V70 Brake issue - shaking

chiefpontiac · Post by **chiefpontiac** » 07 Feb 2011, 13:21

I've got a 2000 V70 that has had intermittent brake issues where the car starts to shake at 55mph or above after I've done some city driving before I get on the highway. My gas mileage goes down to 15mpg and the rotors get hot, sometimes driver's side, sometimes passenger side. After it started it took about 3 weeks before my brakes were basically "locked" on. I bleed the lines, but no results. I replaced both calipers, hoses, rotors and pads on the front. The car ran great for a few days and it started all over again. Drove around town, got on the highway shook all the way to work. Parked it, left work later in the day, drove home, no problems. Could it be the ABS pump assy or something else? No lights, no codes.

Post by **jblackburn** » 07 Feb 2011, 13:38

Pull the fuse for the ABS system (I forget what number it is) and see if your problems go away and stay away.

Does your car have a TRACS/STC system? (you will have a button on the dash near the sunroof and INFO switches). If it does, the system may think the wheels are slipping and applying the brakes to "correct" that. The wheel sensors may need a good cleaning.

Bleeding the brakes would make sense if the brakes stuck on all the time, but this sounds to me like it is something related to the ABS system as you thought.

chiefpontiac · Post by **chiefpontiac** » 08 Feb 2011, 08:15

I pulled that fuse, the ABS light came on, but the car started but wouldn't stay running. I put it back in and the car stayed running. Am I doing something wrong?

Post by **jimmy57** » 08 Feb 2011, 12:26

I think I'd jack up the front and apply the brakes and then turn wheels by hand with it in Neutral. I think you have a seized caliper.
If the wheel or wheels are hard to turn then kick the tire (it will push back the pads if the caliper is only tight from last brake apply). Then retry wheel turn.
If the wheel or wheels remain tight then loosen the two nuts holding master cylinder to booster. If wheels free up then it is not caliper it is a brake booster problem instead but you may have to replace front rotors and pads in addition to the booster to get proper smooth brakes once again after they have overheated that bad.

Post by **vjaneczko** » 08 Feb 2011, 20:23

If you replaced all of the braking parts and the problem still exists, take a look at the tie rods (inner and outer), the control arms and the hubs. Jack up the wheels and see if you can wiggle them side to side or top to bottom. They should be rock solid. Any movement and you have suspension issues.

chiefpontiac · Post by **chiefpontiac** » 17 Feb 2011, 04:50

Since I replaced everything including the tie rods, I disconnected the ABS control module and the problem has seemed to go away. I've driven over 100 miles without a repeat (of course I have no abs or speedometer or odometer using a GPS to monitor speed). Anybody replace an ABS module before? I'm looking at getting this one rebuilt. My V70 doesn't have traction or stability control on it.

Post by **vjaneczko** » 17 Feb 2011, 20:37

There's plenty of write-ups to repair it yourself (https://www.matthewsvolvosite.com/forums ... 6827#46827), if you're handy with a soldering iron.

If not, track-down Matty Moo (https://www.matthewsvolvosite.com/forums ... le&u=13052) who can fix them for you.