pulsating brake pedal?

[sewlow]

The main wiring connector to the ABS unit itself.

Thank you!

 

[great white]

Uneven wear would show as run out also (I assume you're checking with a dial). From what I have read (And I may be wrong so feel free to correct me) it takes farm more heat to warp a rotor than is commonly thought. I think the magic number was like 1200 degrees but don't remember exactly.

Yep, it can on a dial gauge. You typically don't put a gauge on a brake disc though, too much time to bother with when doing it for a living.

I've seen 'em warped on a a brake lathe by watching them spin. It's obvious. Often, when turning them down they would drop below min thickness before you got them to run true. So you'd end up chucking them anyways.

I used to put the caliper on the disc and if it was close to min thickness I would recommend they just replace them as cutting them would usually nuke 'em. Even then, lots of customers would gripe to just cut 'em. I would, they'd go below min spec and then get accused of turning them too much on purpose. They got even more irate when they had to pay for turning the rotors and buying new ones anyways. They were told that up front every time; my labor is not free and we did it because you insisted. Still didn't change their griping. It got so bad at one point that I would just refuse to cut certain rotors and would send them away if they didn't like it. just not worth it.

Last I worked repair for a living, it was getting so bad that almost every OEM rotor was damned near min thickness right off the dealers lot. I'm soooo glad I got out of it.......just not worth the hassle anymore.

As to what temp they warp: meh, that's only a part of the equation. Duration of heat soak is just as important as absolute temperature. So is temperature delta across the disc. Same with the disc construction.

Duration is the same idea with running diesel EGT's at 1400F for a short period and do no damage, but run it consistently and you will eventually melt 'er down.

Look at it this way: lets say you get to 400F on a brake disc during heavy breaking. No worries, well below the iron's capability to handle. But, sit at a stop and the pads insulate roughly 1/5 of the disc. the rest start cooling immediately but that 1/5 stay relatively hot. you end up with 3-400 degrees in a localized spot and the rest dropping to around 200 (these are ballpark number pulled out of the air, but work for the purpose of illustration). It you have a 100-ish degree difference across the disc, it is going to move. Heat anything to 100 degrees in a localized area and you can watch it twist.

The question is when it all reaches an equalized temperature whether or not the memory in the metal is sufficient to return it to it's original shape. That's where quality and construction comes in to play.....

 

[great white]

Thank you!

There should be no ABS light if you unplug it there also.

Be careful when/if you unplug it. It should go into bypass, but if it doesn't you may have some odd braking.

It's designed to do so when unplugged, but it's also meant to be hooked up and functioning so tread with caution until you know it is going to react like it should....

 

[SkyHighColorado]

OK so mine isn't all the time. Today the brakes were decent not much on and off feeling at all, but a day or 2 ago was terrible! I'm blaming that abs bs that doesn't even work. I guess its time to bypass and bleed more.