Initial brake feel

[Dev]

One minor thing to consider Dev (probably just in terms of placement) but our RHD cars have the master cylinder on the other side, and the design is cosmetically different too.

Only found out by accident when I realised I'd been harbouring a LHD spare, but the reservoir is a different shape too. I assume your findings re: bore remain the same but just thought I'd mention.

I was aware that it's on the other side and some differences will be there with line fitting orientation but having looked at a detailed picture it is a different sourced part and you are right it looks entirely different. The manufacturer is JKC for the RHD and for the LHD It's Aisin. However they are the same bore diameter which is embossed on the part being 7/8". 

[Dev]

It is looking more likely that Toyota intentionally gave us better feel in the brakes by making them stiffer.     

As I obeserved there is sóme initial design (emergency brake and abs) ´give´ in the system but from there it is quite good. The initial give is probably a good safety thing for the vast majority of the intended buyers. It precludes immediate lock up by the heavy footed but still gives good modulation for spirited driving.

Going with the larger bore on a oem system you need to exert more foot pressure therefore immediate lock up is delayed because it's harder to achieve. It would be a safety concern on the street where you need to build enough line pressure to give maximum breaking force in a shorter period of time.
However the benefits of the larger bore is necessary to move more fluid if you are adopted larger calipers and at that point the brakes will feel relatively normal again if it is calculated.

Other factors that come into play is the brake booster and the pedal fulcrum for mechanical advantage. All of these things make it a very complex thing to get right if you want to modify for a better pedal feel.
Fortunately the Willwood calipers by shear serendipity of having less displacement achieves better pedal feel.

[The Other Stu]

Bleed brakes. Properly.
Change of pads. The Yellowstuff are a cost-effective way to get that "bite".
That and your flexi lines may be past best. Replace or replace with braided.

Sorry Jason to take this slightly away from topic, but is there a "how-to" for the brake hoses Patrick?

I was looking at mine (I have a brand new set of braided ones which I won in a competition a couple of years back) and I don't understand how they come apart.

[shnazzle]

Bleed brakes. Properly.
Change of pads. The Yellowstuff are a cost-effective way to get that "bite".
That and your flexi lines may be past best. Replace or replace with braided.

Sorry Jason to take this slightly away from topic, but is there a "how-to" for the brake hoses Patrick?

I was looking at mine (I have a brand new set of braided ones which I won in a competition a couple of years back) and I don't understand how they come apart.

There isn't to my knowledge but it would be a short one.


Only things to bear in mind;

- use a new copper washer and bolt on the caliper side when refitting
- use correct flared spanners for the lines. Keep mole-grips handy in case of severe rust. GT85/PlusGas aplenty.
- lines are different front and back. Don't mix
- HEL lines had some fitment issues with the bracket. Not sure if this has been resolved. Mine have been on without shifting for over 5 years now.
- fresh OEM lines will be as good as braided on the MR2 but braided are generally cheaper. (oddly).
- depress brake pedal fully before starting and hold in place with a bar against the seat or something. It will stop the lines continuously dripping once disconnected 

The rest is just.. Take line off, put line on, bleed brakes.

[Alex Knight]

The brakes work fine and stop very well.

I know there is supposed (and is) free play

But I'd just like the pedal to be a little firmer at the top.

Any tips?

Let me tell you a story:

Many moons ago, I replaced the front discs and pads on my ST205 GT-Four.

The initial brake feel worsened significantly straight away. I was perplexed. I bled the absolute beans out of the brakes, several times.

I changed the lines. I reinstalled the brakes several times.

Things were no better.

In a fit of clarity, I decided to revert back to the last known good configuration, ie: the old discs and pads.

Low and behold, strong initial bite came straight back.

The culprit? Warped, brand new front discs. They had literally never been used, but were warped.
They were pushing the pads away from the disc and into the caliper as they rotated.
This caused the first initial press of the pedal to only take up the slack, not really biting into the disc straight away.

The moral of the story? Check your disc runout, even on brand new discs.

[Petrus]

The culprit? Warped, brand new front discs.

Warped front discs I have had too.
Apart from more distance of the pads it gave slight vibration when pushing the car.

Sorted with Brembo discs and pads.

Still, there is still some initial slack in the system. It is imo the boost and abs.

Overall véry satisfied with the braking, with the modulation. I can swith right or left foot brake whenever I want. That is a huge compliment to the system as even when experienced the left foot is not instantly as sensitive as the right.

[Dev]

I did a brake job a few months ago for my other car that had a slight amount of pulsing that I tolerated.
 I used something new that came into the market about a year ago that I never heard of called high carbon rotors. They are a premium and cost a little more but well with in realistic pricing to pay the difference.
 These rotors were formulated to have a different mixture of metals and process for the benefits of virtually no chance of warping or pulsing due to over heating.  One of the other benefits is no pad squeal because the rotor dampens vibrations due to its metallurgical properties which would be great for those that run aggressive pads. I found out that they are available for our car and I am sure if you look hard enough over there there might be a supplier that has them.
 

[Petrus]

The way the Brembos rust -> high carbon steel.
Des te roestie, des te remtie (The more they rusty the more they braky) 

Don´t know how ´high´ in high carbon for the discs in your response is defined.

A crucial thing with high carbon steel is the way it tempers.
Brake discs should come well tempered from the manufacturer. As important as the material.
Not much different if at all from blade making.

[Dev]

The way the Brembos rust -> high carbon steel.
Des te roestie, des te remtie (The more they rusty the more they braky) 

Don´t know how ´high´ in high carbon for the discs in your response is defined.

A crucial thing with high carbon steel is the way it tempers.
Brake discs should come well tempered from the manufacturer. As important as the material.
Not much different if at all from blade making.

 I am not the one defining the term and I am not going to make assumptions of any negative effects. It is what the industry is selling as a premium product and many OEMs come with these kind of rotors from what I read. These rotors are not steel they are cast iron but with a different blend and process of making them resilient to pulsing and brake squeal.

See here.
 https://knowhow.napaonline.com/brake-rotors-the-six-different-types/
https://centricparts.com/company/news/february-2017/new-centric-premium-high-carbon-rotors-offer-impro
https://www.bremboparts.com/america/en/products/innovation/high-carbon

[Petrus]

ah good old marketing of time proven oldie with a twist 

[Dev]

ah good old marketing of time proven oldie with a twist 

  I see nothing wrong with the marketing if they do offer the benefits they claim over traditional cast iron rotors. Most high quality standard rotors come well balanced and well cast as an industry standard. These rotors are a premium product over standard rotors that can handle a higher level of heat and therefore resist creating high spots that cause pulsing. They are becoming popular as an option and are not a rebranded product as your cynicism suggests.   

 Standard rotors can be fine depending on how the braking system is designed however there are some vehicles  where that are notorious for pulsing like my Lexus, this product offers more resistance to this issue.
 I imagine that this will become standard on all OEM cars from the factory because there are no downsides except cost which is not much more than standard.

[Petrus]

because there are no downsides except cost which is not much more than standard.

Even a dime is important depending on the sector.
Also rusty discs are an issue depending on the sector/wheel design.

We are dwelling from the topic though.

[Ardent]

Having bled twice.

Something that popped up here.
I have always been engine off.
A reference to Rouge bleeding engine running.

Pros cons?

General searching gives 80 20. In favour of off.

Another variation
I was opening the bled screw, op2, pressing the pedal. Then closing.
Toyota say.
3-4 pumps and hold. Then open. Pedal sinks. Then close. Release.
No mention engine on or off.

[Alex Knight]

Engine doesn't need to be on.

You can drop the brake pedal to the floor pretty much once you open the bleed screw. That's all you need.

[Joesson]

My early cars had no brake booster so no point in having the engine running.
My understanding is that the ( modern) booster reduces the pedal pressure necessary to operate the brakes.
As @Alex Knight says there is very little pedal resistance when a bleed valve is opened, having the engine running to create vacuum to power the booster will have no helpful effect on the bleeding of any entrained air from the system/ fluid.

PS.
Not mentioned thus far is the brake fluid. Assuming the correctly specified fluid , recently purchased, noting the typical small retail packaging as it has a limited shelf life once opened due to its hygroscopic nature.
The container should be kept tightly closed and unshaken as that will entrap air.

[Dev]

You can have someone press on the brakes and hold it. Then you loosen the bleeder valve a little to let very little fluid though and close it quickly.  Give the command to the person to let go of the pedal and repeat.  This way the pedal does not hit the floor and having you have to lift it off the floor with your hand. 
 Keep inching with opening and closing quickly and you will never induce air or run into a difficult bleed. Often times what happens with two man on one woman and one man bleeding is a loss of communication when to press and when to close which causes air to go back into the system.  In a nutshell do not open the bleeder and then have the person press on the brakes as that would be bad. 

 I do not do any of that now. I gravity bleed which is the easiest method. Attach the clear plastic tube on the bleeder screw and undo the screw to where where fluid is flowing out slowly and thats it. If there are any bubbles in the line you can observe them as they make their way though the system and into the tube. Just make sure to top off. I always get a rock hard pedal this way and I can do it by myself, just takes a little longer but a lot less mess.

[Joesson]

@Dev said:
"This way the pedal does not hit the floor and having you have to lift it off the floor with your hand".

Prior to my owning my 2 (2011) the last time I had need to bleed brakes was around '86, but I don't recall having to retrieve the brake pedal while bleeding on previous cars.
MrsJ has often helped with the pedal pushing on various cars over the years since the '60's and retrieving the pedal has not been necessary. Indeed, until this year that has been the case with my 2.
But, this year, I had acquired a one man bleeding system ( A length of rubber tubing with a lateral split and a blocked end) and so was bleeding solo and found that the pedal did stick down.
I used a length of cord looped around the pedal and gave that a tug ( was going to say a yank but thought better of it).

 

[Ardent]

cheers for replies all.

[Ardent]

Not mentioned thus far is the brake fluid. Assuming the correctly specified fluid , recently purchased, noting the typical small retail packaging as it has a limited shelf life once opened due to its hygroscopic nature.
The container should be kept tightly closed and unshaken as that will entrap air.

All above boxes ticked.

[Joesson]

Not mentioned thus far is the brake fluid. Assuming the correctly specified fluid , recently purchased, noting the typical small retail packaging as it has a limited shelf life once opened due to its hygroscopic nature.
The container should be kept tightly closed and unshaken as that will entrap air.

All above boxes ticked.

I'm beginning to think that the OP has very sensitive feet!

[Dev]

@Dev said:
"This way the pedal does not hit the floor and having you have to lift it off the floor with your hand".

Prior to my owning my 2 (2011) the last time I had need to bleed brakes was around '86, but I don't recall having to retrieve the brake pedal while bleeding on previous cars.
MrsJ has often helped with the pedal pushing on various cars over the years since the '60's and retrieving the pedal has not been necessary. Indeed, until this year that has been the case with my 2.
But, this year, I had acquired a one man bleeding system ( A length of rubber tubing with a lateral split and a blocked end) and so was bleeding solo and found that the pedal did stick down.
I used a length of cord looped around the pedal and gave that a tug ( was going to say a yank but thought better of it).

 

There are many of these one man bleeder kits. I do not know the particular one you have but there are some that induce a vacuum to pull the fluid though. I had  one of these and also had one that hooked up to my compressor to create a vacuum  attached to a bottle.  The problem I found with these is when you loosen the bleed screw the air can get past the threads of the bleeder. 
I also had one that pressurized the master and had a bottle that fed fluid though the system.  All you had to do is open the bleeders and it just comes out. The problem is it wastes fluid and can be messy.

I even tried a kind of bleeder with a one way check valve which was really nice but over time the ball in the valve corrode and locks up. 

After looking at some Youtube videos on gravity bleeding I tried it and never looked back. All you need is a clear tube and a container to catch the fluid. Open the bleeder and wait for it to clear. No mess no fuss just easy.
Some people gravity bleed all four lines at the same time which is fast but I don't mind taking my time. It really doesn't take that long probably 5-7 minutes for each corner. 

The problem with doing it the traditional way is coordinating with the person by the pedal. It is difficult to call out commands and just about every time someone does listen and messes up causing the pedal to drop to the floor.