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So I was trying to change out the wheel bearing on my left wheel and had a friend press the brakes so the wheel wouldn't spin while I loosened the center nut. But they did this while the car was off, which I realize in retrospect wasn't the way to go, since I should have had my car turned on while they press the brake pedal. Now my brakes aren't as responsive. I have to press them nearly to the floor just to get my car to slow down, while before, the same action would have locked up the wheels and it would have been a hard stop. So now what I need to know is if I did something where I have to replace a part of the braking system, or is it something that just has to be adjusted? (ie the brake pedal). I'm taking my car to the mechanic on Monday just to be sure, but any help would be appreciated. I checked under the hood and the brake fluid reservoir is at max, so no leakage.

Sorry to break it to ya but the only difference between pressing the brakes when the car is on or off would be that there will be no power assist with the car off so the brakes will be MUCH harder to press. So other than that there is no difference, you must have messed something up or something happened.

+1

Check for leaks around the wheel or wheels you were working on. You may have clipped a line or pulled on something you should have. Check the master cylinder fluid level. If it has gone down that's a good indication that it's leaking. I had a banjo bolt on one of my front calipers just decide to loosen off one day and lost my brake pressure completely in traffic. Super fun.

Other than that, make sure that the vacuum hose on the booster is in place and intact (not kinked or split or punctured) and have a general look around all the hydraulic lines from the master as far as you can. I'm betting you'll find a leak somewhere.

And the others are right. There is no issue at all whith applying the brakes when the engine is not running. That is not the cause of your problem.

So I got the wheel bearing replaced. But it wasn't a good idea to leave the busted bearing in for so long. In doing so, The hub bearing, along with the rotor, got bent/warped. A new hub bearing should come in the mail today and I'm gonna replace both those parts, which might or might not fix my brake issues. Anyone experience this? I'll keep you guys posted on the what happens

It's sounds like you're maybe being misinformed...or that you might not fully understand how the hub and spindle are assembled.

There is only one bearing in the hub assembly. If you've already had the wheel bearing replaced, there is no other bearing in the hub assembly.

Look at this picture from the repair manual...
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The Wheel Bearing presses into the Steering Knuckle and then the Hub presses into the ID of the bearing. If the wheel bearing was already addressed and someone is telling you that the "hub bearing" is warped they are either mistaken or lying to you.

The hub itself or the steering knuckle may have been damaged by riding on a bad bearing for a long time, but I highly doubt that. Rotors are cheap so I would suggest changing them if you're not sure because it's good maintenance. If the wheel bearing has been changed and there is still a hub alignment issue either they installed the bearing incorrectly or there is a problem with the hub itself. If someone installed the wheel bearing for you and it's wrong they should be replacing it not you.

Yes #4 in the diagram is the only bearing you have. They sell for around $60 and usually the strut assembly is removed to get them pressed in. I did mine, brought the struts into a garage and they did them on their press for around $30 bucks. Rotors usually warp from heat and or being worn too thin. Umm, you could cut a hole in the floor of your car then the brake pedal would have more room to depress and that would solve that problem. Cheers

Even if your rotors are warped you would still have regular braking if they are warped you can have them shaved (if in specs) or just buy new ones, shaving them is half the price of new. The main problem with warped rotors is your car has a slight vibration when the brakes are applied. Rotors can be warped for a number of reasons, as mentioned above, one of the most common reasons is not putting the tire back on at the proper torque, which most regular hobbyist don't have torque bars for putting tires back on.

yes, sorry, #4 in the diagram (the wheel bearing) was replaced and #2 (the hub assembly) is what will be replaced along with the rotor. but keep in mind, the braking problem occured BEFORE installing the bearing. As I said earlier, I tried to change the wheel bearing myself but couldn't loosen the lock nut. I had my friend press on the brakes to keep the axle from spinning while I tried to loosen the nut (and the car was off which would have stiffened the brake pedal). But i couldn't get the nut loosened so I put everything back together, and the brakes weren't as responsive as they were since then.

You may have damage the rotor when you did that or something. But the question of applying the brake with the car off is not an issue at all.

as a person of former brake problems and many accidents due to it two things come to my mind when u say u lose pressure one is a leak in the line even the smallest pin prick in a line can cause air to get into your system. which is how your pedal would fall to the floor the other is ur mc is failing i would bleed the brakes first and see if that helps. also when bleeding the brakes use the right wrench for the bleeder screw if u strip it you will not be able to get the screw out.

It's not uncommon for the axle nuts to be a real SOB to get off. I used a 5ft. pipe with a 280lb guy bouncing on the end of it to get a nut off my car. So ya sometimes they're really tight. Just make sure they go on real real tight when you reinstall them. I think the torque is like 220ftlbs but check the manual.

got my car back, brakes are fine! There was a nut or a bolt or something or other that wasn't properly fastened that was causing my brakes to work under par. But it's good to go now. On another note, I now have to get an alignment, my car veers a little to the right, but at least my bearing doesn't squeel when I make hard turns