single knocking sound in front end

[Kruzer]

I have a 98, 4x4 with 130k on it. When I brake, I get a single knocking sound. Today though I heard from one side then the other. It was the first time for that.

So far I changed the upper and lower ball joints, all new front brakes, new shocks, control arms ( last year one of the arms was done and recently the other was) and new sway bar bushings. The truck rides tight, it should after all that, and I don't hear that sound even over hard bumps. When I turn ether direction I don't hear it. Only when braking. When I lightly brake and don't hear it, I will apply more pressure and it will do it. I had a mechanic that I've known for years and is good go over it a few times. He found nothing. He went through the front brakes, taking them apart and reassembling them thinking maybe a caliper might be the cause and still it does it. It's to a point where I've run out of possible causes. Again, it won't do it over any bumps at any speed but if I come to a almost dead stop, BANG. The sound of it sounds like a medium clunk, to say not heavy steel or light. Just today as stated, it went from one side to the other.

It's the first time posting and was hoping to get some clues. My last resort is the stealer.

 

[4x4Dude]

You should take a video of the problem so we can hear what you are experiencing. that really helps a lot if we get that

 

[green03]

it could even be a little drivetrain slack somewhere that is normal and you might be hearing the transmission downshifting when coming back to idle. This is pretty common on a 4x4 since there will be a little bit more slack becasue of the transfer case. If it always happens at the same speed I would put money on the transmision downshift causing this and it being perfectly normal depending on how bad it is......

Matt R

 

[Kruzer]

Originally posted by 4x4Dude
You should take a video of the problem so we can hear what you are experiencing. that really helps a lot if we get that

I'll try that.

 

[Kruzer]

Originally posted by green03
it could even be a little drivetrain slack somewhere that is normal and you might be hearing the transmission downshifting when coming back to idle. This is pretty common on a 4x4 since there will be a little bit more slack becasue of the transfer case. If it always happens at the same speed I would put money on the transmision downshift causing this and it being perfectly normal depending on how bad it is......

Matt R

It's not the drive train. It's happens when I just about come to a stop, I can be rolling in first and then hit the brakes and "POP". I can be rolling very slowly with the brake applied lightly then give it more pressure and it will do it too. I've had many 4x4's and never heard this including a 83 CJ which I used to beat the crap of in the mud. I purposely went over a road today that's loaded with frost heaves, pot holes to see if I could hear anything and nothing.

Since it happens when I hit the brakes, would the calipers be moving and make a loud enough rap? The brakes were gone over again but nothing was found.

I'm going to make a sound/video file as suggested and get another guy to look at it that I know.

Thanks for the replies.

 

[AvroAero]

Is there a change in braking power after the pop? Not a sticking caliper?

 

[Kruzer]

Originally posted by AvroAero
Is there a change in braking power after the pop? Not a sticking caliper?

No change in braking. I can roll at walking speed and it will do it. i talked to a friend who had a F150 and he asked about a clip in the brakes. I also had a old ford van that the clips would break and the caliper would move. It would make a similar sound that can remember. I'm starting to wonder if that's the deal. Is there a diagram out there that shows where this clip would be? Also could I move the caliper by hand if the clip was the culprit or would it take the force of the truck to do it.

 

[Kruzer]

I found the source of my knocking sound. It seems when the mechanic who did my brakes reinstalled the old clips that were worn. The pads showed signs of moving. I put new clips in and no more sound.

 

[AvroAero]

Glad to hear!