818S ABS brakes

[Quiny]

Has anyone successfully incorporated ABS into their build? I'm in process of stripping my donor car (2002 WRX wagon) and wondering if I should bother. I have seen in these forums that some people are including them in the build but I haven't heard about any testing or results. It doesn't appear to be that difficult just somewhat time consuming but is it worth the effort? If anyone did choose to use it I'm curious to what was used for a proportioning valve (new, stock, both?). I was considering installing a switch so that I could use the feature or leave it off. I have heard that the 2002 ABS system was a little quirky and that Subaru made an update to the program, I'm not sure how to determine if I need to update the firmware or not. Where as I will not receive my 818 till late next year I haven't started a build thread yet. I can't tell you how much this forum helps, a big thanks to you pioneers for sharing so much info it is very much appreciated.

[pt00323i]

few are doing the build now with ABS not sure how they turned out yet, here is one post, there is another on the 818R

http://thefactoryfiveforum.com/showt...ghlight=brakes

[AZPete]

Is ABS worth the effort? I think so. I put ABS into my FFR roadster and it saved my butt when a Prius stumbled out of a hidden driveway. Besides, ABS is free! Erik Treves installed ABS but I haven't heard yet if he has tested it and if it's working - see his build thread. I'm installing ABS and have nearly finished the brake lines, but I won't know if it works until it's on the road and I can conduct tests. See my thread entitled "ABS Plumbing". Your 2002 may not have the internal proportioning system that my 2006 has so do some research in Subaru manuals. Also check if your donor has the diagonal setup for brakes. When dissecting your donor I suggest you save the ABS control module and mounting bracket so you will have the choice later. Take photos before you take it out and note which port goes to which wheel and look for any proportioning valves between the ABS module and the calipers. Your 818 kit includes brake lines so you can discard the donor brake lines.
Pete

[Goldwing]

By the time you get your kit, several builds (hopefully mine too) will have ABS worked out. Wayne's is just about done and he used ABS. It's a safe bet to save it and decide later. Having 4 separate brake pedals just might make the difference in a bad situation, so I'm using it. Check your year's hardware, I'm not sure what year started using a "g" and steer angle sensors to add EBD functions as well. The tech was around in '02, but my quick search couldn't verify if WRXs had it or not (04+ do). My understanding is ABS wheel slip function will work without the extra stuff, but it's just another few parts to save in case you want EBD too. The g sensor is by the Ebrake handle. To answer your question, It seems the consensus is two proportioning valves after ABS, 1 on each front line.

[Goldwing]

Hey Pete, what is this "internal" proportioning valve you speak of? Is it built into the ABS or master unit? I have an 07.
Thanks
Rich

[AZPete]

Rich, I was referring to the EBD . .

The Factory Service Manual includes this: (ABSCM = ABS Control Module)

E: EBD (ELECTRONIC BRAKE FORCE DISTRIBUTION)
The EBD system utilizes the function of the conventional ABS. This system prevents premature locking of the rear wheels by using electronic control instead of a proportioning valve. The system provides a feature to optimize the brake force distribution to the front and rear wheels according to change in loading conditions or displacement of the center of gravity during deceleration.

The ABSCM calculates the optimum brake force distribution from the difference in speed between the front and rear wheels. Based on the results, the ABSCM controls the rear wheel brake pressure through the ABS hydraulic unit (H/U) to achieve the optimum brake force distribution suitable for the driving condition.

The proportioning valve is disused on EBD equipped vehicles.

Quiny, see the last sentence? I don't know if your 2002 has EBD. If not, it sounds like your donor may have a proportioning valve on the rears.

[Quiny]

Thanks AZPete, I do have a proportioning valve, its located on the right front shock tower. I also agree with you about the ABS in general. I appreciate all the advice.

[Quiny]

Thanks everyone for the advice, I will plan on using the ABS. All good info, the free part is the best. I spent years bending and flaring brake lines so I think the extra time is worth it. Since this is a father and sons project my boys will learn a some new skills. I will keep checking back to see how everyone does with it. I have no problems with stealing good ideas shamelessly.

[Bob_n_Cincy]

Thanks everyone for the advice, I will plan on using the ABS. All good info, the free part is the best. I spent years bending and flaring brake lines so I think the extra time is worth it. Since this is a father and sons project my boys will learn a some new skills. I will keep checking back to see how everyone does with it. I have no problems with stealing good ideas shamelessly.

Quiny
hear is a link to the nuts you will need.
Bob

http://store.fedhillusa.com/search.aspx?find=22

[Quiny]

Thanks for the link, much neater than reusing the old nuts. I also like your brake plan listed in another thread. I will do exactly the same thing when the time comes, I may even be able to skip a few steps depending on what you discover. Please share all your results, its a huge help. My donor does have a double proportioning valve after the ABS pump to the rears. Too bad it's not adjustable. I'm still stripping my donor and finding all kinds of extra stuff hacked into the harness, turbo timer, aftermarket gauges, alarms (2 I think). Why would someone have a micro-switch attached to the gas pedal?

[Xusia]

Quiny
hear is a link to the nuts you will need.
Bob

http://store.fedhillusa.com/search.aspx?find=22

What exactly are these for?

[Bob_n_Cincy]

What exactly are these for?

If you are flaring your own brake lines, you don't need the pink adapters, if you use these metric flare nuts.
Bob

[Goldwing]

Thanks Pete! I'll wait for feedback about any need for using adjustable proportioning valves. Maybe we won't even need it. Sounds like fun to test it out.

[mn_vette]

Why would someone have a micro-switch attached to the gas pedal?

Sounds like someone has a shot of Nitrous on their car. People put a micro switch on the pedal to make sure it only goes off at WOT.

[pt00323i]

I have an 02 donor also, I'll be install the ABS also, thanks for all the early build guys! lets hope it works well.

Thanks Pete! I'll wait for feedback about any need for using adjustable proportioning valves. Maybe we won't even need it. Sounds like fun to test it out.

[DennisL]

Anyone have the full ABS system up and working i.e. both hydraulic and electronic components? Any problems and is it worth the extra work?

[Quiny]

Well after much thought I am not going to incorporate the ABS into my build. It's a shame since I already bought a sensor, built the bracket to mount the unit and dieted the wiring harness accordingly. What changed my mind is the research I did mostly on the Subaru forums. It seems that the ABS on early models like the 2002 have some strange quirks. What I have read is that the ABS will sometimes activate if you hit a decent size pothole or bump while braking and the only way to get brake control back is to release the brake and apply again. Apparently the problem was corrected in later years. My plan was to have a switch to turn it on or off but if it behaves like that then I would just leave it off all the time. I still believe ABS is a very worthwhile when it behaves as it should.

[billjr212]

Yup - I had an '02 as a daily driver and I definitely remember that "quirk" (to put it nicely). They did a software update on this that mitigated the issue, but didn't really eliminate it entirely.

The thread below is typical of Subaru forums (in my opinion) and bounces all over with half-informed comments, but eventually gets to the point.
http://www.wrxtuners.com/forums/f51/...s-recall-8932/

[Quiny]

This was what changed my mind.

http://forums.nasioc.com/forums/show...3&page=1&pp=25

http://forums.nasioc.com/forums/show...3&page=1&pp=25

[Buzz Skyline]

I don't think this has been addressed explicitly on this thread . . .

If you're installing ABS, do you need a manual proportioning valve at all? You just need proportioning valves when you want to disable your ABS to run on a track or something, right?

Also, where are people mounting the ABS units? Pictures would be great.

Thanks,

Buzz

[Boog]

Wouldn't two proportion valves (if properly adjusted) on the front two lines allow you to achieve a higher level of braking before a wheel locked and ABS engaged? Assuming the rears lock first, it would let you drive/brake harder without constantly riding the ABS.

[Goldwing]

I mounted my ABS unit between the battery and the forward firewall, using a trimmed factory bracket. Pics in my thread at the bottom of page one, spilling into page 2.

As far as proportioning valves go, without them, you would be relying on the ABS to make up the difference in braking capacity between each axle. Maybe the new dad thing is corrupting my thoughts and making me worry, lol. I felt the safer path was to balance the system so everything is close to locking up together, all balanced. I used a second valve so each front line would have its own valve. For now, I have them open, I'll adjust them once I'm on the street.

Finding a second valve was easy.

[Buzz Skyline]

Thanks, Goldwing. This helps a lot.

-Buzz

[tmoretta]

Hey Goldwing - I also am using the ABS and two valves. On my first start of the engine yesterday, all was fine except the ABS light stays on. All connections/sensors are intact and connected. Any ideas?

[Goldwing]

Parking brake switch and console mounted g sensor in place and connected? Fuses? Off the top of my head possibilities.

[tmoretta]

Parking brake switch no. I will check that - thanks.

[Goldwing]

While I don't think the brake fluid reservoir sensor directly affects ABS (rather usually causing a "brake" light), the ECU might command the ABS light to light up as well. If you aren't using the stock fluid reservoir, play with opening or shorting the fluid level connector to see if it helps.

[Louisromersh]

So reading everything I could about abs on the forms I'm still confused were the proportioning valves go?
Could some one provide a diagram on the plumbing if one was to use the abs system.

Thanks
Louis

[Goldwing]

If non ABS, the single proportioning valve goes after the brake master before the tee that splits the line to the two front brakes.

For ABS, we do the closest equivalent. Since each front brake gets it's own line from the ABS unit, which is pre-plumbed to diagonally split the main and secondary brake lines, each front brake gets its own proportioning valve. You place the valves between the ABS unit and each front brake. I mounted mine in an easy to reach spot right next to the flex brake line mount tab at each front wheel. Pics in my build thread. post 58