Bad ABS hydraulic unit

[rebrown]

Anyone had to replace their ABS hydraulic unit. I think mine is bad. When I brake I get a slight pull to the right. In the past year I replaced all ball joints, tierods, idler arms, shocks, pitman arm, had it aligned. I just recently replaced both calipers again. Only thing I can think of is that I have some blockage on the opposite side. I put it up on a jack and had my wife give a little brake pressure and can feel a difference in the amount of braking between the front tires. Any help is appreciated.

Thanks,
Rob

 

[Redwingvksm]

Anyone had to replace their ABS hydraulic unit. I think mine is bad. When I brake I get a slight pull to the right. In the past year I replaced all ball joints, tierods, idler arms, shocks, pitman arm, had it aligned. I just recently replaced both calipers again. Only thing I can think of is that I have some blockage on the opposite side. I put it up on a jack and had my wife give a little brake pressure and can feel a difference in the amount of braking between the front tires. Any help is appreciated.

Thanks,
Rob

1. Whad do you mean you can feel the difference between the amount of braking between the front tires? She held the brake and you spun the tires? Only a 'little' pressure will not be the same as normal braking so don't waste your time with that.

2. You have brakes. Where did you get that it may be your hydraulic unit? If you have abs than it's good.

3. Try to flush the brake fluid? That gets NASTY in 6 months even in a sealed system. Try to flush the brake fluid.

4. Check the rotors/pads. Look for any discoloration on the rotor, any un-even wear on the pads. Even a SLIGHT amount of rust will throw everything off.

5. Are your rears cleaned/adjusted? The rears can cause that too if one side is engaging way before the other. Have them cleaned/adjusted (you can do this w/ a regular garden hose.)

6. Just because you recently replaced the callipers doesn't mean that you DID NOT get a good one. This type of mistake is made all the time.

That's all I can think of for now - if I come across more I'll let ya know

 

[rebrown]

On your point #1. I had the front up. And with a slight pressure on the brake pedal, I was able to spin the drivers front tire and not the passanger side. Hence one caliper was getting more fluid/pressure or the other was not and possibly a restriction in the line or in the solenoid valve of the hydraulic control unit of the ABS.

2. I read that if the blake fluid doesnt get changed out every 3 years, there could be a possibility that moisture built up in the fluid could corrode the hydraulic solenoid valve and you could get a restriction.

3. Did that.

4. Replaced rotors/pads, same issue.

5. On the rear had replaced the drums the following month. Checked everything. No change.

6. This is the second caliper in 6 months. It releases fine when I let off the brake.

One that I have noticed is that when I first start off it will brake straight for the first couple of miles. Then it will start with the issue. Also, when your running over 40mph and step into the brake a little to slow down, I'll get a noticiable brake pull and then release( almost like you pull the steering a little then bring it back to center).

thanks for your feedback though.

 

[Redwingvksm]

The way it warms up and than pulls - that does indicate that the pads/rotors are something to blame, but let me think more.

Everything is flushed out from the caliper change over...how are the tires? Are they un-evenly worn? That would make a huge change - remember too when you press the brakes the nose dives down so your steering geometry is kinda goofy.

Hm...i'm running out of ideas here! lol - it may be a plugged up valve - have you tried to do abs stops (5-10) and than re-flush the system to see if you can get some gunk out?

 

[rebrown]

I'm off next week, so I'll do a complete flush.

Thanks,
rob