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Old 04-05-2016, 09:21 PM   #721
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Quote:
Originally Posted by OGRacing View Post
with the caliper pistons being as tiny as it is i see a requirement for a .625 =5/8 master cylinders. on front and rear. this will net a requirement for the MC's travel to be 11mm your pedal will need to travel 40.25mm. make sure you have enough room.
I'm running 0.625" master on the front, 0.700" master on the rear and my balance bar is set approx 65% rearward. I have a spare 0.625" master that I'll put on the rear next fluid change and see if it squares up the balance bar a little.

I have brakes similar to you, based off bbundy's setup.
Up front I have 11.75" rotors with Dynapro radial mount calipers
In the rear I have 11.44" rotors with NA6 calipers on a DIY offset bracket

This brings the bias slightly more rearward on my car vs yours so OG's suggestion of 0.625" on both makes sense.

In terms of pedal travel, isn't that more governed by pad choice? I find with my Ferodo DS1.11 pads I get a very firm pedal on the track with about the right level of pedal travel for feel and control. It's hard to gauge as I don't change pad choice often and I haven't driven a lot of other cars plus it depends on what you like as a driver.

I've ended up sticking to the stock 4:1 pedal ratio rather than moving the pivot. I think it might be better at a higher ratio but it's a bit of work to change it and I'm happy with the feel at the moment.

Here is the link to the dual master setup: Brake booster delete/
And the link to my thread and DIY baffle on the oil pressure dip: Oil pressure dip under brakes/
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Old 04-05-2016, 10:15 PM   #722
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...


Edit , yes it can.

Last edited by OGRacing; 04-06-2016 at 02:51 PM.
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Old 04-05-2016, 10:34 PM   #723
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Pedal travel shouldn't be effected by pads. It can be effected by flexing calipers...
I noticed it when I first switched from Ferodo DS3000 to the DS1.11 in that the pedal travel was less. Not much but I think it helps counteract the bigger travel when you switch to smaller masters.

Here is the marketing blurb from Ferodo. It might have a bigger impact on higher-end braking systems where there is less caliper flex. As you point out the caliper flexing probably has a far greater impact.

Quote:
Ferodo Racing DS1.11
Several brake pads on the market boast 'ceramic' technology. DS1.11 is the real thing. It is based upon a chemical family known as Siloxanes. Unlike carbon based materials, siloxane chains do not decompose at high temperatures and so DS1.11 keeps on working up to the highest temperatures a brake pad could ever see. That means it won't fade and has excellent life, the best in the Ferodo Racing range. Moreover the performance remains exactly the same throughout the pad's (long) life. It is formulated to provide a very flat friction profile at a medium/high level of friction. The pad compression is very low, always, and so pedal travel is short and consistent. The main characteristics of DS1.11 are:
High coefficient of friction (0,50) at all speeds and temperatures
Excellent life of pad and disc
High initial bite
Predictability and control because of the unvarying torque output
Low off-brake drag/Excellent release
Unvarying performance throughout pad life
Firm pedal. Always
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Old 04-05-2016, 10:53 PM   #724
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Quote:
Originally Posted by OGRacing View Post
Pedal travel shouldn't be effected by pads. It can be effected by flexing calipers...
Its an old FSAE judging question, "whats the elastic modulus of your brake pads?" No one outside of the pad companies know that answer unless they measured it themselves. And no one even thinks about it really, but its one way to tune brake feel. A low modulus pad can give you longer easier to modulate pedal but makes the brakes feel like of like a box truck it takes away confidence, where you can stiffen up the pad and it feels like the brakes work better. But of course you kind of have to go on tribal knowledge or an exceptionally knowledgeable sales guy to know what a stiffer or softer pad is. Its not like huge differences here, but its noticable, like this is part of the reason why HP+ feel like you're just pushing on a block of wood duct taped to the firewall.
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Old 04-06-2016, 12:45 AM   #725
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Pedal feel is very much affected by pad compound. Some compounds are more compressible than others. I prefer a slight compressibility or medium modulus and medium-to-high friction.
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Old 04-06-2016, 12:58 AM   #726
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Johnny said pedal travel, not pedal feel. Is travel affected by different pads?
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Old 04-06-2016, 01:09 AM   #727
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Pedal travel becomes more of an issue when you go dual masters as you're trying to get as much leverage on the brakes as possible without the booster. This means sizing smaller masters like 0.625". This results in more pedal travel and so selecting a pad compound with less squish becomes more important to counteract the extra movement from the smaller masters.

The balance I have stumbled on works well. Firm pads, 4:1 pedal ratio, 0.625" masters. I think moving to a 5:1 - 6:1 pedal ratio may be slightly better, but then you get even more pedal movement as a result. I find I can step on the brakes hard enough to be at the limit of the tyre grip, reading around 800-1000PSI in the brake line pressure, which is similar to what I was seeing with the booster. If you have 275 Hoosiers and big aero you might need more.
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Old 04-06-2016, 02:50 PM   #728
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Quote:
Originally Posted by OGRacing View Post
Pedal travel shouldn't be effected by pads. It can be effected by flexing calipers...
nope i'm wrong. i ran it pads the PFC engineering department. the PFC's are known to be a herder pad, and with less compress.
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Old 04-07-2016, 02:29 PM   #729
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What a great thread. I havent had a chance to read but about 1/3rd of it but have already learned a lot. I need to rethink my braking approach from 93 mainly street car.

It is a factory ABS car, so that makes it interesting. I need to learn more about the balance of the system.

I have a set of stock MSM front brakes for it that i plan to install. I am now afraid that it will cause too much imbalance combined with the stock rear 1.6 brakes. undecided on pads yet. I also need to read up on the appropriate way to bleed the abs system, i dont want to screw that up.
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Old 04-07-2016, 02:30 PM   #730
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Turn off car, ground the abs diag wire, hold down pedal, turn on car, bleed while it cycles.
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Old 04-08-2016, 01:27 PM   #731
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Thanks for the help. Tilton 600's with 5/8" master cylinders ordered and received. The pedal assembly is legit, solid; feels like a piece of equipment. Can't wait to experience them on-track and get the balance dialed-in.
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Old 04-08-2016, 07:01 PM   #732
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Quote:
Originally Posted by wildo View Post
Thanks for the help. Tilton 600's with 5/8" master cylinders ordered and received. The pedal assembly is legit, solid; feels like a piece of equipment. Can't wait to experience them on-track and get the balance dialed-in.
Interested to see how you mount it.
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Old 05-10-2016, 07:31 AM   #733
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Solid rotors with fixed calipers = lots of drag. drag kills rotors and pads. the rotors move too much and really should be used with a floating rotor or a floating caliper.
i'd like you to develop this point.
Lots of popular "big brake" kits offer fixed calipers and 2 pieces rotors.
I understand that 2 pieces rotor (as the wilwood...) will allow some thermal expansion between the ring and the hub, which will reduce warping due to thermal stress and as consequence will reduce drag...
Or did you mean mean "full floating" rotor that present axial free play? Are a "must do" when switching to fixed calipers for the track enthousiast that is not competing? Full floating rotor seems to be quite rare, especially for the less than 300m diameter... and quite costly!
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Old 05-10-2016, 08:45 AM   #734
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I think he was referring to a floating rotor. They are noisy and expensive, but are a necessity with a fixed caliper, to avoid unwanted heat and drag. That's how I read it in the brake q. And a. Thread.
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Old 05-11-2016, 12:45 AM   #735
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Quote:
Originally Posted by ryansmoneypit View Post
I think he was referring to a floating rotor. They are noisy and expensive, but are a necessity with a fixed caliper, to avoid unwanted heat and drag. That's how I read it in the brake q. And a. Thread.
AFAIK every Miata BBK on the market uses fixed calipers and non-floating rotors, they seem to work fine.

--Ian
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Old 05-11-2016, 02:56 PM   #736
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It's a matter of Bad, Better, Best.
Floating rotors are the best (and not available in any Miata kits). 2-piece non-floating rotors are FAR better than 1-piece rotors (such as factory rotor).
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Old 05-13-2016, 01:15 PM   #737
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Quote:
Originally Posted by ryansmoneypit View Post
I think he was referring to a floating rotor. They are noisy and expensive, but are a necessity with a fixed caliper, to avoid unwanted heat and drag. That's how I read it in the brake q. And a. Thread.

exactly that.
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Old 05-24-2016, 11:29 AM   #738
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So, Wildo: How did your pedal assy install go? Do you have acceptable pedal travel and effort?

I am so done trying to track my ABS car and it's "numb" brake pedal. After reading these 700+ posts for second or third time, I'm going to summarize my thoughts so I can just come back to this point.

If I have understood correctly:

You want to use an 11.75" front rotor kit and a sport-brake rear rotor. It's a better value to pay more for better metalurgy/manufacturing. Static and dynamic runout slow you down with drag and increase your pedal travel. Directional vanes are good. J-vanes keep the rotor from deforming as much. Parts store/china rotors have oil impregnation issues.
wilwood dynapro radial mounts (not lug mounts) are only slightly more rigid than dynalites. These are offered in 3.00 and 3.54 sq in piston volume. dynalites are 3.00 sq in.
wilwood powerlites have been successfully used in the rear (1.58 sq in piston area); but no e-brake.
If you want an e-brake, then the sport bracket + nb non-sport calipers (.910 sq in), or sport calipers (1.07) are your piston volume choices.
Brake boosters take away modulation "feel".
Dual mc pedal assy need to have a 5:1-6:1 pedal ratio, although some have used the oem 4:1 pedal and say they have acceptable pedal effort.
5/8" mc sizing may give appropriate pedal effort, but might give an unacceptably long pedal and/or cause your pedal to go past 90 degrees.

I didn't understand the discussion about taking into considerations in straightline braking vs.trailbraking... but I think that this might have been more of a pad selection issue
It was suggested that the 11.75 BBK vendors may have slight differences, but the merits not discussed.
most ducting seems to be 2.5" and 3". Are these pointed at the caliper in addition to the backing plates? (I think my TSE backing plates are smaller than 2".)

Last edited by gtred; 05-24-2016 at 11:42 AM.
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Old 05-24-2016, 09:51 PM   #739
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I know it's probably easy for everyone to say this about their brakes, but I'm finding my set up is working very well. It's cheap to do if you can DIY and you get close to the best braking capability in a Miata.

11.75" fronts on Dynapro radial mounts - any 11.75" kit will work
11.44" bbundy Honda Wilwood rotors with a DIY stock caliper offset plate MADJAK's NA8 - 200+HP N/A - Page 1 - mx5cartalk.com
DIY booster delete modified pedal box with dual masters (0.625" front, 0.7" rear) - stock pedal ratio (4:1) https://www.miataturbo.net/suspensio...-delete-86683/
In cockpit balance bar adjustment
DIY 3" brake ducts to front spoiler
Ferodo DS 1.11 pads (DIY cut to shape) - I'm not sure how important pad choice is, but I'm running this pad due to it's low compressibility and flat friction curve. It's working well so far.

You really want to run the biggest rotors you can fit in the rims so that the heat load on the pads and rotors is reduced. The Dynapro radials are nice because they have thicker pads so you get longer life out of them that other calipers. The booster delete and dual masters made a massive difference to me however my engine is very extreme and so my vacuum booster was basically ineffective. I think for track work, you really need the balance bar adjustment as track conditions change to maintain optimal brakes.
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Old 05-24-2016, 10:42 PM   #740
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looks like that 11.44 setup is what 2 pounds lighter than the sport rotors too? almost 4 pounds if you buy the super weight weenie drag racing only scalloped rotors.
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