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Brake FAQ - Rotor, caliper, MC sizes

58884 Views 72 Replies 29 Participants Last post by  Ignatius_Reilly, 
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Brake FAQ - rotors, calipers, master cylinder sizes, proportioning valves, etc.

This post summarizes the specs and operation of brake components for the MkII MR2. The focus is on North American cars but the info should apply to other cars as well.


Rotors:
Rotor diameter and thickness is given. To calculate effective radius for brake torque calculations, use Re=((OD?+ID?)/2)^0.5 where OD is outer-diameter and ID is inner diameter where the brake pad ends. For best all-around track/race performance, choose plain OEM-style rotors and steer clear from "cross-drilled" or "slotted" rotors.




OEM Pads:
  • Front
  • 1993+ Turbo MKD582 (50cm?)
  • 1991-1992 Turbo MKD489 (49cm?)
  • 1991+ NA MKD242 [15mm thick] [105mmx47mm overall size]
  • Rear
  • 1991+ NA/Turbo MKD657 - all cars use the same pad



After-market Pads:
  • Front NA
  • Hawk HB191.590 [HPS/HP+/HT-10/Blue-9012]
  • Porterfield AP242 [R4/R4E/R4S/R4-1]
  • Ferodo SD242 [DS2500/DS3000, etc]
  • Axxis Ultimate 109.02420
  • Carbotech CT242 [Bobcat,AX6, XP8, XP10, XP12]
  • Front Turbo 1991-1992
  • Porterfield AP489 [R4/R4E/R4S]
  • Ferodo D489 [DS2500/DS3000/etc]
  • Axxis Ultimate 109.04890
  • Carbotech CT489 [Bobcat, AX6, XP8, XP10, XP12]
  • Front Turbo 1993+
  • Porterfield AP582 [R4/R4E/R4S]
  • Ferodo D582 [DS2500/DS3000/etc]
  • Axxis Ultimate 109.05820
  • Carbotech CT582 [Bobcat, AX6, XP8, XP10, XP12]
  • Rear (all)
  • Porterfield AP309 [R4/R4E/R4S]
  • Axxis Ultimate 109.06570
  • Ferodo D528/D657 (not available any more)
  • Wagner PD309/PD657
  • Carbotech CT528/657 [Bobcat, AX6, XP8, XP10, XP12]



Aftermarket high-performance brake pad compound data
Included in this list are approximate friction coefficients (determines max brake torque) and temperature ranges (fade resistance and cold bite) Note that pad compounds rarely have a constant cF over the whole temperature range. for example EBC pads:

  • Street/Track
  • Axxis Ultimate [cF=0.40] [0?F-900?F]
  • EBC Yellow [cF=0.55] [0?F-900?F]
  • Porterfield R4-S [cF=0.40] [0?F-900?F]
  • Hawk HPS [cF=0.40] [0?F-750?F]
  • Hawk HP+ [cF=0.45-0.50] [0?F-900?F]
  • Ferodo DS2500 [cF=0.50] [100?F-1000?F]
  • Carbotech Bobcat [cF=0.45] [0?F-900?F]
  • Carbotech Panther Plus/AX6 [cF=0.54] [150?F-1250?F]
  • Track/Race
  • Porterfield R4 [cF=0.485]
  • Porterfield R4-E [cF=0.485??]
  • Ferodo DS3000 [cF=0.62] [300?F-1500?F]
  • Hawk Blue 9012 [cF=0.52] [250?F-1000?F]
  • Hawk HT-10 [cF=0.55] [300?F-1600?F]
  • Carbotech Panther XP8 [cF=0.58] [200?F-1350?F]
  • Carbotech Panther XP10 [cF=0.6] [300?F-1600?F]
Note that Hawk and Ferodo pads are only available for front brakes. Rears are not produced any more.

Pad life on the racetrack?
http://mr2oc.com/showthread.php?t=403191

Calipers:

1993+ turbo calipers have the same size pistons as 1991-1992 calipers, but the caliper and bracket are much larger to accommodate the larger rotors.

  • Front
  • 1993+ Turbo dual piston front caliper [2x36.5mm = 2092.6mm?] (identification stamp: AISIN 36T30)
  • 1991-1992 Turbo dual piston front caliper [2x36.5mm = 2092.6mm?] (identification stamp: AISIN 36T25)
  • 1991+ N/A single piston front caliper [1x51mm = 2026.8mm?]
  • Rear
  • 1993+ Turbo single piston rear caliper [1x42.9mm =1452.2mm?] (idetification stamp: left:22VL right:22VR)
  • 1991-1992 Turbo/1991+ NA single piston rear caliper [1x41.3mm = 1339.6mm?] (identification stamp: left:16VL right:16VR)



Brake proportioning valves:
  • Here is how it works. After the threshold line pressure is reached, the valve kicks in and begins to reduce pressure to the rear brake pistons. So for moderate pedal pressures, the front and rear brake pressures are the same, but once you start to squeeze the pedal harder, the front pressure continues to rise, but the rear pressure rises at a slower rate.
  • Because the weight of the car transfers forward to the front axle under braking, the front tires have more grip and the rears have less grip. Because the rears have less grip, you need to reduce the braking force on the rear with respect to the front to prevent the rear wheels from locking up. Without a proportioning valve, the car would skid out of control very easily under braking. So Toyota, like most other manufacturers, installs a proportioning valve at the factory.
  • For the turbo cars, not only is the threshold line pressure higher, but the bias is more rearward. There are several reasons for this:
    • additional rear weight of turbo engine & accessories
    • wider staggered rear tires.
    • more piston area in front dual-piston calipers
  • Many track junkies report that with non-ABS cars, the front axle tends to lockup well before the rear. It follows that with proper brake pad and tire choice, the brake bias can be moved slightly rearward to better optimize braking performance under extreme braking conditions. So an OEM turbo brake proportioning valve is a suitable upgrade for an N/A car using wider rear tires and the turbo front brake calipers. Some folks opt for an aftermarket adjustable proportioning valve which allows finely tuned braking performance depending on tire choice and changing track conditions.A plot of NA vs Turbo proportioning valve performance:
Factory prop valves:
  • 1991-1995 NA with ABS (very rare, very expensive)
  • 1991-1995 NA without ABS
  • 1991-1992 Turbo with ABS
  • 1991-1992 Turbo without ABS
  • 1993-1995 Turbo with ABS
  • 1993-1995 Turbo without ABS
Although there are several different part numbers available, there is no evidence that the various valves have different proportioning profiles than described above.


Master cylinders:
  • 1991-1995 NA & 1991-1992 Turbo 7/8" bore size (~22mm)
  • 1993-1995 Turbo 15/16" bore size (~24mm)
  • Other options: http://www.mr2oc.com/showthread.php?t=185454
  • There are physical differences between master cylinders with ABS and without, but the bore sizes are as shown above.


Brake boosters:
  • 1991-1992 NA (with or without ABS)
  • 1991-1992 Turbo (with or without ABS)
  • 1993-1995 NA (with or without ABS)
  • 1993-1995 Turbo with ABS
  • 1993-1995 Turbo without ABS


Continued at: http://mr2oc.com/showpost.php?p=3250142&postcount=6
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N
93+ turbo vented front rotors 275mm*?? is *30. I know this because I just bought some front pads for my '93t & it says 275x30 on the box :)

90-92 Turbos also had 2 piston calipers up front I'm pretty sure.

Good post tho, If all info is there and correct should be sticky! :)
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T
Great post.
'91 turbo has dual piston fronts.

Also, here are the specs for proportioning valves (at least for '91-92)
5S-FE -- linear to 30kg/m squared with 60 to rear at 80
3SGTE -- linear to 60kg/m squared with 84 to rear at 100

So how it reads is that for 5sfe, it's linear to 30kg/m^2 with 60kg to rear at 80kg sytem pressure and so forth.
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T
Eggroller had compiled some information on piston area:

91 n/a front caliper has one 51mm diameter piston per side = 320.442mm^2 area
91 turbo front caliper has 2 36.5mm per side = 458.673mm^2 area
93+ turbo front caliper has 2 36.5mm per side = 458.673mm^2 area
91 rear calipers has one 41.3mm per side = 259.496mm^2
99+ turbo rear calipers has one 42.9mm per side = 269.549mm^2
Click to expand...
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B
good info. does this mean 91-92 turbo rotors would work on a 91-92 na?
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FAQ Continued

FAQ CONTINUED


Brake Ducts:


Parking brake todo: (re-organize this section)
  • The MR2 uses an integrated parking brake mechanism which rotates the rear caliper piston in its housing when the parking brake lever is pulled.
  • A common issue with this design is a failure of the parking brake cables. There are two rear cables and an adjustment. Cables from different model years and Turbo vs NA are different part numbers and slightly different lengths, but they are all interchangeable given that there is a quite a bit of adjustability in the parking brake mechanism. Do refer to the shop manual for proper adjustment procedure. The cables do stretch and wear out over time, so this is a good maintenance items to check.
  • For best operation of the parking brake. Hold the brake pedal firmly with your foot while pulling up on the parking brake lever. This will pre-load the caliper piston and allow maximum clamping force on the rotors. Also, manual transmission cars shoudl always be left in-gear when parking as an additional protective measure.
  • When changing the rear brake pads, you need a special tool to rotate the caliper piston while pushing it into the housing at the same time. Harborfreight has an "import rear caliper piston tool" or "caliper piston reset tool" available which works great. Or you can rent the tool from any national autoparts store. You can also use a c-clamp and pliers or an "import cube piston tool". But in my experience, the Harborfreight tool is the easiest to use.

http://www.harborfreight.com/18-piece-disc-brake-pad-and-caliper-service-tool-kit-97143.html
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stevrock
Does anybody know for certain if the JDM brakes are compatible with USDM cars and vice-versa?
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6
hmm so since the front turbo 91 calipers are the same size as the front 93 turbo calipers, would the rotors fit too? or would there be really no difference in braking?

i have 91 turbos in front and 93s in rear just curious if it would affect braking much.
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xlr8d said:
hmm so since the front turbo 91 calipers are the same size as the front 93 turbo calipers, would the rotors fit too? or would there be really no difference in braking?

i have 91 turbos in front and 93s in rear just curious if it would affect braking much.
Click to expand...
'91 turbo and '93 turbo front calipers are not the same size. The area for the piston is the same. The '93 turbo rotors are thicker as well as larger in dia. The '93t calipers are wider to fit the thicker rotor. The brackets are different to accomodate the larger dia rotor.

The '91-92t and all NA have the same rear brakes (rotor, caliper, bracket). All models have the same rear brake pad. I do not know if the '93t rear calipers are the same or not.

If you have '93 NA rears, then you are fine. You basically have '91-92t brakes minus the brake prop. valve. If you have the '93t rear brakes, then you have a slight rear bias. This may not be ideal since you may lock up your rears too early and not getting maximum braking. Also if this happens when not pointed straight could lead to exiting the road back end first.
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traffic said:
The '93 turbo rotors are thicker as well as larger in dia. The '93t calipers are wider to fit the thicker rotor. The brackets are different to accomodate the larger dia rotor.
Click to expand...
Since this is true couldnt you use 91t calipers on 93t Brackets and 93t rotors since the brackets accomodate the larger rotors? I remember a while back that someone was saying that I could get 93t caliper brackets and the 91t rear caliper fits right on thus allowing the extra room now for the larger diameter of the 93t rotors. Can anyone verify this for sure? The only downside I can think of is that you might have to shave the brake pads a little to fit the thicker rotor, but we arent talking much here(5-6mm so 2-3mm per pad tops).
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MKIITMR2 said:
Since this is true couldnt you use 91t calipers on 93t Brackets and 93t rotors since the brackets accomodate the larger rotors? I remember a while back that someone was saying that I could get 93t caliper brackets and the 91t rear caliper fits right on thus allowing the extra room now for the larger diameter of the 93t rotors. Can anyone verify this for sure? The only downside I can think of is that you might have to shave the brake pads a little to fit the thicker rotor, but we arent talking much here(5-6mm so 2-3mm per pad tops).
Click to expand...
You could try. Why not get a full 93t set and full 91t set side by side and take some measurements for us? Perhaps its as simple as fabbing a small adapter out of billet aluminum or something?
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phatvw said:
You could try. Why not get a full 93t set and full 91t set side by side and take some measurements for us? Perhaps its as simple as fabbing a small adapter out of billet aluminum or something?
Click to expand...
the holes would be too close together to work out. they're even pretty close going from a stock 91t to a 12" rotor. i actually have brackets drawn for a 12" rotor upgrade using the 91t calipers, but i'm going to use porsche 996 calipers/supra (if they fit, or LS400 if they don't) rotors in the front instead.

the stock caliper upgrade would have used acura RSX-S rotors up front, and front rotors from the 96-01 rav4 on the rear. they're almost exactly the same dimensions as the 91t rotors, only larger diameter.

i'd be happy to fork over the details to someone who wanted to actually contemplate building it, so long as it's not for profit...

i've done a LOT of brake research in the past 5 years :D
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scarecrowX said:
the holes would be too close together to work out. they're even pretty close going from a stock 91t to a 12" rotor. i actually have brackets drawn for a 12" rotor upgrade using the 91t calipers, but i'm going to use porsche 996 calipers/supra (if they fit, or LS400 if they don't) rotors in the front instead.

the stock caliper upgrade would have used acura RSX-S rotors up front, and front rotors from the 96-01 rav4 on the rear. they're almost exactly the same dimensions as the 91t rotors, only larger diameter.

i'd be happy to fork over the details to someone who wanted to actually contemplate building it, so long as it's not for profit...

i've done a LOT of brake research in the past 5 years :D
Click to expand...
VERY GOOD INFO. Thank you! Sent you a PM with my email so you can send me the details, Ive been researching rotor specs to upgrade using oem 91t calipers for a while now. Glad you can help.
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M
You can add this:

Front Pad area: 50cm2 (1993); 49cm2 (1991/92)
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MKIITMR2 said:
Since this is true couldnt you use 91t calipers on 93t Brackets and 93t rotors since the brackets accomodate the larger rotors? I remember a while back that someone was saying that I could get 93t caliper brackets and the 91t rear caliper fits right on thus allowing the extra room now for the larger diameter of the 93t rotors. Can anyone verify this for sure? The only downside I can think of is that you might have to shave the brake pads a little to fit the thicker rotor, but we arent talking much here(5-6mm so 2-3mm per pad tops).
Click to expand...
This may work for the rear brakes. But not the front. MAYBE you might be able to just slide the backing plates into the '91T calipers onto a '93T rotor. The rotors are much thicker. Hence the hefty weight too.
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jazzcornet
maybe im confused here. i just invested in rear hubs and brakes from a 93t to install on my 91t. according to this thread, i just wasted my money. can someone put it dee dee dee terms for me???
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jazzcornet
also, for the solefact of superior area, has anyone tried to use the front calipers in the rear? can it be done?? it would mke more sense to me to have more bias in the rear anyway and upgrading the rear brakes would prove to be more logical than upgrading the fronts.
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jazzcornet said:
also, for the solefact of superior area, has anyone tried to use the front calipers in the rear? can it be done?? it would mke more sense to me to have more bias in the rear anyway and upgrading the rear brakes would prove to be more logical than upgrading the fronts.
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the pistons in the front calipers are too big to ever get the bias forward enough to make the car safe to drive.
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jazzcornet
makes sense, but then why do people buy big brake kits?
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jazzcornet said:
maybe im confused here. i just invested in rear hubs and brakes from a 93t to install on my 91t. according to this thread, i just wasted my money. can someone put it dee dee dee terms for me???
Click to expand...
No difference in hub. Caliper carrier, caliper, rotor are different. Pad is the same.
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