6 rear suspension travel Options

[nditiz1]

So I have posted on this before and am still confused.

How much rear suspension travel should there be on a 6?

74 chassis
2.4L engine
Springs appear to be 100 lb ones
Shocks are Bilstein C clip at lowest setting
No rear sway bar

With this setup the car sat low - cool, but there was no rear suspension travel. It was stiff back there. I push down and there is no give. Now, maybe that is how it is supposed to be?? I remember my 4 having a little bit of rebound, but that was with 200lb less back there.

So I am in the process of clicking up two spots on the Bilsteins to get some rebound back. Seems counter intuitive though. If I compress the spring more it will be more stiff. My thinking here is that there is now travel with two clicks up since before when down on the ground the spring and shock were already compressed so no suspension travel was left on the console and or the shock. Thoughts?

[mepstein]

Changing the height of the shock won’t change the stiffness of the spring. It is linear until it’s out of travel. (Unless you have progressive springs but most 914 springs are not progressive)

[Superhawk996]

Changing the height of the shock won’t change the stiffness of the spring. It is linear until it’s out of travel. (Unless you have progressive springs but most 914 springs are not progressive)

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The notches on the rear of Bilstein's with the snap ring retainer are for adjusting ride height. Has no effect on spring rate and/or the amount of spring compression required to hold the car up at curb weight.

I'm not sure if I'm misunderstanding but want to clarify definitions:

Upward (in Z height) travel of the wheel is called compression or jounce. [Tuning terms are defined from the perspective of wheel motion]
Downward travel of the wheel is called rebound.
Sag -- this is the amount of suspension travel used to support the vehicle at curb weight.

So what you have is basically a situation where the rear damper ride height is set so low that what you have used 100% of the available compression travel for the damper and have no travel left on the damper road. Another way to think of this is that you have 100% sag. i.e. you used all available rear suspension travel just sitting at curb height.

By raising the rear spring perch, you'll gain back some of that compression travel.

I'm going to stop there or this will be come a white paper on spring selection and where the damper should be as a % of its travel at curb ride height. As a general guideline - you want more compression travel than rebound travel. If / when you start hitting the jounce bumpers, the suspension changes character quickly (in a bad way). Bottoming the suspension is also drives very high spike loads into the chassis and leads to component and/or sheet metal fatigue.

Bottom line: Make sure you have plenty of compression travel. If the rear ride height ends up being visually unappealing to you, then you'll need to step up the spring rate.