Mas madiin ang apak sa preno.

[reym]

Hi Guys, my ride is an assembled jeep (toyota 4k 4 speed, frond disk brakes, rear drum brakes).

Just recently I felt that sometimes I need to push the pedal harder and deeper but sometimes it does not need much effort to push it (for a full stop at 10 - 20 km/hr).

I discovered I had a leak in one of the rear brake cylinder so I replaced both left and right rear cylinder rubber boots.
I also replaced the brake linings with a re-bonded lining.

Now comes the problem.
1. the original problem persists.
2. Noise every full stop.

Any help would be appreciated thanks...

[lancer5790]

possible causes:
1. broken hydrovac diaphragm
2. system needs bleeding
3. brake shoes needs some more outward adjustment
4. front disc cylinders stuck up
noise:
1. poor quality of break shoe pads
i assume the break drums were cleaned during replacement of pads...

[benchman]

screeching noise po ba?
maybe your disc brake pads are worn out already, noise sometimes indicates brake pads for replacement due.

hard pushing for brakes?
though you have worked out your rear brakes...
but mostly, brake fluid pressure issues yan, check starting from the hydrovac(when was the last time you inspected/replaced your repair kit?) all the way to the caliper assembly, better to overhaul the disc brake's pistons for cleaning and inspections na rin kung matagal na syang hindi nabubuksan... baka sticky na yung pistons due to rust/dirt buildups, replace the kits if needed.
these pistons who are to much extended outside it's cylinders due to thinning brake pads are prone to stuckups, they are prone to weather exposures kahit may rubber boots pa sila, worse kung sira na yung boots.

how about your discs/rotors? they should be makinis and deep lines free hangga't maari to have a smooth/noise free brakings.
if your pads are at due, much better to have your discs a re-facing job done if they have those deep lines already... isabay mo na sa pagpalit ng disc pads mo para mas maganda ang brakes mo.

hope it helps somehow...

[reym]

Thanks for the reply guys ...

possible causes:
1. broken hydrovac diaphragm
The feel is much different when the engine is shut off. When the engine is off the brake is really hard, but when the engine is running the pedal is softer, the vehicle slows down with a bit of press but requires a bit more power to make it stop. DO you think this is a break booster problem?
2. system needs bleeding
I bled both rear wheels already

3. brake shoes needs some more outward adjustment
Brake linings are very thick and it required me to remove some of it, the adjustments are at max outward already.

4. front disc cylinders stuck up

Haven't done this yet .
noise:
1. poor quality of break shoe pads
i assume the break drums were cleaned during replacement of pads...
I have cleaned them including the cylinders and back plate.

[reym]

Thanks for the reply.

The Disk rotors have been refaced 2 years ago along with the front brake and rear break assemblies. The master cylinder and hydrovac has been with the vehicle untouched since i bought it 4 years ago.

The rear break was overhauled 1 year ago, the break linings were replaced by re bonded ones due to the conversion of the lining frame.

Ever since the replacement the noise lingers on.

screeching noise po ba?
maybe your disc brake pads are worn out already, noise sometimes indicates brake pads for replacement due.

hard pushing for brakes?
though you have worked out your rear brakes...
but mostly, brake fluid pressure issues yan, check starting from the hydrovac(when was the last time you inspected/replaced your repair kit?) all the way to the caliper assembly, better to overhaul the disc brake's pistons for cleaning and inspections na rin kung matagal na syang hindi nabubuksan... baka sticky na yung pistons due to rust/dirt buildups, replace the kits if needed.
these pistons who are to much extended outside it's cylinders due to thinning brake pads are prone to stuckups, they are prone to weather exposures kahit may rubber boots pa sila, worse kung sira na yung boots.

how about your discs/rotors? they should be makinis and deep lines free hangga't maari to have a smooth/noise free brakings.
if your pads are at due, much better to have your discs a re-facing job done if they have those deep lines already... isabay mo na sa pagpalit ng disc pads mo para mas maganda ang brakes mo.

hope it helps somehow...

[benchman]

as we all knew, it's normal to have a hard feel(parang lusot ang preno,hindi kakagat) on the brake pedal when the engine is not running.

since you have mentioned never been touched yung hydrovac mo, better check it.
and wait, assuming na wala ka nang fluid leaks ngayon... does it consumes brake fluid abnormally kahit wala kang leaks?
if yes, chances are; dun napupunta sa hydrovac/master mo yung kinakain na brake fluid.... i saw a similar case like that

[reym]

DI na sya nagbabawas ng fluid.
Funny thing is pag binigla ko ung preno at 10 kmh, para syang dumudulas bago sha huminto pero walang iyak gulong or guhit ng gulong sa daan.

as we all knew, it's normal to have a hard feel(parang lusot ang preno,hindi kakagat) on the brake pedal when the engine is not running.

since you have mentioned never been touched yung hydrovac mo, better check it.
and wait, assuming na wala ka nang fluid leaks ngayon... does it consumes brake fluid abnormally kahit wala kang leaks?
if yes, chances are; dun napupunta sa hydrovac/master mo yung kinakain na brake fluid.... i saw a similar case like that

[desert fox]

me singaw yan somewhere.....

[benchman]

hmmm... weird nga ano? pa-check mo na yung hydrovac/master mo, mahirap na lalo na ngayon maulan... pasumpong sumpong ang brake mo, ingats na lang sa pag-drive

[basti08]

hydrovac! observe kung kelangan i-bomba para mag preno ng maayos or if mas kumakagat sa pangalawang tapak. if so, that's it.

[desert fox]

DI na sya nagbabawas ng fluid.
Funny thing is pag binigla ko ung preno at 10 kmh, para syang dumudulas bago sha huminto pero walang iyak gulong or guhit ng gulong sa daan.

hangin ang singaw...sa hydrovac nga....

[benchman]

ayun sir reym, dalawa na ang nag-agree.... it's your hydrovac, wala ng duda.

[desert fox]

para ding utot natin, kapag ayaw lumabas, kabag...so di tayo makapagperform mabuti anuman ginagawa natin...

kapag nauutot ganun din...pipigilin.....

jk.

[benchman]

bingo! hehehe!

[reym]

meron ba nabibili bago brake booster lang?

[benchman]

parang assembly ang mga bagong nabibiling bago sir e... di ko sure
pwede na po siguro ang surplus, isama mo na lang yung mekaniko para mapili nyo yung good na pyesa. imho lang

[reym]

Mukhang tama nga kay mga sir, nasubukan ko isang beses di noble ko apak tumigas ung preno na napakatigas. Hahanap ako ng booster next week. TY.

[miked]

Types of Brake Noise
1. Squeak noise when brakes are cold
- usually occuris during 1st few stops
- this is a normal condition and no service action required

2. Squeak noise with brakes at normal operating temps
- semi-metallic pads are noisy compared to OE or ceramics

3. Loud continuous squeak/squeal noise
- occurs with or without braking
- normal brake function when brake pad wear indicators contact the rotor.
indicates brake pads are worn out and need to be replaced
- foreign materials could be trapped in between pad and rotor

4. Groan noise when slightly releasing the brakes after coming to a stop
- sometimes called "creep groan". this is normal and no service action required

5. Groan noise during stopping
- usually caused by glazing of rotor surface as a result of frequent heavy braking
- replace brake pads, then resurface rotors and finish with sand paper

6. Single clunk noise from front suspension when applying the brakes
- can be duplicated by lightly touching the brake pedal
- if brake pedal is pushed hard, the noise is less likely to occur
- the noise is a result of the brake pads shifting in the direction of rotor rotation when brakes are applied
- install appropriate shims and brake grease to pad's steel sliding surfaces

7. Multiple clunk noise
- ABS self-check. vehicle's ABS systems performs a self check when the brakes are applied after initial start-up. this is normal and no service action is required

8. Rear brake squeal
- due to accumulation of brake dust and dirt in between pad/shoes and rotors/drums. clean and lubrication is required

Brake Judder
- caused by rotor thickness variation (RTV) when the inner and outer surface of the rotor are not flat and parallel, the brake pads will follow the low and high spots on rotor during braking causing the brake piston to "knock-back" causing pulsation in the pedal

RTV causes:
1. Rotor run out - if the rotor is not true (perpendicular) to the hub center
2. Vehicle storage - area not covered by pads will rust affecting the friction characteristics between rusted and un-rusted areas
3. Lug nut overtorque - if lug nuts (studs) are overtightened usually with an impact wrench


Hope this helps. i'm sure there are other tsikoteers here with the same problems as yours.
Guys, just add some info. i'm sure my "brake bible" is not that complete.

[t2erns]

check mo nuna booster before mo palitan.engine off tapakan mo brake pedal hanggang tumigas, hold mo tapak sa brake while starting the engine, pag bumaba ng konti ang pedal that means ok pa ang booster.

yung stopping power depende sa quality ng pads, yung mga composition brake mahina talaga kumagat lalo na pag mainit na. try mo din ibleed amg system or better i flush mo and replace with new fluid. check mo din adjustment ng rear brake shoes.

[reym]

Bumababa naman sya pag start ng engine kaso minsan mas madiin apak ko para huminto tapos kanina malapit ako sa hump i pressed the brake one time, bumagal ung sasakyan at normal ung apak ko (2 seconda ang difference sa una) sa brake ung pangalawang apak ko eh mataas at napakatigas ng brake. (ung parang di umaandar ang makina ang height at tigas).

check mo nuna booster before mo palitan.engine off tapakan mo brake pedal hanggang tumigas, hold mo tapak sa brake while starting the engine, pag bumaba ng konti ang pedal that means ok pa ang booster.

yung stopping power depende sa quality ng pads, yung mga composition brake mahina talaga kumagat lalo na pag mainit na. try mo din ibleed amg system or better i flush mo and replace with new fluid. check mo din adjustment ng rear brake shoes.