Hi i have a 2000 chevy blazer LS and I have a problem with the lower or upper control arm. When I brake from the front nothing happens, everything is normal. But when I back up a thud is heard. I put the vehicle on drive and I arrive at a stop sign and again the dull noise occurs and this from the driver's side. Same thing when I reverse what is the problem? Can anyone help me. Thank you!

 

You need to get the wheels off and do a good inspection on the calipers and pads.

Almost sounds like a pad has become dislodged and is moving around inside the caliper bracket. VERY rare, but usually only happens when the pad is way pass due being changed and has no friction material on it any more, in which case you would have heard squeaking and grinding noises a long time ago.

Another possibly that comes to mind, somehow a caliper mounting bolt has backed out or sheared off and is letting the entire caliper shift around.

Either way, neither is desirable... Personally, I would leave it parked and drive something else until I got to the bottom of it. It's one thing to be broken down on the side of the road because the engine stopped running. It's quite another to be in a serious accident, possibly injuring yourself or others, because the braking system was neglected... I do not play around when it comes to properly functional brakes. In my line of work I see WAY too many wrecked vehicles, which really puts a different perspective on it for me...

 

i gonna check for the caliper but i change them 3 months ago, the upper and lower control arms bushing are nasty busted

 

Is yours 2wd or 4wd?

I know on my 4x4 the uppers went out and would make a pretty noticeable "pop" sound during suspension flex, either when off the pavement or in hard braking. On a 4x4 they're pressed in, so you have to have a shop press the new ones in. I'm not 100% sure on a 2wd

 

Mine is 4wd and do the same "pop" but only when i brake a little bit hard. My bushing look a little bit worst than yours