weird brake pedal (or else) clunk on release and soft pedal problem

[fenixus]

Need advice on brakes again, or rather pedal assembly and booster.
some old ghost returned - a single clunk happening literally every time I press and release the brake pedal when driving. sometimes it happens the moment I release brake pedal (e.g. while it is returning) and some other times it will happen even after 3 seconds (when pedal is up already)...

I had this "clunk" problem which I could hear when releasing the brake pedal before. I don't think this was caused by anything other than pedal assembly itself or mechanical parts immediately related to it (clevis, springs, booster and such).

ehhh, this will be kind of a continuation of some posts from other thread:
12 MPG city in Winter, 1mz-fe
pages 7 & 8 mostly, contain some video I recorded in Winter.

In above thread initially I considered that maybe the new (junk yard) ABS pump was causing weird pedal behavior (not quite possible), then it was about seized caliper slide pins (fixed by now), then went towards MC replacement (old was shot and had a rusty back of piston and was causing all brakes to drag). Since MC replacement the pedal behaves normally while braking (no longer sinks down sometimes).
Was still soft, but quiet, and the "clunk" problem was gone for some time or happening very rarely.

well it returned in past week or so, mostly when booster is active (vacuum). However brakes are not dragging like back then (MC is new OEM), brake pedal still feels very soft when engine is running.

I hear it coming from the dash (but may be wrong), tried locating the source with my head down there and with hand touching different things like pedal assembly, clevis, spring, firewall (thinking it's booster related) when releasing the brake pedal, but I cannot feel it anywhere, I just hear it ... very annoying

I am kinda worried about the "clunk" sound, why did this return, what is causing it, and if it is safe. so I recorded some more videos, this time was able to catch that sound happening 2-3 times in 2nd video and then almost every time I release (and also when I gently depress) the brake pedal with hand in 3rd video.

any idea what it might be?

Video no.1

You Tube

You Tube

1:00 min long general video showing how things look alike, I cannot see anything out of order here except for the fact that pedal moves slightly side to side, is it a problem?


Video no.2

You Tube

You Tube

1:48 min long video showing:

a) First I am playing with brake pedal on running engine

Initially I wanted to show you how deep I can press on brake pedal while engine is running (goes to the floor if I press very hard).

At first I press on brake pedal two times just like I do to stop the car before red light or so (moderate braking).

Then at 0:13 I press as hard as I can (e.g. emergency stop) and the pedal travels to the floor (pedal arm touches it, not the pedal itself).

b) at 0:30 I shut the engine off (and toss the keys on the seat)

since 0:36 I want to show you how pedal reacts right after shutting the engine off, it seems to be properly rising as vacuum gets used up.
however it does not get rock solid, there is some sponginess about it and if I press hard it can go deeper.

at 0:48 the first "clunk" happens when I am gently pressing and releasing the pedal. then again at 1:02 (harder to hear)

at 1:09 I press the pedal very hard, it can go quite deep...

c) at 1:21 I hold the pedal pressed down (very hard) at shut off engine and then start engine up again with pedal depressed, it properly goes deeper (booster vacuum), but isn't it a tad too deep?

Video no.3
1:27 long video - playing with pedal right after shutting car off (many more clunks), close up under dash:

You Tube

You Tube

What do you think, what is making this "clunk" sound?


Sorry for super long post, but I just don't get what is happening and am again worried about brakes (soft pedal).
Seems like I have air in system again (pedal can travel deep), but where from?
and what is this damn "clunk" sound, is it related to anything or a separate issue?
is the booster bad? then why pedal is so soft while with bad booster it should be very hard ...


it's so annoying ...

[pmesfun]

I can't really tell if my car does the same, but I made a video. My brakes are shit btw, they don't bite and the rotors have a glazed surface.

First part is with the engine off.

You Tube

You Tube

[fenixus]

thanks for a video! it's nice to be able to compare.

hehe, it seems that you have same shitty soft pedal as I do ...

however my brakes bite hard and even though pedal feels soft I can stop the car quickly when I press on it hard.
For instance if during driving I stomped on it as hard as I do in my video (touches floor) ... oh well I would loose my teeth probably

when you press on it as hard as you can (with engine running), does the pedal's arm touch the floor? mine does.

at least yours doesn't do the dreaded clunking (check my video no.3)

Originally Posted by pmesfun

I can't really tell if my car does the same, but I made a video. My brakes are shit btw, they don't bite and the rotors have a glazed surface.

First part is with the engine off.

[pmesfun]

Originally Posted by fenixus

thanks for a video! it's nice to be able to compare.

hehe, it seems that you have same shitty soft pedal as I do ...

however my brakes bite hard and even though pedal feels soft I can stop the car quickly when I press on it hard.
For instance if during driving I stomped on it as hard as I do in my video (touches floor) ... oh well I would loose my teeth probably

when you press on it as hard as you can (with engine running), does the pedal's arm touch the floor? mine does.

at least yours doesn't do the dreaded clunking

I think my mc and booster stuff is good, its just my brake pads and rotors are shit. On friday I almost rear ended a car. This was with the brake fully pressed, no difference in braking power and abs came on. Simply put, it was just all fail. Anyways thats a future project for me.

I just went back, and no it doesn't go to the floor no matter what. With two floor mats, I was able to fit my left big toe under the pedal and move it around.

I just heard the noise from your videos, thats sound bad. It looks like the pedal stops for a split second, makes a popping/clunking sound then returns.

[fenixus]

wow, those brakes must be very weak then ... I would invest into decent pads, at least Akebono ProACT or even more biting (front aplication only) like Akebono Street Performance or Hawk HPS. and resurface all rotors if they are good for it yet.
that's all I did on both cars, even on super soft/spongy V6 it helps a lot.

think about doing 2-man bleeding all around, this seems to work best and fastest.

When I put my foot in a shoe under pedal and fully depress (meaning as hard as I can) with other foot then the pedal touches my shoe, not too good...

yeah, that clunk when it happens makes the pedal jump a little, wondering what that is ... maybe the clevis is worn out? but why it happens most often when booster is active (loaded with vacuum)? booster pushrod rather did not stick, It was moving freely with no MC on the other side and there is no real reason why new MC would cause that jumping ... I'm totally lost with it ...

Originally Posted by pmesfun

I think my mc and booster stuff is good, its just my brake pads and rotors are shit. On friday I almost rear ended a car. This was with the brake fully pressed, no difference in braking power and abs came on. Simply put, it was just all fail. Anyways thats a future project for me.

I just went back, and no it doesn't go to the floor no matter what. With two floor mats, I was able to fit my left big toe under the pedal and move it around.

I just heard the noise from your videos, thats sound bad. It looks like the pedal stops for a split second, makes a popping/clunking sound then returns.

[pmesfun]

Originally Posted by fenixus

wow, those brakes must be very weak then ... I would invest into decent pads, at least Akebono ProACT or even more biting (front aplication only) like Akebono Street Performance or Hawk HPS. and resurface all rotors if they are good for it yet.
that's all I did on both cars, even on super soft/spongy V6 it helps a lot.

think about doing 2-man bleeding all around, this seems to work best and fastest.

When I put my foot in a shoe under pedal and fully depress (meaning as hard as I can) with other foot then the pedal touches my shoe, not too good...

yeah, that clunk when it happens makes the pedal jump a little, wondering what that is ... maybe the clevis is worn out? but why it happens most often when booster is active? booster pushrod sticks? It was moving freely with no MC on the other side and there is no real reason why new MC would cause that jumping ... I'm totally lost with it ...

Yup, that is what I'm gonna do. Brembo blanks and AK ProACt(isn't this what you get from Toyota?). It should run me about 270. btw the Nissan pads I got for the quest said AK then numbers.
I did have the brakes flushed/bled when I got air in the system last time. BTW to give you another idea on how bad the brakes are, when the A/C idles up turns on and I am at a stop light, the car will actually move WITH my foot on the brake. lmao.

Maybe something isn't lubricated and is sticking. MC is ruled out since its new, I would look in Booster Diagnostics and lubricate stuff if thats necessary. A little word of advice if you have to replace the Booster buy Toyota please. We installed a AZ booster on my old Voyager and it was worse. After driving that, it made the Avalon seem like it had Corvette quad system front calipers and 13 inch rotors, lol.

[fenixus]

well, it's a lottery on pads from Toyota, but yes if they have AK letters then they should be Akebono ProACT.

why don't you resurface the rotors first? it's cheap, like $12 each at local Strauss Auto or other chain... if they have never been turned yet and are not warped (no banging when braking down hard) then they should have enough meat on them still even at 130k miles IMO.

Wow, that's really low biting power you have over there ... just a quick question, does the engine idle properly at 700 rpm?

Last time I messed with accelerator cable adjustment on wife's 5s-fe some years back I made it idle at 800-900 or so (tightened cable too much at TB) and I was barely able to hold the car down in place while waiting at traffic lights...

as per my problem ... before I start messing with booster, I really need some kind of confirmation if there is the problem ... it's a PITA to remove MC in order to remove booster ... just to discover it's OK ..
... if it ever comes to booster replacement, I think i'd rather get a used OEM booster from wreckers ... new OEM one is horribly expensive like $800 or so ...

Originally Posted by pmesfun

Yup, that is what I'm gonna do. Brembo blanks and AK ProACt(isn't this what you get from Toyota?). It should run me about 270. btw the Nissan pads I got for the quest said AK then numbers.
I did have the brakes flushed/bled when I got air in the system last time. BTW to give you another idea on how bad the brakes are, when the A/C idles up turns on and I am at a stop light, the car will actually move WITH my foot on the brake. lmao.

Maybe something isn't lubricated and is sticking. MC is ruled out since its new, I would look in Booster Diagnostics and lubricate stuff if thats necessary. A little word of advice if you have to replace the Booster buy Toyota please. We installed a AZ booster on my old Voyager and it was worse. After driving that, it made the Avalon seem like it had Corvette quad system front calipers and 13 inch rotors, lol.

[pmesfun]

Originally Posted by fenixus

well, it's a lottery on pads from Toyota, but yes if they have AK letters then they should be Akebono ProACT.

why don't you resurface the rotors first? it's cheap, like $12 each at local Strauss Auto or other chain... if they have never been turned yet and are not warped (no banging when braking down hard) then they should have enough meat on them still even at 130k miles IMO.

Wow, that's really low biting power you have over there ... just a quick question, does the engine idle properly at 700 rpm?

Last time I messed with accelerator cable adjustment on wife's 5s-fe some years back I made it idle at 800-900 or so (tightened cable too much at TB) and I was barely able to hold the car down in place while waiting at traffic lights...

I may turn them, I'll see when the time comes. The have been resurfaced once at 60-70k miles and that was in 05 I think. They are not warped, but I just want to start with fresh rotors since they are so bad lol. I just thought about turning them at school and not replacing anything for now, since the pads have alot of meat on them. My teacher did note that there were hot spots on the front rotors, idk what that means.
Yeah, it idles at the same rpm whether the A/C on or I'm in different gears. I guess its at 750, the line below 1, its right at that line. When the A/C idle up turns on it will go to about 800 and come back to that line.

[fenixus]

it should idle right at 700rpm, 1mz-fe are pretty steady on it sitting like +/-5rpm around that number.

750 is too high. and the line below 1 is actually 800rpm I think. you may have overtightened the accelerator cable a little when you re-installed the TB. I would back off the lock nuts on that cable (upper one) more, I think leaving less threads on the right side (when standing in front of car) of lock nuts will loosen it.

I would try turning them at school for free and see what happens, not sure what hot spots on rotors mean. are they different color or something?

Originally Posted by pmesfun

I may turn them, I'll see when the time comes. The have been resurfaced once at 60-70k miles and that was in 05 I think. They are not warped, but I just want to start with fresh rotors since they are so bad lol. I just thought about turning them at school and not replacing anything for now, since the pads have alot of meat on them. My teacher did note that there were hot spots on the front rotors, idk what that means.
Yeah, it idles at the same rpm whether the A/C on or I'm in different gears. I guess its at 750, the line below 1, its right at that line. When the A/C idle up turns on it will go to about 800 and come back to that line.

[carsrus]

The main question is does it stop good?

If it does then its fine. Maybe the rear drums need adjustment if it has drums. I can get my car to make alllll kinds of noises but I just turn the radio on and forget about it.

The brake system is bullet proof. On any car. Things like the master should never have to be replaced. Brake fluid in general doesnt have to be replaced but since were all anal we replace it.

I dont really see an issue with the pedal. If your stopped the pedal is gonna do that....

[pmesfun]

Originally Posted by fenixus

it should idle right at 700rpm, 1mz-fe are pretty steady on it sitting like +/-5rpm around that number.

750 is too high. and the line below 1 is actually 800rpm I think. you may have overtightened the accelerator cable a little when you re-installed the TB. I would back off the lock nuts on that cable (upper one) more, I think leaving less threads on the right side (when standing in front of car) of lock nuts will loosen it.

I would try turning them at school for free and see what happens, not sure what hot spots on rotors mean. are they different color or something?

The hash marks on the cluster are different on the camry/solara vs. the avalon. If you look closely at the avalon cluster, you can see the line under 1, that is where mine has always been at. I guess that is 700 rpm.

I will turn the front rotors at school if we are allowed to bring cars in since its the end of the year. I about to google hot spots right now lol.

[fenixus]

haha LOL

I like that answer
yeah I usually turn the radio up to and forget about all the annoying things, it makes life easier

I have discs in rear, drums only for e-brake. it stops not bad, quite good actually with new pads and turned rotors. only 2 annoyances are that damn clunk (radio surely overwhelms it ) and quite deep pedal travel on running engine.
general pedal sponginess seems more or less normal on all camry based cars, I think replacing rubber lines with braided SS lines helps on that, but I'm too lazy to do that ... yet.

well, the brake pedal on wife's 5s-fe is harder and feels more solid though, so I don't know, something is up still, but I have no clue what, maybe rubber brake lines have more miles on them and that's all it is about. On her car I cannot push the brake pedal down to floor no matter how hard I try (on running car). but maybe it means I did lame job with vacuum pump bleeding, who knows hehe...

However I totally disagree on "lifetime" brake fluid and MC, it's a no no, look below and see what happened to original MC piston, brakes were dragging all around before I replaced it. This car likely never had the brake fluid flushed until I got it at 122k miles:

Originally Posted by carsrus

The main question is does it stop good?

If it does then its fine. Maybe the rear drums need adjustment if it has drums. I can get my car to make alllll kinds of noises but I just turn the radio on and forget about it.

The brake system is bullet proof. On any car. Things like the master should never have to be replaced. Brake fluid in general doesnt have to be replaced but since were all anal we replace it.

I dont really see an issue with the pedal. If your stopped the pedal is gonna do that....

[fenixus]

you're right, I forgot you have different cluster in avy.
however I think that line below 1 is actually 750, since field below 1 on your RPM gauge is divided into 4 sections ... best if you could hook up your car to live OBD2 scanner and see for real, analog dash gauges are an imprecise bull shit anyways

you should get something like that finally

Originally Posted by pmesfun

The hash marks on the cluster are different on the camry/solara vs. the avalon. If you look closely at the avalon cluster, you can see the line under 1, that is where mine has always been at. I guess that is 700 rpm.

I will turn the front rotors at school if we are allowed to bring cars in since its the end of the year. I about to google hot spots right now lol.

[pmesfun]

I may get that app, maybe once I'm done with the car, and start modding it like a new sound system and full led conversion, lol. I'm actually do those things this summer.

When the rpm is below that line the car will start vibrating, and its been at the same line for as long I driven it, about 3 years I think.

[fenixus]

OK, get it double checked anyways, too tight accel cable could be causing your weak brakes feeling. it would be an easy fix for the braking system performance if that's the case, otherwise it will take more money and effort to make it feel right

have fun with those LED conversions I have no patience for such stuff hehe ... I am same lazy and terrible with all exterior repairs/fixes ... can't help it

I think I should get a helper for effective 2-man brake bleeding and re-check the brake pedal travel again after that.

if anybody has a clue or any idea what might be causing the brake pedal clunking/popping as in Video no.3, please post.
issue seems to be rare, but I'd like to know what might be causing it. don't quite like the idea of removing booster for inspection (seems to be working properly according to FSM testing), so if that's the case I'd rather ignore it

Originally Posted by pmesfun

I may get that app, maybe once I'm done with the car, and start modding it like a new sound system and full led conversion, lol. I'm actually do those things this summer.

When the rpm is below that line the car will start vibrating, and its been at the same line for as long I driven it, about 3 years I think.