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Thread: What Angle?

  1. #1
    Registered Member Belair-o's Avatar
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    What Angle?

    Hi,
    I've installed CPP's 500 power steering box on my 57, and think the steering seems restricted - the wheels don't seem to turn out far enough, and the turn radius will be too big. I have read that the turning radius can be tightened by doing some grinding on the pad on the steering arms. I am not sure of the target though; are there production specs for what angle off of straight the tires should turn out?
    Thanks, Doug

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    Registered Member 56Mark's Avatar
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    I don't know the factory spec but after I put CPP drop spindles on I lost a lot of turning radius. I ground the spindles where they hit the stops a little at a time to get all the angle I could without my tires rubbing something. It doesn't take much material removal to make a difference. I am happy now with turning radius and I did not hit the limits of the 500 box.
    56-210, 283, 200-4R, Power steering, Power Brakes

  3. #3
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    There are specs published. The ones I have are in a book called "Chevrolet 55-56 Restoration Guide" which has lots of reprinted specs from GM literature.

    Thing is, are you set up to measure them? Probably not.

    Any time the steering arm is moved inboard, you'll lose steering travel - whether it's from a disc brake caliper bracket for a stock spindle or a dropped spindle that's thicker than the stock spindle. The fix for that is removing material from the stop on the steering arm.

    There are other sources of losing steering travel. A stock steering box has over 100 degrees of travel. A CPP 500 box has about 90 degrees of travel. Thing is you don't get the full 100 degrees with the stock box because the stops on the steering arms limit that to less. In fact to about what the travel of the CPP box is. I had a McGaughy's 605 box that was modified to limit the travel to about 75 degrees - close to matching what you got with their spindles when using stock steering arms with full height stop pads. Totally unnecessary, don't know why they did that.

    So there's multiple reasons for not having full travel, you need to check everything out. It's a shame that suppliers won't tell you this up front. Part of this is that you may have fender rubbing problems with full travel, especially on a lowered car (dropped spindles). They'd rather not have your tires rubbing and have you be ignorant on the steering travel.
    Last edited by Rick_L; 12-18-2017 at 07:25 PM.

  4. #4
    Registered Member chevynut's Avatar
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    Here's the specs: http://chevy.oldcarmanualproject.com...esto/56031.htm

    Toe out on turns (I assume this is at full lock)

    Inside wheel 20 degrees
    Outside wheel 18 degrees 10 minutes
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


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    Registered Member Belair-o's Avatar
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    Hi Guys,
    Thanks for the replies, the information, and the specs. Rick, I agree I can't measure the angle to much precision, but thought close would be good enough. Maybe that is where I am wrong, that the turn radius is very sensitive to small angle differences. Maybe I could just establish a straight line on the floor, turn the wheel all the way one direction, measure that angle off of 'straight', turn the wheel all the way the other direction, measure that angle off of 'straight', sum the angles, and know the full angular travel. That would let me know if my setup was close to spec, or not?
    Thanks, Doug

  6. #6
    Registered Member WagonCrazy's Avatar
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    don't know the factory spec but after I put CPP drop spindles on I lost a lot of turning radius. I ground the spindles where they hit the stops a little at a time to get all the angle I could without my tires rubbing something. It doesn't take much material removal to make a difference.
    I did this same procedure on my 9 passenger wagon after adding CPP's drop spindles (with a manual steering box). It worked...
    1957 Nomad- LS1/T56 on C4 chassis
    1959 Fleetside Apache 1/2 ton, shortbed, big window, 327ci.

  7. #7
    Registered Member Belair-o's Avatar
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    I just did my semi-crude angle measurement. I held a straight edge along the tire near the center of the hubcap. Established a 'center line' by using two combination squares to drop two points down to the floor off of the straightedge. Rotated the wheel all the way one way, dropped two points, fully rotated the other way, dropped two points.

    I measured 19.3, and 18.2 degrees with my Wixey angle finder, for a total travel of 37.5 degrees (I know I don't have tenth of a degree accuracy). Chevynut cited 20 (inside wheel), and 18.2 degrees (outside wheel), for a total travel of 38.2 degrees, so to me, my settings seem pretty good, assuming I can equate my measurements to the inside wheel/outside wheel reference measurements. I don't really understand inside wheel, outside wheel though, compared to what I measured.
    Regards, Doug

  8. #8
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    The "inside wheel/outside wheel" thing is the "Ackerman effect". What it means is that when you turn left, the driver side wheel turns further than the passenger side wheel, opposite for a right turn. This means they don't fight each other, they roll about the same turning radius (for the whole car). The "Ackerman effect" comes from the steering arms being angled inward if the steering linkage is behind the spindles, outward if in front. "100% Ackerman" is when the steering arm tie rod end lies on a line from the lower ball joint to the center of the rear axle. You don't need "100% Ackerman" but you do need a significant amount, and you don't want it backwards, which is what would occur if you swapped the steering arms side for side and mounted a rack or steering linkage in front of the spindles.

    What I would suggest you do is count the number of turns from full left to full right with everything connected up. Then disconnect the steering at the pitman arm and count the number of turns again.

    I don't remember the exact numbers, but a CPP500 box has a little more than 90° travel, and a stock box a little more than 100° of travel. But, and this is a big BUT, the travel with everything connected up with a stock box is far less because of the stops on the steering arms with fully stock steering and brakes. So when you are checking, see if the steering arms hit the stops. (I know I'm repeating myself here.)

    There are other factors here too. Did you change your brakes or spindles along with the steering box? Most if not all stock spindle disc brake conversions, as well as many of the dropped spindles, move the steering arms inboard from stock. This means the steering arms will hit the stops sooner than stock. This can be fixed by grinding material from the stop pad on the steering arm.
    Last edited by Rick_L; 01-07-2018 at 05:25 PM.

  9. #9
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    Hey Rick, Do disk brake kits that move the wheel outboard a bit effect steering radius, and which way? I haven't measured my lock to lock angles but I sure do have a nice small turning radius. I have a factory box/factory P/S.
    Last edited by 55 Tony; 01-07-2018 at 07:47 PM.
    Tony

    1955 Bel Air Sport Coupe

  10. #10
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    Widening the track width would not affect it much, it's how much the steering arms are moved and whether that is corrected by grinding the stops.

    Of course if this means you have tire rub (and that often happens) that's another problem that has its own solutions (or maybe no or limited solutions).

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