Shocks: Rebuild or Revalve?

One of the benefits of a good set of coilovers is that you don’t have to throw them in the trash when they wear out. Not all shocks and coilovers can be serviced easily, but it’s something to consider when purchasing a set of shocks.

Okay, your shocks have 40 track days, 60 autocross weekends, and 50,000 miles on them. It’s past time to send them in for service. But do you need a rebuild or a revalve? What’s the difference?

First, a rebuild will return your shock internals to factory fresh. Shock fluid gets old, seals wear out, and you may lose gas pressure. You’re usually not replacing the piston and shims unless they’re damaged. Rebuilds are normal shock maintenance.

A revalve includes all of the above as well as changes to the actual valving of the shock. This means changing out the piston and/or the shim stack controlling how the shock actually functions. You’re changing the compression and rebound characteristics of the shock.

So why would you want to change things up? Let’s say you were running Michelin Pilot Sport 4S tires when you first got your coilovers. In the next year, you got a little faster, you switched to those new sticky Falken RT660s, and you bought a used 2012 Subaru Forester as a daily driver. You might want stiffer springs to better control body roll and make your car a little more responsive.

If you’re planning on a big change in spring rate or overall change in chassis behavior, your shocks may require a revalve even if they’re adjustable.

A common rule of thumb is that a change of more than 2 kg/mm (112 lb/in) in spring rate requires a shock revalve, but this is highly dependent on the shock you’re using. Some adjustable shocks are flexible enough to handle that and more without issue. Other shocks have lots of adjustment range on paper, but the way their adjusters work means that the extreme ends of adjustment are not consistent or have other compromises.

Plus, being stuck at one end of the adjustment range means you don’t have much room to fine tune anything.

If your shocks are leaking a lot, making lots of noise, or just feel extra sloppy, it’s probably time to have them serviced. Intervals vary by manufacturer and your usage. Nothing lasts forever.

Some shocks are rebuildable but not easily revalveable. This doesn’t mean they’re bad shocks, just that they are designed for a specific application.

Whether you’re looking for a simple rebuild or you’re thinking about a revalve, talk to your suspension tuner or shock manufacturer about your options.