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brake fade versus pedal effort 

 

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 Post subject: brake fade versus pedal effort
Posted: Mon Oct 20, 2008 10:58 pm 
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I think it's worth noting that if you want more powerful brakes and your brakes aren't fading, then you don't need bigger calipers. You might still want to fit bigger calipers, maybe for looks, but that's pricey, and don't forget bigger brakes usually weigh more.

If you just want more powerful brakes then you could fit a twin-diaphragm brake booster (if you don't already have one), otherwise you could get your master cylinder sleeved or a smaller one fitted.

 

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Posted: Mon Oct 20, 2008 11:30 pm 
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more brake booster would also lead to an overly sensitve brake pedal.

and a smaller master cyl will cause long pedal travel.

if 'cheap' options like that worked properly, people would be doing it.

 

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Posted: Tue Oct 21, 2008 12:11 am 
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Just about any car made in the last 20years has more brake power, than tyre grip. So there's no need for bigger brakes for emergency stops.

Only benefit of bigger brakes (more from bigger rotors) is resistance to fade. I can take my GT-P around a track all day long, and it's the tyres that f**k out before the brakes. Had I the XR spec brakes, they wouldn't last more than a handful of laps before fad set in.

Both however will stop the car (in an emergency situation) the same. Only way to improve that is add more tyre grip. If you lockup (or ABS kicks in) the tyres aren't as good as the brakes.

 

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Posted: Tue Oct 21, 2008 1:32 am 
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Yes, heard that one - provided your brakes can lock up at speed then your already at maximum braking capacity. However the advantage of bigger brakes is to sustain this ability.

 

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Posted: Tue Oct 21, 2008 9:44 pm 
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I hazard a guess bigger brakes give more control over braking force. They give enhanced ability to maintain the braking just below lock-up for maximum decceleration.

 

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Posted: Tue Oct 21, 2008 9:52 pm 
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tickford_6 wrote:
more brake booster would also lead to an overly sensitve brake pedal.

I find my XG's and my EB's brakes a bit dull. Too much force is required which reduces control. I reckon more sensitivity and more assistance would enable better control.

Quote:
and a smaller master cyl will cause long pedal travel.

Yes, but this method had been done plenty of times before and works when done properly and moderately. Obviously you wouldn't make a dramatic reduction in piston area without making serious checks that it will work.

Quote:
if 'cheap' options like that worked properly, people would be doing it.

Ford themselves offer a twin diaphragm brake booster on V8 models and possibly to my knowledge on some XR6 models as well. As mentioned before the master cylinder mod has been done heaps and has worked heaps. Braided brake lines in some or full measure compensate against longer pedal travel.

 

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Posted: Tue Oct 21, 2008 9:56 pm 
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What do you mean by 'bigger'.

Larger rotors simply provide great area for friction (provided bigger pads are used), and more heat soak / cooling (more resistant to fade).

Bigger pads/more pistons in the callipers, again are there to provide more friction, the extra pistons ensure the force on the pads is applied evenly.

The master cylinder sizing (compared to the size of the calliper piston(s)) combined with the vacuum assist and pedal level sizing controls how much 'feel' and control you get.

 

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Posted: Wed Oct 22, 2008 7:36 pm 
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relaxed_diplomacy wrote:
I hazard a guess bigger brakes give more control over braking force. They give enhanced ability to maintain the braking just below lock-up for maximum decceleration.

When i wrote this i didn't have a clear explanation for it. I'll see what i can come up with.

Lets say you have a car with small rotors and pads. The braking force from these just below lockup may be erratic due to excessive shearing of the pad material, greater line pressures creating more flex in the system (lines, links, calipers), and overheating reducing the friction level.

 

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Posted: Wed Oct 22, 2008 8:34 pm 
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relaxed_diplomacy wrote:
tickford_6 wrote:
more brake booster would also lead to an overly sensitve brake pedal.

I find my XG's and my EB's brakes a bit dull. Too much force is required which reduces control. I reckon more sensitivity and more assistance would enable better control.

Quote:
and a smaller master cyl will cause long pedal travel.

Yes, but this method had been done plenty of times before and works when done properly and moderately. Obviously you wouldn't make a dramatic reduction in piston area without making serious checks that it will work.

Quote:
if 'cheap' options like that worked properly, people would be doing it.

Ford themselves offer a twin diaphragm brake booster on V8 models and possibly to my knowledge on some XR6 models as well. As mentioned before the master cylinder mod has been done heaps and has worked heaps. Braided brake lines in some or full measure compensate against longer pedal travel.



do you have a fetish for posting stupid ideas and then arguing you way around circles to come back to same point? or are all these threads just a random coincidence?

 

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Posted: Thu Oct 23, 2008 9:20 pm 
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"Brake Fade " is when the resin that holds the fibres together in the friction material, boils, causing gassing. This gas " floats" the disc pads off the rotors, giving a soft feel to the pedal.
That is why slotted rotors are used, the slots act as degassing ports.
Better brake pads handle higher temps better, hence why you pay more for them.
Bigger brakes make for better heat disspersion, and less pedal effort.
Changing brake fluid reguarly helps maintain brake efficiency, and checking the condition of the brake caliper slides.

 

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Posted: Fri Oct 24, 2008 12:32 am 
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Nicely summed up.

Of note pads that handle higher temps, generally don't work as well if they're not hot enough, so aren't so good on the street.

The DS2500's I fitted after the stock Brembo ones wore, need some warming up to be their best. They are after all a street/race pad.

 

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Posted: Fri Oct 24, 2008 2:28 am 
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tickford_6 wrote:
more brake booster would also lead to an overly sensitve brake pedal.

and a smaller master cyl will cause long pedal travel.

if 'cheap' options like that worked properly, people would be doing it.


And a sensitive brake pedal is a bad thing? I fitted the dual booster to my car and its great! It may sound like a contradiction but you do get increased braking force for less brake pedal pressure and you can also "feel" the grip level better through the pedal. Hence, can use those s**t stock brakes more effectively.

You say "if cheap options like that work than people would be doing it" well Tickford did do it! and they obviously did it for a reason, and it worked. So unless you've done this mod and can argue to the contrary... get you facts straight. Do you know more than the engineers at Tickford?

 

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Posted: Fri Oct 24, 2008 4:49 am 
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EF/EL get a dual diaphragm booster straight off the bat, it was EA-ED that it was only in 5Ls and XRs.
I agree that it is a very worthwhile mod!

 

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Posted: Fri Oct 24, 2008 10:26 pm 
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Steady ED wrote:
EF/EL get a dual diaphragm booster straight off the bat, it was EA-ED that it was only in 5Ls and XRs.
I agree that it is a very worthwhile mod!

Does anyone know if the EF/EL one's fit straight into an EBII?

 

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Posted: Sat Oct 25, 2008 12:34 am 
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FLASH wrote:
tickford_6 wrote:
more brake booster would also lead to an overly sensitve brake pedal.

and a smaller master cyl will cause long pedal travel.

if 'cheap' options like that worked properly, people would be doing it.


And a sensitive brake pedal is a bad thing? I fitted the dual booster to my car and its great! It may sound like a contradiction but you do get increased braking force for less brake pedal pressure and you can also "feel" the grip level better through the pedal. Hence, can use those s**t stock brakes more effectively.

You say "if cheap options like that work than people would be doing it" well Tickford did do it! and they obviously did it for a reason, and it worked. So unless you've done this mod and can argue to the contrary... get you facts straight. Do you know more than the engineers at Tickford?



yes a sensitive brake pedal IS a bad thing. if you ever get a chance, test drive a 2005 camery altise. you'll soon learn how much it sucks.
What it can also lead to is over braking in a panic/emergency situation.
this is very bad in a car with no ABS.

It doesn't sound like a contradiction, because thats what the brake booster does. It's letting you achieve more master cylinder piston travel for the same pedal effort.


as for your last comment RE: the engineers at tickford.

the original post was broad statment and was not model specific, Tickford made an upgrade to a particular model. They would have also done ALOT of testing to get the pedal to feel right and have the brakes perform in the right way.

Fitting a factory option like the duel booster from the XR or from ANY EF/L
will not cause an overly sensitive pedal because it was designed to be there.

the problem with jumping on a forum and posting things like that is some people believe every thing the read with out question. The original post was far to general and could lead to some people making some very bad choices.


jumping in an changing things like piston size is asking for trouble,

if you need a 'softer' pedal, you probably just need to hit the gym and beef up your right leg a bit. on a street car the ONLY benefit to 'upgrading' any part of the brakes aside from the pads and maybe rotors is purely the WANK factor.

 

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