Progressive Rate Springs

[kellzey]

Does anyone know anything about progressive rate springs such as those offered by Eibach and H&R? They sound intriguing.

Can anyone provide input on the advantages/disadvantages of progressive rate springs?

Are they available for the rears on the 914 with an adjustable coil-over setup?

Just trying to do some research....

Thanks,

[Ron Meier]

I'm sure you know that progressive rate springs were used to "soften" the ride on some production cars. As long as the body is level, the low rate portion of the spring is in use, giving your butt the comfy ride.

As you begin to create roll (in a turn), the spring exhibits increased resistance to compression. The utlimate end is to reduce the body roll associated with a low resistance constant rate spring (can you say stock 914 springs). The initial turn in to a corner would, for a moment, exhibit a rate akin to "door handle scraping" body roll and then stiffen as you progressed.

The problem I would personally have is the fact that the torsion bars (front) are constant rate and the rear springs would be variable rate, allowing more body roll in the rear than in the front. This would give a tendency for the car to "pick up" the inside front in the turn sooner than with a constant rate. To my mind, this would give an uneasy feeling as you rolled into a corner. If you are racing a car, to me, this would be a definite no-no, as the input your butt feels would be inconsistent.

Just my opinion (we never ran progressive rates on our race cars).
My Volvo street car had progressive rates.

Now, if the -14 had coils on all four corners, Ah........., never mind.

[DDS]

I have a set for sale if you want to play around with them.

[3D914]

Karl,

I have 165# progressive rate springs on rear of my street 914, and no bar currently in the front. I still have some body roll, as I think it would take some pretty stiff springs alone (with out anti-roll bar) to elliminate it completely, but its not dramatic like stock.

If you're going with a six, you may want even more than the 165# springs. No experience there - still tootin with fours.

Regards,