I have added an electric clutch to the hydraulic power steering and now can switch it on and off with the push of a button! My truck is a '97 Ford Ranger extended cab, 4x4 with the 4.0 OHV engine and manual 5 speed transmission.
First the back story: So the mod came about as my wife was overseas with her job for six months, and like all good modifications, I was drinking lots of beer. It occurred to me that my old AC unit hadn't worked in years, and as I needed a new serpentine belt, why not get the non-AC belt? With the belt off, I noticed that the electric clutch on the AC unit allowed the pulley to spin with freely, so I really wasn't improving mpg's by not having the belt on the old AC. On the other hand, the power steering pump took a good bit of effort to turn. So as an experiment, I swapped my new belt on to the AC and left it off the power steering. I instantly felt the power difference. Ofcourse, as many have noticed, it is nearly impossible to drive without power steering (try it on a 4.0 v6 4x4 with an old Ford Twin Traction Beam~ the axle alone weighs over 200 lbs)
I did some research and found a few DIY's electric conversions, but they seemed expensive, complicated, and prone to electric gremlins. But I came across a few threads mentioning the electric clutch, but no DIY’s. That's when the beer kicked in and I thought, "hey, I've got one of those clutch things on my broken AC unit... why not put it on my power steering?" Stupid question. Thankfully to my fellow ecomodders, I was drunk and my wife was gone for half a year. So here's the DIY.
1. Take off the old AC pump. You need to have it professionally emptied or you will burn a whole in the atmosphere (plus it's illegal). I know, cause although mine hadn't worked for years, a few twists of the wrench and the high pressure blast blew the wrench out of my hand. At least the sun came out and it got nice and warm.
2. There is no way to attach the electric clutch to the power steering; it is designed to fit on the AC and that's it. So obviously, the second step is to make an electric clutch bracket by sawing the front of the AC off. (should have seen the sparks!
) In order to maintain proper belt alignment, cut it all the way to the inner piping at the front of the pump; its about 1/3 an inch thick when done. Notice the old screw holes that held the pump together. You will use these to attach your fabricated electric clutch bracket to the power steering mounting bracket.
3. Remove the power steering pump and aluminum mounting bracket. Take the pulley off the power steering pump. Ford has a special designed pully puller. I rented mine to save a few bucks.
4. Now that the pulley is off the power steering unit, you'll notice the shaft on the pump fits perfectly in the whole of your fabricated electric clutch braket. This is critically useful for drilling holes in the right location. One hole on the mounting arm can be reused: The hole on the top left lines up with the original power steering mounting hole, I just needed to ream out the Electric Clutch bracket hole a bit for the bolt to slide through. Two new holes in the mounting arm need to be drilled: Reattach the power steering pump to the mounting bracket. Now slide the fabricated electric clutch bracket right over the power steering shaft. Line up the drill bit through the old AC unit bolt holes and drill some new bolt holes in the power steering mounting bracket. This is the top right and bottom left holes with the bolts in on the picture below. Now the Electric Clutch bracket can be secured to the mounting arm. However, the bracket partially blocks the mounting arm's lower left and right holes needed to attach the pump. So the last step is to carve out a grove in the Electric Clutch bracket for the power steering bolts. Hard to visualize, but you can see from the pictures.
5.a. The worst part of the job. The old power steering pulley was a press fit, while the electric clutch was designed to go on a grooved shaft. I'll spare the details, but I am on my third attempt and hope this doesn't break: I bought a 1/2 inch thread tapper drilled out then tapped 1 inch into the power steering shaft.
5.b. Then I used a half inch, 3-inch long grade 8 steel bolt and used a thread cutter to thread it to the bottom. Thread a nut on it when you are done.
6. Take the electric clutch plate and put your 3 inch bolt through it (you'll need to drill out the clutch plate a bit) and add spacers. These spacers will hold the electric clutch plate off of the electric clutch pulley, thus allowing the contraption to be disengaged. I used 4 washers and one locking washer.
7. Now it is ready to be assembled. First, attach the electric clutch bracket to the power steering mounting bracket.
8. Next attach the power steering pump. You can see I clamped the whole unit down to my work bench. As you slowly threaded the the power steering pump into place, you need to stop when as the pump shaft just starts to go through the electric clutch bracket. Now secure a good channel lock pliers to the pump shaft to hold it steady and wrench your clutch plate into the power steering shaft. Use some thread locker for good measure. This is very tricky. If the three power steering bolts are not threaded the same amount, the pump will be slightly cantilevered now allowing it to spin freely. However, with the clutch place on, you cannot see if it is centered. Just takes trial and error. As you tighten everything down, frequently turn the grade 8 bolt to make sure the pump spins freely. A few extra pictures for this step:
9. Remember you threaded a nut on the grade 8 bolt after you finished thread cutting (step 5b.)? Now turn that bolt on to push the clutch plate down till the locking washers are tight. If you've used the right amount of washers, you'll have a slight space between the electric pulley and the clutch plate allowing the pulley to turn freely until you flip the switch. If you used too many washers, the electromagnet won't be strong enough to engage the plate; too few and the plate will already be tight against the pully (permanently engaged). As with everything in the job, it took a few attempts for me to get it right.
10. Reinstall the assembly on the engine and attach the belt.
11. Now when you are casually driving around a corner and turn your HVAC control's you're steering will suddenly shut off and you'll go flying off the road. So, naturally, the last phase of the project is to wire a new relay. There are plenty of good DIY's on relay's, so I'll skip that one here. I set mine up with a nice push-button switch.
Electric Clutch Power Steering
(10-23-2010), 
(10-23-2010)
