Weird noise from brake pedal??

[Gemini]

I've noticed this strange "knock" sound coming from my brake pedal. I've been trying to diagnos it while driving and notices that it doesnt always make the sound. This is what I'm exeperiencing, when I press on the brake pedal to stop and have my foot on the pedal for more than 10 seconds, upon releasing/removing my foot from the pedal about 1-2 after I hear the pedal make a "knock" sound (kinda sound like something hit the firewall) If i just press the break a little for a short period of time it does dont it, only when moving off from a stop sign, stop light after I've had my foot on the pedal for little longer time. I've took a quick look at the pedal but nothing looks strange to me. I'm wondering if this might be a issue with booster? Any comments?

[LinX]

My brother is having similar symptoms with his del sol. Every time he brakes it makes a knocking sound and it feels like theres a cam lobe rotating under the brake pedal. I told him to check the rotors and more importantly the axles.

[Gemini]

My brother is having similar symptoms with his del sol. Every time he brakes it makes a knocking sound and it feels like theres a cam lobe rotating under the brake pedal. I told him to check the rotors and more importantly the axles.

I'll check my axles tomorrow and se whats up.

[Gemini]

bump....still havent pin pointed the prop. Anyone knows whats exactly behind the firewall behind the footrest? Or even behind where the pedals are mounted that could be making a knocking sound?

[accordaffair]

Dude I think my 93 is having the exact same problem, its done it since I bought it in Jan/Feb, its like a clunk or knock, but it only happens once, it isn't repetitive like its coming from the engine...I was thinking maybe sway bar bushings but it sounds more like an axle or the brakes.... I can't localize whether its the left or right side its actually coming from but it is forward of the driver...

[TypeG]

i'd check the rear motor mount. later.

[Gemini]

Dude I think my 93 is having the exact same problem, its done it since I bought it in Jan/Feb, its like a clunk or knock, but it only happens once, it isn't repetitive like its coming from the engine...I was thinking maybe sway bar bushings but it sounds more like an axle or the brakes.... I can't localize whether its the left or right side its actually coming from but it is forward of the driver...

EXACTLY bro!!! It only does it once and not all the time. I've parked the car while running and continiously pushed teh break ans still cant pin point where its coming from

[Gemini]

i'd check the rear motor mount. later.

U think so? I'llcheck it out but the sound seems lower but wouldnt hurt to check.

[Gemini]

Still havent found the source but I now know that its not the brake. I put my car in N at the light and when it said Green I put it in D4 and drove off and I heard the same clunk/knock sound......I used no break....I even heard it going over speed bumps slowly. I' more than sure its the axle or some suspension part.

[accordaffair]

But it only comes on in drive right?

I think its an axle, I think it occurs when the transmission makes that last down shift to 1st as your decelerating, it must have some kind of quirk that jerks the driveshaft and makes a clicking metal on metal sound. When I had my car inspected at Honda the tech noticed the drivers side axle had about a 1 MM play in and out. Perhaps its related.

I will check the rear motor mount though, but you can activate/deactivate that in N or P by manipulating the throttle, right? It doesn't rely on the car being in drive does it? Just on whether the idle is above/below 8-900 rpm...

[Gemini]

But it only comes on in drive right?

I think its an axle, I think it occurs when the transmission makes that last down shift to 1st as your decelerating, it must have some kind of quirk that jerks the driveshaft and makes a clicking metal on metal sound. When I had my car inspected at Honda the tech noticed the drivers side axle had about a 1 MM play in and out. Perhaps its related.

I will check the rear motor mount though, but you can activate/deactivate that in N or P by manipulating the throttle, right? It doesn't rely on the car being in drive does it? Just on whether the idle is above/below 8-900 rpm...

I think it is the axle....because only happens when I slow down or move off from 1st(no other times.

I dont understand what you mean by activate/deactivate? What are you reffering to exactly? sorry if I'm slow

[accordaffair]

Well our rear motor mount has a little arm that acts on the mount to stiffen or harden it. At idle it is soft, when the rpms raise it stiffens. I believe it acts at 900 rpm. If you look under the hood at the little arm on the motor mount (may need a flashlight) and manipulate the throttle by hand you can see it go on and off. If it doesn't move at all, it may not be working correctly.

[Gemini]

Well our rear motor mount has a little arm that acts on the mount to stiffen or harden it. At idle it is soft, when the rpms raise it stiffens. I believe it acts at 900 rpm. If you look under the hood at the little arm on the motor mount (may need a flashlight) and manipulate the throttle by hand you can see it go on and off. If it doesn't move at all, it may not be working correctly.

OOOOHHH....I'll do that for sure tomorrow...never knew that, good info bro

[Gemini]

Well our rear motor mount has a little arm that acts on the mount to stiffen or harden it. At idle it is soft, when the rpms raise it stiffens. I believe it acts at 900 rpm. If you look under the hood at the little arm on the motor mount (may need a flashlight) and manipulate the throttle by hand you can see it go on and off. If it doesn't move at all, it may not be working correctly.

Ok, I tried what you recommended but i didnt see anything moving on the rear mount. Which side should I be looking at, drivers or passengers?

[CallMeRay]

Is your cb an auto transmission? TSB says that on autos, a single click or pop sound heard while slowing down could be a defective rear mount (which is vacuum controlled).

Mitchell says to plug the vacuum hose and vacuum port for the rear engine mount, if the sound goes away when you test drive it, then the mount is defective..