Pulsing brakes and ABS light on, related?

[lcgoatboy]

I had my 92 Camry in to a shop to have the abs light scaned.The code showed left front speed sensor. I decided to put on new front rotors and pads because of a feel of a warped rotor,took it for a test drive,seems to be the same feel (warped rotors).I though I should have changed the rear instead of the front.After reading this forum I'm leaning toward the abs light being related to brake pulsation.The pulsation doesn't feel like it would if I was on snow.Any help would be great thanks.

[LynchburgCSI]

Originally Posted by lcgoatboy

I had my 92 Camry in to a shop to have the abs light scaned.The code showed left front speed sensor. I decided to put on new front rotors and pads because of a feel of a warped rotor,took it for a test drive,seems to be the same feel (warped rotors).I though I should have changed the rear instead of the front.After reading this forum I'm leaning toward the abs light being related to brake pulsation.The pulsation doesn't feel like it would if I was on snow.Any help would be great thanks.

The left front speed sensor should be replaced then. Why did you mess with the brake pads and rotors?

[oldfirebird]

I assume you put the rotors on to kill two birds with one stone? (Wheels are off, rotors are warped, might as well do them too)
The pulse felt in the pedal or in the steering wheel? I've noticed bad front rotors in the wheel long before the pedal.
It may not hurt to pop the back ones off and take them to a garage. Ask them to surface them (not turn or cut them cause if they're warped you're better off replacing them) and explain you'll get new ones if they're warped. You'll either get confirmation your rotors are flat and now ready for new pads or they'll tell you they're warped and maybe charge you for setting one up on the lathe (Should only be around 10 bucks each) If one's warped just spring for a new pair.

[73sport]

One other possibility is that there is something trapped between the rotor and the hub creating run-out on the outer edge of the new disc.

Even at home you get a feel for run out.

Thread a couple of lug nuts and washers if needed on to the studs to hold the rotor secure. Put the car in Neutral and rest a screw driver next to the rotor. Get it as close to touching as possible and then monitor the gap for changes as you rotate the rotor (vise grip the screw driver if you can or have a helper spin the rotor). If it has changes, clean the mating surface, recheck. If it still has run-out, you might opt for replacement. Hint even new can have defects. Not likely, but possible.

As for location:
Seat of the pants vib is back brakes, steering wheel is front brakes. So, does the car shake or the wheel?


Edit: no, not related

[lcgoatboy]

Originally Posted by 73sport

One other possibility is that there is something trapped between the rotor and the hub creating run-out on the outer edge of the new disc.

Even at home you get a feel for run out.

Thread a couple of lug nuts and washers if needed on to the studs to hold the rotor secure. Put the car in Neutral and rest a screw driver next to the rotor. Get it as close to touching as possible and then monitor the gap for changes as you rotate the rotor (vise grip the screw driver if you can or have a helper spin the rotor). If it has changes, clean the mating surface, recheck. If it still has run-out, you might opt for replacement. Hint even new can have defects. Not likely, but possible.

As for location:
Seat of the pants vib is back brakes, steering wheel is front brakes. So, does the car shake or the wheel?


Edit: no, not related

[lcgoatboy]

Thanks for getting back to me so soon, I never thought of putting washers and nuts on the rotors. I do have a dile indicator at home. As far as where I feel a pulsation it's in the pedal. Honestly it feels like ABS. I'll check for rotor run-out front and rear and get back.

[73sport]

Originally Posted by lcgoatboy

Thanks for getting back to me so soon, I never thought of putting washers and nuts on the rotors. I do have a dile indicator at home. As far as where I feel a pulsation it's in the pedal. Honestly it feels like ABS. I'll check for rotor run-out front and rear and get back.

You're in a good place to find the root cause if you have a dial indicator! Hopefully you have a magnetic base, if not wrap some plumbers strapping tape around the spindle base and secure it with a bolt & wingnut and washers should do the trick.

This is more work, but I might suggest you do both sides of the rotor which would mean removing the calipers at all four corners. But you wanted to grease the slides anyways yes?! Then again you may find the answer on the outside(s).

Something you might consider while the calipers are off is to remove any suspect rotors and clean the rust between the hat and the hub. Here an angled die grinder with a 40grit scotch brite Roloc discs gets donw inside and works pretty well. Other than that its some form of manual scrapping to get the rust off.