Setting Up

[gofasterrosssco]

I have found out that my Import MR2 mk2 has some tasty Ohlins adjustable dampers fitted. Does anybody have any tips for setting adjustable dampers up; I dont want to start twidling knobs and end up getting it too hard at the back (oversteer) or to hard up front (possibly understeer)..... or is it a case of try it and test it??

I am guessing its a very individual thing for each car model, but any tips would be handy...

Cheers in advance

Ross

[GreenV8S]

It is possible to use the dampers to tweak the front'rear handling balance of the car (i.e. harder at the back promotes oversteer etc) but this is not the best way to do it. Ideally you should establish the handling balance using spring rates and geometry and just use the dampers to control the oscillations, doing no more than a very fine tuning on top of the basic handling characterics. So where you have a smooth race track with minimal bumps you might want to stiffen up the suspension to damp out roll and pitch movement quicker, and on rougher surfaces you might need to sacrifice body control in order to let the suspension ride over bumps instead of smacking into them. So from that point of view you are trying to find the range of damper settings that suit that car (mass, geometry, spring rates etc) on the types of road that you tend to drive on.

Having understood what you are trying to achieve by adjusting the dampers, the actual process is quite straight forward. Adjust all four dampers by the same amount. Depending on the valve specs and the characteristics of your car you might find that you need different amounts of adjustment front and rear to get the same effect, and when I say 'same amount' I mean so you get the same effect front/rear, for example two clicks at the front might be equivalent to one click at the rear.

You will find it is quite difficult to work out the effect of small damper changes, so the way to do this is to start from two extremes and gradually work towards the middle. So pick a hard and soft setting and drive the car to see which you prefer. If you are starting from scratch the 'hard' setting might be the damper's "max" setting and the 'soft' setting might be the damper's "min" setting. If you already have a working setup then "soft" might be "a bit softer than normal" and "hard" might be "a bit harder than normal". Decide which setting seems worse, and move that setting one click towards the other setting, then try again. You stop when both settings are the same, or you can't tell the difference between them, then set the dampers to half way between the two.

If you feel like playing the front and rear dampers off against each other or varying bump versus rebound you would use the same approach except that you wind one adjuster up and one down. Keep the total damping the same and soften rebound as you stiffen bump (and vice versa) and soften the front as you stiffen the rear (and vice versa). I expect you will quickly get into diminishing returns here and won't get much benefit unless you are taking detailed performance measurements and also optimising the other factors (geometry, spring/roll rates, tyre pressures etc) at the same time. When you can't feel any noticeable improvement, that is your clue to stop.

[gofasterrosssco]

Green,

Cheers for the very helpful and thorough response. I had a 'play' with the adjuster knobs (didnt even have to jack the car up) and firstly set them all to the softest setting, which was to the right; I assumed to the right would have meant tighter/stiffer but never mind. Anyway on this setting there was a very noticable differnce in overall control. The car bobbed along, obviously due to the springs being stiffened I assume, and felt far more 'aloof' for want of a better word. It also felt initially slightly more grippy, but I had the felling if I pushed it harder into a bend either the front or rear would loose traction. Ofcourse it is cold and very wet whcih doesnt help.

I returned and put the settings to the far left. The difference was immediate and much better. Although it felt slightly rougher over the crap roads (there aint a shortage of these) it felt far grippier, the steering was sharper feeling and more accurate and was generally far better.

I might just keep it on the stiffest setting for now; as you said, the subjective difference by going a bit lower may not even be noticable.

Thanks Again

[bugsy]

You will find that the Ohlins have quite a narrow band of adjustment because they generally set up cars on a shaker rig to find the best settings, so I would start in the middle and try up and down a couple of clicks to see what suits you best.

[rlk500]

Just bear one thing in mind. You mention that your car is an MR2. Being mid-engined makes a difference on how the weight transfer process will occur in comparison to a front engined vehicle. i.e stiff rear end generally causes oversteer on a font engined car, on a mid engined car the same degree of stifness may not have the same effect. Equally, with less weight at the front, you may be able to run the front quite soft, to increase grip levels. It's defeinatley, a trial and error jobbie, but it may be worth contacting one of the Jap tuning companies to see what sort of rates they run for MR2's.