99audia407

My girlfriend has a 99 Audi a4 quattro and we stopped to get gas yesterday and when we were leaving it felt like one of the rear brakes was locked on but we kept driving and it seemed fine until we got about a mile down the road and there was a chattering noise coming from the rear end and all of a sudden it locked up. We had to get home so we kept driving and it will do it every once n a while but if you seem to stomp on the breaks that it will let it break free so I was thinking maybe one of the pads broke loose ( everything is only about 3 months old) but I was wondering if these cars had any issues that maybe I should check into. Thanks.

Huskerbob

( everything is only about 3 months old)

Are you talking about a recent rear brake job? If so you need to get the vehicle back to that shop for a diagnosis.

You can take a look yourself if you have the tools and skills.

Sounds like something is hung up in a wheel or axle.

99audia407

Yes I was referring to the brake job, new rotors and pads all the way around and a new right rear caliper. I took everything apart tonight and everything free spins, the pads seem fine, nothing looks out of the ordinary and I checked all the abs sensors to make sure nothing was broken and everything was clean. I test drove it after and as long as you are on the throttle its fine but when you let off it sounds like something is starting to catch but as soon as you get back on the throttle it goes away, I'm just not familiar with these cars at all and am not sure which direction to go, any help is appreciated

Huskerbob

When you said it "locked up" what exactly did it do? Did you start dragging a wheel or wheels?

Make sure your emergency brake is working properly.

When you took the wheels off did you by chance see what sort of play you had in the suspension by trying to move stuff around?

99audia407

I can't tell if its one or both wheels, I tried to get it to lock up and get out jack it up quick and see if one or both wheels were locked up but I can't seem to do it quick enough or putting it in park seems to be freeing it up I'm not sure. I tried to check some of the suspension components by hand, not having a pry bar on hand, and it seemed ok but with the getting on and off the throttle I wasn't sure what to make of that. It will break perfectly if I keep one foot on the throttle and use the other to operate the breaks. Also parking break seems to work fine and I even pumped the breaks a little to make sure the caliper pistons would turn back in without any issues

Huskerbob

and you checked the cv joint boots and they are all okay and not torn?

Next place to look it at the center drive shaft. It has cv joints at both ends and a carrier bearing in the center. Maybe something there is hanging up.

Mine makes a clicking noise once in awhile but it hasn't caused any problems like you describe. In my case it's the rear cv joint on the center drive shaft.

To get at it you need to jack up all 4 corners and slide under. There is a heat shield held on by four nuts and you have to sort of bend it around to get it past the exhaust pipe.

Then you can inspect the shaft to see if it is loose or by rotating it you may be able to tell if it catches someplace. ??

99audia407

The only problem is that the car is an hour away from me because she's at school but I'll keep you updated when I get the car home and I'll put it on my lift, I don't wanna do it on the ground in the snow lol but thanks for the help so far

tommyleea

Why was the caliper replaced? Maybe your brake hose is bad. They sometimes collapse inside and casue lockup. Or, maybe that side is working, and the other side isn't, making it appear as it is locking up. Just a thought. If it was fine prior to the brake work, then I would focus on that area first.

99audia407

The caliper was replaced because the piston boot was ripped and I couldn't get the piston to push back in but the brake job was done about 3 months/ 7000 miles ago and like I said it just started doing it after stopping to fill it up with gas but the brakes seem to work properly I just have to keep my foot on the throttle and keep the rpms up and it won't lock up, the more I think about it I think its a bad pinion bearing or something in the actual drive line to the differential

99audia407

Just wanted to let everyone know that it was a bad pinion bearing, when it locked up its because the pinion gear was grabbing the spider gear housing...got a new rear end for 150 bucks and she's back up and running. Thanks for some of the advice.