Brake effort?

[GUNS]

Hey guys, I've go-karted my 818 a few times now and I can't figure out the brakes. I don't know if it's just because they aren't boosted or if there's an issue, but it seems like it take a lot of effort to get this thing to stop. I've only driven it around the neighborhood, so top speed was about 30 mph. I have to push really hard to get it to stop and I couldn't get the wheels to lock either. Just checking to see if you guys are experiencing something similar or if I have to chase some brake system gremlins. BTW, I've bled the system multiple times and there aren't any leaks so I don't think that's the issue.

[C.Plavan]

Do you have the Wilwoods?

[wleehendrick]

New pads/rotors need to be bedded in.

[GUNS]

OEM brakes from my 02 donor. Pads and rotors should be bedded in. I bed them in when they were on the WRX, so I wonder if I need to re-bed them since I didn't keep the same pads w/ the same rotor.

[Scargo]

What pads? Street/common/OEM pads don't need bedding and they wouldn't need re-bedding. I didn't hear "soft" and assume you know what you're doing. De-glaze the pads and if that doesn't work get something like a Hawk HPS pad. I've not heard complaints about excessive pedal pressure being required.
I hope something is not flexing excessively.

[GUNS]

They are Carbotech Bobcats (their street pad). I'm going to try and re-bed them. I didn't keep track of which pad went where so the grooves aren't matched. If that doesn't work I'll look into other potential issues.

[wleehendrick]

Did you drill a new hole for the clevis pin in the brake pedal? This gives more leverage on the MC. Is your BPV open all the way? Thats about all I can think of...

BTW, from my experience, even street pads, while maybe not requiring a formal bedding procedure, do need more effort on fresh rotors until some material is transferred. But it sounds like thats not the issue.

[Scargo]

This could do you a lot of good. Flex-Hone for rotors (http://www.amazon.com/Brush-Research-Flex-Hone-Rotors-Fine/dp/B007SOW0WC/ref=sr_1_1?s=automotive&ie=UTF8&qid=1421540875&sr=1-1&keywords=abrasive+rotor).

[lap_dog]

I had similar issues with my 818R. I have '06 WRX brakes running Carbotech XP8 pads. Even after sufficient break-in, the pedal effort was far too high. In order to slow the car at the end of a straight away at the track, I had to push the pedal absolutely as hard as could. The brakes were not near locking, and the car did not feel like it was at max deceleration. I confirmed that the guys who built my car did the clevis mod referenced by wleedhendrick above.

My next course of action was to find a small diameter master cylinder (the small diameter generates greater line pressure for a given amount of pedal effort). My donor master cylinder had a 1" diameter. After quite a bit of searching and some trial and error, I found an early 1990s Nissan master cylinder that is the exact same configuration as the WRX part, but with a 7/8" diameter. The OE Nissan part number is 46010-1M320. The mounting flange, reservoir and brake line location are all identical to the Subaru part, making it a drop-in replacement.

With the 7/8" master cylinder, the brake effort is definitely improved. It still takes a healthy effort to get max decel, but on the plus side, it is very difficult to lock up. If I could find one, I would like try a 3/4" master cylinder. Alternatively, when it comes time to replace the brake pads, I will go with something with more initial bite. Note that my 818 is an early car that does not have the mounting option for the Wilwood pedal kit. I am sure the Wilwood pedals offer many master cylinder sizes. However, it would require some major rework to install those pedals now that my car is assembled.

[Buzz Skyline]

I have found similar braking issues. I've only go-karted around the neighborhood, but I was surprised to find I couldn't lock up the tires not matter how hard I pushed. And even at very moderate speeds, the braking distance was frightfully long. I'm using the donor pads with the rotors they were matched to before dis-assembly. I still have the brake booster, and was thinking of putting it back in. If it won't work, I might try lap_dog's cure. I'd rather not have to invest in the Wilwood brakes if I can get the donors to work.

Has anyone else tried to keep the booster?

[Scargo]

Wow! An old-timer and his first post... I bet you have lots you could share.
Such a compromise pad you ran. Are you streeting your R?
Even with my Stoptech STR-40s they recommended this: Master Cylinder Size: Front: ¾”, Rear: ¾”, Pedal Ratio: 5.61
Still, this is the first I have heard of people complaining about the brakes being inadequate.

[lap_dog]

I have only had the car out twice for a total of 6-7 sessions. I spent most of the summer fixing various items and installing a "tall man" roll bar (I'm 6'4" and my helmet was about 3" taller than the stock roll bar due to having to sit very upright in order to get enough leg room). One of the downsides of having a unique car like an 818 is you seem to be the last in line to get work done at a race shop. Guys want to focus on what they know (be it Corvettes, Porsches, etc.) and not get side tracked with odd-ball machines. As such, development has been slow.

My initial concept was to street and track the car. However, I believe the car is going to become track-only and perhaps a club racer. My winter projects include getting rid of the FFR corrugated cooling hose (I have multiple leaks with low time on the car), installing an air-to-water intercooler (heat soak was slowing the car 1-2 seconds per laps after about 3 laps) and put in a VCP tuner shifter (the 3 to 4 shift with the standard push cable is brutally slow and costing lap time for sure).

[metalmaker12]

My brakes stop on a dime and smoke tires now. I had to bleed them a few more times and pads had to bed in. At first it was a slight effort, but nothing abnormal. Now they are just great. I have 06 subaru 4/2pots with Stoptech street pads and centric rotors with stainless lines

[Buzz Skyline]

I'm hoping it has something to do with the brakes sitting in the garage for a year. But once the rust is scraped off I'd have thought they'd be fine. The other possibility is that the have some grease or something on them. I'll try some cleaner and see if they improve with use.

[Scargo]

lap_dog, I was just discussing the unique aspect with my racing guru Pete Agapoglou. Who can help you at the track when you break down and have a mish-mash of parts (saying bastar*ized here is not allowed) and some parts are very custom, like Howe or Allstar adjustable ball joints? With my STi there might be a chance someone at the track would have some parts or know how to fix it. Finding a shop has now been narrowed down to specialty places and a long wait. Getting my low STi on an alignment machine was a headache and certain equipment they used didn't match-up. Some places would not touch it. I've gone to doing it myself rather than trailering it forty minutes away. I can see the 818S being that way to some extent.
I even had McMaster-Carr try to misconstrue my desire that they physically measure a bolt for me to mean that I was asking race car application advice, so they balked and totally refused to measure their high-strength bolt inventory. Now I am almost on my own due to all this wacky stuff I have. There sure are some mechanics (not to mention emissions inspection people) who scratch their heads and back away. Tire mounting, alignments, etc. all become "specialty work".

[wleehendrick]

My brakes stop on a dime and smoke tires now. I had to bleed them a few more times and pads had to bed in. At first it was a slight effort, but nothing abnormal. Now they are just great. I have 06 subaru 4/2pots with Stoptech street pads and centric rotors with stainless lines

That's good to know, since I have pretty much the same set-up: 06 WRX brakes, SS flex lines, StopTech SP pads and turned OEM rotors. Are those comments with the clevis relocated? Thanks...

[Bob_n_Cincy]

I'm also running the StopTech Street Performance Brake Pads 30909290. $44 per axle
http://www.rockauto.com/catalog/moreinfo.php?pk=2022418
But with 2 pot Subaru cast iron calipers on all four wheels.
Clevis pin moved per ffr instructions. I am very happy so far.
Bob

[metalmaker12]

That's good to know, since I have pretty much the same set-up: 06 WRX brakes, SS flex lines, StopTech SP pads and turned OEM rotors. Are those comments with the clevis relocated? Thanks...

Yeah I did the relocation

[TouchStone]

Does any one have pictures of the relocation?

[Buzz Skyline]

It's in the section of the manual discussing donor prep. The pictures are pretty clear, as I recall. (I haven't looked at the manual in months, so I don't know page numbers.)

[CNC_Geek]

Common sense says the same brake system that stops a 3,200lbs. car should work great on a 2,000lbs. car. Of course I won't get to test that theory for several months. I could find myself on the computer, looking for that thread about improving the brake system.

[Bob_n_Cincy]

Common sense says the same brake system that stops a 3,200lbs. car should work great on a 2,000lbs. car. Of course I won't get to test that theory for several months. I could find myself on the computer, looking for that thread about improving the brake system.

Don't forget that most don't have a power booster.
Take a look at the pressure difference.
43919

[Hendow]

I've been running mine with the booster installed for around 2000kms so far. Yes the brakes are touchy, but I guess I have just grown familiar with them.

Others that have driven the car either love it (very direct) or hate it (too twitchy) so 'its horses for courses'. I did try the brakes without booster assistance and found the pedal force to be very high, and brake performance poor as described by the OP. Having said that, I have not yet relocated the clevis pin pivot point.

Mine has the donor master cylinder and pedals, but has the Wilwood big brake kit (obviously!).

[Mr B oldschool]

see page 48 for new hole placement & parts to use

[Tamra]

With upgraded pads (ebc yellow stuff) I have to be conscious of not using too much force else I'll lock up the tires. With cheap Napa pads prior to bed in they required a LOT of force and didn't lock up the tires (all of my body weight sort of thing). The EBC Yellow Stuff stopped better than the Napa pads prior to bed in, and stop VERY good after bed in. This is with OEM WRX 2 pots, relocated the master cylinder linkage per the manual, OEM master cylinder, and included wildwood pro portioning valve (which we used to take away front bite since the car was too easy to lock up... On Hoosier A6 race tires!

I'm ~130 lbs. if I can lock up the tires, you guys should be able to!

[TouchStone]

I did the relocation but moved the pivot point up about 0.6in instead of 0.5in. It is really amazing how much better the brakes feel. I'm running the OEM brakes (2 pot front 1 pot rear) with the Red stuff pads. I was able to lock the wheels up before it just felt like the seat was going to break.

[07FIREBLADE]

So it looks like a downgrade in available pressure if one decided to run the sti brembos. Might need to switch to a smaller bore master or play with pad setups.

[suttonb3]

Where are you guys running the proportioning valve? I don't remember seeing a recommended setting to at least start out with.

[TouchStone]

Fully open is the recommend setting to start with. Should be located between one of the master cylinder outlets and the "T" that splits to the front brakes.

[CNC_Geek]

I've been running mine with the booster installed for around 2000kms so far.
Please send me a photo of your booster installation. I tried every which way and could not physically maneuver the booster into position. I received my kit April 2015 and have 2 boosters from 2001 and 2004. Was my chassis altered from early kits? Does Subaru have different size booster units? I am building mine for the street and wouldn't mind having the booster in place.

[Junty]

Hey all, I'll confirm earlier comments on this thread - Yes I have an ABS system working(although switched), and yes I have a small master cylinder. I took a mild step, 15/16 inch instead of standard Subaru 1 1/16. I also am running upgraded pads - let them bed in - but I wanted more stopping without feeling like I was pulling the steering wheel off! Ive also moved the clevis - following FFR install, prior to installing the new smaller master cylinder I also tried a new position 3/4 inch up - this perhaps resulted in the same as a smaller cylinder however the changing angles concerned me, and at risk of bending a push rod I decided to keep the pressure perpendicular with the smaller reservoir. This is long term safety!
I have now also installed Legacy GT front callipers (2 pot) and relocated my WRX 4 pot to the rear along with bigger Brembo rear rotors. Someone else with more mathematical ability than I calculated that I should now have about 2-5% front bias based purely on the cylinder/rotor size and pressure applied. I am very very happy with what I've ended up with, thankful to all input from others and for experimenting and testing from them and myself. Note - more information is available within my build thread, my system has no bias valve, and my own logic from historical mass produced sports cars with mid or rear engine which have same front and rear rotors with no bias is where i started working from... Best of luck to all!!!

[suttonb3]

Fully open is the recommend setting to start with. Should be located between one of the master cylinder outlets and the "T" that splits to the front brakes.

Thanks for the quick reply. I'm in go kart mode and only have about 15 miles on the car, just cruising around the neighborhood. The braking performance has been weak, but I rebuilt the calipers and have brand new rotors and pads (north east donor, everything was rotten) so I figured everything just hasn't had a chance to bed in. This discussion reminded me that I installed the valve but never adjusted it. I looked at it and found that it was all the way closed. I opened it all the way up but haven't been able to take it for a spin because it seems like all of Florida is underwater. I'll update you all after I go for a drive. Thanks for all the help!

[Bob_n_Cincy]

Thanks for the quick reply. I'm in go kart mode and only have about 15 miles on the car, just cruising around the neighborhood. The braking performance has been weak, but I rebuilt the calipers and have brand new rotors and pads (north east donor, everything was rotten) so I figured everything just hasn't had a chance to bed in. This discussion reminded me that I installed the valve but never adjusted it. I looked at it and found that it was all the way closed. I opened it all the way up but haven't been able to take it for a spin because it seems like all of Florida is underwater. I'll update you all after I go for a drive. Thanks for all the help!


Be careful adjusting the knob. It kind of works backwards as you might think. Below is off Wilwood's datasheet.


The adjusting knob is marked with an arrow indicating the direction required to decrease line pressure to the
calipers. The knob rotated all the way out (counter-clockwise) will provide a maximum pressure reduction of
57%. Rotating the know in (clockwise) will incrementally increase line prressure, up to full pressure. If the
range of adjustment in the valve is not sufficient to properly balance the vehicle’s bias, changes to other
components within the system may be necessary.

[CNC_Geek]

Be careful adjusting the knob. It kind of works backwards as you might think. Below is off Wilwood's datasheet.


The adjusting knob is marked with an arrow indicating the direction required to decrease line pressure to the
calipers. The knob rotated all the way out (counter-clockwise) will provide a maximum pressure reduction of
57%. Rotating the know in (clockwise) will incrementally increase line prressure, up to full pressure. If the
range of adjustment in the valve is not sufficient to properly balance the vehicle’s bias, changes to other
components within the system may be necessary.

Thanks for the heads up! First thing I did was to unscrew the valve expecting that would provide an unrestricted flow to the brakes. I haven't completed my car to the point of driving it yet so your advice has probably prevented an unhappy incident.

[Mulry]

...My next course of action was to find a small diameter master cylinder (the small diameter generates greater line pressure for a given amount of pedal effort). My donor master cylinder had a 1" diameter. After quite a bit of searching and some trial and error, I found an early 1990s Nissan master cylinder that is the exact same configuration as the WRX part, but with a 7/8" diameter. The OE Nissan part number is 46010-1M320. The mounting flange, reservoir and brake line location are all identical to the Subaru part, making it a drop-in replacement.

With the 7/8" master cylinder, the brake effort is definitely improved. It still takes a healthy effort to get max decel, but on the plus side, it is very difficult to lock up. If I could find one, I would like try a 3/4" master cylinder. Alternatively, when it comes time to replace the brake pads, I will go with something with more initial bite. Note that my 818 is an early car that does not have the mounting option for the Wilwood pedal kit. I am sure the Wilwood pedals offer many master cylinder sizes. However, it would require some major rework to install those pedals now that my car is assembled.

FYI RockAuto has these master cylinders on wholesale closeout. Part number listed above works just fine. Original use was in a 95-98 Nissan Sentra or 200SX if anybody wants to go junkyard hunting in the future. Cheers.

[Hendow]

Please send me a photo of your booster installation. I tried every which way and could not physically maneuver the booster into position. I received my kit April 2015 and have 2 boosters from 2001 and 2004. Was my chassis altered from early kits? Does Subaru have different size booster units? I am building mine for the street and wouldn't mind having the booster in place.

Hi CNC,

Apologies for the delay in response, as its virtually impossible to get the camera into that area with the body and windshield etc on.

Anyway, I recently upgraded my front LCA's to the STi aluminium ones, which allowed me to get the camera in there.

4558945590

Bear in mind, my steering wheel is on the right (correct!) side...!

I hope this helps, and shout out if you need more info.

Cheers!

[Quiny]

Since I was removing the nose on my 818 to change over to the new nose I figured I would see what I could do about the braking. I was using the stock 2002 WRX brakes and master. They work but I do not like that I think I'm going to break my seat when panic stopping. The stock master offered a rock solid pedal that had almost no travel. I tried an older master that was advertised with a 7/8 bore, that was a little better but I think it was actually a 1" bore. I found a booster delete kit online so now I will try that. It uses a heavy aluminum plate counter bored to accept a master and the plate mounts to the stock booster mount locations. I like the design since it now uses all 4 bolts to mount the pedal assembly and it also uses the stock rod location so no offset master cylinder. The only thing I don't like is that it is a jelly jar(single master), I am looking to see if I can find a tandem 3/4" master that will work but so far all I have found is a 1975 Ford Courier but it is designed for rear drum brakes. It may have a residual pressure valve built into it. The new unit does fit and bolts in very nice, I'm hating having to adjust the brake lines but I did figure out a way to bleed the clutch master in about 5 minutes. I had relocate the clutch master line to make room for the plate. I know this will have some travel in the pedal but I think I would prefer that. Has anyone else come up with any other options? The booster just seems too big.
4979449795

[Hindsight]

Bringing this thread back up.

Seems like a couple people have now tried 7/8" master cylinders and they didn't make a big enough difference?

My brakes stop the car fine on the track but I have to push as hard as I can on them and that means I am not able to modulate them. I'm very willing to swap out the master for a 7/8" bore size but obviously only want to do that if it will definitely make it better.

[C.Plavan]

Bringing this thread back up.

Seems like a couple people have now tried 7/8" master cylinders and they didn't make a big enough difference?

My brakes stop the car fine on the track but I have to push as hard as I can on them and that means I am not able to modulate them. I'm very willing to swap out the master for a 7/8" bore size but obviously only want to do that if it will definitely make it better.

I would just go to a gripper pad. I ran the crappy pads that came with the Wilwoods one track day- I had the same issue you describe. I then went to my trusty Raybestos ST43 (or 46 will work) pads.....It was a night and day difference.

[Hindsight]

Thanks Chad - I did change pads the other week, before the race. I went with Ferodo DS2500 which are supposed to be very grippy, even when cold. They are much better than the Hawks I had on there previously but I still have to stand on them to get to where the ABS starts kicking in.

[Hindsight]

Anyone running the Wilwood pedal box with Subaru brakes? If so, how is the brake effort with that setup?

[Hindsight]

I posted this in my build thread but thought I would add it here as well. I have experimented with moving the brake pedal hole up higher. I've moved it up 1 1/4" above the OE hole, and also 7/8" above the OE hole. The 7/8" position seemed to me to be the perfect balance between pedal feel and pedal effort. The 1 1/4" was way too spongy and it felt like it ran out of travel. This is with stock 1" master with 4 pot front and 2 pot rear stock 06/07 WRX calipers. You may need to remove the brake pedal from the pedal cluster in order to drill the hole at 7/8".

[axelthrasher]

Not to bump an old thread, but my 818 has the higher hole drilled on the brake pedal - pedal is still far too stiff for my liking. So, looks like I am going with the Nissan 7/8" master cylinder swap... perfect time as I plan to be adding STI Brembos as well... below is some info I found on the Subaru master cylinders:

02-05 WRX MT = 1 1/16" or 26.99mm bore diameter
06-07 WRX MT = 1" or 25.4mm bore diameter
04-07 STi = 1 1/16" or 26.99mm bore diameter

Hope this helps someone considering/dealing with the same issues.

[Hindsight]

I wasn't happy with just the higher pedal placement. Ended up going with the 7/8" master and some much more aggressive XP10 racing brake pads. It's much better. Still not ideal, but acceptable. Just fine for street driving but on the track I could stand to have more modulation under hard fast braking.

[wirenut]

Which 7/8" master cylinder are you using Hindsight? About to mount my stock unit and figure I might as well just plumb in the 7/8" up front.

[RM1SepEx]

The OE Nissan part number is 46010-1M320

[Hindsight]

Thanks, Dan beat me to it.

I'd also suggest drilling the hole in the brake pedal for the pushrod just a bit higher than FFR suggests. I'd drill two, one where FFR suggests and another just high enough above it that there is enough metal between the two holes. Once the pedal is in the car with the dash and everything else in place, it's a SERIOUS pain in the butt to take the pedal cluster all the way out, disassemble it, and drill the second hole (if you decide you want more leverage). You will need to disassemble the pedal cluster to drill that second hole, BTW, since the bracket gets in your way. Just tap the spring pins out with a roll pin punch and the whole thing comes apart.

[RM1SepEx]

what model 90's Nissan was than PN used in? 240?

[wirenut]

Thanks guys! Great advise. Just ordered the MC and will go ahead and drill the second hole.

[Hindsight]

what model 90's Nissan was than PN used in? 240?

I can't remember. Either 240 or 300 I think. I found the part number here and bought it from Rock Auto if I recall correctly. It was dirt cheap. The brake fluid feeder barb attachments were a bit different; on the Nissan master cylinder, they just stay on in a press-fit whereas on the Subaru one, there is a boss in the casting with a hole through it that a roll pin goes into to help secure things. I like the Nissan version better.

[DodgyTim]

Nissan part number is 46010-1M320, Nissan Sentra or 200SX
69740

[RM1SepEx]

Nissan part number is 46010-1M320, Nissan Sentra or 200SX
69740

Awesome, I'm sure this will help a bunch of people

[tgf05354]

resurrecting this thread as I need some advice for brake pads. My 818S is now legal and I've put 100 miles on it. Brake pedal effort is like the OP, major effort to bring the car to a stop. I figure the first thing to do is change pads, but which ones, some like Hawk, some like Stoptech. I'm running 2006 4 piston calipers with new rotors. I think the pads were centric posi quiet ceramic. This car will be 100% street, so I want something that grabs well when cold. Yes I drilled the option hole in the brake pedal per FFR manual.Thanks

[tgf05354]

resurrecting this thread as I need some advice for brake pads. My 818S is now legal and I've put 100 miles on it. Brake pedal effort is like the OP, major effort to bring the car to a stop. I figure the first thing to do is change pads, but which ones, some like Hawk, some like Stoptech, others EBC. I'm running 2006 4 piston calipers with new rotors. I think the pads were centric posi quiet ceramic. This car will be 100% street, so I want something that grabs well when cold. Yes I drilled the option hole in the brake pedal per FFR manual.Thanks

[Harley818]

I just licenced my 818S this week and am having the same issue.
I can almost lock them up if I push really hard, but I would rather have much better braking.
Tamra is using the EBC yellows and says they are night and day. Hindsight has Raysbestos ST43 and he is happy.
Wayne has been recommending Hawk, but they don't make the best ones for 2002 donor double pots.
I just ordered some EBC yellow pads from Wayne Presley - vendor on this forum... verycoolparts.

I am going to try the pads first, then smaller master cylinder bore.

[tgf05354]

Also would like to verify the brake bias adjuster. Is full counter clockwise full front brake pressure or is it full clockwise. I have it at full counter clockwise right now.

[Hindsight]

It wasn't me with the Raybestos...not sure who it was. I've tried both Hawk HP, Ferrodo DS 2500, and Carbotech XP10. Carbotech were the best of the bunch for street, but none of them are great for the track. They all fade. And even for the street the Carbotech improved things but not as much as I would prefer. Pedal effort is still higher than I would prefer. That is also with a 7/8" master cylinder (which is smaller than the 1" stock WRX master).

Bob seems to have the best working setup (though it's tough to say that definitively because pedal effort is subjective and I've not tried his brakes) by using the same calipers front and rear. The more piston area you have, the more leverage you get (assuming the same size master).

I've spent days researching, running numbers, testing different pads, etc, and have come to the conclusion that the best option is to go with the full wilwood setup including the pedal box so that you can have the front to rear balance bar. Either that or someone needs to find a bolt-on 3/4" (or even smaller) master cylinder.

[EODTech87]

I purchased a 200SX master that's 7/8". It fits the same and is easily adapted to use the reservoir relocation kit I have.

http://www.ebay.com/itm/BRAKE-MASTER-CYLINDER-FITS-NISSAN-200SX-SENTRA-oio-/262968860485?hash=item3d3a2a5f45

[taco20]

I raised the hole in the pedal another 1/2 inch per the Wilwood tech I spoke to. The problem is we don't have enough leverage with the pedal because the brake booster is gone. If we start using smaller master cylinders we could run out of fluid volume to apply the brakes evenly. The extra leverage the higher holes gives us keeps the extra volume and still helps the pedal effort. I have 05 Sti brakes on my car and have no issues stoping the car with stock pads and nice soft pedal feel. Have been 140+ at the track and had no problems stopping. If anyway needs a better explanation just call Wilwood and talk to the tech department and they should explain our pedal ratio is off so the simple new hole will take care of the problem.

[Frank818]

Taco, which Wilwood brakes you got? I mean, you say you got 05 STI brakes, if they are OEM why did you call Wilwood? They have nothing to do with OEM brakes, so I assume you got 4 or 6-piston Wilwood brakes "for" 05 STI?

[EODTech87]

Another option would be to run the Wilwoods with larger Pistons. Both the front and rear calipers are available with a total piston area of 4.8 which would both increase braking force and even out the brake balance front and rear.

[taco20]

Taco, which Wilwood brakes you got? I mean, you say you got 05 STI brakes, if they are OEM why did you call Wilwood? They have nothing to do with OEM brakes, so I assume you got 4 or 6-piston Wilwood brakes "for" 05 STI?


Hey Frank,
I do have stock 05 Sti brakes. I contacted Wilwood because I was looking into buying one of the master cylinders. They sell 3/4 and 7/8 inch master cylinders so I wanted to know which they recommended for our cars. I also saw on their page they have a pedal ratio chart and when I measured my pedal ratio and told them the number I had compared to the ratio they use for their pedal that is when they told me to move the hole up and correct the ratio and get the leverage proper for not having a brake booster. They can get away with having smaller master cylinders because they are using two master cylinder not just one. They told me I can get more total braking pressure with the bigger master cylinder but need the extra leverage from the better pedal ratio to get the feel you need. I have brake pressure gauges on my car and have seen way over 800 psi possible with my setup. To me it is just a little work to remove the pedal and drill another hole verses buying a hole new brake setup, so that is why I did it. I cannot complain about how the brakes feel now. Since I have not gotten my car titled yet all I do is play at the track. Anyway anyone can measure their pedal ratio and compare it to what is sold with aftermarket pedal and see there is a difference that can be fixed with a simple hole being drilled.

[tgf05354]

I just was able to crawl under my dash to look at drilling a new hole. Does not look like fun! Getting out from under was even less fun. Glad my wife wasn't lurking nearby with her camera. Anyway, I think I came up with a solution I'd like some opinion on. I'm thinking of removing the clevis pin and bracket that connects the pedal to the MC threaded rod. Then weld some tabs to the bracket with drilled holes so that I can use the same hole in the pedal arm but effectively raise the threaded rod for better leverage. Not sure how well I'm explaining this. Basically drilling a different hole in the bracket rather than the pedal arm. Seems it would be a little bit easier.

[Frank818]

Tnx Taco, I clearly understand now!
I already drilled a little higher than FFR's recommendation but I don't know if it's high enough.
However drilling another there I need to remove a lot of stuff in order to remove the pedal box! It's one of the worst part to remove.

[Hindsight]

I just was able to crawl under my dash to look at drilling a new hole. Does not look like fun! Getting out from under was even less fun. Glad my wife wasn't lurking nearby with her camera. Anyway, I think I came up with a solution I'd like some opinion on. I'm thinking of removing the clevis pin and bracket that connects the pedal to the MC threaded rod. Then weld some tabs to the bracket with drilled holes so that I can use the same hole in the pedal arm but effectively raise the threaded rod for better leverage. Not sure how well I'm explaining this. Basically drilling a different hole in the bracket rather than the pedal arm. Seems it would be a little bit easier.

I wouldn't trust that for brakes - lots of force there and there isn't much to the clevis bracket to weld to. You are right about it not being fun to get in there. To drill higher than FFR suggestion, you have to remove the pedal from the cluster and I haven't been able to do this without removing the whole pedal cluster from the vehicle. Lots of fun.

[taco20]

Tnx Taco, I clearly understand now!
I already drilled a little higher than FFR's recommendation but I don't know if it's high enough.
However drilling another there I need to remove a lot of stuff in order to remove the pedal box! It's one of the worst part to remove.

Hey Frank
Glad we are on the same page now.
It wasn't that hard for me since on the second time around building the car is when I talked to Wilwood and made the decision to drill the new hole and the car was in go-cart mode. I had no interior or body panels to remove to get the pedal assembly out. It may seem like a struggle to do but redesigning your brake setup for a different master cylinder won't be much easier. With the new hole all the hard work you put into getting the brakes done is already over so you get to enjoy the fruits of your labor. I wish FFR had told us from the beginning to go higher to fix the issue which almost everyone using the stock pedals has.

[phil1734]

I wish FFR had told us from the beginning to go higher to fix the issue which almost everyone using the stock pedals has.

They did. It's at the end of the donor disassembly section of the manual.

Do keep in mind that the higher you go on the pedal the less travel you have. Removing the pedal to go as high as possible will not necessarily make things better.

[Hindsight]

They did. It's at the end of the donor disassembly section of the manual.

Do keep in mind that the higher you go on the pedal the less travel you have. Removing the pedal to go as high as possible will not necessarily make things better.

He means to drill up even higher than the higher hole FFR suggests. Shouldn't changing the master cylinder bore size and changing the pedal ratio should essentially accomplish the same thing? A reduction in the amount of fluid moved per amount of pedal travel. The less fluid that moves, the more leverage you have on the brakes and the lighter the effort. The only down side to all this is if you run out of pedal travel.

[phil1734]

He means to drill up even higher than the higher hole FFR suggests. Shouldn't changing the master cylinder bore size and changing the pedal ratio should essentially accomplish the same thing? A reduction in the amount of fluid moved per amount of pedal travel. The less fluid that moves, the more leverage you have on the brakes and the lighter the effort. The only down side to all this is if you run out of pedal travel.

Yeah, I think we're on the same page but getting there in different ways. I was pointing out that you still need a certain (small) amount of travel in the master to work the brakes, and as you go higher with the hole the more the pedal face has to move, eventually leading to massive amounts of travel (at the pedal face).

E.g., If you somehow managed to move the hole all the way up to the pivot point of the pedal, you would have no brakes at all, but infinite pedal travel. At some point there will be a point of diminishing returns with going higher and you'll only be increasing pedal travel - not what you want from a performance standpoint.

[iblackwe]

I just was able to crawl under my dash to look at drilling a new hole. Does not look like fun! Getting out from under was even less fun. Glad my wife wasn't lurking nearby with her camera. Anyway, I think I came up with a solution I'd like some opinion on. I'm thinking of removing the clevis pin and bracket that connects the pedal to the MC threaded rod. Then weld some tabs to the bracket with drilled holes so that I can use the same hole in the pedal arm but effectively raise the threaded rod for better leverage. Not sure how well I'm explaining this. Basically drilling a different hole in the bracket rather than the pedal arm. Seems it would be a little bit easier.

I know what you mean... I even had my interior in when I had to drill the hole. My trick was using a 90* drill adapter with an impact ready bit that was quite a bit short than a standard bit. I was able to get my new hole about 3/4 higher than previous hoping that it will be enough. https://www.amazon.ca/DEWALT-DD5120-Impact-Titanium-16-Inch/dp/B01B83MKBO/ref=sr_1_4?ie=UTF8&qid=1502122249&sr=8-4&keywords=dewalt+5%2F16+impact

https://www.amazon.ca/DEWALT-DWARA100-Right-Adapter-Attachment/dp/B00C0VSNKQ/ref=sr_1_1?s=hi&ie=UTF8&qid=1502122279&sr=1-1&keywords=dewalt+90+degree

On another thread about this subject I there was a recommendation of using some ceramic brake pads from Hawk, I think it was their "yellow Stuff" pad and Tamara has had great results with it.

[taco20]

Hey I did find a nice page on pedal ratio and how it is measured and what range we should be in. http://techtalk.mpbrakes.com/how-to-series/calculating-pedal-ratio

My pedal travel did increase but before the pedal was so hard it didn't move much at all. Now it has a more OE feel to it and pedal height car always be adjust with the adjuster rod to make it lower or higher and get it away from the floor
if it travels to much for your liking.

[Frank818]

pedal height car always be adjust with the adjuster rod to make it lower or higher

Come again? We can adjust the height of our OE Impreza pedal?

[Frank818]

I know what you mean... I even had my interior in when I had to drill the hole. My trick was using a 90* drill adapter with an impact ready bit that was quite a bit short than a standard bit. I was able to get my new hole about 3/4 higher than previous hoping that it will be enough. https://www.amazon.ca/DEWALT-DD5120-Impact-Titanium-16-Inch/dp/B01B83MKBO/ref=sr_1_4?ie=UTF8&qid=1502122249&sr=8-4&keywords=dewalt+5%2F16+impact

https://www.amazon.ca/DEWALT-DWARA100-Right-Adapter-Attachment/dp/B00C0VSNKQ/ref=sr_1_1?s=hi&ie=UTF8&qid=1502122279&sr=1-1&keywords=dewalt+90+degree

I already got that right angle adapter but only a 1/8 bit. That might be a lot easier to buy a 5/16 bit and not remove the box rather than removing the box. That's a very good alternative!

I'll read taco's page and see where I did my hole.

[phil1734]

You can make small adjustments by threading the master cylinder push-rod in or out from the clevis on the pedal.

Your brake pedal should be hard as a rock with as little as travel as possible. It drives most people that have only dealt with over-boosted OEM brakes crazy but once you get used to it you won't want it any other way. Try sitting in an Indycar (or similar non-boosted application) and working the brakes if you ever get a chance.

Ed: If you need a bit of travel to safely stop your car, go with the bit of travel. I hope that goes without saying but you never know.

[axelthrasher]

I'm not sure if this will help anyone, but I put STI Brembos (front and rear) on my car, and while doing this also did the 7/8" Nissan master cylinder. WOW! Fantastic brake setup. I love the way it feels now. Before I had the OEM WRX master, and WRX 2-pot front/1-pot rear calipers. Pedal was insanely stiff and extremely uncomfortable - even with having the clevis drilled high as per FFR instructions. After doing my master cylinder swap, car feels like almost anything else out there with a brake booster. I didn't get a direct comparison though, as I did the Brembos with more aggressive pads than what was on originally.

[Frank818]

Oh Phil I get it, about the clevis adjustment! I thought you meant the pedal itself could be lowered at the very bottom of the pedal.

My brakes are exactly as you describe, hard rock not much after I press on them, almost instantly after and the brake travel is much less than boosted OEM Subaru I thought this thread was about hard rock brake effort yielding to no braking, maybe I misread.

[lsfourwheeler]

Has anyone tried to dial in a boosted setup? As in going to a larger master cylinder with the boosted brakes to lower pressure and make the brakes less touchy at light applications? It seems like that would be the ideal way to balance having a smooth brake pedal but also high maximum brake pressure.

[Hindsight]

Frank - no you read correctly. Based on the mechanics of it, I don't see how you could get high-torque braking with a super-firm pedal and not a ton of pedal effort. I haven't been able to get anywhere near that with all the various setups I've tried. If I change things to get the brake line pressure I want, I don't get a super-firm pedal anymore. I'd rather have strong brakes with a pedal that's a bit softer feeling, than very poor brakes with a really firm pedal.

lsfourwheeler - There was a guy on the forum who went with a booster, but he didn't change the master cylinder size. I can't remember now whether or not he liked it.

[DodgyTim]

Hendow (post #23) on this thread, had a standard booster and master cylinder, undrilled pedal, and wilwood brakes