Adding ABS

scottzg · Post by **scottzg** » Mon Sep 29, 2003 6:57 pm

Well, I'm considering a WRX brake upgrade, and while i'm at it, ABS would sure make me happy. Does anyone know what would be involved in adding ABS to a non- ABS vehicle? Can i add it before the brakes go in?

Thanks

Fernely · Post by **Fernely** » Mon Sep 29, 2003 7:10 pm

Wow its actually quite involved. I am not sure if I am getiing all the components but here it goes. ABS rings and pick up sensors on all four hubs. ABS hydrolic contol in the engine bay. All the bent metal lines to go to and from the master cylinder. The front to rear proportioning valve I belive. There may also be an independant ECU for the ABS system. I belive that is a start. There may be more, good news is you can probably get it all from a scrap yard car.

Brat4by4 · Post by **Brat4by4** » Mon Sep 29, 2003 7:27 pm

I feel there would be tons of line to be run with some systems having 3 or 4 channel ABS. And I don't know how it taps into the master cylinder or anything but you might have to change it. Most likely this would be a "my car is down all winter so I might as well try it" deal. Not get it on quick before snow comes idea. I also noticed special brackets inside the fender to hold the ABS sensor lines before they attach onto the brake shield... not to mention the extra holes for the lines to come in and out.

LaureltheQueen · Post by **LaureltheQueen** » Mon Sep 29, 2003 11:08 pm

you'd probably be better off just selling your car, and getting one with abs. It'd be more cost efficient i'd imagine.

Yukonart · Post by **Yukonart** » Tue Sep 30, 2003 12:22 am

This is kinda like wanting to do just a tranny swap without going for the whole engine swap, too. It's definitely another case of "MUCH easier to get another car with that option".

However, since you're converting to all-WRX brakes, it may not be that much more of a big deal to add the ABS. Just make sure whatever brake system you pull off a WRX already has the equipment you need.

At the very least, you're looking at a ton of custom work.

Post by **Legacy777** » Tue Sep 30, 2003 2:24 am

don't even try it......it's so involved....it's just not worth it.

If you're looking to do a WRX brake swap, I'd suggest an H6 upgrade in the rear to help balance the forward bias that the WRX calipers will give.

Brat4by4 · Post by **Brat4by4** » Tue Sep 30, 2003 2:38 am

Oh, Josh, by the way. The whole bias shift deal is for the non Turbo Legacys. All it does for the sport sedans and touring wagons is increase the heat sinking capabilities because of a larger front diameter. Everything else is identical to a WRX braking system except the front rotor diameter and we have BETTER rear brakes. Just in case some turbo members were getting worried about the WRX upgrade for their cars throwing off the bias. If you could throw that disclaimer in there every once in a while that'd be great.

I had my new brake setup at the track (see sig) and it is neutral with Kuhmo 712's and VERY powerful now with all new stuff (pads, rotors, ss brake lines, super blue fluid, front calipers). My professional racing instructor even complimented them, I was blown away by that. And that's only on stock WRX front pads! I wish I still had the Endless pads but don't miss the brake dust.

ciper · Post by **ciper** » Tue Sep 30, 2003 2:39 am

So the front calipers on the turbo vehicles are different? Shows how often I pay attention!

vrg3 · Post by **vrg3** » Tue Sep 30, 2003 3:01 am

We do have more weight over our rear wheels than WRXes though...

The ABS system does have a computer unit, and also a G sensor on manual transmission models.

The master cylinder is definitely different. Larger bore, and only 2 ports rather than 4. The proportioning valve also only has 2 ports rather than 4.

Even if you could handle the plumbing, the wiring alone would be a nightmare. I second the notion that you're better off getting a car that came with ABS, or just dealing without it.

Post by **Legacy777** » Tue Sep 30, 2003 2:33 pm

Brat4by4 wrote:Oh, Josh, by the way. The whole bias shift deal is for the non Turbo Legacys......

I beg to differ...

It may not be as pronounced as mine, but it's still there. I have turbo legacy rear brakes. so that is the same between my car and the turbo cars.

As for the front brakes, the caliper piston size is the same between the turbo legacy and the WRX caliper. The caliper design is slightly different in how it attaches, but that's not really a big deal.

I just went out last weekend and put the completed brake setup through its paces, it stopped damn good! I was pretty pleased with the final results. I still could use a little more rear bias to keep the rear end from jacking up.

I agree my weight distribution is going to be different but that doesn't change the fact, increasing front rotor size, increases front brake torque, and forward brake bias.

Here's some calcs with actual percentages
http://www.main.experiencetherave.com:8 ... kemath.xls

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Adding ABS

Adding ABS