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post #1 of 11 (permalink) Old 07-15-2015, 09:13 AM Thread Starter
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Variable power steering

I have posted here concerning my recent UCA and tie rod installation. The advice was spot on and valuable, but only made me more certain I have done the job right. My car still drives like I am on ice at speed. After checking and re-checking torque specs and assembly technique and giving everything another check, I have come to the conclusion my power steering no longer becomes heavier as my speed increases. This seems counter intuitive. Shouldn't the power assist fail in the more difficult to steer mode? I admit very little knowledge as to the mechanism of this, but assume that the variable part is a nozzle that decreases the fluid pressure as speed increases. I am going to flush the pump today and put clean Mercon V in it, but I thought I would post to see if anyone had ever encountered a problem like this, and what they did about it. My car is a '98 MarkVIII that is still on air and was aligned the day after I replaced the front end parts.
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post #2 of 11 (permalink) Old 07-15-2015, 09:43 AM
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You might need to replace your rack and pinion bushings. I did some research on these bushings since I recently had my rack and pinion replaced. Some people describe the "drives like I am on ice" just as you and the cause was bad bushings.....this isn't specific to MN12's BTW.
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post #3 of 11 (permalink) Old 07-15-2015, 11:43 AM Thread Starter
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I changed both inner and outer tie rods, and the loose-ness I would usually see as a symptom of worn rack bushings was not there. I am not quick to dismiss any advice, but wouldn't I have other problems than the vagueness and lack of response I am experiencing? Maybe I am just reluctant to go back in there and deal with those "fun" bolts and nuts. When I started this fiasco, I was just trying to eliminate a slight shudder when braking from 50mph or higher. Well, that got cured by the tie rods, but I couldn't leave well enough alone and ordered new UCA's because the boots were all beat up. I guess I didn't take my own advice and tried to fix what wasn't broke.
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post #4 of 11 (permalink) Old 07-15-2015, 12:27 PM
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So you're saying the tie rods fixed a high speed shudder. Did the steering wheel rock back and forth with a slight clicking sound?

I get that on my car on occasion, I thought it was warped rotors.

Back to your issue - I assume you had an alignment at a quality shop?

Al

97 T-Bird LX 4.6 - 80k miles
94 Supra TT Auto - street/strip car
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post #5 of 11 (permalink) Old 07-15-2015, 01:43 PM Thread Starter
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T6Rocket - No click, but the wheel shook back and forth like a warped rotor or wheel. Those were the first things I eliminated as suspects. The outer tie rods cured it, but I changed the inner ones so both would be starting from the same mileage. The car goes down the road absolutely straight, just has no precision to the wheel input anymore. Previously, any movement of the wheel made the car change course. Now, I can move it 2 inches before anything happens, and it feels wonky and loose. Make sense? Like I said, I am going to do two things today - flush the power steering and rotate my tires to the front. Then I am going to look for the plug that gives the power steering variability and disconnect it and see what happens. T6R - that is a quick TBird and a blindingly fast Supra
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post #6 of 11 (permalink) Old 07-15-2015, 10:18 PM
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Olddavidp - One more thing. Be SURE to check the rag joint and the U-joints. If they start to go bad, you'll get that play.

Also, that's a sign the rack is failing if all that is solid.

Have you tried having someone else move the wheel and seeing what does, and does not, move? Before you swap any other parts, I'd do that.

(BTW - The most common failure mode for the EVO is to fail OPEN, which means full assist all the time.)

RwP

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post #7 of 11 (permalink) Old 07-15-2015, 10:32 PM Thread Starter
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Ralph - I would have guessed different - I'm thankful for the tip on EVO failure. Can it be repaired, or is the usual fix another power steering pump? I guess instead of bothering you guys I should invest in a shop manual.
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post #8 of 11 (permalink) Old 07-15-2015, 11:44 PM
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At first I didn't think any new pumps came with the EVO actuator but some of the ones I saw on Rockauto did. Before then the one I bought from Advance did not and it wasn't until after installing the new pump that I realized my problem had been carried over to the new pump thanks to the EVO actuator. Finding an EVO actuator by itself brand new seems impossible so going to the junkyard is almost the only other option. All that work to replace what I thought was a noisy pump when I could have just replaced the EVO actuator which is basically only held in place by an Allen bolt. I myself am still looking for a new actuator.
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post #9 of 11 (permalink) Old 07-16-2015, 10:15 AM Thread Starter
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V8ThunderCat- So, to be specific, your car now has full assist all the time? With the inherent problems that being high boost all the time brings? I am just going out to take it apart now and will look for the actuator. There is a local with a couple of Marks that he is parting out. If I end up going to him would you like me to see about two at the same time? I am sure this will be a go - no go type of repair, yes?
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post #10 of 11 (permalink) Old 07-20-2015, 01:06 AM
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Quote:
Originally Posted by olddavidp View Post
V8ThunderCat- So, to be specific, your car now has full assist all the time? With the inherent problems that being high boost all the time brings? I am just going out to take it apart now and will look for the actuator. There is a local with a couple of Marks that he is parting out. If I end up going to him would you like me to see about two at the same time? I am sure this will be a go - no go type of repair, yes?
I did unplug the actuator which should have made it go into 24/7 full assist mode but for the longest time it seemed to only work when it felt like it. Otherwise I had no power assist and I had to use brute strength to park or take turns. When I had an alignment done a little over a month ago the shop plugged it in thinking it would help but for that day it did not. Then the next day all of a sudden it started behaving like normal but it still moans like a cheap whore all of the time. I wish it was because the high pressure hose fitting was installed too tightly but the moaning started right out of the blue before I ever touched the pump.
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post #11 of 11 (permalink) Old 08-01-2015, 02:23 PM Thread Starter
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My solution has been to flush the fluid out of the pump and lines - which was almost without useful life - and replace with Mercon V and two ounces Lucas PS additive. I also removed the plug for the EVO and cleaned it with tuner cleaner and crimped it so it fit tighter. The pump has been quiet and it seems just slightly better on the road, but it could be the placebo effect - you know, when you work on your car it HAS to drive better -right? When the heat wave breaks, I will loosen everything associated with the UCA's, remove the liner to get to the access hole and tighten everything over again to spec. I am leaning toward rack replacement if improvement isn't coming, but I will replace the strut rod bushings and LCA's before going that direction. My tire guy says I should replace the bags with steel, but I cannot believe this is necessary. I will keep the board posted with my progress because I am sure I won't be the last to need this diagnosis figured out. Again, I thank everyone for any input - it all helps.
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