It is a well known fact that lowering the centre of gravity of a vehicle, makes for improved cornering ability. With a lower stance, the car stays flatter in turning, reducing body roll, containing the inherent inertia of the weight of the body, thus keeping the vehicle under control during the change in direction.
As with all things, there is a certain amount of compromise, you can’t go too low ‘cos your sills will be on the floor, and your dampers won’t be working. The amount of “drop” introduced by shortening springs, which is the usual, but not the only method of lowering a car, should be tempered by an understanding of what’s going on within the suspension system as a whole.
If a substantial lowering is contemplated, 60mm plus, for instance, then it is likely that shorter shock absorbers will be required, in order to balance the shorter induced movement of the suspension and get some kind of rebound control, without “bottoming out” the shock absorbers, and ending up with “tea tray on concrete” syndrome. Shock absorbers offer resistance in both directions, in order to dampen the reaction of the spring, to a greater or lesser extent, depending on their internal design, and the specific use for which they are intended. Most will offer less resistance to extension than compression, although on some higher spec makes, this can be altered or adjusted according to whim or road conditions. Most importantly, for ordinary road use, less resistance is required on extension, whilst greater resistance is offered on compression, in order to contain the inherent “bounce factor” of the steel spring providing the compliance of the suspension over which the vehicle is travelling.
The control of the spring rebound or “jounce” is an important factor as far as road going cars are concerned, and in order that this takes place, the suspension must be able to operate without the interference of oversized bump stops and the shock absorbers being too long. With this in mind, the importance of correct spring selection becomes obvious, too short and the shocks can’t work, negating the action of the suspension, and rendering the vehicle almost un-controllable, wandering, tram-lining, and horrendous tyre wear being some of the symptoms. As already mentioned, as in all things, a compromise must be reached between the ride height of the vehicle, and the operation of the suspension. On BMW E24 and E28 vehicles, the need for lowering is obvious to the serious driver, as the standard suspension, when new, was a great compromise at best, given the great variety of road conditions that are likely to be encountered across a World wide market.
The roads throughout Europe are generally pretty good these days, and so the odd “tweak” to the suspension will not be detrimental to the feel of the car, and will indeed enhance the driving experience. There is a lack of proper test criteria for suspension components, whilst they are still mounted on a vehicle. The standard “bounce up and down” tells you nothing. All vehicles over ten years old need new shock absorbers, and by twenty years old, given that they have spent the time on the road, the springs will have seen their best days too! The replacement of both springs and shockers is not cheap, but the difference, having changed them for new, is nothing short of astounding.
FRITZ’S BITS can now supply a NEW spring set to subtly lower your vehicle, whilst maintaining the overall integrity of the car, and enhancing it’s drivability. E28 and E24 models have, in the past, been sparsely catered for, but we can now supply a new spring set for both models as well as shock absorbers at discount prices for both machines. Please note that THE FRONT SPRINGS FOR E28 and E24 WILL NOT INTERCHANGE. The E24 front springs must be able to carry substantially more weight due to the extended front sheet metal work of the vehicle over the five series. We have been working with a UK company, to produce the required difference in tension and load bearing and the fruits of both our efforts is now available to discerning owners of this range of vehicles, as well as being able to help E28 owners since the well known GERMAN manufacturers have recently deleted these from their catalogue.
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Unit 1, Lobsgrove Park, Greenham, Wellington TA21 0LY