Monday, February 27, 2012

Springs & co.

The spring is one of the most important parts of the suspension. You might say:"well no sh*#, Antony..." Anyway, here are some details which some of you may find interesting: 

If you put a linear spring in a pressing machine. Every other single mm of compression will require an extra equal x amount of force, which is normally measured in Newtons (N). Kilogram force (Kgf) or pound force (lbf) units are also valid to measure the spring rates. Many will speak in Kgf, because it gives people more sense of what they are talking about. Remember however that 1 Kgf is approximately 9,81N. The EIBACH springs, which I have knowledge about, are measured and marked in Newtons (N).

Back in the early 2000's I had a Toyota Corolla WRC and we had EIBACH linear springs for it. On a competition EIBACH spring you can see a number code as, for example: 300-75-0055. Where 300 is the length in mm, 75 the inner diameter in mm and 55 the rate in N/mm. I measured them in our press, just for my own information. Those springs took, for the 55 example, 55 N to compress the first mm. Compressing it 1 more mm required another 55N, therefore 110N for the first 2 mm of spring compression. I noticed that almost all the springs I measured never really gave the same readings. They often varied by 1 to 3N or so. Either my press was inaccurate, or they must be very hard to manufacture identically. My guess tells me springs are hard to make identical. EIBACH does state that there is an allowed 2% tolerance which may go either way on the spring rate, which at worst might come to 4% spring rate difference between a right corner and a left corner on your car. It may be worth checking your springs before you mount them! Maybe somebody could share their experience with me?

In the mid to late 90's, the works Toyotas were running very hard springs, in the range of 50-80N/mm on the front for gravel and as much as 90-100N/mm on tarmac, if I remember correctly. Things changed drastically with the involvement of top Nordic drivers and Toyota Team Sweden (TTS) who went, together with some evolutions of the Öhlins dampers, way down to values around 45N/mm on the front. In those days, this was a revolution. I remember a particular time when, back in and around 1998, we had picked up a Toyota Celica st205 GrA from TTS and took it down to Portugal, in the Fafe Lameirinha and Cabeiciras de Basto area (Northern Portugal) to test it on smooth gravel. This Celica was on the superstrut suspension (anyone heard of this one?) as opposed to Mc Pherson. I thought the car was fantastic so we called the TTS boss and he said something like:"hey, wait your car is accidentally on snow springs, that it is not right..." I thought the car was awesome on softer snow springs (55N/mm on front). The superstrut also helped.

Celica st205 GrA ready for rally

"Superstrut" on Celica st205 GrA
Corolla WRC upright McPherson

Linear springs were used on the Fords I drove as well, except the rates were much lower than on the Corolla and Celica. By the time I had joined Ford they were using 30N/mm on the front generally, for gravel, and around 50N/mm for tarmac (not so sure anymore on the tarmac rates, although I do remember we had a rain setup where the rates went down by 5N/mm all around). On gravel the standard setting was 30N/mm front and 25N/mm rear. I asked for a 30/21 ratio for my car. This gave my car a bit more grip on the rear and hence a bit more understeer, which suited my driving style better. I once tried a 30/27.5 ratio during Acropolis shakedown. It was slow and rubbish for me, way too much oversteer. All this to say that springs are super important for car balance and sometimes you don't know if you have the right setup until you tried them all and compare on the clock. In my case, I was significantly faster with the 30/21 balance even though the 30/25 felt better.

Back to MAZDA, who's initiative (in and around 1987-1992) was to use progressive springs rather than linear. Basically the spring rates had ramps that went from softer to harder, as compression increased. I remember my father saying that they were extremely hard to figure out. He spoke of his engineers making regular custom orders to EIBACH for various rates and ramps to test on the car. I also remember that some of those desired ramps were not achievable due to material constraints. I believe this has probably evolved now (I will make a future post, discussing the basics of metal properties and how this was a major subject in the early 90's for MAZDA). Luckily we had some very good engineers and drivers for this sort of setup work. Timo Salonen and Hannu Mikkola had appropriate feeling for the suspension adjustments and how it translated to corner speed, general car balance and traction. Back in 2006 I crossed paths with an old MAZDA engineer who had moved on to MITSUBISHI during the Tommi Mäkinen years and then on to the Dakar team. I asked if he had taken the progressive spring knowledge over there and he said: "Waddaya think?"

Neverthless the combination of KAYABA dampers and progressive springs allowed the MAZDA to have better traction than the competition in the late 80's and early 90's. KAYABA's gas-cooled damper meant that the damper did not overheat and lose its effectiveness as easily as before (when dampers overheat, they basically become air pumps until eventually they seize altogether, then you're screwed). Thus the damper controlled the spring travel with effectiveness. Traction was the key to the car's success and it was attained thanks to the softness on the first few centimeters of spring travel which then became as hard as necessary for rough terrain. It showed especially on slippery surfaces where Timo, Hannu and Ingvar's skills together with the MAZDA's traction had the edge over the competition's raw, less-controlled power. Unfortunately, as soon as there was good grip, the horsepower disadvantage was a real problem.

An interesting note I'd like to point out is that back in the late 80's and early 90's the popular concept was to let the spring do the work. The damper was merely there to keep it under control, discreetly, if you see what I mean. The philosophy later changed completely. The shock absorber became king. Thanks to advances in technology, dampers became so "bullet proof" and effective that, in a way, springs became secondary. To exagerate a bit you could say that, nowadays, they just hold the car up... here is a little anecdote to illustrate my point about the suspension revolution:

My father often test drove the MAZDA after Timo and Hannu. They would determine a setup and if they had doubts they'd ask him to drive and give his opinion. Although he wasn't competing anymore at that time, he had a pretty good idea of what the car could do. 12 years later he rode with me as I tested the Ford. His reaction to how the Ford "swallowed" bumps and stones was interesting. Driving the MAZDA, you often had to "navigate" around hazards whereas for FORD the motto was "just go".  

On some modern rally car uprights, you will notice a second smaller spring accompanying the main one. This is usually a "helper spring". Below is a clear pic of the helper:
Spring with helper on top
You can see a hint of one (in red), sitting above the yellow spring in the following pic:

EIBACH linear spring on Celica st205 grA

On the following pic you can see a small white spring under the main one. I believe it is a helper as well.   
White helper spring on MINI upright
The helper is used to keep the main one always aligned perfectly and tense during lift off. It has an insignificant spring rate and will be at full coil-bind on normal driving position, therefore it has no effect in terms of car suspension.

There also exists "tender" springs:

Spring with tender on top
Tenders have a significant spring rate and are not at full coil-bind on normal driving position. I know the tenders exist in linear or progressive specification. They have an effect, at least on the start of suspension movement until they reach full coil-bind, at which point the main spring works on its own. Their use, in a 2 spring system, significantly complicates matters. I am unaware if they are used on top rally cars. Maybe someone could fill us in on this.

Sunday, February 26, 2012

New video page

There is a video page from now on. Here is an example of what you can find there :

If anyone would like to make some media contributions to the site you are very welcome.

Thursday, February 23, 2012

To cheat or not to cheat

Here is a question from someone on

"And now a question directly to Antony

What can you tell about manufacturer teams' offences against technical rules? What changes (could) cars had between pre- and post-event scrutineering? What about unauthorized repairs on road sections, changing weight ballasts between the scales? Could a team be sure that officials wont check certain parts of the car? and so on...."

Most of the stories I have heard date way back to the early 1990’s. At the time I was a kid and my dad was running MAZDA RALLY TEAM EUROPE (MRTE). Sometimes he told about stuff that they had seen themselves or heard from 3rd parties. What I am trying to say is I don't know how true or accurate they are. So don’t come and tell me I’m wrong!

On a side note, just to illustrate how unwanted news can easily spread, here is an example where MAZDA was the victim:
MRTE was wondering how, at one point, the press was  coming out with confidential information; by that I mean intricate info about car behavior, setups, reliability problems and so on. Things that the drivers of the time: Hannu Mikkola, Timo Salonen and Ingvar Carlsson couldn't and wouldn't discuss with the press. Let’s face it, the MAZDA 1.6L engine was already at a huge disadvantage compared to the others like TOYOTA, LANCIA and MITSUBISHI who were on 2L engines. The MAZDA's only advantage, which came from its "innovative" gas container damper (KAYABA) and progressive springs (compared to many others who were and still are on linear springs), was definitely not something to openly speak about. It turns out my dad figured out what was going on when he caught a nosy journalist in the act: The journalist had apparently taken the habit of hanging out just below the motor-home window, whenever open. There, the guy just listened away at the drivers and engineers who were discussing... He was caught and sent away.

Stories I heard were, for example, when a factory TOYOTA was getting refueled behind some bushes by guys wearing something apparent to radiation suits... Or a spare wheel being carried out of a Gr. A Celica by three people, cause it was in fact a heavy tank full of gas (I mean gas, not petrol)…Or a MITSUBISHI being replaced in the rally by another brand new MITSUBISHI on which doors and bonnet, from the original MITSU, were bolted. The car made a few donuts on the gravel, so as to look dirty, and on it went... I remember hearing of the FIA technical commission boss of the time, sitting next to my father, on a stage start line watching the Gr.A Celica roar away like an airplane and saying:"Achim, I know something is wrong with this car, but what?" You see, the problem was that people knew they were cheating, but you had to know where and when to look. It was later that I heard they submerged the infamous turbo charger in water and saw air bubbles coming out of places where it shouldn't have. Apparently that turbo was the cleverest cheat the FIA tech guy had ever seen.

Fortunately today it is much harder to cheat. I do not believe official teams are or have been cheating lately, at least not willingly. I could tell you, for example, that I once used an illegal amount of tread patterns in a gravel event. It was a simple accident, really. We were allowed to nominate two different tread patterns. I accidently used three, until we realized. Oops! It's just too risky to cheat willingly and be caught. I remember of one instance, where there was an alert because a works car had lost some plastic parts on a stage, which in turn caused the car to be, let’s say, light. It was an issue. I can tell you also that back in 2002 when I did the ERC (European Rally Championship) there was some proper cheating going on. Illegal cars, illegal fuel, illegal recce, illegal servicing. We saw and heard it all.

I'll make a post about linear and progressive springs soon. I believe it's an interesting subject.

Testing before ELPA Rally 2002

Wednesday, February 22, 2012

RSI: Ivan

Some photos from a Canadian friend who was the chief scrutineer back when we did the Charlevoix rally in 2002 (Quebec). Thanks Ivan!
We were not well prepared for this event. It ended prematurely because we did not have the correct tires for the conditions (gravel with fresh snow and ice on top, no spikes allowed)! I retired on a double puncture but that was beside the point. I will go more into this adventure on a later post. Our experience in Charlevoix could be useful for some, so as not to make the same costly mistake.

Saturday, February 18, 2012

The resolutions

With every New Year come new resolutions, mine come in pair this time. First I wish to thank people who helped me out in the past. Second: I am soon starting a new job! Yay! Handling it is another question. Be sure I will be back on here to brag about it, on a later day, if I manage with it.  
For the time being I would like to blog differently, take a parallel path from what you have been used to. I have been busy both with work and with my MINI project up until now; you know that, don’t you? Finding sponsors is extremely difficult; you know that as well, right? Although for some people it just seems to fall out of the sky. Seriously, for me it’s like banging the head against the wall! Let’s put that aside for a while.
I have a friend who has helped me on various occasions, out of simple kindness. I really appreciate that and feel we are on a same wavelength. As a result I would like to return the favor by writing and posting a bit about him, his company and what his projects are.
Rob Atkinson runs a company called RAMSPORT. I am sure you can remember that name as they ran WRC cars for a number of years at the highest level of rally sport. Fortunately all this know-how is not going to waste and Rob has now been involved in building and restoring historic rally cars as well.
Among the cars they work on is a MK1 Ford Escort, it is FIA historic spec with a mechanical injection BDA engine, quite a rare engine and it worked really well winning on both of its outings. They are currently working on a 1970 Porsche 914/6 GT, it is being rebuilt form a bare shell upward and will finish as a very rare FIA http Rally version of the GT. We will get some more photos on the blog as the build process evolves. In the meantime, check these out:
The Porsche as received from America:

After it was dipped and treated:

After having the cage and arches fitted:

The MK1 Escort:

The engine looks neat: I would love to get close-ups!


The tank: