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The Merc 180’s main problem is the battery and wiper motor

I recently bought a ’99 Mercedes Benz C180 (? 202). Having driven other cars, namely, Toyota, Daihatsu Rocky and Honda, I must say this car is a different thing all together.

The engine delivers real power effortlessly, the handling is very smooth and the fear of excessive consumption, I discovered, is unfounded because its consumption is comparable to most Toyotas with engine capacities above 1500.

I think the Germans build their cars well. I would be glad if you could point out the troublesome areas with this car. So far, I can’t complain about this machine.


Hello Chris,

The W202 (which I guess is what you meant by ?202), like other cars, does have a few problem areas, the first being electrical: wiper motors and indicators intermittently packing up, power seats sometimes malfunctioning and ECU failures. Other known issues include: faulty MAF sensors (this causes erratic acceleration) and automatic transmission problems (rough shifting of gears).

There was an issue with exploding batteries – instigated by gas emissions building up in the boot area and ignited when the owner opens the trunk lid while smoking/using his cell-phone, which causes the hydrogen gas to explode. Some vehicles were recalled while others were fixed under warranty.

A solution to this was for the owner/driver to check electrolyte levels regularly to prevent the gas buildup. To confirm whether your car was part of the recall, check your owner’s manual. There should be big stickers placed over the original battery maintenance information section.

Most of these issues (except for the battery and wiper motor problems) stem from isolated cases and will not necessarily happen to your car. They are just things to watch out for.


Dear Baraza,

I read your column every Wednesday and cannot honestly imagine not having my copy of the Daily Nation on this particular day of the week. It is both informative and well researched.

I currently own  2004 and 2006 Toyota Vitz. Both cars have served me very well for the past year. They are mainly used for town running and are both very efficient. However, my concern is with the 2006 model (I will address the concerns of the 2004 model separately). It has a 1000cc engine, with 3 cylinders. I have noted that there is no dip stick for the gear box. Subsequent research informs me that these cars use long-life oil, capable of running for 100,000 km.

If this is the case, which is the correct oil to use? Over the years I have noted that Volkswagen Golf and Passat gearboxes have failed due to the use of wrong lubricants. Will I run into the same problem?

PS. I agree with you on fuel consumption of Subarus compared with other models. They are less efficient and more expensive to run as non-original parts do not work on these cars. I have experienced it and will share more on that later.Best regards.

Mig Maina

Greetings, Vitz Owner,

Has your car covered the 100,000km yet? If yes, how far is it from the next 100,000km transmission service interval? Does it have FSH (full service history)? It should. Under that FSH, they should specify what transmission fluid was used, if flushing and replacement were done. If it has not been done yet, then it is about to be done, under your care.

Your car does have a service/maintenance handbook, doesn’t it? It should specify what transmission fluid should be used.

Whether or not your car will experience Volkswagen-type problems depends on how badly off the grade of transmission fluid is. For some cars, there is a huge tolerance built into the components, such as the gearbox, to allow for some errors of judgment such as in replacement or maintenance of transmission fluid levels.

For other cars, such as the first-generation Nissan X-Trail, the smallest mistake will lead to the acquisition of a whole new gearbox.


Dear car doctor,

Let me start by saying I have enjoyed every article of yours that I have read, but since the upgrade to the new site, it been hard to get your articles , unless you look at the site on a Thursday. Well, enough of the whining.

I recently bought a Subaru Forester 2006 cross sports, auto transmission, which I have come to love, but there is this button with a selection of three levels next to the gear shift marked   ECO, A/T and Hold, I don’t know what it does, so I would appreciate some help regarding when to use it, but when it’s on A/T the picking is excellent. Warm regards,

Simon Wanjau Maina

Hello Simon,

The ECO button initiates a gearbox setting that improves the fuel economy but at the expense of performance. The “Hold” button, I guess, makes the transmission shift up sooner and holds the higher gear while preventing downshifting unless absolutely necessary, but it still skips first gear.

It is ideal for snow and slippery conditions where the high torque of lower gears would just lead to wheel-spin and little or no forward movement. When used in D, the car takes off in second gear instead of first.

When position 3 is selected using the gear lever, the cars shuffles between gears 2 and 3 (takes off in second and quickly shifts into third). When 2 is selected, the vehicle uses only second gear, skipping first. It is claimed that HOLD also makes the transfer clutch in the centre differential lock up sooner and harder.

By inference, A/T would mean “All Terrain”, which would make the transmission automatically react to the grip conditions, depending on which wheel is spinning. It uses input from the traction control system.

You are right; the format of the new website makes it extremely difficult to locate my write-ups, unless you delve deep into the pages searching piece by piece. It is a bit frustrating to my online readers and you are not the first to complain about this.


Dear Baraza,

I find your column informative and was amazed by what I read in the January 1, 2014 issue. One gentleman thanked God that he had not landed in a ditch despite doing 180 in his Nissan Wingroad.

Andrew claimed that the Prado is very stable even at 170 kph. Please advise the two gentlemen to stop doing these speeds on public roads. They pose great danger to other road users and themselves. Such risky manoeuvres are simply against the law.


Gentlemen, you heard Nick. Maxing out your cars is not safe, and it is illegal… (I don’t know about Andrew’s case, though, since he says he is in Afghanistan, and the traffic laws there are unknown to me).



First things first. Your column inspires me a lot. My dream towards the end of this year is to own a Range Rover, manual transmission, from around year 1990 to around 2000, with 3.9 V8 engine or slightly above. The reason is that I am a —rrain is quite a challenge. Besides, I am a Rhino Charge enthusiast and like tough machines.

Second, I would like to look a bit formal walking in high offices pursuing tenders and the like without switching Machines.

Kindly enlighten me on this since I am an automobile novice if I am willing to spend between 1m

and 1.6m.I have googled one on OLX website: year 1990, mileage 139,000 kms, 4wd with a 3.9 V8 engine going for Sh1.250m but I thought it was a bit old and maybe I will have to make some costly replacements. Hope I can read your article online. Get me into class, please.

Moses Mutwirih

Hello Moses,

A bit ambitious, aren’t we? Your demands are quite specific, and not all of them can be met.

You cannot get a 3.9 litre V8 Range Rover any newer than 1992-spec. The 3.9 engine went out with the Classic in 1992, and was substituted by a bored-out 4.2 V8 until 1996 before being replaced as the range-topper (so to speak) by the 4.6-litre V8 in the P38.The P38 is also available with a 4.0 V8, which should be closest to what you are looking for, but again herein lies another impediment:

The P38 had a manual transmission available on only one spec level: the BMW-powered 2.5 litre DSE diesel. The V8s only have automatic transmissions.

This means the particular car you want cannot be any older than a 1990 model or any newer than 1996. That really narrows down the scope of availability, as these were the final years of manufacture for the Classic model. This means these are the units in best condition. Seeing how they are fast becoming collectors’ items, getting one in good condition for sale is a search for a Land Rover Holy Grail. The people who have them will not likely be selling them, cheaply or at all.

Should you come by one, expect the following: a stiff asking price, rust problems, poor handling and unavailability and/or costliness of parts. Owning a Range Rover is not for the weak of pocket.


Dear Jim Baraza,

Hallo sir. I am recently married and I want to replace my ageing 2001 model Toyota Corona with a bigger, affordable 4x 4. I am a Toyota person due to the availability of spare parts so I was thinking of getting either a 2007 Toyota Harrier 2.4 litre or a 2007 year Toyota Kluger. I have little knowledge of the performance of either and I would greatly appreciate your input on the performance, problems and reliability of the 2007 Harrier and the 2007 Kluger.

Thank you.


Hello Nashon,

Congratulations on your recent nuptials. My name is not Jim.

Performance: Depends on what engine the Kluger is packing. The 2.4 Harrier is a bit underwhelming, but should do slightly better than the 2.4 Kluger. However, if the Kluger has a 3.0 engine, or even the 3.5…. then the Harrier fails.

Problems: none in particular stands out as “recurrent” or “notable”. Most of these seem to stem from poor maintenance. Toyotas are highly reliable. Whichever car you choose, just stay on top of the maintenance schedule and you will be fine.

Reliability: see “Problems” above. The Kluger is more rugged, or at least was intended to be more rugged than the Harrier, so it should suffer less use-related glitches in the course of its lifetime.

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For town service, the Premio will edge out the Noah

Hello Baraza,
Thank you for the good work; it is educating. I intend to buy a vehicle for an airport transfers contract and I am eyeing a Toyota Premio (1800cc), a Toyota Voxy, and a Toyota Noah, all 2005 or 2006 models.

From my research, I am likely to get both the Voxy and Noah cheaper by Sh250,000 in comparison with the Premio. I have received conflicting advice from two different mechanics on the Voxy.

I am made to understand that its 1AZ engine is actually a D4, which one of the mechanics says will have problems sooner rather than later, and that repairing it will bee too expensive, if possible at all.

The other mechanic says the engine should be okay for quite some time (I intend to dispose of the car and replace it with a “new” one after two years), but in case it starts having issues, usually related to overheating, I may have to throw away the engine. Both say a 3S engine would be a good replacement.

a) Comment on the performance and durability of the 1AZ engine in the Voxy and the Noah.

b) If the 3S engine is better, do they instal them any more in Noahs and Voxys?

c) Considering the purpose of the car, which one would you advise me to buy, with the resale value, durability, and cost of spares in mind? Fuel consumption is a non-issue in this case, and any of the cars will give exactly the same monthly income from the contract.Thank you, Samuel,

The fact that you are comparing a saloon car to a van means carrying capacity is a moot point. I will first ignore your questions and tell you this: Get the Premio. It makes much more sense, especially now that you are talking airports (which means you are also talking town driving somewhat).

The saloon is nippier, more versatile, and generally a better and more sensible prospect compared to a van, which is bulkier and wasteful.

Now to your questions:

a) Performance is good (for a van with a 2.0 litre engine, that is). Durability depends on how you use the engine and what you put into it.

b) Who said the 3S engine is better? The 1AZ is actually the successor of the S engines (of which the 3S is one), so it goes to reason that the later engine is a development of the previous. Hence the 1AZ is better.

Just because your mech friends cannot fix a D4 does not mean the engine is rubbish. And, no, they do not use the S engines is Voxies (Voxys?) anymore.

c) Resale value favours the Voxy/Noah. People have an undying thirst for these vans, for some reason, but market demand can be a fickle mistress; what is in demand now could be shunned like the plague in two years’ time.

Remember the Galant? Durability depends on usage, while costs of spares do not vary by much

I will be curt here; buy the Premio.

Hello Baraza,

Thank you for enlightening us on car issues. I would like you to give me the pros and cons of the Mitsubishi Airtrek compared to the Nissan Teana. I am torn between buying the two.


You cannot compare the two outright because they occupy different market niches and are targeted at different demographics. The Airtrek is a lifestyle vehicle whose sales quarry mostly includes yuppies and up-and-coming 20-somethings with plenty of out-of-town action, especially on weekends.

The Teana, on the other hand, is a middle-management executive’s car, not as lowly as the sales-rep’s Tiida/Almera and not as flashy as the Deputy CEO’s S320 Benz (or Fuga, if the said CEO is poorly paid or is a cheapskate).

So the question goes back to you: what do you expect from the car that you buy?


I have owned and nicely maintained for five years a 1995 Toyota AE100 saloon. Lately, it seems to have lost power and the engine seems to howl during drives. This is despite changing the clutch kit and regular servicing, including trying out Iridium spark plugs (I hear they are not for old cars, but I was desperate).

Braking is also not up to scratch and the linings seem to lose friction almost immediately after adjustment. Kindly note I always buy genuine parts from Toyota Kenya. How can I rejuvenate this car that I am so attached to, or is it time to part ways?


I really cannot say what is wrong with your 100, but I can tell you this: the only time I know of engines howling is when they are revved madly — nudging the red line — and the only cure for that is to ease off the accelerator pedal.

Power loss could come from insufficient electricity in the HT leads or bad plugs (usually accompanied by a distant smell of gasoline in the exhaust), compression leakage (too much blow-by), or slipping components in the transmission.

You may have to look at your clutch again. The only conjecture I can come up with to connect the howling with the loss of power is a slipping clutch, which allows your engine to rev up but the corresponding speed in the transmission (and hence the road wheels) is not proportional to the increase in engine revs.

As for the braking system, you just have to do an overhaul.

Hello Baraza,

I recently upgraded from a Vitz to a Belta and I am confused by the new gear lever. I am used to the usual arrangement of P-R-D-2-L, but the Belta has P-R-D-B-S. What is the meaning of the B and S and how do they function? And, in your opinion, is the Belta better than the Vitz?Sarah.

The Belta should be a sort of Vitz sedan (remember the Toyota Echo concept car?) just like the now-defunct Platz. Actually, the Belta is the new Platz, the way the Allion replaced the Carina. Follow?

The only difference between the Vitz and the Belta could be that the Belta has a bigger boot. And is newer. On the gear lever, I have never seen or heard of a P-R-D-B-S arrangement in an autobox, so I have no idea what the B and the S stand for. As for now, just use P-R and D, the most essential gears.

Hi JM,

So many second-hand car imports come loaded with gizmos that add to the complexity of maintenance, increase weight, and result in poor fuel consumption. There is a move in the UK for “back-to-basics” cars:

small, simple, minimalist, and relatively cheap-to-run things. Examples are the Dacia Duster, the Citroen C1 VT, the Chevrolet Spark+1.0, the Suzuki Alto 1.0 VVT SZ, and the VW Take UP!

These all retail in the UK for less than £9,000 or about Sh1.2 million. No electric windows, mirrors, or seat adjustment, just simple, basic motoring.

I think such cars have great potential here. Chevrolet, Suzuki, and VW all have franchises here and I wonder why they do not bring such cars here. There are many, like me, who would welcome a no-frills car. My longest trips are Kilifi to Mombasa or Malindi, and such economical motoring is most attractive.

Tony Gee.

We do have such cars here, or at least one that I know of: the Ford Figo. Another one is coming, from China, to be sold by Simba Colt…. Go figure! Meanwhile, General Motors are dead on their feet.

I had to go to South Africa to try out their Chevrolet cars (nine of them, over three days!) which they do not even bother marketing (the 1.0 Spark is a feisty little fighter while the Lumina SS is a Corvette for introverts).

These cars make sense, especially in the city, due to their manoeuvrability and fuel economy. Doing 500km-plus in one hit in them, however, is another matter altogether. Let us hope our conversation here provokes the franchise holders into taking action.

Hey Baraza,

I am a big fan of your articles and I know that your advice has enlightened many Kenyans into making wise decisions when it comes to acquiring vehicles. Kudos! I would like you to assist me in getting something straight;

I like the Toyota Premio X Edition (1,800cc) because of its high performance and reliability, but I am a huge fan of the manual transmission, which I have not seen so far in these cars. Are there any Premios with manual transmission? If there are not, what is your take on modifying an automatic box into a manual one?


Sadly, the Premios I have seen are all automatic. However, there were manual versions of the Corona Premio, or what people call “the old Premio”. There is nothing wrong with swapping the autobox for a conventional manual.

If anything, I would like to see someone do it. I have this idea of getting a 4WD Allion (Premio’s sister car) and fitting it with a manual gearbox, after which I will bolt on a TRD supercharger to the engine….

Hi Baraza,

I appreciate the good work that you are doing. I must say I am now well versed in cars because of your articles. I own a Toyota AE111 (1,600cc) with a manual transmission which has served me well for the past three years. I have the following queries;

1. Is it true that wheel alignment done on a car fitted with Yana tyres normally has issues? I have been told this by many people when doing alignment. What is your take?

2. Is it a fallacy that engine oil should always be changed every 5,000km. I service my car every 10,000km and have never noticed change in performance.

3. I intend to buy new 185/14’’ tyres to replace my current 175/14’’ ones. How will this affect my car? Thanks once again for the good work.


1. Ahem… eerr… aah… I cannot comment on that just yet.

2. The 5,000km figure is what we call a “ball-park figure”, a general safe zone for changing oil considering all types of driving. It covers both sensible and unwise driving techniques.

With careful driving, you could easily triple or even quadruple that mileage, though this will be major gambling on your part. Manufacturers like Mercedes now make engines with service intervals on a needful basis, that is, the car will tell you when it wants a new shot of lubricant.

The three-pointed star claimed some of their engines could easily run to 22,000km before needing new oil. However, since your 111 does not have that tech, just stick to the 5,000km. A few quarts of oil will be cheaper in the long run than a new engine, which is what you will need if you lose the gamble.

3. You will be able to corner harder since your new tyres are wider than the previous set.

Hello Baraza,

I have a 2006 Pajero Exceed fitted with a 3,000cc petrol engine. I would like to customise it and add a turbo-charger, and my mechs tell me that it is possible, not possible, possible, not possible….

Research on the Net tells me that it is very much possible to do this, but I will have to change the exhaust manifold and also probably the pistons and the brakes. So tell me, is it possible to do it?

If yes, please explain briefly the “how” and the “who” that you recommend for such changes. I am also interested in its performance and would like to push its power to about 250+ horsepower.

Again, is it possible? Please note that I am aware that there are more powerful cars like the 2012 Nissan Patrol and the Toyota VX, but I would like to stick to my Pajero and make these changes. Peter.

Yes, it is possible to turbo-charge the Paj. As you mentioned, you have to change the manifolds (especially exhaust) to accommodate the presence of the blower.

A little mapping of the ECU will ensure smooth running of the “new” engine. It is advisable to instal an intercooler also to go with the turbo, as well as upgrading your cooling system (turbo engines tend to have a lot of heat).

The “who” is very simple. I have an acquaintance who does this kind of thing. Visit Auto Art K Ltd in Industrial Area, Gilgil Road, behind the Total petrol station. Ask to see Amit Mohamed.

On upping the horsepower, yes, it is possible, although I find it odd that you settled at exactly 250hp. Most people give a ball-park figure (“around 230 to 280, maybe 250”, is what a typical statement of request sounds like).

Getting the 250hp involves mapping the ECU and adjusting the boost pressure in your new turbo. However, you can still up the power levels by other tuning methods.

Mohamed can do the turbo adjustment, but I have yet another acquaintance who does ECU maps, a certain Amit Pandya of AMS Performance… no relation to Mohamed despite the similar first names

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Power is nothing without control: My near-death experience at the wheel

Last Thursday, I found myself behind the wheel of a slightly aging Toyota Corona 1.8.

Now, there is nothing as unnerving as finding oneself at the receiving end of one’s own nuggets of wisdom (and advice), but what happened is what happened.

So, what exactly happened? That particular car had lived a rather hard life, driving over bad roads and the first few moments of driving it proved that fact.

The engine was fine, very OK. In fact, you could drive it endlessly in fifth and there would not be so much as a shiver from it.

But the suspension and steering were something else altogether. The shocks were beyond kaput (although the springs were fine, almost), causing the vehicle to sag at an ungainly angle, and that was not even the real problem.

No, the issue was that driving the vehicle at any speed above 50 km/h called for generous endowment in the trouser department.

The steering had an alarming amount of play off-centre. It had also become disturbingly non-linear and the turning circle had degenerated into truck-like dimensions; sometimes I would execute a three-point turn where other cars would simply perform a single U-turn.

There was a terrible shake, especially from the front sub-frame, every time I declutched and came on the power, the sort of shake you get when trying to take second gear conditions in fourth gear, as though the car wants to stall.

And again that was not the biggest problem. Driving in a straight line called for constant sawing at the helm.

Adjustments in road camber or imperfections on the tarmac surface would cause the car to wander aimlessly, darting left and (especially) right like a nervous cockroach.

It also had a tendency to pull suddenly to the right without warning, particularly dangerous given that in Kenya we keep left, so pulling to the right means going right into the face of oncoming traffic.

This could be controlled by incessant adjustments that were necessary to maintain a straight line, but things came to a head when, at one point, I was forced to brake hard.

The car did not just pull to the right, it actually started turning right. Frightened out of my wits, I knew something had to be done. That something was to check the wheel alignment.

The mechanic who looked at it, after seeing the diagnosis from the aligning kit (which looks like a mechanical device used by a dentist from hell), shot me a glance that was a cross between deep sympathy and disbelief that I had not killed myself yet, and he pronounced the vehicle a death-trap.

The boys who were aligning the wheels were trying unsuccessfully not to laugh. However, they did their job.

And a good job they did too, or so I thought. The play disappeared, the steering became linear (almost, but better than before), and the worrisome trembling was minimised to a point where you could barely notice it (but it was still there), so I assumed things were now OK.

The mechanic, in bidding me goodbye, told me to keep my speed at 100 km/h or less, as he was still not very confident about my ride for the day.

Off I went. Somewhere ahead, along unfamiliar roads and in very heavy rain (the sort of Noah’s-flood monsoon-like squall that reduces visibility to less than 15 per cent and renders people homeless), I drew up behind a slow moving truck.

I performed the ritual necessary for a wrong-side pass (also called overtaking).

Downshift into fourth, check mirrors (couldn’t see diddly-squat), confirm no one is coming the other way, downshift again into third, change lane ,and floor it.

That is when I saw the huge speed bump. Apparently, trucks don’t slow down for nothing and I had to conform to the prevailing road conditions (the speed bump), which meant that I had to stomp on the brake pedal as hard as my delicate ankles would allow and without aquaplaning.

Things happened very fast from that point on: the car speared off to the right, so I yanked the tiller hard to the left to counter the bizarrely erratic behaviour of the fore end, but this only led to some sort of understeer as the tyres scraped noisily over the wet tarmac (it was that bad) and the car started to leave the road on the wrong side, refusing to obey and maintaining its unintended north-easterly bearing.

The only way out was to act counterintuitively and release the brakes, so I did. This corrected the course but I still hopped over the bump at about 70 km/h, throwing the aft end of the car alarmingly into the air.

All this took the best part of four seconds (I told you things happened really fast). My passenger gasped “Sorry about that, dude, but did you not see that bump?”

I did not answer because it is at that moment that I realised that the car had even worse problems than I had imagined, and the basis of this week’s article (and the next) started forming in my mind.

The steering system

The steering system of a car is one of the most elaborate pieces of mechanical hardware, more so if it is power assisted (hydraulic or electric) and the vehicle is front-wheel drive.

To best understand it, in today’s classroom we will trace a path from the driver’s palms gripping the steering wheel rim to the rubber tyres gripping the road, and everything in between, but only everything common to all types of automotive steering systems.

This is because in subsequent lectures we will discuss the various steering types and try to troubleshoot the reason I almost ended up in a maize field during a heavy downpour.

The steering wheel rim is connected to the steering column, the “tree trunk” that disappears into the vehicle’s dashboard.

This steering column is nowadays collapsible by law. In the olden days, it was just a solid steel rod that would impale you, penetrating your chest and coming out your back in case of an accident.

The collapsing characteristic is either telescopic (like a TV/radio antenna) or by a universal joint along its length that folds under duress.

The Steering Box

The steering column terminates in a steering box, where the steering ratio is determined (low ratios for smaller cars, higher ratios for bigger and heavier vehicles), and the circular motion of the steering column is differentiated or transformed into the linear motion of the steering linkages.

The vehicle may or may not have power assistance (discussed hereafter), so from the box, the steering effort travels through the steering arm to the connecting rod, tie-rods, knuckles, and finally the king pin axis, to which the front wheels (or back, depending) are attached.

The reason behind the gear reduction within the steering box is to minimise the torque necessary to turn the wheels. Motor cars are generally heavy. We all know that, so turning them must require a lot of effort.

Through gear reduction, the torque applied by your arms at the wheel is multiplied within the steering box before being applied at the wheels, so that, even without power assistance in the steering system (not all cars have the P/S or PAS option checked when at the dealer forecourt), driving a car should not be left to body builders and farm hands only.

Nobody ever mentions this, but I think another reason for the gear reduction is to give a huge margin for error in the case of the inept and the wilfully wayward.

To get my meaning, have a go at the wheel of a go-kart and you will understand why keenness, accuracy, and skill behind the wheel are not only advisable, but a must.

We will look at the various types of steering boxes (rack and pinion vs. recirculating ball) next week, but for now, let us discuss a man called Ackermann.

Ackermann and His Principle

You may or may not have noticed this, but when a car is turning, the inside wheel turns at a sharper angle compared to the outer wheel.

This is because it inscribes a circle of smaller radius compared to that of the outer wheel. This whole setup is what we call Ackermann’s Principle.

If the two tyres turned at the same angle, the inner wheel would push across its width rather than rotate along its circumference.

When a car turns in a full circle, the tyre tracks are supposed to show two concentric circles. But with the wheels at a common angle, the circles (of similar radii) would overlap, and the car would turn in an ellipse rather than a circle.

This is not even possible at constant steering wheel lock. Ackermann’s Principle is made possible by the geometry of the steering linkage.

The geometry, in simple terms, is thus: each (front) wheel is attached to the steering system at two points.

The two points on each wheel, connected to each other and to the corresponding point on the opposite wheel, form a symmetrical trapezium, with the length towards the front of the car being slightly longer than the one towards the centre of the car.

To get the picture, the line joining the centres of the two wheels passes between these two lengths. Each corner of this trapezium is a swivelling joint.

So when turning, the trapezium distorts, losing its symmetry and the angles on one side become sharper (acute) while those on the opposite end widen, or tend towards the obtuse (high school geometry: the sum of all angles within a quadrangle must add up to 360).

The loss of symmetry explains the lack of similarity between the two tyre angles while turning.

Self-centreing of the steering wheel

Now this you must have noticed: whenever you apply lock (i.e. rotating effort) to the steering wheel, it tends to bring itself back to the centre point, that is, it straightens itself out when you let go.

There is no magic behind this, nor is there a pump or a device that does this for you; it is pure mechanics (or physics, or both).

The caster angle, along with Ackermann’s Principle and gear reduction, is one other fundamental concept of the steering system.

The pivot point steering each wheel is positioned slightly ahead of the wheel itself, and this causes a tendency for the wheel in question to align itself with the direction of travel, hence the self-centreing. It is a virtual force that does this, just like centripetal force.

Power Assistance in the Steering System (PAS)

There are two major types: hydraulic and electric/electronic, although, with the advancement of technology, a hybrid system of the two can now be realised.

Hydraulic systems are run by a pump that is driven by engine power through the fan belt (which also turns the alternator and water pump) and a pulley on the pump.

It is hard to explain how exactly the pump works without diagrams and excessive jargon, but in a nutshell, it works a bit similarly to a centrifugal supercharger, only instead of blowing air, it pumps hydraulic fluid.

The vanes within the pump draw in fluid at low pressure (from low torque driver input — we are not that strong) and dispense it at higher pressure, with the help of the engine.

The engine speed determines the amount of flow within the pump, so the general pump design allows for sufficient flow at idle, and the use of relief valves controls the pressure ceiling at high engine speeds when the pressure gets too high.

There are problems with this kind of setup. First, it is hard on the fuel and wastes engine power, seeing that the pump runs full-time, even when going straight or when the car is not in motion.

Then, you do not want your car engine to stall if you are using this kind of jury-rig. The system will stop working (the pump is powered by the engine, remember) and the effort at the steering wheel will be twice as heavy as you not only have to work the steering system manually, you also have to work the entire power-assistance mechanism too.

Disposal of used or dirty hydraulic fluid is also becoming an issue in this heavily policed, environmentally conscious 21st century, and this builds the case for an electric/electronic system.

There is no fluid to top up (or dispose of, or leak), it is infinitely tunable to the vehicle type, road condition, and to a driver’s liking and the system only need work when the wheel is turned.

Most power-assisted steering systems come with a fail-safe mechanical linkage; it is actually compulsory in motor vehicle application.

But where did these systems even come from? The advent of front-wheel drive, and the increase in tyre width (bigger contact patch, bigger effective area for frictional forces to apply) and size made most steering systems quite an effort to work manually without increasing the ratios in the steering box to ridiculous and unworkable numbers.

So power was needed as a palliative to the unplanned workout at the helm. There is plenty more to discuss about steering systems, so future lectures are not to be missed.

Speedsensitive power assistance, variable ratio steering (also called active steering), four-wheel steer, steerby- wire technology — all these will be looked at and explained, but as a parting shot, please take note of this: the Corona that gave me a big scare was not mine.