2004 Rear Drum to Disk Conversion w/Active ABS Sensors
Last Weekend (04/02/2016) I successfully completed the Rear drum -> disk brake upgrade on my just purchased 2004 Sable LS. For the basic directions I used the WIKI as posted here:
Brake upgrades, for all generations, using stock Ford parts! - Taurus Car Club Maintenance and Modification Wiki
(admin: please consider updating such)
I'm not a serious gear head but I had a veteran mechanic friend who understands brakes helping me. I was responsible for the electrical side.
Donor car was my (now junked / sold) rusted out 1997 Taurus GL 3.0 Vulcan w/factory installed rear disk brakes which I'd been driving since 1999. I never intended to sell this car until I found extensive rust hidden underneath the plastic running boards on L&R sides, with a 3/4" gap from the front doors all the way back to the rear... Found it after I jacked up the car to rotate the tires last fall & rust came out from the jack cleats all over the pavement. Even so I was seriously considering having a welding shop fix it until last month, when I easily made a fist sized hole in the rear wheel well facing towards the front of the car. Other side was the same. That finally convinced me not to spend more $ trying to patch the rust.
One year ago the Gen3 rear brakes had locked up on me & I'd paid to have them completely rebuilt. Other $ spent on repairs to this car would be too long to list here.
I did managed to find a 2004 garaged, fully serviced, Very clean Sable LS with 46k miles & DOHC
engine for sale _but with stock rear drum brakes_. (Ford dis-continued rear disk option in 2000)
SEE PIC #1 BELOW (mag wheel w/drum brakes)
I bought the Sable knowing If I could bolt up & keep at least 1 major subsytem from the old car, it would make me feel a whole lot better about scrapping my favorite 97 Taurus, especially as I already owned most of the parts I needed just sitting there in my driveway.
Very last step for me was to Bolt up the Gen4 drum wheel spindles onto the bare Gen3 knuckles, Put the Gen3 15" rear tires back on the car (free wheeling) Throw all the Gen4 drum brake parts into the trunk & call the wrecker to pick up the car. But I did keep the front leather seats (not bolted up, new car has leather), transfer my original license plates, audio system & of course, rear disk brakes.
However 1/2 way through the project I discovered the rear ABS sensors for the 2004 model year were changed from coil pickups (passive) to Hall Effect sensors (active) and are not cross compatible. Years ago I had a job repairing electronic engine control computers & am familiar with the circuitry differences. Early in the morning on the last day of the project I found the info which saved me here: (see post #8)
Rear Abs Sensors
Drum & Disk spindle rings have the same # of teeth which generate the same speed signal rate for the computer. But you must use the original Gen4 sensors which came with the car, mounting hole enlarged. I can't speak to where he got the 15 thousands spec for the sensor gap, only that it worked great for me.
However that info was not easy to find -&- since I'm Very happy with the results I thought I'd try to register on this site again to post a guide on how I did it. Years ago I used to be registered under a different handle, different email address but lost the password. (Sorry for the blurry pics, best I could do)
Black electrical connectors are the (passive) coil pickups 1996? -> 2003
For you guys with ohm-meters they measure about 1.6k ohms.
SEE PIC #2 BELOW (97 abs sensor)
White electrical connectors are the (active) hall effect sensors.
SEE PIC #3 BELOW (04 abs sensor)
Those will measure more than 1 meg ohm (open) and is a semiconductor that is magnetically sensitive.
They are not interchangeable. Ford changed the connector body style on purpose. Don't try to force the connectors to fit by cutting off the polarity tabs. Before I figured this out I had managed to dis-assemble & re-pin the harness connectors on the Gen4 car side without cutting anything (body wire harness colors were the same, Gen3 to Gen4) but was only rewarded by a red ABS
light & the (optional) Traction Control System light blinking & throwing a fault - trying to throttle down the engine & making the whole thing BUCK since it wasn't seeing any speed signal coming from the rear wheels. (Ford had also altered the ABS
computer to run the traction control system.) Naturally I had to put the original white (car side) ABS
connectors back where they were.
After the successful rework (described below) simply pulling the main battery wiped the memory & cleared the fault codes from the engine computer. ABS
& Traction control systems are happy & my brakes stop the car real fast & smooth.
After you've gathered the Gen3 parts from your donor car you have to remove the Gen3 passive sensors off of the rear disk mounting plates. Both Active & passive sensors are held in by one external torx E8 bolt. Remove the Gen3 bolts & discard. (The Gen4 bolts are ~1/4" shorter & must be reused.) Go slowly & don't strip out the steel bolt heads. Rear of the Gen3 sensor body sticks up out the back & caused my 3/8" E8 socket to be at a funny angle making it easy to slip off the head. Deep well socket would have been better. Next remove the sensor from the plate. Left side came right out for me with just light pounding with a hammer & punch. Right side was more difficult & destroyed the Gen3 sensor. Be careful not to damage the plate. you want to re-use the threaded bolt holes. No need to drill / tap new holes, new hole would be well beyond a flat surface & into a roll-off step in the plate on the back side. You should now have round 1/2" holes where the sensors were & usable bolt threads each rear disk plate.
There are 2 types of spring steel clips holding the L&R sensor wire harnesses to the steel control arms:
Away from the wheels are clips (single 1/2 circle "c") that use a 3/16" small tab to press into the middle of the arm holding it down. This tab gets deformed upon removal & I couldn't get them to re-assemble tightly. Bending the tab back just shears it off.
Near the wheels use a different design that is twice as long, is bent in two "c" shapes & clasps over the top & bottom of the control arm. Somehow from both cars I ended up with 6 of the double C type & used 3 on each side to hold down the ABS
harnesses onto the control arms. Run the wires into the middle groove of the control arm as before & clip them down using the bend in the middle of the clip to bind it in. Don't use TY-wraps Especially near the driver side (hot) exhaust which is located just above. I didn't bother trying to buy new clips but that is an option.
To get the Gen3 E-brake cable out of it's anchor on the Driver's side going back to the rear wheel (Other side goes towards the threaded cable length adjuster) - you push back a clip holding it through the hole to back it out of the mounting bracket.
On the Gen4 you have to _Cut Away_ a rubber ring holding it fast to a Groove around the metal Steel Ferrule at the end of the black cable sheath. That sheet metal steel anchor is the same on both Gen3 & Gen4. It gets bolted to the frame once the Gen3 cable is clipped in through it's hole.
Un-bolt the active L & R ABS
sensors from the rear drum plates. Be careful, you need both the bolts & the sensors. Each sensor should easily come off of the plate. Discard the drum plates, drums, shoes, springs, spindles, etc....
Take each Gen4 ABS
sensor & use a round file to enlarge/oval out the mounting hole. File through the brass insert & into the plastic going towards the sensor head. Need to go about 1/2" inward. Be careful. May need to adjust this slightly larger/deeper upon re-assembly.
SEE PIC #4 BELOW (modified 04 abs sensor)
Obtain a short length of 3/8" ID standard fuel line hose. This will center the smaller 2004 Gen4 sensor head into the larger Gen3 hole on the plate.
Also obtain two 3/4 OD
Stainless steel fender washers. These are going to go through the bolt & over the enlarged sensor through hole & keep it from moving around. (I already had #10 washers but #8's would be ok)
SEE PIC #5 BELOW (e8 bolts & stainless washers)
Dill out the holes with a 15/64 drill bit. I like cobalt steel bits. Didn't want to use washers with the larger oversize 1/4 style hardware store holes. Felt that was too big & I wanted the sensors to never move.
SEE PIC #6 BELOW (Sensor, Bolt & Washer)
Go to Home Depot / Lowes & spend $5.00 on a tube of blue 242 Loctite.
Try to clean all the loose rust off which sticks to the magnetic sensor head. Use tissue paper 1st. A can of compressed air helps.
(To repeat from the WIKI) You should have Gen3 Rear Calipers (use old ones as core returns), Rotors, Pads (ceramic - best), Gen3 brake hoses (Uses same mating fitting on Hardline Gen3 to Gen4) , Gen3 E-Brake Cables, Rear disk backing plates & Gen3 wheel spindles. I used my old Gen3 spindles as my mechanic friend assured me the main bearings were ok. Send the extra $ and buy new spindles. Yes you need good bearings but you also need a clean (rust free) surface on the outer ring where the teeth are. Spent too much time with a wire brush getting the rust off the teeth to keep stuff from hitting the ABS
sensor body. Also buy 2 new -required- "rear axle wheel hub retainer" nuts p/n FODZ-4B477-A ($15 ea) .
You need a 1/2" drive torque wrench that can be set to 200 FT/LBS. (runs $80 & up)
If you don't have flat metal feeler gauges get a set at home depot. Going to need 15 thousands.
Bolt up the Gen3 backing plate onto the Gen4 Knuckle. Use the original bolts. Don't bother to buy Stainless bolts as I'm told that is softer steel. If the plate is a tight fit may be worth it to heat up the steel plate with a butane torch first. We just pounded it into place. Torque down all the bolts with Loctite. Next bolt up the spindle with a new retainer nut & the torque wrench set to 200ft/lbs
Take a length of standard 3/8" ID fuel line hose. & cut 2 lengths of 1/2" long.
Fit a 1/2" piece of hose over each 2004 Gen4 ABS
sensor head. Should fit right in. See white fiberglass threads in pic below. This roughly centers the sensor head in the correct location, but still allows for adjustment.
Fit the sensor into it's hole in the mounting plate. Use the Gen4 (shorter) E8 torx bolts with the Fender Washers. Coat the E8 bolt with Loctite. Will be difficult running the bolt in but don't completely tighten yet.
Now the tricky part: I found you Can't just set the gap to 15 thou & torque it down. Upon pressure the bolt causes the washer to rotate & move the sensor body so slightly inward making the final gap too tight. Use your judgment & set the gap slightly larger ?20 thou? then torque it down. Check result. Re-check to make sure. Steel feeler gauge should slide in smooth but not be loose. Make sure to center a tooth next to the ABS
head. Should not need force or you're bending the plastic sensor body. Also make sure when you spin the spindle nothing is hitting. ?1/8 turn? for final torque didn't hurt anything, but remember you are torquing down plastic.
SEE PIC #7 BELOW (feeler guage)
When satisfied Continue re-assembly as described in WIKI (E-brake cables, rotors, pads, calipers, Bleed system, Test drive)
PIC #8 (rotor & caliper bolted on)
PIC #9 (Mag Wheel & Caliper)