First off, I apologize if this is in the wrong section, and if it is, could a moderator move it?

I own a 2004 Chevy Blazer 4x4, and just finished replacing the front wheel hubs and front brake pads. I did check the rotors and they looked fine. After pumping the brakes, I took it for a drive to make sure everything was fine.

The noise from the old wheel bearings has completely disappeared, but a new issue has arisen. Whenever I brake, be it slowly or suddenly, after about a second, I hear a very weird grinding noise, almost like a motor firing up, then spinning down.

During the work I did, I did check the ABS cables going to the wheel hubs, and they were filthy so I cleaned them off and reattached them both securely.

Could this be caused by the ABS? Or is there something else going on?

 

I think your thread placement is fine.

How many miles have you put on the new pads? All pads have a break in period till they have mated with the rotors and I have seen noise coming from fresh pads till the are broken in many times. Also what type of pads did you use? Different pad materials make different noises.

 

When I purchased the truck last year, it had just over 50,000km on it which is barely broken in. The original owner barely drove it and kept it in his garage, which is what led to me having to replace the front wheel hubs (it sounded like constant tire noise while driving). Right now, it's at over 60,000km after a year of driving to and from work.

The original pads that were on the truck when I bought it were completely gone (even the chirp alarm snaps were worn down) and needed replacing, so these brake pads are brand new out of the box, and they are mid-grade (cost me $40)

As for the noise, well this isn't a brake pad noise. This sounds almost like a motor, and it sounds like it's coming from the front driver's side tire. As well, I can literally feel it in the brake pedal when it starts. The brake pedal pushes up and back down.

The new hubs came with brand new ABS lines, but we just used the old ones. Again, I'm wondering if it's something to do with the ABS, and I'm debating on just unplugging the ABS on the front tires, but I'm not sure if that is the cause of this sound.

 

I was actually asking how many miles you have driven since you put the new pads on. If your pedal is pulsing it could also be a warped rotor but you "should" be able to feel that in the steering wheel as well. Also what material are the new pads made of ceramic, metallic, semi metallic..?

 

Sorry :P

I just put the new pads on (as well as the new hubs) about 30 minutes ago, and had to return some rented tools. That's when I noticed the noise. So this isn't even in miles yet. This was just a few kilometers. Every single time I braked, I'd start stopping, then towards the end of the braking, I'd hear the noise start up, then stop and the brake pedal would fluctuate.

As for the pad material, they are mid-grade, and look to be made out of a combination of things like asbestos, what looks to be flecks of copper, etc. This never ever happened before I replaced the wheel hubs and brake pads.

Now I did find this post in a related thread:

Very very similar to what I have going on, except it's a very noticeable noise, and I can feel it in the pedal. Last I checked, the ABS wires were fine, nothing severed, but the connectors were filthy, and I did clean them off.

 

It's possible and not uncommon for the abs cables to get damaged during a hub replacement. If you have them I would swap them and also make sure you clean the abs sensors really well. It may be that one of the sensors/wires is damaged or dirty and causing the abs to kick on due to a bad reading. My abs is loud and I understand what your saying about sounding like a motor.

 

They probably did get damaged during this hub replacement because I had to grab a prybar and a sledgehammer and beat the heck out of the old hubs to get them to separate from that circular panel behind the hubs, because they were rusted together. (I think it's a dust cover of some sort, the ABS line comes through a hole in it, and plugs into the hub). I was pretty careful about not damaging brake lines and the ABS cables and such, but something may have happened.

I do indeed have the new ABS cables that came with the new hubs. I thank you for the info, I'll look into swapping the cables out, and if all goes well (or doesn't) I'll reply back

 

Rust could have gotten on the censer causing the abs system to think the tire is locked up.

 

Also just remember that just because there is no visible damage doesn't mean there isn't actuall damage. IIRC the abs cables have a protective sheathing over them and its common for a wire to break inside there during R&R of a hub. Like 4x4 suggested look for rust or debris something may have fallen in front of the sensor during the work.

 

Hmmm, yeah....Just remembered though, it seems to do it 100% of the time when I brake hard. Halfway home, it started doing it when I would brake slowly to come to a gradual stop.

But no matter how I braked, it was always at the end of the braking.

I'll swap the ABS cables out tomorrow and see how she handles.