Knock Knock Sound After Braking

[1956elli]

05 Land Yacht 30ft

After braking to slow down like at a light after I let off on the brake pedal I get at knock knock sound or clunk clunk does not have a metal ping to it. The sound is evenly spaced until I apply brakes again for complete stop

If I just touch the brake it goes away - any ideas

Pulled front tires can see no problem or play in anything - no in or out movement when pressure is applied to tires, ball joints have been replaced 2K ago

[davejay]

Hey
Do you have a tag axle if so maybe the electric brakes are sticking.
U joints maybe.
Sounds like a brake is hanging up. But wouldn't t be a clunk
Maybe a control arm bushing
Does it do it when the brakes are cold. Like the first time you stop.
If not only when it gets warmed up. I'd be looking at a caliper
Do you have rear calipers.
I'd check them too. If you got a caliper hanging up you should be able to feel the hub it ll be a lot hotter than the other three.
Here s a weird possibility. The master cylinder could be hanging up. Give iij ng you hot brakes all around. Had that happen to me once.
Dj

[Waipio Rim]

Does it have ABS? This sounds like something my Tundra does when it loses traction.

[1956elli]

30 foot so no tag

Drive line is good

Only does it after been on the road a while

Only does it after I take my foot off the pedal on coming to a stop and I take my foot off pedal before complete stop Example - exit interstate to a rest area - slow to enter rest area then coast a bit

If I just touch the pedal the "thump" sound goes away

No pulling to either side - no hot rims

[davejay]

Hey
Maybe a motor mounts. Could a transmission mount.
Is it a deep sounding clunk.
How is your dog bone. That's the bar behind the rear diff. It keeps the rear end square . Sometimes the bushings get sloppy and then the rear end can shift side to side. . Is the noise up front or somewhere else under the coach.
If it's a mechanical thing we ll find it.
To test for a motor mount put it in gear foot on the brake and put a little gas to it. If you got a motor mount gone the engine will lift up. Try it in reverse too.
Oh you got to take the engine cover off to observe the movement. The engine will normally have a little lift to it. But your trying to get it to clunk. The engine shouldn't t lift more than an inch.
Hope this helps. DJ

[1956elli]

Mounts are all good

Pulled tires and calibers off both front and cleaned and reinstalled

Hope to get test drive in the next few days and will advise

The "clunk" sound is receptive as if something is turning and making the sound over and over

What makes me think its something brake related - as I let off the brake to slow down and left off the pedal the sound will start - but - the slightest pressure back on the pedal sound goes away and does not come back

Will see how test drive goes

Thanks for all suggestions

[BayouBiker]

Sounds like one of the leading disk caliper cylinders is sticking just a bit so it goes toe in after breaking, when you tap the brakes again it the lagging cylinder evens it out.

[davejay]

Hey
I think you got a warped rotor. Does your steering wheel have any shimmy when you brake. If it s front rotor you ll feel it in the steering wheel. If it's a rear rotor probably nothing at all. Do you feel a kind of pulsing as you slow down. These things are heavy. On a car you d feel pedal pulsation and a kind of a pulsation while stopping . A sticking caliper will hold the pad against the rotor upon releasing your foot off the pedal the shoe kind of glued itself to the rotor. It ll pop or clunk I guess when you first start moving. Are your rotors shiney. Or are they a little brownish . blueish means you got a ca lip iper that's not releasing. That's my guess too caliper hanging up. Can lead to a warped rotor. Narrowing the search DJ

[1956elli]

Well I think I have the problem fixed - 200 miles and "klunking" sound is gone
After jacking up rear end and spinning drive shaft - all good
Removed passenger side front tire and brake caliper - found no problem
Removed driver side front tire and brake caliper and noting caught my eye as a problem
Then I removed the outer brake pad and noticed that where the back of the "ears" on the pad sit against the caliper there not a flat surface. Appears when caliper was cast there was a bit of extra metal that stuck out just about 3/16 - therefore the top of the pad was hitting the rotor and the bottom was not - so filed it flat and now have good 90 for pad ears to sit on.

OR - just taking apart and clean up fixed the problem

Don't know for sure but noise is gone and after checking ever bolt, screw, steering link and drive shaft part I think its good to go

[davejay]

yup.
That could it. You'd think the pad would seat itself once you put the brakes on a couple of times. I ve had to file a couple of pads too. I don't trust any of the parts stores anymore. Seems like the quality control just isn t there anymore. And the people behind the counter just don t know anything.... or. Im just getting old crabby and impaicent. DJ

[OTRA15]

Glad the problem seems to be fixed.

FWIW the “Knock Knock” in the headline reminded of this:

“If this van’s a’rockin’ . . . don’t bother knockin’ . . . “



FWIW