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Old 19th June 2009, 11:55   #1
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Lightbulb “Braking” – All about brakes, lets Discuss & Learn!!!

Hi TBHPians!!!!

Braking being one of the most important components in the success story of running/modifying/maintaining our cars/bikes, i think it would be a great idea to discuss and learn on the subject from each others practical experience and knowledge.

Just to give the thread a kick start let me post links to some good text that i came across while trying to look for some details on braking -

1. Automobile Brakes - A Short Course on How They Work

2. Car Bibles : The Brake Bible

3. How to Maintain Automotive Brakes | eHow.com

4. http://www.autoshop101.com/forms/brake05.pdf

So lets talk about brakes...
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Old 19th June 2009, 16:22   #2
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Nice links. I like the one on how brakes work. Very clear

Last edited by McLaren Rulez : 19th June 2009 at 16:24.
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Old 19th June 2009, 23:11   #3
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This is as good a place to ask this question as any other I guess.

As of late, my Civic's brakes have become... spongy? They usually have good feel with the bite of the brakes being felt on the pedals and even a slight bit of action rewarded with stopping power. But now, the first 10% or so of the pedal does absolutely nothing and the rest is completely without feel. Almost like drive by wire braking.

My car has run only ~7700KM. Any thoughts?
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Old 20th June 2009, 03:02   #4
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I heard a "Drrr" sound when I brake slightly hard. I see this happening after I changing from 165/80/14 to 205/50/16 with 7J rim size. Could this be the cause?

Braking does not inspire confidence. Can I get ABS and EBD installed now in my swift?

Pls advice
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Old 20th June 2009, 08:45   #5
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Quote:
Originally Posted by anandkumargb View Post
I heard a "Drrr" sound when I brake slightly hard. I see this happening after I changing from 165/80/14 to 205/50/16 with 7J rim size. Could this be the cause?
Two causes that I can think of. 1) Your rims aren't balanced properly. This will show up as vibrations at specific speeds, not just braking. 2) Is that your brake discs have become uneven. Get them inspected and skimmed at a lathe if necessary.

Quote:
Braking does not inspire confidence. Can I get ABS and EBD installed now in my swift?

Pls advice
Nope. Near impossible unless Maruthi themselves do it. ABS is calibrated for a specific car by the manufacturer.
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Old 20th June 2009, 11:54   #6
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I have asked this question before without success so here goes again.
I need a good workshop in bangalore where I can get my accent 1.6 gls brakes looked at/overhauled. The brakes are weak and the left rear brake makes a hissing sound when I use the brakes. The trident workshop has not been able to narrow down the issue. ALso the brakes are sort of weak and donot insipire any confidence.
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Old 20th June 2009, 15:38   #7
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Applying Brakes is a skill on has to master over time. Normally 80% of braking has to be handled by Engine/tyres itself. Balance 20% by the brakes. What do I mean by this.

Always ensure not to press the clutch while braking. Use engine to brake. It would be great you downshift while braking. This is a skill hard to master but very useful. I have completed 40K service of my Swift VDI today and observed that more than 50% of front disk brake pads are intact (please note till day before yesterday I used to run on stock JK tornado tyres.

Now next important aspect of braking is tyres. Good tyres help braking immensely. Shody tyres (read JK tornados) make you loose confidence in your brakes (despite brakes being well maintained). on the tyres please ensure the tread depth on each tyre are more than 1.3mm (This can be easily identified as each manufacturer provides a tread wear indicator which gets exposed after 1.3 mm is reached).

Lastly brakes - front disk brakes get more than 60% of the force (either hydraulic or electrical). Also the rear brakes get the force a fraction of a second late hence it is very vital to have rear tyres better than the front in terms of tread wear (Else you may end up fishtailing - your rear tyres will loose road grip). Typically front brakes are discs and rear are drum brakes. Rear drum brake pads last twice as long as the front disc pads.

This is my two cents on braking.
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Old 21st June 2009, 09:33   #8
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Quote:
Originally Posted by ImmortalZ View Post
This is as good a place to ask this question as any other I guess.

As of late, my Civic's brakes have become... spongy? They usually have good feel with the bite of the brakes being felt on the pedals and even a slight bit of action rewarded with stopping power. But now, the first 10% or so of the pedal does absolutely nothing and the rest is completely without feel. Almost like drive by wire braking.

My car has run only ~7700KM. Any thoughts?
ImmortalZ, your pads are slowly wearing out (nothing to worry). Hence the pedal travel. Brake fluid is hygroscopic (absorbs moisture). Get your fluid flushed, you will be fine.

Due to the moisture, the brake fluid starts getting bubbles (boiling point of water MUCH less than boiling point of brake fluid) within the plumbing, hence the mushy feel.
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Old 21st June 2009, 14:14   #9
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ImmortalZ, your pads are slowly wearing out (nothing to worry). Hence the pedal travel. Brake fluid is hygroscopic (absorbs moisture). Get your fluid flushed, you will be fine.
This is not true. In most modern cars we have callipers which automatically take care of brake pad wear. It is because of higher free play which has been set in immortalz case which can be set easily to standard by any mechanic.
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Old 21st June 2009, 20:17   #10
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well here is the problem i am facing, just bought this army spec gypsy - http://www.team-bhp.com/forum/4x4-ve...ter-gypsy.html

now i need to upgrade the braking setup by adding a brake booster to it. Any idea of the important aspects i need to consider while doing the mod?

has anyone here done it before?
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Old 22nd June 2009, 07:31   #11
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Quote:
Originally Posted by DieselFan View Post
This is not true. In most modern cars we have callipers which automatically take care of brake pad wear. It is because of higher free play which has been set in immortalz case which can be set easily to standard by any mechanic.
Dieselfan, you are partly right. The callipers do adjust to SOME extent, but not all of it. As the calliper pistons move more to get the brake to bite, the pedals have to move a bit more to compensate.

Kaushik, the only point you want to keep in mind is to make sure the booster vaccum pressure is same/ almost same as the original brake vaccum pressure of the gypsy. This is because then the pedal pressure & feel will remain the same. if the systems are widely mismatched, you may get a VERY hard brake pedal & still very little bite!

Last edited by 1self : 22nd June 2009 at 07:36.
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Old 22nd June 2009, 09:36   #12
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Quote:
Originally Posted by 1self View Post
Kaushik, the only point you want to keep in mind is to make sure the booster vaccum pressure is same/ almost same as the original brake vaccum pressure of the gypsy. This is because then the pedal pressure & feel will remain the same. if the systems are widely mismatched, you may get a VERY hard brake pedal & still very little bite!

did you mean the "original brake vacuum pressure" of another gypsy in which the brake booster is company fitted? or what?
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Old 22nd June 2009, 10:55   #13
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Quote:
Originally Posted by DieselFan View Post
Applying Brakes is a skill on has to master over time. Normally 80% of braking has to be handled by Engine/tyres itself. Balance 20% by the brakes. What do I mean by this.

Always ensure not to press the clutch while braking. Use engine to brake. It would be great you downshift while braking. This is a skill hard to master but very useful. I have completed 40K service of my Swift VDI today and observed that more than 50% of front disk brake pads are intact (please note till day before yesterday I used to run on stock JK tornado tyres.


Hi, Agreed , but does engine braking affect FE,gear box or engine in anyway as you find the engine whine as RPM rises .
Kindly advice advise what steps to follow- driving at 80kmp on 5th how do i come to a stand still?

Last edited by Rehaan : 22nd June 2009 at 16:03. Reason: Quote fixed.
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Old 22nd June 2009, 12:16   #14
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Quote:
Originally Posted by PRADEEP KUMAR View Post
Kindly advice advise what steps to follow- driving at 80kmp on 5th how do i come to a stand still?
In my experience the best way to brake under normal circumstances (NOT under emergency braking) to bring the car to half from 80 kmph is - Brake at 5th till 40 or 45 and switch to gear 3 and brake till 20-25 and switch to 2 and brake till you halt and press the clutch and bring the car to Neutral/Gear 1 as the case may be.
Under emergency braking - go all the way and brake fully from 80 down to zero in the same gear (Gear 5). If the brakes lock release momentarily and brake again. Stand on the brakes if required.

Please do not get into a situation of emergency braking. predict future outcomes (Possibilities) and drive defensive.
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Old 22nd June 2009, 12:36   #15
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Quote:
Originally Posted by DieselFan View Post
Under emergency braking - go all the way and brake fully from 80 down to zero in the same gear (Gear 5). If the brakes lock release momentarily and brake again.
This is known as cadence braking. A subtitute for ABS in non-ABS cars, but only if done properly.

Speaking about braking under normal circumstances, how many drivers actaully downshift and utlize engine braking? I guess very few. Most of the driver brake in 5th gear itself if not with a fully depressed clutch!

Many people say that downshifting and 'putting all those load' on the engine is bad for the engine!

Anyway, I downshift and utilize engine braking. I shift to second a bit earlier than what you've suggested.
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