slides in those days) was outstanding and the general presentation of the hardback darned good.

I also think – and forgive my arrogance – that the content was very good. There are perhaps only one or two points in the whole book I’d now change – though of course I could now add a lot more to the content.

I negotiated a small up-front payment for the book and then sat back and waited for the royalties to roll in. I think that history records it as the best-selling automotive modification book ever published in Australia, but getting royalties out of the publisher wasn’t quite what I’d expected. Cheques arrived, but there were never any statements of sales, and the cheques were all round figures…

Maybe everything was above-board (I still don’t know), but it didn’t feel right.

And the royalty amount? I’d have to look it up but I think the book sold (15 years ago!) for around AUD$70 each copy – and I got AUD$3 a book. That’s a royalty of 4 per cent. (Incidentally, second-hand copies of the book now sell for up to US$350.)

I resolved then never to do another book on the basis of traditional publisher royalties.

My next book – in 2004 – was Performance Electronics for Cars, written with John Clarke for the publisher of Silicon Chip magazine, Leo Simpson. At that time, I was a major contributor to Silicon Chip and, while I subsequently decided that writing for Leo was the last thing I’d ever do on Earth, the book deal was fine. I asked for my normal up-front ‘article rate’ for each chapter of the book, and I was free to use the material elsewhere as I wished.

The book sold well – I think – and probably made the publisher a tidy profit. I got paid a decent amount, so we were all happy.

Time passed…. a lot of time.  In fact, it was about early 2013 when I started thinking about book writing again. I’d just read a really interesting book (On a Cushion of Air: The Story of Hoverlloyd and the Cross-Channel Hovercraft) and the authors had self-published it. I wrote to one of the authors (Robin Paine) and asked him about the process. At the same time, I also wrote to a few other authors currently publishing tech stuff.

Self-publishing, it appeared, meant stumping up lots of cash to pay for everything, while the authors publishing through traditional publishers (like I’d done) did it more as a ‘labour of love’ than a money-making deal.

Then I did some more exploring… and discovered CreateSpace, Amazon’s publishing arm.

At first I couldn’t believe it – just upload a properly formatted pdf and they’d publish the book (complete with ISBN) and list it on Amazon. As people ordered, they’d print on demand (POD). There were no upfront costs, the author could set their own price (above a certain minimum that took into account the printing costs and some profit by the publisher), and royalties would be sent to the author monthly…  And that was it.

To say it again: I just couldn’t quite believe it.

I developed a template (actually the biggest effort of the process) and put together a book from my published articles – it was Amateur Car Aerodynamics Sourcebook, published in 2013.

I followed that up with Inventors and Amateur Engineers Sourcebook, Home Workshop Sourcebook and DIY Car Electronic Modification Sourcebook, again all published in 2013.

I then wondered about a smaller book, and did DIY Testing of Car Modifications, also in 2013.

In 2014 came Tuning Programmable Engine Management, Hybrid and Electric Cars Amateur Sourcebook and Thoughts about Driving, Car Modifications and Life (the latter based on these columns – and bought by basically no-one!).

In 2015 I wrote DIY Suspension Development and then, putting on my other hat as a trainer in high-level writing, I produced Writing Effective Arguments: How to Write Strong Arguments in Business and Government.

Also in 2015, I wrote Using the Brilliant eLabtronics Modules!

This year, in 2016, I have written DIY Loudspeaker Building.

As a contributor not just to AutoSpeed but also to UK magazine Everyday Practical Electronics, I have lots of material available to me. That makes it easier to assemble books, although the effort in doing so cannot be understated.

But the advantage is amazing – it costs me nothing in terms of cash… absolutely nothing at all.

And the royalties can be set as you, the author, wish. Remember the royalty I got with 21st Century Performance – 4 per cent? I typically set my CreateSpace royalties at about 40 per cent (but it depends on the distribution channel that the customer buys through). Therefore, sales can be much lower for the same income.

The downsides? There’re no publisher promotions, no placing of books on booksellers’ shelves (they can order it to sell, but often they won’t). On the other hand, eBay sellers often list your book, and you can buy copies of your own book at a discount and flog them off wherever you want… but you soon tire of that.

Me? I am happy writing books (good for my CV!) and receiving royalty cheques that result in monthly trips to the bank (CreateSpace won’t do direct bank transfers to Australia, so they’re always mailed cheques).

Am I making squillions? Absolutely not (though I would if more people bought my books!).

Is it worth it? – unquestionably yes.

If you have a story to tell, I think it’s the way to go.

If you’re interested, see my Amazon listed books here.

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The other day I went and saw Buzz Aldrin.

Yes, that’s right, the second person to walk on the Moon, the pilot of the Lunar Module, and a man who today is 85 years old.

I don’t think in my life I have ever gone to ‘an evening with’ type of show, let alone one hosted by Ray Martin (a local Australian TV celebrity).

I had no idea what to expect, but my wife, 11-year-old son and I all went down to the Melbourne Town Hall. There were two chairs on the stage, and a large backdrop onto which stills and video could be shown.

The show started at 8pm and finished – I reckon – at about 10.45…. so it was no 10 or 15-minute chat.

Ray asked questions – largely banal, and at times ill-researched – and Buzz occasionally answered them. Usually, though, he treated Martin with veiled, slightly amused contempt – and talked about whatever he felt like.

The first half of the show – all about the Moon landing – was just riveting. I have a technical and biographical library on space travel (perhaps 50 books) and so many of the names and events that Buzz mentioned I knew something about.

But this was from the man himself!

Whenever I started to half relax, Aldrin would come out with something that entranced me.

Earth from the Moon looks about twice as big as the Moon looks from Earth.

On the day of the launch, Aldrin paused near the top of the mighty Saturn rocket. He looked down at the tens of thousands of spectators, and thought: I need to remember this; I am going to the Moon.

I liked the man’s humour – very, very dry – and his absolute lack of the need to say something that big-noted himself.

After the break, he returned to talk about how he’d like to see people travel to Mars. A man who did his Doctor of Science in lunar rendezvous, he had plenty to say about rendezvousing on the way to that planet. Martin was completely out of his depth – he didn’t even understand stuff that was explained to him quite simply – but kind of tried to hold on. Buzz got excited – he’d obviously rather talk about the future than the past – but I am more interested in what he did, than what he thinks we can do.

The evening drew to a close, but not before some questions from the crowd. Buzz again tended to ignore the questions and just say whatever he liked, but the questions were sufficiently open that he could do that and get away with it. He leapt to his feet and prowled the stage, gesticulating and motivating.

An old, feisty, out-spoken man, brilliantly intelligent, funny, warm and… and… one of the most extraordinary explorers we have ever had.

He was just wonderful.

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I have recently been reading some engineering autobiographies relating to the early years of piston and jet engine development.

The first, The Ricardo Story: the Autobiography of Sir Harry Ricardo, Pioneer of Engine Research, is the story of the early years of life of a man who, working outside of the major automotive and aircraft engine manufacturers, made a huge contribution to the development of piston engines.

The autobiography, which covers the period between about 1900 and 1930, is especially interesting in the technical area of fuel octane and detonation. In fact, Harry Ricardo invented the concept of fuel octane rating – the resistance that a fuel has to detonation. In those days, what made a fuel effective was not much understood – to the degree that Shell was burning off, as waste, high octane fuels! Why? Because the measured specific gravity of these fuels didn’t match what was then regarded as the requirement for internal combustion engines…

Ricardo was able to physically observe detonation occurring, using windows into the combustion chamber and a moving shutter. He was the first to realise the positive implications of high-swirl combustion chambers, the first to use water injection (unfortunately not much covered in the book), and the first to build an experimental variable compression engine.

The book is written in a flowing, readable style and – for those interested in the technical aspects of his career – doesn’t get bogged-down in personal life meanderings. It’s probably best a book for those who already know something about those early days of motoring (and aircraft – the engine technology was not much different) and want to see more into a world when so much was unknown.

Another book that I have been reading is Engine Revolutions: the Autobiography of Max Bentele. As I write this, I am part way through the book – and what a fascinating treatise it is.

Bentele, a German, started his working career in the late 1930s on turbochargers. Turbos? Yes, the world’s first. He then went on to German jet engines – along with the UK’s Frank Whittle designs, again the world’s first – before the world of German engineers came crashing down in 1945 with the end of WWII.

He then migrated to the UK and then the US, working in the latter country on – among other engines – the Wankel rotary engine. It’s now not so much remembered, but US industry was very serious about the rotary engine and did much development on this design.

As I say, I am currently only part way through this book – but it is already enthralling. The non-English native language of Bentele shows a little in his prose; at times it is a bit stilted and the text more uneasily mixes the personal and professional. On the plus side, the technical detail is very high and these aspects are also well explained.

Harry Ricardo was born in 1885 and died in 1974, while Max Bentele was born in 1909 and died in 2006. Ricardo’s name lives on in the engineering consulting company that he began, but Bentele’s name is much less well known.

Two fascinating books.

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I think that suspension design is one of the most complex areas of automotive engineering. I am not thinking here about just spring and damper rates – but those are of course hugely complex in themselves – but of changes that occur through suspension movement.

For example, a wheel experiencing bump and rebound is likely to have a designed-in change in its camber – going into negative camber when in bump. This helps keep the wheel more upright when the body rolls in cornering (or at least the outside, most important, wheel anyway).

But what about something like anti-dive geometry? This set of suspension angles causes the car’s front springs to resist compression when the car is being braked.

So how does this work? Imagine a very simple front suspension system with a leading arm per wheel – an arm that runs longitudinally to support the wheel. (A Citroen 2CV is the only car I know of with this approach, but that’s OK.) The brake is mounted on the wheel, so the torque loads of the brake are fed back through the suspension arm.

The car drives along, and then the brakes are applied. The brake load causes the longitudinal suspension arm to try to rotate around the wheel, so applying an upward force on the suspension pivot. This prevents that end of the car from compressing its springs as much – more of the car’s weight is being dynamically taken via the suspension pivots than through the springs.

The result is that the car dives less under brakes.

Now as mentioned, not many cars have longitudinal suspension arms, so this arm is often actually virtual, being in effect created by (for example) the front wishbone mounts not being parallel when viewed from the side. If they form an angle that converges towards the rear of the car, anti-dive will occur.

So anti-dive sounds great… but there are also downsides.

Under brakes, the car does not behave as many expect it to – it doesn’t dip its nose as much.

Under brakes, the suspension is less springy – more of the weight (and so vertical acceleration of bumps) is fed through the suspension pivots and not the springs.

Under brakes, in many cases the geometry is such that the wheel moves forward, so meeting bumps more harshly. (And there’s already a higher effective spring rate, remember.)

And it goes on: under brakes and when hitting a bump, the steering geometry (eg castor) may not adopt the same angles as would normally occur if anti-dive were not present… so the car may react to bumps differently when being braked.

So should anti-dive not be used? No – in cars with soft suspension and a high centre of gravity, it can be very effective.

But then again, the amount of brake dive also depends in part on the stiffness of the slow-speed bump damping provided by the shocks.

You see? Every aspect relates to another aspect: not one suspension design criterion can be viewed in isolation.

It’s all very complex….

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My major job – training people in business and government writing skills – takes me all over the country. Usually that involves lots of flights, but recently I chose to take the Greyhound bus between Coffs Harbour and Port Macquarie.

The bus travel was actually very pleasant – though I didn’t envy the driver threading his way through the dusk traffic on narrow roads constrained by constant roadworks.

When I was sitting in the bus, I started analysing its ride quality over the often poor road surfaces.

To cope with the large variation in possible load while still giving the best ride quality, long-distance buses typically use air suspension. (This also lets the bus ‘kneel’ as people get on and off.)

The air suspension stiffness is set to give a natural frequency of about 1Hz – the best frequency for ride quality.

And, in the bus, the ride felt about right for a 1Hz natural frequency – the absorption of large bumps was superb.

However, sitting back and admiring the flowing scenery outside the window, I thought I could feel another ride quality characteristic – and this one was not so pleasant.

Superimposed on the soft suspension movements was a higher frequency judder. It was like riding in a conventional car travelling on a road that had long wavelength bumps – but a corrugated surface.

Rather than guess any longer, I whipped out my iPhone and, using the ‘Vibration’ app, recorded the ride accelerations being experienced by the bus body. The seat next to me was empty and so I put the phone down on the cushion and gently held it in place.

Ten seconds later I had a record, and a moment after that I used the software to perform a Fourier analysis, giving the dominant frequencies in the waveform.

This showed a peak at 1Hz (the air springs) but also another peak at about 10Hz. The latter was the juddering “corrugations” I could also feel.

But what was causing this higher frequency of vibration?

The higher speed juddering was caused by the natural frequency of the unsprung mass – the weight of the suspension acting on the “springs” that comprise the tyres.

But it gets more complex. How do the 10Hz unsprung weight vibrations get through the 1Hz air spring isolation? With the forcing frequency (10Hz) so far from the natural frequency (1Hz), wouldn’t the transmission be almost zero?

I am not completely sure, but I think it has to do with the massiveness of the unsprung weight. Was that rapid shaking of the huge tyres and suspension arms feeding a vibration through the suspension mounts that I could feel?

Reflecting on this, I realised that I’d felt all this before – but to a lesser degree. In 4WD passenger cars using solid front and rear axles (ie a high unsprung:sprung mass ratio) you can feel something similar… it’s a bit like the car is being shaken by the suspension. So the soft main springing was being subverted in ride quality by the high unsprung weight bouncing on the tyres.

Here’s another point: dampers need to control suspension movement at both the suspension and tyre natural frequencies…. but the requirements for controlling each mode are quite different. One requires damping of large amplitude, low frequencies (the movement on the body springs) – and the other damping of high frequency, low amplitudes (the movement on the tyre springs).

It would be interesting to talk to a damper manufacturer about the decisions in damper design that they must be making.

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Well, it’s nearly the end of the year, and I have been reflecting on my busy car modification 12 months.

All the modifications I have done have been to my little Honda Insight.

Fitting a turbo, water/air intercooler and making and fitting a new airbox. Installing a MoTeC M400 ECU, and then doing all the engine mapping on the road. Fitting a MoTeC CDL3 dash, and then upgrading to an ADL3 dash.

It’s been a huge amount of fun turning the all-alloy, two-seater Honda hybrid into a fuel-efficient turbo with about 70 per cent more power than standard from its 1 litre, 3-cylinder engine.

None of these mods was cheap, but all gave the results I’d been hoping for.

And in the last few weeks I have been playing with the suspension. And, so far, this has been cheap! I calculated the required specs for new springs front and back, sourced them at near zero cost, then installed them. That step was very successful, so then I fitted a new rear antiroll bar – this time, for a cost of less than fifty bucks.

The car is absolutely transformed in both ride and handling – and I am yet to fit the new dampers, which at the time of writing, are on their way from the US.

Sitting in the corner is the next Insight modification – a Tritium Wavesculptor200 high voltage electric motor controller. It will be used to run the Honda’s standard 10kW electric motor, although not always at only 10kW. Given the nature of electric motors, I should be able to over-rate it for short periods, gaining perhaps 20kW for huge short-term torque.

I plan on controlling the Wavescluptor200 using outputs from the MoTeC ADL3 dash. The dash – really, a digital control system that happens to have a display – has a full range of programmable maths functions and can use 3D look-up tables.

The new high voltage battery pack and battery monitoring system? I am yet to decide on these things.

I don’t know if I will achieve my final aim of 0-100 km/h in the Sixes and fuel economy in the high Twos (litres/100km), but the challenge is enormously exciting and rewarding.

In the meantime, we’re off to the United States for five weeks. We’ll be concentrating on the eastern side of the country, and have on our itinerary a long list of technical and automotive sights – and sites. We hope to next year bring you a series in AutoSpeed that describes some of what we see.

Finally, I also published another three books this year – if you are interested, search on Amazon under my name.

Have a safe and happy Christmas and New Year, and remember: for fun and challenge, nothing beats modifying your car!

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Never have I had such fun when playing with a car! So what am I excited about?

Tuning programmable management on the road.

Regular readers will be aware of our Honda Insight series. As you’d expect, the publication of the articles in that series lags well behind where I am actually up to with the car. (I don’t want to run into a problem and have a big gap in the middle of the series, so it’s best from a publishing perspective that I take this approach.)

So I am around three months ahead of the series in what I am actually doing – so explaining my recent tuning of the MoTeC M400.

In the last month I’ve been tuning crank and start, fuel, ignition, idle speed control, turbo boost, exhaust gas recirculation, acceleration enrichment, wide-band closed loop feedback and lots of others.

All has been done in my shed, driveway or on the road.

It has been an immense learning curve – I’ve never before tuned a programmable management system – with some problems to overcome along the way.

But what I have found so rewarding is the degree of control that you can have over how the car drives. Tuning an interceptor (that I have previously done) or making minor tweaks to factory ECU inputs and outputs allows you to do lots of things, but tuning programmable management allows you to do so much more. (The same would also apply to factory ECUs where the software has been cracked – not the case with the Insight.)

Having so much control means that you can stuff things up absolutely mightily. I am not talking about blowing the engine (though that of course isn’t difficult with wrong timing or fuel figures) but how the car can be made to drive so badly, so easily.

Or, more positively, you can tweak and tweak and tweak until you achieve things that appear initially impossible.

The Insight is running without its hybrid electric assist at this stage, so the bottom-end torque normally provided by the electric motor is missing. With just a 1 litre engine, very high gearing (especially in first and second) and 4800 rpm peak torque, getting the car tractable around town has been no mean feat.

That’s especially the case when no ‘start-up’ map exists for this car – the MoTeC has had to be programmed literally from scratch.

The excitement of activating and then mapping exhaust gas recirc that boosted part-throttle low-rpm torque to a major degree was sensational; getting acceleration fuel enrichment sorted so the turbo boosts much more quickly after a throttle movement was fun; mapping the control of the water/air intercooler pump so that the pump works only when needed was intriguing; and designing the boost table in three dimensions to give exactly the boost behaviour I want was exciting.

I can now see better why a friend of mine years ago talked about driving to work each day, laptop on the passenger seat and making tuning tweaks at every set of traffic lights! With literally thousands of data points able to changed, and often interacting with each other in the driving, getting the perfect tune could be a lifetime pursuit.

But in the mean time, it’s a helluva lot of fun.

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I’ve written before about the enormous range of automotive parts now available through eBay, but until I have been working on my little Honda, I’d never realised how well developed such a part-sourcing network it now is.

As I write this morning, I am watching the tracking on my DHL express package that contains the stainless steel gasket set for my turbo. The package, in the last three days, has been through five countries. It started off in Latvia, went then to Lithuania before reaching Germany. Then it travelled to Heathrow airport in London, before arriving (this morning at 2.20 am) in Sydney. Out in country New South Wales, I reckon I’ll get it in the next few days.

And the exhaust gaskets are not alone in having travelled far.

My Bosch fuel pressure regulator came from the US, the fuel rail adaptor from the UK. Also from the UK came carbon fibre sheet for making a new dash panel, and replacement ignition coils. Other stuff direct from the US has included oil temperature and pressure sensors, the boost control solenoid and a water/air intercooler pump.

From China there has been a host of parts – the front-mount radiator for the water/air intercooling system, fittings, hose clamps, hose joiners and rubber grommets. On its way now from China are a thermocouple adaptor board, a weld-on bung for the thermocouple, and the thermocouple itself.

And of course I have bought plenty of parts locally.

With the fast availability of parts, cheaper than ever before, from all around the world, there’s never been a better time to be modifying cars…

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