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BRAKES - Any experts here ?

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Joel Now containing 100\% E-Wang

9,368 posts · joined Feb 2006 ·

#907922
Thanks Steve, I'll find out what they have
Matt Ryan wrote:Rule of thumb is to replace pads or shoes when they are worn to half thickness or over. Then there is far less risk of scoring disk or drum by the time next service or brake check comes around.

Regards,

Matt.
I really cringe when I see Mr or Mrs average non mechanical savvy driver in thier car going screeech screech screeech without a care in the world.

My brakes are making an annoying screech noise, meh I'll just turn the radio up more 🙄

Thank god atleast NSW has annual roadworthys, stops things like this being on the road

vlad01 Compulsive Aussie Vee Dubber

4,270 posts · joined Jun 2010 ·

#907923
Matt Ryan wrote:
68AutoBug wrote:
Aussie Dubbin wrote:Lee, ifg you have a better feeling pedal, with no lockup then sounds great dont change a thing... As long as the braking distance hasnt been increased. From what you have listed i am assuming the material is slightly different. Did you replace front pads in 2005?
No I used the old pads, must have had a lot of material still on them..
as I had the new pads I fitted them instead of wearing the old ones right down, which is safer anyway..

LEE

Rule of thumb is to replace pads or shoes when they are worn to half thickness or over. Then there is far less risk of scoring disk or drum by the time next service or brake check comes around. Also good quality pads replaced at this interval can slightly true up a disc or drum, mainly because bugger all damage has been done yet. (did my apprenticeship on fleet maintenance).

Regards,

Matt.
some pads will out the rotors faster than the actual pads 😂

71 notchback,
Past owner of, 70 NB, 73 SB and 72 FB TLE

vlad01 Compulsive Aussie Vee Dubber

4,270 posts · joined Jun 2010 ·

#907924
Joel wrote:
Matt Ryan wrote:Rule of thumb is to replace pads or shoes when they are worn to half thickness or over. Then there is far less risk of scoring disk or drum by the time next service or brake check comes around.

Regards,

Matt.
I really cringe when I see Mr or Mrs average non mechanical savvy driver in thier car going screeech screech screeech without a care in the world.

My brakes are making an annoying screech noise, meh I'll just turn the radio up more 🙄

Thank god atleast NSW has annual roadworthys, stops things like this being on the road


🤪🤪🤪🤪 😂🥲

71 notchback,
Past owner of, 70 NB, 73 SB and 72 FB TLE

Matt Ryan Fahrvergnugen

890 posts · joined Jan 2006 ·

#907925
Joel wrote:
Matt Ryan wrote:Rule of thumb is to replace pads or shoes when they are worn to half thickness or over. Then there is far less risk of scoring disk or drum by the time next service or brake check comes around.

Regards,

Matt.
I really cringe when I see Mr or Mrs average non mechanical savvy driver in thier car going screeech screech screeech without a care in the world.

My brakes are making an annoying screech noise, meh I'll just turn the radio up more 🙄

Thank god atleast NSW has annual roadworthys, stops things like this being on the road


I bet the customer said "it only started making a noise just recently"


Regards,

Matt.


http://portvwforum.freeforums.org

Yogie Moderator Custom Title Time!

1,609 posts · joined Jun 2003 ·

#907926
At least they won't overheat anymore🤪

Uber Kafer Wolfsburg Wizard

414 posts · joined Nov 2009 ·

#908117
vlad01 wrote:only shit brakes lock up is the rule, good ones don't. I am surprised how many people don't know this? they should, its just physics.
.
I am interested to hear the physics clarified, how it relates to non ABS of course.
For example, you have brakes that are capable of pulling up a fully loaded vehicle from high speed in the absolutely shortest possible distance, which would mean braking to the limits of adhesion, awesome performance. Then on another occasion you do a panic stop at low speed with an empty car, naturally those awesome brakes are capable of locking up the wheels.

Does that make them 'shit brakes' ?

matberry Moderator Go hard or go home

8,114 posts · joined Mar 2006 ·

#908120
mmmmm 🙂

I'm with you Mr Kafer
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE

BiX Veteran Volks Folk

2,499 posts · joined Sep 2002 ·

#908136
I am with kafer on this one two. Without ABS good brakes should all reach lock up at about the same time. For safety the fronts should go first, so you don't loose the rear end. if you can't reach lock up, you still have more braking to go.

I will be trying to the QFM pads next time i change. They will put various compunds on your old backing plates for non standard cars/pads. Won't do shoes though for the drums.

Drew
I have no sympathy for my car, only the wallet that pays for it!
Go hard or go home!!!!

68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 ·

#908168
Matt Ryan wrote:
Joel wrote:
Matt Ryan wrote:Rule of thumb is to replace pads or shoes when they are worn to half thickness or over. Then there is far less risk of scoring disk or drum by the time next service or brake check comes around.

Regards,

Matt.
I really cringe when I see Mr or Mrs average non mechanical savvy driver in thier car going screeech screech screeech without a care in the world.

My brakes are making an annoying screech noise, meh I'll just turn the radio up more 🙄

Thank god atleast NSW has annual roadworthys, stops things like this being on the road


I bet the customer said "it only started making a noise just recently"


Regards,

Matt.
Read in the paper recently about people complaining having to replace their front brake discs after 30,000klms...
their first 30,000klms..
Ford say they have fitted very abrasive pads... and that is normal....
FORD FOCUS cars... imported..

I never let brake pads get down near the metal... YIKES

LEE
- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---

68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 ·

#908681
That is why I don't like rear disc brakes.... lol

You just never know what is going on back there...
😂😂😂😂😂😂

Lee
Matt Ryan wrote:
Joel wrote:
Matt Ryan wrote:Rule of thumb is to replace pads or shoes when they are worn to half thickness or over. Then there is far less risk of scoring disk or drum by the time next service or brake check comes around.

Regards,

Matt.


I really cringe when I see Mr or Mrs average non mechanical savvy driver in thier car going screeech screech screeech without a care in the world.

My brakes are making an annoying screech noise, meh I'll just turn the radio up more 🙄

Thank god atleast NSW has annual roadworthys, stops things like this being on the road



I bet the customer said "it only started making a noise just recently"


Regards,

Matt.
- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---

bajachris88 The international telephone dialing code for Antarctica is 6

6,661 posts · joined Apr 2005 ·

#908724
But rear discs pull such awesome handbrake-ies 😂
(ô_!_/ô) (ô_!_/ô)
69' baja: kombi box, thing spindles, irs, disc front, type 3 rear drums, 2 inch lift kit, 31x10 rears. 👍
New engine in process: 94mm p&bs, 74mm C/w chomol Crank, 35.5x39 SP heads, turbo. Wierd combo, hopeful torque monsta!

vlad01 Compulsive Aussie Vee Dubber

4,270 posts · joined Jun 2010 ·

#908758
bajachris88 wrote:But rear discs pull such awesome handbrake-ies 😂

not necessarily! most cars if not all these days use a mini drum brakes for the handbrake inside the hat of the disk. only old 80s to 90s had calipers with integrated handbrake.

71 notchback,
Past owner of, 70 NB, 73 SB and 72 FB TLE

psimitar Son of Jim - Creator of Good

2,506 posts · joined Jan 2009 ·

#909684
vlad01 wrote:
bajachris88 wrote:But rear discs pull such awesome handbrake-ies 😂

not necessarily! most cars if not all these days use a mini drum brakes for the handbrake inside the hat of the disk. only old 80s to 90s had calipers with integrated handbrake.
Fraid not. My Bro's 04 Seat Ibiza has integral handbrake calipers as do the same age VW Bora's, Golfs, etc. They are far cheaper to manufacture than a seperate mini drum.
madness is in the eye of the beholder 👍

psimitar Son of Jim - Creator of Good

2,506 posts · joined Jan 2009 ·

#909690
Joel wrote:Thanks Steve, I'll find out what they have

I really cringe when I see Mr or Mrs average non mechanical savvy driver in thier car going screeech screech screeech without a care in the world.

My brakes are making an annoying screech noise, meh I'll just turn the radio up more 🙄

Funny you say this Joel as the wife came home one day and said the brakes are making a weird noise. Low and behold no pad material left. 'oh it made the noise a few days ago but then went away so I didn't tell you. And now we need new rotors 🙄 She must have a bloody heavy foot cos they were under 5k old.

Anyway..............................🙄🙄
madness is in the eye of the beholder 👍

Joel Now containing 100\% E-Wang

9,368 posts · joined Feb 2006 ·

#909727
I used to see that alot at the garage.
With so many of todays cars being auto and modern brakes are big and vented these days, alot of drivers just sit on the brakes all the way down hills and wait till the last sec and brake heavily at traffic lights and intersections.

You see their front wheels and even the back on some cars look like they are matte black but it's just all the brake dust.

68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 ·

#909801
Joel wrote:I used to see that alot at the garage.
With so many of todays cars being auto and modern brakes are big and vented these days, alot of drivers just sit on the brakes all the way down hills and wait till the last sec and brake heavily at traffic lights and intersections.

You see their front wheels and even the back on some cars look like they are matte black but it's just all the brake dust.
Yes. I used to notice that a lot when in Sydney, watching the traffic... lol

ALL european cars front wheels were black.... really black compared to the rears...

BMWs seemed to be the worst...

but Now I even notice it on European cars in Scone...
can't tell with local cars as they are all covered in mud or dust.. lol

LEE
- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---

68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 ·

#909803
On the service record of One of Our Lancers it even had how thick the brake pads were....
now that's dedication... lol

We got a years worth of free service with the car.. lol

LEE
- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---

vlad01 Compulsive Aussie Vee Dubber

4,270 posts · joined Jun 2010 ·

#909831
Uber Kafer wrote:
vlad01 wrote:only shit brakes lock up is the rule, good ones don't. I am surprised how many people don't know this? they should, its just physics.
.
I am interested to hear the physics clarified, how it relates to non ABS of course.
For example, you have brakes that are capable of pulling up a fully loaded vehicle from high speed in the absolutely shortest possible distance, which would mean braking to the limits of adhesion, awesome performance. Then on another occasion you do a panic stop at low speed with an empty car, naturally those awesome brakes are capable of locking up the wheels.

Does that make them 'shit brakes' ?
very hard to lock good brakes, but pretty easy in the wet though 😂

but I am saying is if the brakes lock easy with little control over it, is either something wrong, or they are too small, or they are drums. Thats what I mean by shit brakes. Most people are like "oh they lock easy they must be great!" 🙄

If the brakes are large, with correct piston sizing ratio to MC piston and high quality pads, locking the bakes become very difficult and only happens in the extreme cases typically at the last 0.5- 1m remaining to a dead stop, or gravel or wet road (normally eliminated if you have ABS)

it mostly comes down to relation ship between static and kinetic friction. Better and larger brakes have a greater % of kinetic friction while having reduced static friction which = greater stopping, greatly reduced locking.

btw are you making the assumption that I was referring to ABS? well I wasn't.

like I said simple physics 🤓

71 notchback,
Past owner of, 70 NB, 73 SB and 72 FB TLE

vlad01 Compulsive Aussie Vee Dubber

4,270 posts · joined Jun 2010 ·

#909833
Joel wrote:I used to see that alot at the garage.
With so many of todays cars being auto and modern brakes are big and vented these days, alot of drivers just sit on the brakes all the way down hills and wait till the last sec and brake heavily at traffic lights and intersections.

You see their front wheels and even the back on some cars look like they are matte black but it's just all the brake dust.

I F**ken hate that! with their brake light on all the time you can't tell if they are stopping or their brake light switch has failed until they suddenly stop at the last sec and you nearly hit them. I bet 9/10 rear ender happen like this.

watch out for the inversed ford territorys. brakes light on when no brakes and they turn off when they brake 😬


seriously, they need to force people to use their brakes properly or put brake effort bar graph type brake light that show a % of pedal effort so people know how much the person in front is braking.

71 notchback,
Past owner of, 70 NB, 73 SB and 72 FB TLE

cb john Wolfsburg Wizard

470 posts · joined Jun 2007 ·

#909846
it mostly comes down to relation ship between static and kinetic friction. Better and larger brakes have a greater % of kinetic friction while having reduced static friction which = greater stopping, greatly reduced locking.
[/quote]

I'm aware that "static friction " term si being used, but makes me wonder how correct it is...my understanding is, there is no friction between two stationary objects....the friction factor steps in at the moment, when one of the objects becomes kinetic...this falls to the same category as "army intelligence"...

vlad01 Compulsive Aussie Vee Dubber

4,270 posts · joined Jun 2010 ·

#909999
maybe you need to revise your physics, static friction just the friction that keep 2 surfaces from moving while force is being applied. Just because it isn't moving doesn't mean it hasn't got friction. Its like saying, if I kill you does the universe exist? of course it does! Just you are not conscious to experience it anymore.

Without static friction nothing in our sense of reality of the physical universe wouldn't exist.

71 notchback,
Past owner of, 70 NB, 73 SB and 72 FB TLE

cb john Wolfsburg Wizard

470 posts · joined Jun 2007 ·

#910081
Thanks, you REALLY enlightened me....

bajachris88 The international telephone dialing code for Antarctica is 6

6,661 posts · joined Apr 2005 ·

#910087
cb john wrote:Thanks, you REALLY enlightened me....
No help is he 😂

The usual 'textbook' terms is sliding friction and static friction, but alot do call sliding friction kinetic friction instead.

Friction requires a force to be present. without a force, there is no friction. Why? Because Friction = Net Force x Friction Coefficient. This coefficient represents how 'rough' or 'smooth' a surface is. Larger the coefficients value, the rougher the surface, larger the friction force.

Now! If we have a force present, we have Mass & an Acceleration. Why? Well, Force (F) = Mass x Acceleration. Newton's Law. Mass could be a car (kg), person, anything thats matter. Acceleration could be you putting your foot down in a car, or even gravity (because gravity tries to accelerate you 'downwards' to the ground).

Friction is a force that 'opposes' motion. if you want to 'accelerate' something one way, friction will push against you in the other direction.

So whats sliding friction and static friction?

Sliding friction: is the friction force (opposing force) present when two contacting surfaces 'slide' across each other. For example, when a car has hit the skids, the wheels lock up, and thus the car 'slides' across the road. The car will eventually come to a stop, because a 'sliding' friction force has opposed the cars motion and slowed you to a hault.

Static friction: Is again, the friction force (opposing force) present when two surfaces are simply in contact without any sliding. The car example complicates this phenomenon so lets use a different one. Simply put, your standing still, and take a step forward. You pushed on one foot to move your body forward when taking your step. The foot you pushed with, pushed on the ground, it does not slide across the ground. There is some force preventing your foot from sliding on the ground, this is your 'static' friction force. Without this 'static' friction force, you would be slipping over, there would be no 'grip' on the ground. Its called static friction as the surfaces (your shoe and the ground) are still and not moving or sliding across each other, although you yourself are actually moving forward.

From the car example, if you stop your car without locking up the wheels, the tyres do not slide. They provide a 'static' friction while rotating and NOT sliding across the surface. This friction force is a force opposing the direction of motion and thus your vehicle stops.

To make it complicated, sliding friction is present when your brake pads are sliding over the rotating brake disk as your wheels spin. If the wheels lock up, then the brake pads are providing static friction, as the friction force is holding the brake rotors still (hence static) and the surfaces are no longer sliding.

In general, the 'size' of the force for static friction, compared to sliding friction is greater regardless of the application. Hence why you can stop your car sooner if you do not lock up the wheels. This is why ABS was invented, such that your car can maintain static friction between the tyres and road surface and thus a 'stronger' opposing force can be present to stop the motion of the vehicle sooner.

Hope that helps.
Chris.
(ô_!_/ô) (ô_!_/ô)
69' baja: kombi box, thing spindles, irs, disc front, type 3 rear drums, 2 inch lift kit, 31x10 rears. 👍
New engine in process: 94mm p&bs, 74mm C/w chomol Crank, 35.5x39 SP heads, turbo. Wierd combo, hopeful torque monsta!

HappyDaze Superannuated

2,887 posts · joined Jun 2009 ·

#910098
As the song says, "There's a fraction too much friction" going on. 😁

Lee simply wanted to know why his new pads were behaving differently.
I'd rather wear a Beetle out by racing it than by polishing it!

vlad01 Compulsive Aussie Vee Dubber

4,270 posts · joined Jun 2010 ·

#910121
HappyDaze wrote:As the song says, "There's a fraction too much friction" going on. 😁

Lee simply wanted to know why his new pads were behaving differently.

different compounds obviously.

71 notchback,
Past owner of, 70 NB, 73 SB and 72 FB TLE

vlad01 Compulsive Aussie Vee Dubber

4,270 posts · joined Jun 2010 ·

#910122
cb john wrote:Thanks, you REALLY enlightened me....

I might as well be talking to a brick wall ey 🙄

71 notchback,
Past owner of, 70 NB, 73 SB and 72 FB TLE

vlad01 Compulsive Aussie Vee Dubber

4,270 posts · joined Jun 2010 ·

#910124
bajachris88 wrote:
cb john wrote:Thanks, you REALLY enlightened me....
No help is he 😂

The usual 'textbook' terms is sliding friction and static friction, but alot do call sliding friction kinetic friction instead.

Friction requires a force to be present. without a force, there is no friction. Why? Because Friction = Net Force x Friction Coefficient. This coefficient represents how 'rough' or 'smooth' a surface is. Larger the coefficients value, the rougher the surface, larger the friction force.

Now! If we have a force present, we have Mass & an Acceleration. Why? Well, Force (F) = Mass x Acceleration. Newton's Law. Mass could be a car (kg), person, anything thats matter. Acceleration could be you putting your foot down in a car, or even gravity (because gravity tries to accelerate you 'downwards' to the ground).

Friction is a force that 'opposes' motion. if you want to 'accelerate' something one way, friction will push against you in the other direction.

So whats sliding friction and static friction?

Sliding friction: is the friction force (opposing force) present when two contacting surfaces 'slide' across each other. For example, when a car has hit the skids, the wheels lock up, and thus the car 'slides' across the road. The car will eventually come to a stop, because a 'sliding' friction force has opposed the cars motion and slowed you to a hault.

Static friction: Is again, the friction force (opposing force) present when two surfaces are simply in contact without any sliding. The car example complicates this phenomenon so lets use a different one. Simply put, your standing still, and take a step forward. You pushed on one foot to move your body forward when taking your step. The foot you pushed with, pushed on the ground, it does not slide across the ground. There is some force preventing your foot from sliding on the ground, this is your 'static' friction force. Without this 'static' friction force, you would be slipping over, there would be no 'grip' on the ground. Its called static friction as the surfaces (your shoe and the ground) are still and not moving or sliding across each other, although you yourself are actually moving forward.

From the car example, if you stop your car without locking up the wheels, the tyres do not slide. They provide a 'static' friction while rotating and NOT sliding across the surface. This friction force is a force opposing the direction of motion and thus your vehicle stops.

To make it complicated, sliding friction is present when your brake pads are sliding over the rotating brake disk as your wheels spin. If the wheels lock up, then the brake pads are providing static friction, as the friction force is holding the brake rotors still (hence static) and the surfaces are no longer sliding.In general, the 'size' of the force for static friction, compared to sliding friction is greater regardless of the application. Hence why you can stop your car sooner if you do not lock up the wheels. This is why ABS was invented, such that your car can maintain static friction between the tyres and road surface and thus a 'stronger' opposing force can be present to stop the motion of the vehicle sooner.

Hope that helps.
Chris.
Also I will add, by maintaining kinetic friction at the brakes rather than at the tires allows more heat to be generated in a shorter time frame whilst being absorbed from the conversion of kinetic energy to thermal energy without loosing too much overall friction in the system otherwise lost when rubber liquifies, then evaporates from the heat of sliding and reduces its friction coefficient thus decreasing the efficiency of the system.

in other words the pads and rotors are far better at converting movement into heat faster with minimal lost of efficiency in that system than what rubber sliding over a road would do.

just another point of view, food for thought? or too hard to understand

Also one very important point, you can steer if the brakes don't lock and still brake hard at the same time.

If you lock and try to steer, well you're ***ked unless you let go and continue pulsating the bakes so you can steer and stop at the same time, or like Chris mentioned ABS can help 🤓 I think? last time I seriously drove an ABS car it wouldn't stop 😂

71 notchback,
Past owner of, 70 NB, 73 SB and 72 FB TLE

matberry Moderator Go hard or go home

8,114 posts · joined Mar 2006 ·

#910125
Well done Chris. Remnded me of Maths 2 at high school
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE

68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 ·

#910193
HappyDaze wrote:As the song says, "There's a fraction too much friction" going on. 😁

Lee simply wanted to know why his new pads were behaving differently.
Yes, as they are Not locking up as they were before and very easily..
One corner coming off the highway onto a wide side street , and having a truck doing 50kmh at least on Your tail
I usually go round the corner at 50 and then brake, but if the road is wet, the front would lock up and I would go straight ahead towards a median strip... so I would have to take My foot off the pedal and then steer left... lol

Well. I did the same thing a few days again in the rain, and the Left hand front was just starting to lock up but the RHS one didn';t and I steered around the corner...

So, really, I don't care how it all works, I was just wondering why two new front pads would make that difference..
Same tyres.. but new shock absorbers but old gas shocks still worked.. were a soft monroe gas shock.

I did fit another front end as one wheel was positive camber
also aligned the front wheels correctly..

anyway it brakes and steers etc all perfectly... excellent

it may have just been a lot of things all corrected---
toe in - camber - caster? - new shocks - NEW PADS ....??

LEE

- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---