Spring Preload & Ride Height
What Preload Is
- The load on the spring before the vehicle's weight is on it.
- It determines where the shock sits in its stroke.
- It is not the same adjustment as ride height, though on many shocks one control changes both.
Where It Puts the Shock
- More preload — the spring pushes harder, so the shock settles further extended, nearer the end of its rebound travel. Less droop left before it tops out.
- Less preload — the shock settles further compressed, nearer the bump stop. Less compression travel left before it bottoms.
What You Feel
- Topping out — not enough rebound travel, so the chassis falls into undulations in the road.
- Bottoming out — not enough compression travel, so you feel it every time you hit a pothole.
- One spring rate can give two completely different ride qualities depending on where the shock is sitting.
- If the car rides badly on good coilovers, check this before changing spring rates.
Two Types of Shock
- Preload adjustment only. Ride height can only be changed with preload, so the height you want may compromise your shock travel. You are choosing between the two.
- Preload plus a separate length adjuster. The two are independent — set the shock where you want it in its stroke and set ride height separately.
Corner Weighting
Corner weighting is more involved than it looks, and which adjuster you use to do it matters. This is where the two types of shock come apart in practice.
- If you have a separate ride height adjuster, corner weight with that. Ride height changes without moving the shaft within its stroke, so stroke position stays matched left to right — and the bump stops engage at the same point on both sides.
- If you corner weight using spring preload, you are changing stroke position at the same time. The two sides can end up sitting at different points in their stroke, so the bump stops engage at different points left to right, and the car behaves differently over a bump on one side than the other.
- If preload is your only adjustment, you do not get the choice — but bump stop packers can be used to even up where the bump stops engage. A few millimetres of difference left to right is not a problem; once you are seeing 5–10 mm or more, that is worth raising a flag over. Most people will not go this deep, and most cars do not need it, but it is worth keeping in the back of your mind when you set corner weights.
If You Run Out of Adjustment
- Usually means the wrong spring length for the height you want.
- Contact us before forcing it.
More detail and photos to follow. If you have a question this does not answer, contact us and we can help guide you.