butters149

iTrader: (1)

Hi,


I am fairly new to suspension and have a couple questions hoping to learn more of how coilovers work. Currently I have my ohlins with no pre-load on the springs in order to get the ride height that I want. Ohlins doesn't recommend running no pre-load but their height adjustment recommendation is only about 15mm up or 15mm down MAX. Initially I have tried to get the height I want by adjusting the shock body only but it would hit the CV boot.


My question is, what exactly does pre-load and no pre-load do exactly besides changing ride height? And which is the best way to drop a car? By changing the middle (spring perch) or the bottom perch (shock body)?

Iowa999

iTrader: (1)

Pre-load is both an accurate label and a very misleading label. It's accurate in the sense that it's the energy stored in the spring at full droop. It's misleading because that doesn't tell you anything about why we adjust it.

Preload determines where in the entire length of shock travel you are at static ride height. It determines the ratio of bump travel and droop travel. In general, you want to have all of the possible bump travel available. If it is possible for the wheel to move up three inches from static (before tires hit fenders, etc), then you want to set the preload such that you have 2.9 inches of bump travel.

The only other issue is that you want at least 25# of preload (maybe more), no matter what. This is to keep the springs aligned at full droop.

mi2slo

U shouldn't drop the car by using preload. Use the bottom perch, that's what its for. For ohlins I wouldn't drop it too much from the recommended settings. For preload I just used the rrecommended 2mm

Iowa999

iTrader: (1)

I'll just pretend that you simply didn't see my post (to avoid being annoyed).

When you lower a car using only the shock-body adjuster, you maintain the same amount of bump travel as before (because the shock's piston remains in the same location within the shock at static ride height). But lowering the car reduces the amount of bump travel that is possible before there's contact by something other than what's inside the shock. Therefore, you not only risk damaging contact - i.e., contact that doesn't involve a bump-stop, such as tire into the top of the fender - but you are often throwing away droop travel, which can cause you to lift an inside front tire at corner exit.

So, no, you don't always lower a car using the shock-body adjuster. You should do what I said previously: get measures of the available travel and make an informed and intelligent decision. It's not rocket science, but it isn't Legos, either.

Cyp

How are you hitting your CV boot? Do you have the Ohlins R/T?