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Why do we use the same rated springs across the same axle?
mark chandler - 16/1/16 at 05:41 PM

Why do we use the same rated springs across the car?

Putting my little car back together, only gets driven by me so heavy on the OSR, bike engine loads the NSF so why do we always seem to use the same rated springs across the car?

I have put it back with the loaded corners having 25lb heavier springs, years ago I have had road cars with handed springs, I believe my classic Range Rover had these as did an early series 2a.

Now if I was setting up to carry a passenger then across the same springs across the axle makes a lot of sense, so am I wasting my time and making the car worse?

Cheers Mark

[Edited on 16/1/16 by mark chandler]

bi22le - 16/1/16 at 06:06 PM

The off centre COG is dialed out with spring pre load. This allows for all most even force through each corner.

You need even springs on a circuit ( not the case for oval tracks) so the car behaves the same in left and right corners.

Also note that cross axle is as important as diagonal corners balancing.

mark chandler - 16/1/16 at 06:14 PM

I get the preload with corner weighting, however hit a bump and the heavy sides spring will deflect more, so hit a bump evenly and the cars body will lean as the light side gets pushed up

Range Rover / landrover had the engine offset because of the transaxle, I see my car being in the same position.

[Edited on 16/1/16 by mark chandler]

coyoteboy - 16/1/16 at 10:40 PM

quote:

however hit a bump and the heavy sides spring will deflect more, so hit a bump evenly and the cars body will lean as the light side gets pushed up


How far out of whack is your CofG?!

Changing the rate per corner seems like a mistake - reckon you'd end up having to balance dampers too, and you'd end up with weird roll characteristics.

snapper - 17/1/16 at 06:40 AM

Give it a go and report back
If your still alive

mark chandler - 17/1/16 at 10:52 AM

Hmmm not sure of the COG, when balancing diagonally to set up the drivers rear perch is cranked up 3/4" higher than the passenger side as is the passenger front but if I was to plot it would have a 60/40 bias with the weight at the rear but it would be pretty central across the car.

Thinking about it the cars I have had did not have a mechanism to set ride height so you woul use heavier springs to level the car.

britishtrident - 17/1/16 at 06:21 PM

Big manufacturers used longer springs or moved the spring platforms on the struts.
The problem with fitting harder springs is it raises the spring rate so the wheel frequency becomes asymetric.
Neither solution is ideal but increasing the pre-load has more predictable results.