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Just completed steering box upgrade, now I'm baffled

Discussion in 'Chassis / Drivetrain / Suspension / Wheels' started by 454GrandPrix, Oct 16, 2017.

  1. 454GrandPrix

    454GrandPrix Master Mechanic

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    Over the last few days, I removed my leaking 605 power steering gearbox and replaced it with an 800 gearbox (spec'd for an '87 Monte Carlo SS). My pitman arm didn't swap over, of course, so I installed one from Allstar Performance at the same time. For now, I'm still using my stock steering shaft. All other steering components were retained in this operation; I literally removed the one steering gearbox (with attached pitman arm) and installed the new box (with attached pitman arm) in its place.

    Here's where it gets strange: now my steering wheel is off by about 60 degrees. It had been perfectly straight--in fact, I just had the car aligned one week before doing this gearbox swap. I went for a short, slow drive around my neighborhood and there doesn't seem to be any outrageous tire scrubbing; the tires look nice and parallel, and the car seems to drive straight so long as I leave the wheel cocked as described.

    Yesterday I explained this to a friend who has years of experience as an alignment/suspension tech. He gave me an assignment: when I'm going dead straight, see how far the steering wheel turns in each direction. Does it turn the same amount in both directions? I told him I'd try it and report back.

    This afternoon I performed my test in a nearby parking lot. When I turned left, the steering wheel rotated a full turn and a half (1.5 turns). When I straightened out and tried turning right, the wheel did not quite turn one and a quarter rotations (say about 1.20 turns). I've heard this gearbox is supposed to turn 2.7 turns lock to lock, so this math made sense to me just from a numbers perspective.

    From behind the wheel, I felt like the car was actually turning tighter left than right... so, in a flash of wisdom, I decided to stop and get out at each steering extreme just to take a look at what was happening. Sure enough, the tires would turn more sharply to the left than to the right. Alarmingly, while cranked to the left I noticed the right wheel's rubber brake line was drawn tight enough to pluck it like a guitar string. When cranked to the right, there was still significant slack in the left wheel's brake line. Hmm.

    And thus the $64,000 question: why does the new gearbox steer more to the left than the right? And what can/should I do to correct the situation? The pitman arm is keyed to the gearbox in such a way that I might be able to rotate it 90 degrees, but that would be way too much of an adjustment. (I did verify that when the car is pointed straight, the new pitman arm is parallel to the 'slave' arm on the other end of the drag link.) Could there be an issue with how the steering shaft went on to the gearbox? I swear it was keyed; I thought it could only go on in one way, but am I wrong? Do I need to make a monster adjustment to my tie rod ends to correct for this?

    Anybody have any ideas?
     
  2. TURNA

    TURNA Comic Book Super Hero

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    Went through this problem with 3 boxes before I got one that worked right.
     
  3. Wageslave

    Wageslave Master Mechanic

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    You could just realign the front end again. 60 degrees on the steering wheel shouldn't be beyond reason to adjust at the tie rods.
     
  4. fleming442

    fleming442 G-Body Guru

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    Pretty sure the column side isn't keyed. That seems very strange because the pitman arm is keyed, correct?
    Now you got me worried. I was going to get a GC box this afternoon.
    What application did you get? I don't want to be messing around in the you-pull-it popping a bunch of steering boxes..
     
  5. pontiacgp

    pontiacgp Canadian Prime Minister

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    was the input shaft was on the center and the wheels straight it would have been noticeable if the spline did not line up for the pitman arm. Are you sure you have the pitman arm indexed properly?. I think your steering is off by 45° and not 60°

    if you watch this video you'll see when the box is put together you can't change the indexing of the pitman arm shaft

     
    #5 pontiacgp, Oct 16, 2017
    Last edited: Oct 16, 2017
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  6. 454GrandPrix

    454GrandPrix Master Mechanic

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    Correct. The pitman arm has a key notch every 90^. By definition, this means you could install it 90^ off... but there is no way it would go together. That would be grossly out of position.

    It's a (reman) unit for an '87 Monte Carlo SS.

    I made sure the tires and the steering wheel were all straight when I removed the old box. Getting the shaft onto the new box input was pretty easy--I barely had to fiddle with it for it to engage properly. At that point, I thought everything was going perfectly.
     
  7. pontiacgp

    pontiacgp Canadian Prime Minister

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    you're right, I said 45° by mistake......

    you can make the ° buy holding down alt and keying 0176
     
  8. Z48LT1

    Z48LT1 Apprentice

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    I think this must be the answer, but it should be easy to check. Everybody look at the pile of steering boxes in their discard box and see if any of them have keyed input shafts. Looking at the pix on RockAuto shows torque paint, presumably at the 0° mark, but if there's any index spline, it doesn't show up.

    I'm pretty sure the asymmetric turn limits in the two directions means the remanufacturer assembled the box incorrectly. Obviously not a user adjustable item, although if someone has a trash 800 box he doesn't mind operating on, he might take it apart to investigate what it would take to reclock the input vs the output shaft and report to the OP whether this would be an alternative he'd want to consider. Otherwise, taking it back for an exchange or refund would seem to be indicated.

    The possibility I'm completely wrong shouldn't be ignored, just trying to apply any remaining mechanical engineering brain cells.

    Cheers - Gary
     
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  9. Z48LT1

    Z48LT1 Apprentice

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    Replying to myself. After watching the video pontiacgp posted, and following the trail to the third of that series, I've changed my mind about indexing of the input shaft, at least for some applications. But also in the third episode of the rebuild series it appears an inattentive rebuilder may have clocked the input shaft 180 degrees out of alignment, which might be enough to change the amount (and direction) of the OP's problem into a realm where tie rod adjustments could resolve the rest of problem. Still, a problem. At least, that's what I'm gonna stick with for now.

    Her's the video of which I speak:



    Cheers - Gary
     
  10. 454GrandPrix

    454GrandPrix Master Mechanic

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    When attaching the steering column to the input, I may have inadvertently rotated the steering wheel a bit. Either way, it doesn't matter. My alignment guy and I followed through with our original plan: we put the car on the rack and steered it until the gearbox was in the center of its range. We then adjusted the tie rod ends to make the wheels point straight at that position. At that point, the steering wheel was still a bit off center... so we removed & reinstalled it to make it point straight.

    Now the car tracks straight when the steering wheel is pointed straight, and it turns about equally in either direction. Good enough for me.
     
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