simonstorey

How many of you have done any full brake stops at high speed?
I'm trying to figure out the ABS capability of my 1991 C4 and I've had
a few different experiences now.
The first stop was from around 100mph on mostly smooth freeway with a few bumps. The wheels chirped a few times from lockup and I had the modulate the brake pedal myself.
The next time on the same section of freeway I was able to go full braking and could feel the brake pedal and ABS doing it's thing. There was no lockup at all - even on the rough road.

Spyerx

Just get in the pedal hard and don't modulate. You'll know if abs is working.

Earlydays

+ 1...push the pedal "through the floor".
It's surprising how many first time autocrossers I've instructed at AX Schools that have never experienced ABS braking on the street.

Spyerx

What's even more fun on the more modern cars are things like ice mode and abd modes. Fking unnerving on track. One day I'll put a proper Motorsport system on my rs.

simonstorey

It felt a little different both times.
I guess I'll have to head out again for some high speed stops.
Oh the things I have to do...

Goughary

Keep in mind that many of our cars have sticky pads due to plate lift (corrosion under the spring plates in the calipers). This dramatically affects the abs performance. And isn't all that safe either.

So, if you change your own brake pads, notice the pad travel and make sure that you don't have plate lift before testing the abs...cuz your test results won't tell you much. (This btw is the case w my car and the reason I am rebuilding a new fresh set of calipers to swap out)

Also...and this is probably obvious...test your abs in the rain first. Cuz if you are locking your wheels at high speed in the dry, you're going to have terrible flat spotting...

cajonfan

Also remember that our cars have three ABS channels (front left, front right, and rear axle) and that feeling the ABS "working" through the pedal does not confirm all three channels are actually working. Sneak up on it!

This is one of the reasons why I wanted a tester for my C2 ABS.

simonstorey

Good idea about testing in the rain.
It's not that obvious because we don't get rain in So Cal!!