Caprice or Roadmaster Power steering?

I'm doing a bunch of work to my RMW this weekend and I'm looking for a few opinions. I'm removing the front accessory drive and was wondering if I should put the RMW power steering pump back in or put in a Caprice wagon power steering pump in. I already have the Caprice pump out of my winter car so it won't cost any extra money.... I don't think. The variable effort steering on the Roady is starting to get temperamental (goes to full assist on the thruway - LANE CHANGE!) I'd like a little less boost too so I was thinking of going to the Caprice pump, disconnecting the variable rate stuff, and getting one of those pressure reducer kits at Summit.

So does all this make sense, or am I talking out my backside?

Mike

200OZ wrote:

getting one of those pressure reducer kits at Summit.
So does all this make sense, or am I talking out my backside?
Mike

Ha ha,. lordy thats begging for a smart ass reply,. (get it?? smart ass??)

anyway i stoll this gem off the buick forums,.might be the easiset for you,.

Quote :

So after driving the Road Master for about 1000 miles, I found the variable power steering suddenly going to full assist in the middle of a corner (there are many curvey roads here in Western North Carolina) to be very irritating. After reading through a bunch of posts, I'm sure the steering position sensor is giving an intermittent false signal. Not wanting to replace it, I unhooked the connector as some have done to make the system go into full assist default mode. However, I found that during intestate travel the steering is to sensitive for my tastes.

I took out the old multimeter and did some checking. From the red wire to the black wire on the sensor it reads about 10K ohms all of the time. From the red wire to the green wire the resistance varies from 10K to 5K to 10K. On the other side of the connector the red wire is 5 volts to ground. The green and black are 0.7 volts to ground.

I went to the internet and although I could not find anything that exactly tells me, I believe this is an optical sensor that sends out pulses. A number of quick pulses tells the system the steering wheel is being turned quickly and the power steering assist is increased. So I cut off the connector from the sensor and soldered in a 10K ohm resistor from the red wire to the green wire (sensor output) and a 10K ohm resistor from the red wire to the black wire (what tells the system the sensor is attached?). This in effect pulls up the two inputs to 5 volts.

Now I have the reduced power assist all of the time! It gives much better feel on the interstate and is really not that bad in the parking lot (more what I am used to anyway with other cars). More importantly no more sudden change of steering feel in the corners!

Nick

Thanks Nick, that might be the way I go.

Mike, I have the exact same problem (variable-rate steering occcasionally goes to full assist or "LANE CHANGE" mode on the thruway.

I was under the impression that the pumps are identical because the pressure regulator valve is removable and screws into the back of the pump.

I would leave the pump in place and try to clean/fix your steering shaft sensor. I have a spare sensor I picked up in the junkyard from a lower-mileage car I want to try. Once I get that one in, I may disassemble my existing one and see if it's fixable inside. EDIT - JaySS posted that you should be able disassemble and fix the sensor. I have yet to try it.

I unplugged mine at the rear of the pump and the column.......

BigBlackBeaSSt wrote:

I unplugged mine at the rear of the pump and the column.......

why both ends??

nick

A quick update for anyone who is dealing with this same problem.

I don't have pictures ready yet but will post them at some point, so bear with my 1000 words.

I disassembled my sensor. WARNING - it is very delicate - use a pocket knife around the edge to gently pry it open; do NOT stick the knife blade or a screwdriver blade deep inside and pry or you will break stuff. Also, if you open it, be aware that there are two small o-rings, two teflon washers, and one big o-ring inside in addition to the two ends and center disc.

It is essentially a rotary potentiometer. Inside, there are two traces that run 360 degrees in concentric circles. A disc with a pair of wipers connected together (one on each trace) connects the two. Each of the outer wires are connected to traces that alternately feed the outer circle every 90 degrees. The center wire attaches to the inner trace. The unit appears to have built-in resistors that have unique values for each of the outer traces before they even touch the circles.

So.. as you turn the disc (which grabs the steering shaft), the resistance between the center wire and each of the outer wires varies. The faster you turn it, the more it varies. I suspect what happens is that a computer monitors the rate of change and increases steering boost proportional to the rate of change. If you have dirty or lousy connections inside the unit, then the rate of change will be very spikey at times and cause erratic boost levels.

What I did notice was that mine had a lot of dirt/dust and some other sort of random globs of goo in it. I gently cleaned it out with Q-tips and isopropyl alcohol, then carefully wiped it all down with a cotton towel soaked with isopropyl alcohol. Then I put the whole assembly back together and reinstalled it. I have not road-tested it as the car is disassembled for a large number of maintenance items.

Another alternative is to bypass the whole thing entirely and connect a 5-10K resistor between the center pin and each outer pin. This will give a constant output and leave you a minimum assist state.

I finally got around to getting this taking care of. I cleaned the steering wheel speed sensor last summer and it worked just about to the end of summer until the "twitches" started again.
As Sherlock said, It's delicate, I cracked the housing taking it apart, and there was quite a bit of corrosion in there.

Anyway, I decided to by pass it and put the resistors in the circuit instead of the speed sensor. I picked up some 10K and 5K resistors at Radio Shack, and soldered one end of a 10K resistor to the black wire, one end of a 10K resistor to the red wire, then soldered the two bare ends together to the green wire. It works, no more twitches, sweet. I was hoping for a little more steering wheel effort, but it's a little heavier than stock. Here's some pics to give you a better idea of what I did.

FYI: The first post says to use the resistor to connect the black wire, to the red, and then the green to the red.... Using the red as the common connection. After looking at the FSM, it looks like Sherlock's way is the right way.

Thanks for the help Nick, and Joel.