Brake routing suggestions- Post your pics

[Junty]

Hey team,
Ive also discussed with Wayne (early last year) and my 2004 donor ABS system is working fantastically in my 818S RHD (by swapping the routing as touchstone detailed above). Only exception for me is I have not used any proportion valves anywhere. Some of us have previously discussed in another braking thread - many mid/rear engine sports cars, have the same big callipers and disks on rear as front. My theory was that we will always need more rear axle braking than the standard 2 pot callipers. Due to my lack of including any proportioning valve - I could have easily used the standard subaru routing - however if one of either circuit from the master cylinder was to ever fail - I personally would prefer to retain either both front or both rear as the second backup emergency stop circuit. With standard subaru 4x4 the LF RR versus RF LR might be more balanced, however my own inexperienced knowledge expects that the standard subaru layout will undoubtedly result is uncontrollable 360 spins if heavy braking was required with only one circuit working?
I still intend to add larger rear disks and add 4 pot WRX front callipers to the rear of my 818 to improve the braking performance overall - still no proportioning valve!

[Scargo]

Couldn't there be a difference in one year/model vs another in how the ABS system is designed to operate? How far back does EBD go? If appropriate, I wonder if it would be helpful to this discussion if comments and results were put in the context of what year/model is being used/discussed with you system or someone clear the air about what is common to all GD WRX's, GD STi's, etc.
As an example, my GR STi's ABS still works great with all the stability control inputs disconnected. I have no idea if the G sensor is active. It seems perfectly happy standing alone (if it is).
It sounds as if Bob has a functioning ABS without the PV. Is that because of the electronics? Do all or only some have the rear lift activated proportioning valve? I don't think my GR has any rear proportioning valve.
What about what Stoptech says? Their warning about mixing proportioners?
What happens when you, like I do in my STi, are pushing the limits of the (modified) braking system at 145?
I'm not starting with ABS on my 818R. Stoptech engineers designed the brake system for my 818R and I am using a Tilton unit with bias bar.
Then again, after seeing my friend ruin his tires this past weekend without ABS I am having second thoughts. I don't like contemplating multiple sets of tires and rain tires. I don't even have a second set of slicks for my STi (though I'm looking).

"however my own inexperienced knowledge expects that the standard subaru layout will undoubtedly result is uncontrollable 360 spins if heavy braking was required with only one circuit working?"

You need to have something to initiate the spin. Just having two wheels braking at opposite corners of the car should not do that. Oversteer, a slick spot, etc. could get the car rotating and no braking system could stop it adequately. As I told my friend who flat-spotted his tires, the ABS does not do anything if you are sliding sideways.

[C.Plavan]

My .02 cents.
1. I have the proportioning valve in use like FFR suggested, but I made it so I could adjust from the cockpit.
2. I have the 4 pot Wilwood caliper/rotor upgrades on all for corners (Don't waste your money on the 6 pot brakes).
3. I do not have ABS, nor do I want it. 200+ track miles and no flat spots on any of the tires.
4. I have great "feel" under braking, and you know if you are about to lockup. (locked up the fronts once at a start of a race in the first corner)
5. I have not noticed any ill braking issues once I upgraded to racing pads.
6. I have not noted anything different in braking than other cars I have raced.

[Bob_n_Cincy]

My .02 cents.
1. I have the proportioning valve in use like FFR suggested, but I made it so I could adjust from the cockpit.
2. I have the 4 pot Wilwood caliper/rotor upgrades on all for corners (Don't waste your money on the 6 pot brakes).
3. I do no have ABS, nor do I want it. 200+ track miles and no flat spots on any of the tires.
4. I have great "feel" under braking, and you know if you are about to lockup. (locked up the fronts once at a start of a race in the first corner)
5. I have not noticed any ill braking issues once I upgraded to racing pads.
6. I have not noted anything different in braking than other cars I have raced.

Great info Chad, as usual.
Are your 4 pot Wilwood all the same piston diameters?
Bob

[C.Plavan]

Front caliper specs-
http://www.wilwood.com/Calipers/Cali...no=120-7378-RD

Rear caliper specs-
http://www.wilwood.com/Calipers/Cali...no=120-9706-RD

[Jaime]

Assuming that the Subaru master cylinder pistons are equal for the front and rear circuits (I think they are), those brakes give you a 71% front/29% rear braking distribution. That's pretty close to how the weight would be distributed on hard braking.

[Bob_n_Cincy]

Front caliper specs-
http://www.wilwood.com/Calipers/Cali...no=120-7378-RD

Rear caliper specs-
http://www.wilwood.com/Calipers/Cali...no=120-9706-RD

Chad
Your brakes "Total piston area" 4.12F and 1.58R is similar to a stock WRX.
You Like it, don't change a thing.

I am running 4.46F and 4.46R with no PV.
I like it,
BUT
I have not test brakes over 80 mph.

I'll see if I can get some video of some high speed hard stops this weekend.
Bob

[Samiam1017]

bob what rear rotors are you running to use the front calipers or are you putting a shim between the pad and calipers

[TouchStone]

When I started my build there wasn't a good answer "for or against" having ABS on the 818. So I decided to included the ABS module because if I don't like it then I can disable it easily by unplugging the connector.

[Bob_n_Cincy]

bob what rear rotors are you running to use the front calipers or are you putting a shim between the pad and calipers

Samiam
I am running the CENTRIC Part # 12147025 rotors. They are 17.9 mm thick. My outside pad has a double thick backing plate welded together.
More info here http://thefactoryfiveforum.com/showt...l=1#post173658

Bob

[Hindsight]

Do we have anyone with a working and tested ABS setup?

[AZPete]

In Post #81 above, Junty says, "my 2004 donor ABS system is working fantastically in my 818S RHD."

[Junty]

Hey Team, reiterating my post above. Yes my ABS system is working and fully functional. Ive tested braking from about 65m/hr,(100km/hr) with both the ABS system active and earlier in the build deactivated. If I had a track car (R) I might have skipped the ABS, but I have a street RHD 818 with a 2012 2.5L engine running Motec ECU - base tune with mere 12 PSI boost the car has 247Kw at rear wheels. So it goes very quick, and unlike the usual high quality tarmac on the track, street driving includes many unseen and unknown parameters (oil spills, pot holes, lose metal on the road, and cars and trucks traveling in opposing directions etc etc) so I'm very happy to have a great ABS setup working well.
With JDM engines and a little more than the standard HP - ABS certainly is essential for any street 818.

[AZPete]

Yippee, my ABS works! I just got back from a run around my 'hood and tried several hard stops from 60 mph. The ABS is definitely working and I could feel the system pulsating without skidding. It stops amazingly quick and straight with no pull. The two proportioning valves on the front brake lines are set full open. I know the fronts are gripping evenly but couldn't tell if the rears are gripping, but they aren't locking up. I'll try disabling the ABS and then do hard stops on pavement and then dirt roads to see what the rears are doing. But, I'm thrilled that the ABS is working!

[bbjones121]

Yippee, my ABS works! I just got back from a run around my 'hood and tried several hard stops from 60 mph. The ABS is definitely working and I could feel the system pulsating without skidding. It stops amazingly quick and straight with no pull. The two proportioning valves on the front brake lines are set full open. I know the fronts are gripping evenly but couldn't tell if the rears are gripping, but they aren't locking up. I'll try disabling the ABS and then do hard stops on pavement and then dirt roads to see what the rears are doing. But, I'm thrilled that the ABS is working!

Awesome! Congrats. I am running my lines now.

[Junty]

Congrats AZPete. Just like you it was a great relief and I'm very happy the concept and system works. Light weight cars for obvious reasons accelerate well - I'm very pleased that this same logic transfers to them stopping very well also.

[Hindsight]

I don't really know, if its different that diagram may not be 100% effective. This statement from the manual has given me some doubts:

Attachment 41709​<--Picture (click to zoom)

I'm trying to wrap my head around the idea of switching the output lines and ABS sensors to have just one line from the master controlling both front wheel cylinders (as Wayne has also suggested). But in reading that bit you posted from the manual that I quoted here, it seems like maybe that option may not work because of the different algorithms for front vs rear no?

[Junty]

Hey Hindsight,
Im certainly not a brake/ABS expert. So I looked at alternative systems, and I consulted experts such as Wayne. Then using the best advice and logic, I applied what I perceived to be the best option and system setup for my 818.
It is a fact that the Subaru ABS system is a 4 channel independent on all 4 corner system - so regardless of how it is setup, the brake pressure is independently regulated by the ABS system to each wheel - directly dependant upon which single one is changing rotational speed in relationship to the 3 others and the G force sensor. I have never received any conclusive advice that I am confident in relating to proportioning valves either before or after the ABS control unit? I therefore elected to setup as Wayne suggested with any valves - if I ever wanted to change back to the Subaru system, this is relatively easy (as I merely need to move the brake lines about 1 inch left to right at the control unit, and move the wires).
And in conclusion, the system works very well. I merely want more brake effect in the medium term, simply by increasing the callipers and rotors on the rear. This is m personal perspective and will prove itself or be reverted back upon testing - the ABS however will remain as is working very well...

[Chef818]

For the ABS users did you use the factory rear proportioning valve?

[bbjones121]

For the ABS users did you use the factory rear proportioning valve?

No I did not. It is not adjustable. I bought another willwood proportional valve and have both of them on my front. I don't know if it is absolutely necessary since the ABS system will try to prevent lockup on its own.

[DMC7492]

Hi guys here a link to the abs updates
http://thefactoryfiveforum.com/showt...ave-it-working

[phil1734]

No I did not. It is not adjustable. I bought another willwood proportional valve and have both of them on my front. I don't know if it is absolutely necessary since the ABS system will try to prevent lockup on its own.

You would still need one to maximize performance.

Unless you are running a high-end aftermarket system, I believe the Subaru ABS system from the donors is a simple on/off circuit. It'll prevent lock-up, but won't do anything to adjust line pressure front to rear. You could easily have the fronts locking/unlocking with abs and only a fraction of the pressure in the rear line needed to extract any use from the rear brakes.