Shaking while braking but now I hear a knock...

[surbey]

Background and setup:2004 Pontiac Vibe AWDI replaced all four tires in August. They were old, crappy, and had been under inflated for some time due to my negligence. So, the DAY that I got them replaced I noticed my car started shaking when I braked. The issue would go away (or atleast be less noticable) and then return periodically. I'm going on a car trip this month and I'd like to get it taken care of beforehand. Speaking with a few individuals, the consensus is "car shakes while braking, it's rotors."However, this morning I heard a knock when I made a left hand turn. A real distinct knock. It made it again the next left hand turn I made. I tried it once more and heard nothing. From my previous experience, this knock is a bad ball joint. (Had a Chevy Lumina that had a bad ball joint, same kinda knock, and the axel fell off)So, obviously I'm worried about driving it now and know I need to get SOMETHING replaced. Can shaking be a sign of a bad ball joint? If so, how easy are they to replace? If I don't do it myself, what kinda costs am I looking at?I have started doing my own car repairs lately and have been getting descent at it. I don't have a problem attempting an easy to moderate level project; I just don't want to get in over my head.Any help would be GREATLY appreciated.

[moonstonemike]

Well as for the shaking, yes it is most likely the rotors are warped. You can probably have them machined strait but by the you paid someone to do that you will be at the same price of buying new rotors. Plus they would generally warp again because they are machined thinner now.As for the knock i would first try re torqueing the wheel nuts. The can loosen up (Its happened on my car before, usually when aluminum rims are on it)To check the ball joint jack up the front of the car grab the top and bottom of the tire and in a quick/firm snaping motion wiggle it it and out. You will hear or feel if it feels firm or if it is loose.You can also grab the sides of the wheel and do the same motion to check the tie rods.If you do all that and you still get a knock then it could also be a broken swaybar link or your front strut needs changing.

[star_deceiver]

Does the knock change with speed? you might have a bad CV joint.

[surbey]

I do not hear the knock with high speed. Both time I was accelerating through a turn.

[star_deceiver]

Quote, originally posted by surbey » Both time I was accelerating through a turn.Did it make a clunka clunka clunka sound that went away as soon as you straightened the wheel? Or was it a single sharp knock as you straightened the wheel?

[surbey]

it was a knock while I was turning and beginning to straighten it out.this afternoon I noticed it knock while I went over some bump asphalt. This time, I was going in a straight line.

[star_deceiver]

Quote, originally posted by moonstonemike »To check the ball joint jack up the front of the car grab the top and bottom of the tire and in a quick/firm snaping motion wiggle it it and out. You will hear or feel if it feels firm or if it is loose.If you do all that and you still get a knock then it could also be a broken swaybar link or your front strut needs changing.Check this ^^^ But it's most likely the ball joint, IMO.

[keithvibe]

I would also check the most basic thing.... check all the lug nuts to be sure they are all tight. Years ago I was driving one of my cars and felt a wobble. I pulled over just in time to find that I had two out of five lug nuts left.