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Aurornistoday at 6:12 AM1 replyview on HN

> so you can hit them at significant speed and not damage anything.

That’s the point. They’re not supposed to damage the car. They’re supposed to be a little uncomfortable if you’re going too fast.

It’s more reminder than a physical stopper.

> In fact the faster you hit them or the more load you're carrying the better the suspension handles it because you open up the high speed compression valves.

This is a case of knowing just enough about a topic to be dangerous.

Entering the higher shaft velocity part of the damper curve doesn’t mean the suspension is handling it “better”. The high speed behavior of the valving simply means the damping forces aren’t increasing linearly with shaft velocity. They trade extra travel for reduced peak forces.

Make no mistake, though. The faster you go, the higher the forces. The high speed valving (if the OEM dampers are even digressive) isn’t changing that.

If the speed bump is tall enough and the bump stops get completely compressed you could bottom out the damper, which is not good for it.

> I'll often hit them at 30mph+ with no issue.

Just because nothing immediately breaks doesn’t mean you’re reducing the life of the OEM dampers. Repeated high speed impacts and will shorten the life. Getting the wheels bumped up into the range where you’re compressed bump stops transfers a lot of energy into the bushings and other components.

> Rolling over them at a slower speed where your shocks stay uncompressed forces your whole car to go up and then down again, instead of absorbing the energy in the shocks.

That’s the ideal way to do it. This is better than the sudden sharp impact of high speed crossing. You’re not doing your car any favors by driving quickly over speed bumps. Fortunately for you, OEM replacement dampers aren’t too expensive but replacing prematurely worn bushings is kind of a pain.


Replies

potato3732842today at 1:22 PM

>This is a case of knowing just enough about a topic to be dangerous.

>Entering the higher shaft velocity part of the damper curve doesn’t mean the suspension is handling it “better”. The high speed behavior of the valving simply means the damping forces aren’t increasing linearly with shaft velocity. They trade extra travel for reduced peak forces.

>If the speed bump is tall enough and the bump stops get completely compressed you could bottom out the damper, which is not good for it.

Oh the irony!

In practice none of the suspension parts on any car are in any danger until you run out of up travel and determining where the deflection will happen becomes a competition between the air in your tire and the suspension components.

No automotive suspension is designed so that the damper bottoms out. You'll have an external bump stop somewhere, sometimes on the damper shaft, in any case the damper itself isn't bottoming out, you'd know, probably even hear it specifically if it did.

Regularly traveling rough roads, hitting rumble strips, comically out of round tires or anything else that creates oscillation is going to be way, way, way worse for component longevity (dampers, bushings, etc) than a hard bump from time to time.

Source: live it