Grand Starex rotor discs replaced 3X after 18K odo only! What gives?

[arsen]

Theoretically, there is no such thing as “warped” disc because brake disc is usually made of cast iron, a brittle material. Cracks and breakage is a common damage of cast iron but plastic deformation like warping (bent, twisted out of shape) is uncommon.

What most brake disc has that causes the vibration on the steering wheel is brake pad materials that permanently stick onto the surface of the disc. The initial transfer of materials usually happen if the brake disc is overheated then while at full stop, the brakes are kept applied thus the dust and loose materials on the surface of the pads are melted and thus stick onto the surface of the disc.

AFAIK
sa front disc lang prone to warping because of the weight of the vehicle is shifted to front when braking, thus more grip is needed thus more heat thus mor prone to warping

thats why mas malaki ang frond disc pad kesa sa likod

yung rear rotor disc wala naman problem

that also the reason why dumihin front wheels ng GS

Yes the weight of vehicle is shifted to the front pero ang direction ng weight remains perpendicular sa direction ng travel ng car. Also, ang front and rear wheels are connected by a rigid structure (chassi) kaya always equal ang torque sa lahat ng wheels as long as the wheel does not lock (or skid) and as long as same ang outside diameter ng tire. So kahit magtransfer pa ang weight sa front same parin ang value ng torque na pipigilin ng brake pads at the moment that the brake was first applied.

What really happen when the weight is transferred to the front is: the front tires are pushed harder on the ground, thus the front tires contact friction on the ground increases thus the less chances the tires will skid thus front wheel braking capacity is designed higher than the rear.
Whereas, when the weight on the rear wheels is reduced, mas prone ito sa sliding at maglolock lang ang tires sa rear kung parehas ang braking capacity ng front and rear brakes.

Usually braking force is biased between the front and rear wheels, around 60% front 40% rear or 70/30, basta may bias heheh. Sa brake system na may pressure equalizing valve (delivering same pressure sa front and rear brakes) larger ang piston diameter ng calipers sa front compared sa rear. Larger piston mas greater ang squeezing force.

Sa disc brakes, what really matters is the effective radius ng brake disc na depende naman sa position ng center ng brake pad area. Kung mas malayo ang center ng area ng pad sa center ng wheel (which also means bigger diameter disc) mas tataas ang braking capacity.

The bigger pads will not significantly increase the braking capacity pero ang reason kung bakit mas malaki ang pad sa front dahil sa kapag bigger mas matagal mapudpod at much lower ang temperature ng disc.

[civic1990]

I see the Starex's braking woes are still back even with the newer GS.

Our 2005 Gen 3 doesn't have ABS, and its brakes, all OEM pads and rotors, don't seem to be adequate enough for its power. And yes, have had to machine the front rotors twice now, and that's only with 23,500 kms on the clock.

Mahina ba ang brake bite ng GS?

OK naman ang brake bite ng GS ko. Didn't notice na mahina.

[civic1990]

Theoretically, there is no such thing as “warped” disc because brake disc is usually made of cast iron, a brittle material. Cracks and breakage is a common damage of cast iron but plastic deformation like warping (bent, twisted out of shape) is uncommon.

What most brake disc has that causes the vibration on the steering wheel is brake pad materials that permanently stick onto the surface of the disc. The initial transfer of materials usually happen if the brake disc is overheated then while at full stop, the brakes are kept applied thus the dust and loose materials on the surface of the pads are melted and thus stick onto the surface of the disc.





Yes the weight of vehicle is shifted to the front pero ang direction ng weight remains perpendicular sa direction ng travel ng car. Also, ang front and rear wheels are connected by a rigid structure (chassi) kaya always equal ang torque sa lahat ng wheels as long as the wheel does not lock (or skid) and as long as same ang outside diameter ng tire. So kahit magtransfer pa ang weight sa front same parin ang value ng torque na pipigilin ng brake pads at the moment that the brake was first applied.

What really happen when the weight is transferred to the front is: the front tires are pushed harder on the ground, thus the front tires contact friction on the ground increases thus the less chances the tires will skid thus front wheel braking capacity is designed higher than the rear.
Whereas, when the weight on the rear wheels is reduced, mas prone ito sa sliding at maglolock lang ang tires sa rear kung parehas ang braking capacity ng front and rear brakes.

Usually braking force is biased between the front and rear wheels, around 60% front 40% rear or 70/30, basta may bias heheh. Sa brake system na may pressure equalizing valve (delivering same pressure sa front and rear brakes) larger ang piston diameter ng calipers sa front compared sa rear. Larger piston mas greater ang squeezing force.

Sa disc brakes, what really matters is the effective radius ng brake disc na depende naman sa position ng center ng brake pad area. Kung mas malayo ang center ng area ng pad sa center ng wheel (which also means bigger diameter disc) mas tataas ang braking capacity.

The bigger pads will not significantly increase the braking capacity pero ang reason kung bakit mas malaki ang pad sa front dahil sa kapag bigger mas matagal mapudpod at much lower ang temperature ng disc.

I guess baka nga madumi or may diperensiya ang brake pads ko. I think I will change it na din together with the disc rotors.

Meanwhile, I am following an earlier advice here to see if mawawala by itself ang problem by continuing to use the vehicle. Baka kusang matanggal ang mga dumi na dumikit sa disc rotors by frequent use.

[arsen]

I guess baka nga madumi or may diperensiya ang brake pads ko. I think I will change it na din together with the disc rotors.

Meanwhile, I am following an earlier advice here to see if mawawala by itself ang problem by continuing to use the vehicle. Baka kusang matanggal ang mga dumi na dumikit sa disc rotors by frequent use.

Google the term "brake judder" at marami rami na rin ang mga nag-open ng topic at nagbibigay ng suggestions.

Eto yung common pattern ng mga suggestions baka gusto nyo e try instead of hayaan na lang at baka sakaling mawala? I modified nga pala some of the values pero may explanation naman heheh.

1. Hanap ng maluwag na daan (meron kaya?)

2. Make 8 to 10 series of deceleration from 70kph to around 15-10kph by pressing the brake pedal firmly (without locking or activating the ABS, kung naka-expience na kayo ng naglock ang tires while braking mga 80percent lang dapat ang pwersa ng apak) then accelerate back to 70 then decelerate again to around 15-10 without making a complete stop (sorry kailangan talaga ng maluwag na daan at hinde nakakasagabal sa ibang motorist).

Note: sa mga websites, 60mph ang recommended or around 95kph but most of them American sites so most likely they are talking about American cars. I recommend 70kph because Korean (KDM) at lalo na Japanese cars (JDM) are designed for city/country roads of Korea and Japan na ang speed limit is either 60 or 50kph (pero mahuli ka sa 70kph na takbo sa 60kph marked road ay pwede pa patawarin ng pulis, di naman pwede gumawa ng series of deceleration sa kanilang expressway may minimum normal cruising speed naman).

3. Tandaan kung paano ang car nag behave while doing item 2. Kung kelan nag fade ang brakes at kung kelan nangamoy ang brake. (post it here ??). Mga twice nung kung kelan nagstart mag fade ang brake matatapos ang first exercise (usually daw during the 5th pero pwede rin sa 4th pa lang kaya the exercise may end during the 8th time) or kung you feel unsafe na to continue dahil sobrang faded na ang brakes, its up to you to finish the first exercise then proceed to cooling and the finale.

4. After completing the 8-10 series of decelerations without making a complete stop ang finale ay to cool the brakes by accelerating gradually until you reach your maximum safe driving speed then apply brakes firmly to decelerate at around 15-10 kph, and again without making a complete stop. Let the brakes cool down by driving at slow speed for 10-15minutes without braking.. kung kailangan na mag full stop do the final stop by not using the brake (let the wheel roll until the car stop)

During the finale you can also verify if there is no more vibration or if the vibration has abated.

Once the vibration has abated, siguro naman enough encouragement na yan to repeat the process once more? In some situation, beneficial daw ang third set pero normally ang dalawang sets ay enough na.

By the way, the above process is the same recommended procedure to bed-in the brake disc kapag brand new ang vehicle or katatapos lang magpalit ng brake pads or katatapos lang magpalit ng buong brake disc assembly.

So gudluck!

[cocoy]

kaya pala hindin nag warp and replacement rotor ko ng starex ko.. kasi palagi ko naka hard braking. hehehehe.. mind you hindi pa GS starex ko ha.. so everything is manual.. walang ABS walang EBD... so plain old hydraulic braking system.. heheheh...