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Watch this. He did a previos video which explains the only situations big brakes are beneficial.
Yeah, that guy is completely right.👍

There are not much people who understand the difference in brake force and brake capacity.

And also the connection between brake effort (from your right foot) and brake force is not clear for most people..
 

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will the EBC 330x28mm grooved and dimpled vented discs fit on my 1.9 jtd GT. (2010, Cloverleaf)
I went for MiTo's 305mm Brembo calipers (fits Plug&Play on GT), solid disc's, Brembo pads (produce lots of dust) and braided hoses all around. It's night and day compare to factory set up. All
 

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I think that is a good modification, even if it is unlikley to make the car actually stop better.

'Fixed' calipers (such as those Brembos) tend to be more rigid than 'floating' style calipers. With 'fixed' calipers the caliper bodies themselves tend to be stiffer (probably not universally the case), and the attachment to the hub carrier is also more rigid (which is universal). These factors tend to reduce both pedal free play and 'sponginess' (compared to an equivalent floating caliper). Both free play and sponginess contribute to a subjective sensation of lesser brake performance, even if there is no objective difference between the actual retardation created by a fixed vs floating caliper (all else being equal).

In my experience, a good 'solid' feeling pedal with little free play or sponginess (not the same things, and with different causes) contributes strongly to a higher subjective confidence in the brakes. Other than the pedal, the MC piston, and disc rotation, in an ideal braking system the only components that should move or flex at all are the caliper pistons (ie. pushing the pads against the discs).

Any other component movements or flexures are going to create either free play or sponginess at the pedal, both of which tend to make the brakes feel less confidence inspiring. In varying degree, floating calipers have signicant internal movements in addition to just the pistons moving, but fixed calipers only have piston movement, so contribute less to pedal free play. Fixed calipers tend to be more rigid and so are likely to flex less than fixed calipers, so contribute less to pedal sponginess.

If the driver has less confidence in the brakes because of excessive free play and / or sponginess, he / she may be less confident to apply the brakes as hard as otherwise they might, so actual braking performance may be decreased because the driver may not feel as confident to 'stand' on the brake pedal as hard as is actually possible (...?). I know this affects me, I feel less confident to brake as hard as absolutely possible if the pedal feel is poor. I also tend to automatically back off slightly when the ABS starts to make the pedal feel like something is breaking (as opposed to 'braking'...).

This is one reaon why 'braided' hoses tend to increase driver confidence when braking heavily, even if they don't actually improve retardation (despite the driver possibly 'feeling' that they do...). The more rigid braided hoses make little difference in normal use, but when braking heavily they expand somewhat less than rubber hoses, and in turn this means the brakes feel significantly less spongy when used aggressively, so there is a subjective sensation of improved braking performance...

Regards,
John.
 

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The thing to remember though, and one reason why many people upgrade to braided hoses, is that the rubber hoses degrade over time and allow air/moisture into the system. Also, as they tend to expand under pressure, the actual pressure reaching the caliper is reduced, something that doesn't happen with braided PTFE hoses.
 

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I see you've now edited your first post, adding "using brake callipers from 166 ".

You'd obviously need adapter brackets for the 166 calipers.
The discs would need redrilling to 5x98mm PCD and you'd need rings to bring the centre bore down to the correct size.

Far easier to get the MiTo Brembos and a set of off-the-shelf GTV V6 / GTA 305x28 discs.
 
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The thing to remember though, and one reason why many people upgrade to braided hoses, is that the rubber hoses degrade over time and allow air/moisture into the system. Also, as they tend to expand under pressure, the actual pressure reaching the caliper is reduced, something that doesn't happen with braided PTFE hoses.
That is not true: brake pressure will be exactly the same only the stroke of the brake paddle will be a bit longer.

Also, I had rubber brake lines in use which were 30+ years old with no problems. Just replaced them to be sure.
 

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Also, as they tend to expand under pressure, the actual pressure reaching the caliper is reduced, something that doesn't happen with braided PTFE hoses.
Pressure reaching the calipers is unaffected by any hose expansion, regardless of the degree of expansion. Pressure causes the hoses to expand and as a consequence the pedal travel increases, more so the more the hoses expand, but with no other affect, ie. there is no loss of pressure.

It's my undestanding that all flexible brake hoses expand under pressure, rubber hoses a bit more than 'braid' covered plastic hoses, so pedal travel is somewhat greater with rubber hoses. This is only significant when braking hard with higher system pressures. Rubber hoses are pretty good for normal use, because they are internally reinforced with woven kevlar 'braid' that is quite resistant to expansion.

Regards,
John.
 

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Have you actually tested this yourselves? I've done so and there is a drop in pressure at the caliper using OEM hoses of a certain age, admittedly on bikes but the principal is the same.
Admittedly no, I haven't actually tested this, but physics says it must be correct. If we pump X pressure into a rigid walled pressure vessel, the pressure will be X and the vessel capacity will not increase. But if we pump X pressure into an expandable pressure vessel the pressure will still be X, but the capacity will increase as a result of the vessel not being rigid in expansion.

The pedal travel will increase because it isn't the variable capacity of the hose that limits pressure input and output (both X pressure), but rather it is retardation rate and possibly tyre traction, ie. the driver pushes the pedal as hard as needed to achieve the fluid pressure required to acheive the required braking affect, regardless of hose expabsion or pedal travel.

There will be a very transient loss of pressure caused by hose expansion. The expansion will cause a reduction in the rate at which fluid pressure changes, but it will be only a very slight 'delay' mostly because it takes longer to move the pedal a greater distance. The ultimate pedal travel will be greater, but the ultimate fluid pressure will still be much the same for a given effort on the pedal pad. Hoses with significant expansion will tend to 'cushion' the rate at which pressure rises and falls, but not reduce the peak pressure.

Note that fluid pressure is the same throughout the entire hydraulic circuit operating a particular caliper, because the fluid is for all intents and purposes incomprssible.

But there may also be small indirect mechanical affects. If hose expansion causes pedal travel to increase significantly enough, then there may possibly be a small indirect affect on system pressure caused by a change in the pedal geometry caused by angular changes to the push rod, caused by the increased arc of pedal arm swing.

E.g. if the push rod is statically at 180° to the MC piston axis, then a short pedal travel will see little change in that angle and pretty much all push rod force will act in a straight line with the piston movement. But, if the pedal travel is significantly longer (as might occur if the hoses are soft in expansion...), then as the push rod moves it will not move purely in line with the MC piston but also move vertically at the pedal pin. The push rod angle relative to the MC piston will change and so the leverage will change, in some degree.

I suspect this could be why your test with bike brakes saw a pressure loss with old softened hoses relative to new hoses, ie. the brake lever geometry may well have changed when the lever travel increased as a consequence of greater hose expansion...?

Regards,
John.
 

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Have you actually tested this yourselves? I've done so and there is a drop in pressure at the caliper using OEM hoses of a certain age, admittedly on bikes but the principal is the same.
That can be true: it means they are broken up internally. It happens when they are VERY, VERY old or when wrong fluid is used (normal oil for example).
When both types are in good order there is no difference in pressure: those are the laws of nature, not the laws of feelings.. 😉
 

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Bikes tend to exhibit more lever travel increase due to weakened hoses than cars due to the smaller diameter master cylinders which displace less volume of fluid. The hoses are ostensibly the same but cars have master cylinder bore volumes many times of that of the hoses.

A collapsed hose is what can cause a pressure drop or failure of brakes to fully release or at least release immediately.

Brake fluid is generally of the same chemical base. Differences are in viscosity (lower for later ABS/ stability control systems). 5.1 is thinner for that reason as well as having higher wet and dry boiling points. Unfortunately it degrades quicker and has reduced lubrication properties even though it still has a higher wet boiling point. In any case, it plays an often overlooked important part in stopping things like slave cylinders developing leaks.

Rigidity of calipers and their attachments has been covered and aids linearity in brake application. That can be a major benefit of larger brakes. Downsides can be reduced brake temperatures (colder climates) especially if added to a car with lighter power train and performance pads are used which are intended to work best at over 200° Celsius. If so, the modification may be a definite downgrade. People selling these products don't explain that so common sense is needed.

In any case, the brakes in the 4 cylinder cars were rated as good by professional magazine testers. For that reason, I think there are better areas to spend money on if someone finds the specification a bit lacking. It makes sense if changing things to start on things which incur no (significant) functional downsides such as reinforced brake hoses, and larger anti roll bars. 5 and 6 cylinder cars probably need a different approach though.
 

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The linked video (above) explains that OE brakes are specced to be perfectly adequate to cope very well with any reasonable demand in normal road use. I more or less agree with this, but it should be noted that the factory fitted pads will not be rubbish, unlike some cheap aftermarket pads.

A few years back I had an instance of cheap pads fading badly during an emergency stop from about 100kmh or so. The initial 'bite' and braking effect was acceptably OK for maybe 30 metres or so, but then the pads 'outgassed' and the braking effect decreased dramatically, with the car failing to stop as required (would have hit an animal had I not been able to steer around it). I binned those pads and fitted new ones (TRW) then deliberately repeated the 'test', with a hugely improved result, the pads didn't fade and car pulled up in a far shorter distance...

Regards,
John.
 

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Discussion Starter · #20 ·
I see you've now edited your first post, adding "using brake callipers from 166 ".

You'd obviously need adapter brackets for the 166 calipers.
The discs would need redrilling to 5x98mm PCD and you'd need rings to bring the centre bore down to the correct size.

Far easier to get the MiTo Brembos and a set of off-the-shelf GTV V6 / GTA 305x28 discs.

i have Brembo 310mm on my GT, from Alfa 166 with custom made adapters, from link above. You need Alfa 166 310mmx28mm disc and you need new holes drilled
Thanks this is exactly what I’m looking for but can you please send me the exact link for where I can buy the adapters because I don’t understand the language, thanks a lot:)
 
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