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4ringcircus 10-23-2010 10:25 AM

Electric Clutch Power Steering
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: 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 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. Of course, 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. Then 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 had plenty of beer so here's the DIY.

1. Removed the old AC pump. I believe there is a law requiring old AC systems to be professionally emptied. I figured mine was already empty as my AC hadn't worked for years, and I decided to just take the pump off. A few twists of the wrench and the high pressure blast blew the wrench out of my hand.

2. Cut the electric clutch off of the AC pump: Yes, it can be removed without destroying the pump, but 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. The easiest solution I could come up with was to use the AC itself as a bracket for the electric clutch.... which meant sawing the front of the AC off. (should have seen the sparks!:eek:). I needed to keep about 1/3 inch worth of the AC at most, otherwise the clutch would stick out too far to align with the serpentine belt. Notice the old screw holes that held the pump together. I used these to attach the remains of the AC unit to the power steering mounting arm.

3. My next step was to remove the power steering pump and mounting arm, then remove the pulley from the power steering pump. Ford has a special designed pulley puller. I rented mine to save a few bucks. With the electric clutch, power steering, and mounting arm removed, I went over to the work bench for the rest of the build.

4. Once at the work bench, I made two fortunate discoveries. First, the shaft on the pump was basically the same size as the shaft hole of the clutch, allowing me to slide the two together. Second, the bolts holes on the pump and clutch were almost the same radius from their respective centers! Although the bolt patters were different, this meant that I could align the two pieces on the mounting arm by reusing the most conveniently positioned hole, and simply drill holes in the mounting arm for the other clutch bolts.

Hole "A" in the photo below was the best option for reusing. I started by reattaching the power steering pump to the mounting arm using holes "D" and "E".

I then slid the electric clutch over the power steering shaft and lined up hole "A". This aligned the three parts. You can see where I reamed out hole "A" in the clutch to get the bolt through. With everything aligned, I placed a drill bit in holes "B" and "C", and drilled through the mounting arm allowing me to secure the clutch with holes A, B, and C, while mounting the pump with holes A, D, and E.

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 (UPDATE~ it is now 2013 and this third attempt has help up for the past two years): 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. I needed to thread it to the bottom in order to put a nut on it... important for use in step 8.

6. I took the magnetic plate of the clutch, slid the 3 inch bolt through it, and added spacers. These spacers hold the magnetic plate off of the clutch pulley, thus allowing the contraption to be disengaged. I used 4 washers and one locking washer.... Also important for step 8.

7a. The final assembly: First, I attached the clutch to the mounting arm.

7b. With the whole unit secured down to my work bench, I carefully threaded the the power steering pump into place. This was very tricky. If the three power steering bolts (A, D, & E) are not threaded the same amount, the pump will be slightly cantilevered causing in the grade 8 bolt to hit the inside of the clutch rather than spin freely. It just took trial and error, but as I tightened everything down, I frequently rotated the grade 8 bolt a full 360 degrees to check for clearance.
A few extra pictures for this step:

8. Now for the nut on the grade 8 bolt from step 5b and the washers from step 6. I simply tightened the bolt down till the clutch plate pressed locking washer tight. As with everything in the job, it took a few attempts for me to get it right, but this is how I figured out how many washers to use: With the right amount of washers, I had a slight space between the pulley and the electromagnet, allowing the pulley to turn freely until the electricity was turned on. With too many washers, the gap was too large for the electromagnet to work; too few and the electromagnet would already be tight against the pulley (permanently engaged).

9. With everything put together, I reattached the mounting arm to the engine and the belt. 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.

dcb 10-23-2010 10:37 AM

Now THATS what I'm talking about :)

FYI, if you right click on dem images you can "copy image location" to the clipboard and paste them into img tags:


dcb 10-23-2010 10:48 AM

Also a controller to turn the pump on at say, below 5mph, would be fairly simple.

tjts1 10-23-2010 11:29 AM

Great idea. I hope you get the pics fixed.

4ringcircus 10-23-2010 01:40 PM

A controller sounds nice, but might be dangerous. You really have to drive this to understand how instantaneous the 'on-off' is. When I finished, I let buddy drive it around the block. When he came back and pulled up, he was laughing so hard he nearly fell out of the drivers seat! I think his exact words were "It goes from completely un-drivable to bones stock-you'd never know anything was different". I think the manual control is important cause you got to be ready for it!:p

dcb 10-23-2010 01:49 PM

Yah, I know what you mean. When I bump start my little saturn in a corner (frequently), it is very easy to oversteer as the pump kicks in immediately. It is made more manageable by the fact that I'm in control of the timing of the bump start.

NiHaoMike 10-23-2010 06:03 PM

For all that work, couldn't you just get a 14.4v cordless drill motor (easy to find one for free when the battery goes out) and attach it to the pump? You can even reuse the PWM circuit.

TomO 10-23-2010 06:31 PM

Nice DIY! Beer does solve some things!

RobertSmalls 10-23-2010 06:57 PM

How about a controller to automatically turn it on whenever you're in 5th gear?

Have you taken the truck on the highway yet? I bet it feels more stable and easier to drive.

Weather Spotter 10-23-2010 07:12 PM


Originally Posted by NiHaoMike (Post 200485)
For all that work, couldn't you just get a 14.4v cordless drill motor (easy to find one for free when the battery goes out) and attach it to the pump? You can even reuse the PWM circuit.

would one of these have the power to run the pump at the speed needed? My junk drill is good for 1400 rpm max. Would there be enough torque?

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