ABS brake trouble/conversion.

[scottamann]

Wondering if anyone out there has converted their van from ABS brakes to non-ABS?

We have a 93 LE that needed front pads. In the act of replacing those pads, it was determined that the right front had a bad wheel cylinder. After replacing that, the ABS unit will not pass fluid from the master cylinder to the wheel. The other wheels work fine.

Theory: never had to worry about it before, but I found out there's defensive pad replacement technique where you pinch the hose going to the wheel cylinder (along with opening the bleed valve) before compressing the cylinders so they can accept the newer/thicker pads. That wheel cylinder was a mess internally that I couldn't see and I probably squirted ca-ca right back up into the ABS actuator unit.

Well, since I couldn't get the actuator to pass fluid to that wheel to save my life, I took it out and started hacking, knowing full well that it would probably be easy to screw up. There was a broken spring in the pump valve area, but otherwise I couldn't get those solenoids out to clean 'em. Didn't work (though it did pass a little more fluid than before.)

So I suppose I could get a used one, drop it in and hope for the best. However, could I just go non-ABS?

The lines are all there. Front line from the MC splits and goes to LSP then to actuator. Just tie that line to the front calipers. Other line from MC for rear gets tied to the second line going to LSP for the rear. This violates the typical non-ABS redundancy circuit of opposite front and rear wheels on one circuit, but it still gives either front or rear power (maybe the front going to the LSP would mask the rear MC unit failing?)

Any thoughts? Sure would be cheaper. Don't need the ABS for general driving conditions here (I'd just change the ECU to show a failure of power to the actuator and have it default to the failsafe of doing nothing, leaving everything else the same. Maybe I'd extinguish the dash light if it came on.)

Thanks.

[scottamann]

Well, nothing like pulling the heart out of one your "gotta work" subsystems and hoping for the best.

The ABS actuator is gone, the ABS light is on, and I have brakes. I Have Brakes.

Did exactly as planned, with the fronts getting one side of the MC circuit and the rears getting the other. The only complication was that the parts store had no tri-connector blocks for Japanese (metric) brake lines (along with only 2 couplers and 2 8"x3/16" metric brake lines.) I needed to cut the tri-splitter for the LSP from the 95' SE S/C we have for parts. Otherwise it was just some tubing bending and connector fu to accomplish.

So, it seems that you can remove the ABS from the system if that's your bent. Hopefully, you don't get into the trouble that I got into.

Reading on the internet about my woes, the lessons for this amateur mechanic (especially with older vehicles) is to pinch the brake line along with opening the bleeder valve before pushing the cylinders back while replacing the pads. Several sites also recommend just flushing the entire brake fluid mass through the whole system every 2 years at a minimum to maintain the more sensitive parts. Seems like a good strategy to me given that the true repair was more than the value of the car.

Now the only thing is disabling the ABS light. It's just a light, now, and I don't feel bad about cutting the wire, ultimately.

Thanks.

[Burntboot]

I remember when ABS first came out and we were all sent on courses to learn how to deal with the new systems, first thing they taught us was to crack the bleeders wide open prior to compressing pistons to avoid pushing particles back up into the valve body.
What I learned later at Jag was to flush the brake fluid on a regular basis.

At first I thought it was a load of crap but over the years I saw the benefit of regular fluid changes, those that did never had to get into the brake system, those that didn't were replacing calipers, masters, lines.... and complaining about the poor design, cost of parts...
They also had a lot more issues with general brake performance, intermittent pulling....

Brake fluid should be the colour of honey and the reservoir should be clean and free of muck at the bottom.
Brake fluid absorbs moisture,the more moisture it absorbs the lower the boiling point of the fluid and the more likely it is to boil.
(boiling brake fluid = no brakes)
If it absorbs too much, it starts to fall out of suspension (that would be the "mud" in the bottom of your reservoir) and will collect at any low point in the system. If that goop in the bottom of the reservoir gets sucked into the master, it has the same effect on seals/bores as sand.
When I overhauled the van's calipers, I tossed several cores that all looked good from the outside but were heavily corroded in all the low spots.

Not sure if there will be any long-term implications to your mod ( other than resale value) but is nice to have all 4 brakes working equally again.