adjusting the crossover presure
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Thread: adjusting the crossover presure

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    Default adjusting the crossover presure

    Anyone in Melbourne or around with test bench 3654-T and knowledge how to adjust the crossover pressure on d special steering rack. After installing fully recondition rack its operating hard when turn right and I'm suspecting crossover pressure needs to be adjusted. I don't think any mechanic in Geelong is up to this challenge.

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    skp
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    Roger Parker (Oleopnuematics) in Adelaide has the set-up. Does a good job.

    skp

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    Doubt it is the X-over pressures. Basically the X-over pressure is the 'holding ' pressure against the power piston (static pressure inside the power piston) when the steering is in a steady state position. For post 68 cars that value is in the 975psi range. If not correct (unbalanced) the typical problem is a 'flickering' or back and fort oscillation of the steering wheel in either the straight ahead position and/or at full lock in either direction. If the pressure is set to low it can prevent the rack from getting full system pressure in either direction. If set to high, the steering will feel overly sensitive while driving.

    Sounds like something is preventing pressure from getting to one side of the power piston. Could be a blockage in one of the lines or inside the rotating union. Or one of the Teflon 0-rings inside the RU got compromised when it was rebuilt. However, both of these conditions would or should have been caught when the rack was benched tested after the re-conditioning.

    If you put the front of the car on stands does the steering turn smoothly in each direction or does it feel notchy or binding every 1/2 steering wheel revolution when going to the right? If this is the case then the problem is the alignment of the steering column to the RU - typically the rotational alignment. However it could also be a combination of rotational as well as lateral.

    Steve

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    A flat tire will cause it too.
    Otherwise, set the car on stands.
    Run the steering wheel back and forth as previously mentioned. Most rack problems that appear right after install are alignment issues.
    On LHD cars, the RU and the power piston can be changed in situ if you have some skill and the tools to R&R the pin on the power piston.

    Any chance you can get a seasoned mate over there to assist you? Diagnosing over the internet can cause havoc and I wouldn't want to see a guy racking his brains if he took the wrong advice.
    adjole likes this.

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    Hi Steve. I think it is quite possible I didn't install the rack properly and it needs to linear and angular adjustment for witch I don't have special tool -jig. I'm looking to borrow the tool from someone and I'm planning to make one for me.

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    You can do it with a keen eye. I've put hundreds of these together. Never used a jig. I have one. Never used it.
    The only ones that had trouble were a failed overhaul. For instance, a power piston that wasn't correct.
    The rack and wheel should spin freely without binding when the wheels are hanging in the air.

    Wing off, wheels in the air. The rack should move freely left and right. Get a helper, just to spin the steering wheel while you eyeball the steering shaft at the RU. If you can see the shaft move up and down with 180 degrees rotation, unclamp the rack and rotate it up and down a little to make it true at the joint to the RU.

    And occasionally, the clamp in the bulkhead that supports the steering shaft can be set too tight. That will cause a bind as well. Release that clamp first. If the rack becomes free, you have isolated the problem.

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    I take it back. I used the jig once because he had it and just had to use it. His car had a flat tire. Didn't steer for love nor money.

    Does this car have a flat tire?
    No.
    I get out and look.
    Left front tire had about 10 pounds of air in it.
    Funny stuff.

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    Quote Originally Posted by adjole View Post
    Hi Steve. I think it is quite possible I didn't install the rack properly and it needs to linear and angular adjustment for witch I don't have special tool -jig. I'm looking to borrow the tool from someone and I'm planning to make one for me.
    The lateral measurement is in 814 Vol 1 under steering. Being that yours is most likely a RHD model I am not certain that the same measurement applies - would be best to double check with someone in your area. The tool is only used to set the vertical (or rotational) alignment of the rack to the steering column. Basically you want the respective center lines of the RU and steering column to be in perfect alignment. IOW as you turn the steering there should be no wobble or up/down movement where the splined end of the column is attached to the RU.

    Normally when they are not aligned you will feel a 'notchy feeling' or harding of the steering every 1/2 turn of the wheel. Should happen in either direction, but have run across a couple were it only took place in one direction.

    As we have both mentioned, place the front of the car on stands and turn the steering left and right. If it feels smooth in both directions yet you still feel like you are not getting power when turning right then something else is going on. Do keep in mind that the DS's power steering was never all that 'strong' to start with. So it really does not take a lot of resistance anywhere in the system to make it feel as though there is a lack of power.

    Steve

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    Tyres are fine.

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    mnm
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    Here's a pic of the alignment tool. My brother made one for me based on these measurements. It did the job, but it only works if the collar with the notch in it ?? is removed from the rotating union (on RHD cars).





    Matthew
    Last edited by mnm; 9th October 2014 at 09:27 AM.
    GreenBlood and adjole like this.

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    Checked with Roger Parker and for LHD cars lateral dimensions is the same as for RHD and is 122.5 +-2,5 as in 814 vol 1 .
    My was about 10mm out and that caused steering rack not to operate properly.
    After adjusting this and setting up angle without jig the rack was working perfect.
    Today I checked angular position with jig I borrowed from Rob and it was almost spot on. Thanks again Rob.

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    thanks this is awesome. I'll get one made up this weekend.

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    Quote Originally Posted by adjole View Post
    thanks this is awesome. I'll get one made up this weekend.
    Good to hear it was, basically, a simple fix .

    Steve

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