stock braking system

D

DazedNConfuzed

Registered User
The 90 SC i have, with the retarded ABS unit, runs completely off the electric pump correct? With the engine off the motor runs everytime i step on the brake. This leads me to believe the ABS accumulator is bad. Since i have the motor pretty much apart, i'm thinking if i should swap to the standard braking system, or attempt to replace the accumulator... Is the accumulator hard to replace?
Thanks
 
I was the under the impression that the only way the pump could run with the engine off is if the ABS relay is bad.
 
JimmyDean said:
I was the under the impression that the only way the pump could run with the engine off is if the ABS relay is bad.
Click to expand...

Thats what I would think also. Mabe not the relay but some wireing probblem because I don't think the pump should run when the key is off.
 
Yes KOEO, sorry for not clarifiying. I was wanting to ask if the stock ABS booster relies solely on the electric motor or is it a dual setup where it is also vacuum operated, but when engine vacuum drops, the electric motor engages? I don't see any vacuum lines going to it, but this engine compartment is a mess in terms of lines running everywhere. Right now i'm trying to decide if i should ditch the abs unit while i have the engine compartment apart, or replace the accumulator, which i think is bad. The electric motor runs, but runs everytime i step on the brake = bad accumulator.
 
You know my power just recently went off in my abs before it did i had a buzzing in the peddle i could feel is this what you meen by electric motor? can you feel it in the pedal? cus my ~~~~ dont work no more and trying to figure the problem out
 
My ABS pump never ran all the time, it was good up till i started rebuilding the motor, but i think the accumulator over time went bad.
 
My $.02

DazedNConfuzed - This sounds like the accumulator... does the ABS & BRAKE warning lights flash on the instrument panel when you apply the brakes? At any rate, if the accumulator is the original it's time to replace anyway (a lot cheaper than a new system). Contact Prior Remanufacturing...

91ScDrIvEr - Sounds like the ABS Pump Relay went bad (replacement = GP Sorensen MR120). Hopefully it didn't cause the pump to overheat. Also check the fuse (40A, I think) in the main power box under the hood. The stuck relay may have blown the fuse.

no164ford - If the relay sticks in the closed (circuit continuity) position, the pump will run until the battery is drained, or the pump overheats, or the ABS fuse opens, even with the key OFF.
 
Can anyone verify that the Crown Vic brake fluid distrubution block is just a big 3 way tee fitting? I don't want to run to the junkyard for one, when i have a t fitting here that i can use, i can see how they might regulate the pressure a little bit to compensate for the long run of line, but the line is steel, so there wouldn't be a pressure drop, and the fluid is already at the caliper so there is no delay in pressure building. But i just want someone to verify this.
Thanks
Patrick
 
IIRC, the distribution block routes different volumes of fluid to each line. The rear brakes need more fluid than the front because they are doubled. If the rear calipers are a different bore size than the fronts, this will also dictate a different amount of flow to them.

The other thing is that Crown Vics had rear drum brakes for a long time. If you have a SC, you have rear discs. This would be a problem. If you have a hybrid setup, maybe getting an adjustable proportioning valve would be a good idea.
 
The block is just for the front brakes only. Its a 4 way fitting, an inlet, pressure switch, and two outlets for the front calipers. The rear are on their own circuit.
 
It sure sounds like just a T then. Plug the switch port, shoot some compressed air (or even blow) through it and see if it comes out the other two w/o any resistance. If it does, than it's just a T. If there's resistance, there's something else going on.

Then you should rinse it with rubbing alchohol to remove any moisture.
 
I don't have one available to me. I've owned several crown vics and i remember the block with the pressure switch, and several of the pressure switches leaking through the center... Anyway thats why i was asking here, i didn't know for sure if it was just a 4 way or if it channeled fluid toward one opening more than the other. i highly doubt that it would, and i'm at the point where i can't wait anymore, i need to get the top of my motor back on and i've got the booster and a new bendix master cylinder waiting in the garage.
 
Fact: The Crown Vic "distrubution block" with the pressure switch in it, is indeed just a large T fitting. I have one sittin on my desk right now from a trip to a junk yard. I grabbed both a 92's and a 94's, one with ABS and the pressure swtich for cruise control. They both flow the same amount of fluid to the left and right front calipers.
Now for the master cylinder, i bought one for a Crown Vic, 93. But it has the huge brake fitting for the rear, not exactly ideal when you're using a brand new master that doesn't come with it, the remans don't either. Sure you could just go to the junkyard and get one, but for people like me where a junkyard is a rarity in the area... I chose to go with a master cylinder out of a 94 Ford Explorer. Its a two fitting style brake master like the crown vic, but lacks the huge fitting off the master. If you chose a master from a Ford explorer, make sure it does not have ABS, the ABS units have a port for a pressure switch at the end of the master.
 
If you are going to conventional master cylinder you need to get one from a vehicle that had 4 wheel disc brakes. Otherwise the rear brakes won't work because you will not have enough volume of fluid to get the rear calipers to actuate. You also need a new proportioning valve.
 
Another Thought

There is a good reason that Ford used the electric motor setup. You way not always have enough Vacuum present to properly operate a standard style booster. Something to keep in mind.
 
Sorry....but not true on the vacuum. The 94-95's have a Teves Mark IV ABS System which is not intergral like the Mark II System the majority of us have. It uses a Vacuum Booster master cylinder and a separate hydraulic actuator system mounted in the LH front fenderwell that only operates when a anti-lock situation is sensed. The speed control unit also uses vac. There is a vac. accumulator on T Birds...looks like a round ball mounted in one of the fenders...forget which side now and there are check valves in the vac. sytem to "maintain" vac. If you do the swap just hook into the vac. system where a 94-95 does and you will be fine.
 
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