Wilwood 4pot, again!


M

Marco

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Joined
Nov 4, 2008
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414
After 1year with Wilwood midilite with 1.75" piston im able to say that I do not like pedal feel with this setup.

My base its EK4, but at this moment my brake spec is:

Front:
wilwood midilite 1.75" pistons
282mm Tarox g88
Ferodo racing ds2500 pads
braided lines

Rear:
ek9/dc2 caliper
260mm ebc sloted discs
Ferodo racing ds2500 pads
braided lines

ek9 abs ecu
brake master cylinder stopper
DC2 1" master cylinder and brake booster

The car stops good with no problem but i dont like at all my pedal travel, its too long.

A friend of mine whant to buy my caliper and im thinking do sell and buy wilwood with smaller piston.

Piston areas (searched on google)

vti oem - 3.56in2
ek9/dc2 oem - 3.94in2
Spoon twinblock - 4.01in2
Spoon monoblock - 3.58in2
wilwood 1.38" piston - 3in2
wilwood 1.50" piston - 3.54in2
wilwood 1.62" piston - 4.12in2
wilwood 1.75" piston - 4.80in2

Im thinking to swap for 1.50" or 1.62" piston size, what do you think?did i see any pedal feel from 1.75" to 1.62"?

My goal its get better pedal feel, like oem. but i do not whant to much hard pedal as its block wheels faster.
 
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Have you not considered uprating your Master cylinder to a 1" one?
 
A EK9 / 98 dc2 1'' master cylinder will shorten the travel and increase performance if you haven't added it already.

If you really want to change calipers , the 1.62'' pistons with 1'' MC feels good.

Kieran beat me on the MC
 
I forget to say, i have dc2 master cylinder and brake booster installed, i will updated on topic specs
 
In last year i bleed the brakes more than 6 times to despite any air on brake lines.
Try bleed brakes with pressure, vacuum and with a friend (manually) and using ATE super blue racing oil.
Installed 260mm rear brakes 3 weeks ago, and re-bleed system. It get worst then when I have 240 rear (more fluid :( to move on 260mm )
 
There must be a way to solve the problem without having to buy a new brake set up?!
 
I dont know, visual inspection its ok with no leaks or damage interior slave.

All of people that install this wilwood aclaim same problem as mine, long pedal stroke.

I will try to re-bleed one more time brakes and inspect brake lines, if not working i will buy master cylinder or new caliper maybe with 1.62" piston

With 1.62" piston its 5% bigger than ek9 one, with 1.75" its bigger 22%.
 
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It's the pistons for sure.

The EK4 piston is 3.56sqin, to move the pads 1/8" with a 5:1 pedal, on a 1" MC, that's 2.84" of pedal movement.

The Wilwoods have 4.81sqin of piston area, to get the same 1/8" pad movement, it's now 3.83" at the pedal, a 35% increase.

The 1-5/8" pistons will be an improvement, they'll put the same pad movement at 3.2", 15% up on standard.

The 1-1/2" pistons will work best, they'll put the pedal travel back to within 1% of stock, but I would recommend DS3000 up front and keep the DS2500 at the back as it will be bordering on rear biased with DS2500 all round. The pedal travel with this arrangement will be stock, as will the bias. :nice:
 
Kozy, do you know if the pedal ratio of ek4 is the same as ek9/dc2?

At this moment as i have everything of ek9/dc2 brakes dont you think its better 1.62"? its the caliper size that goes more like oke ek9 3.94in2 vs 4.01in2
 
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Yea the pedal ratios will all be the same.

Either the 1.62 or the 1.50s will work, but the 1.50s with DS3000 would be my choice personally. You'll have a better balance (more rear %) and a firmer pedal, the piston area will be the same as the EK4.
 
I kozy :)

I know 1.50 will be same area as ek4 oem,but in this moment my brake setup is the same as ek9 and thats i im asking if is not better 1.62 as its size that more aproach from oem ek9 pedal/brake feel

If i have got ek4 brake i understand that 1.50 its better as igot same piston area,pedal feel and balanced

With 1.50 wich have less piston area than ek9 front caliper i will loose clamping/braking power or not?

Im afraid to buy 1.62 and pedal stil goes to floor or buy 1.50 and feel smaller for1" mc/ek9 brakes
 
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Yes, you do lose some clamp force, however with the 260mm rear brakes, this means more rear bias which is good. It's actually a little bit too much rear bias, which why I would balance it with the more aggressive DS3000 pads. Remember that the tyre doesn't know or care where the brake force comes from, only how much there is, so you can trade rotor diameter for piston size or for pad friction.

As I said, either will work, but I would personally go for the 1.50s. :nice:
 
Thanks Kozy :)

Must think better wich onde i choose.

1.5 same piston area as spoon monoblock,Brembo dc5,Brembo ek9 Stevens..maybe this will be a litle more stiff then ek9 brakes with mc1"

1.62 virtual same piston área as spoon twinblock, this il be litle sofrer then OEM ek9 because bits 5% bigger and got more pedal trave than oem.more clamping force

The best is try 2sizes and choose but i cant buy more 2 calipers :( ...in Portugal dont very people use wilwood.

If i know that 1.62" give pedal trave/feel like OEM ek9 i will choose that to maint NEAr OEM bias with same pads
 
To calculate sliding caliper type piston area must put x2?

NSX 91-96 caliper is dual piston sliding type, 40mm+36mm...NSX piston area its same as 4pot 38mm?
 
Yes regardless of caliper type, you always take the pistons on one side to calculate the piston area, then to calculate clamp force it is:

Clamp force = fluid pressure x piston area x 2
 
Here's the numbers, all run with the same rear brake setup. The stock EK9 bias will be 15%.

1.75 pistons with DS2500 up front (what you have currently)
Front bias 6.5%
Pedal travel +22%

1.62 pistons with DS2500
Front bias -6.5% (rear biased )
Pedal travel +5%

1.62 pistons with DS3000
Front bias 11%
Pedal travel +5%

1.50 pistons with DS3000
Front bias -1% (slightly rear biased)
Pedal travel -10%

NA1 NSX with DS3000
Front bias -3% (slightly rear biased)
Pedal travel -10%

NA2 NSX with DS3000
Front bias -8% (rear biased)
Pedal travel -14%

Hopefully that should be useful. :nice:
 
Yea I know. I send myself loads of PMs to make me seem important. :naughty:

Emptied. :nice:
 
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