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  1. #1
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    Caster Angle Questions and understeer over steer etc.

    So been reading the 4907 Manual again ( I do this regularly to catch what may have been missed) and I caught something. The Caster info shows the front Wheels/Arms and explains the diff between 4,7,10 degree and the effect it has on steering etc.
    I am curious about the rear Caster does it have the same kinda relation to Oversteer and Understeer that the front have?
    I ask as I found my RPM arms apppear to be built with between 7-10 Id guess 8.5 degree Caster while I noticed my rear seems to have 4 degree.
    Should I make the rear match the front( ie Higher caster to increase Oversteer/Reduce Understeer and Lower caster to reduce oversteer/increase understeer??)
    I have major oversteer and do not know exactly why for sure unless it is to be expected.
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  2. #2
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    Do you have the protrac kit or whatever it's called. I just replace all four corners on mine with rpm stock replacements. They are same part numbers front,rear,left,right. I would think the castor angles are built into the bulkheads or hubs.

    Unless you mean camber... then yes, rear camber will affect steering, consider where the weight is transferred when turning, accelerating, or braking.
    Last edited by mnewbolds; 02-16-2013 at 12:23 PM.
    The best thing about Groundhog Day??? Bill Murray.

  3. #3
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    let me re look at info I may be incorrect I get confused on the 2 in real full size vehices too, one I know changes the f-r angle of knuckles adn one changes the contcat area of tire or its in-out angle
    ya its caster on the stock arms ya have shims and Spacers that go in front or back of upper arms on Pivot points or shafts, the front RPM arms have no space to insert anything so they must be pre made with specific caster designed in.
    btw Castor is the oild used as Lube Caster is the angle of the knuckle compared to straight up and down usually top is angled toward rear like this / just not so drastic not trying to be smart just I hate it when I talk about something andam spelling it like something else drives me crazy when I do that and I do that a bit.
    @mnewbolds Good point about weight transfer in turning etc. I bet it effects traction to
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  4. #4
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    My tablet auto corrects sometimes. Sorry for the spelling error.
    The best thing about Groundhog Day??? Bill Murray.

  5. #5
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    oh no prob, I was not complaining more like pointing out to anyone who may be new and could be wondering how Castor Oil and Castor angle be HUH?? no problem trust me I am the typo and mispelling Master I was not being critical at all that be the pot calling the kettle black so to speak or at least thats is a saying I remember anyway.
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  6. #6
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    I appreciate the reply aand info as I had not thought about Camber and weighttransfer etc. as a matter of fact I bet my Camber is all caddy wampus I know it is to be honest.
    T-Maxx 3.3 :)

  7. #7
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    Caster is all about steering; it is the angle of the axle carrier center line/pivot balls in relation to being completely vertical to each other.
    The front bulkheads (mounting tabs where they connect to the chassis) and the front skid plate (the upward bend) has 7 degrees of angle built into them which gives a caster angle of +7 degrees when the a –arm shims are located 1 front and 1 rear. You can change the caster angle by 3 degrees + or – from the +7 degrees by putting both shims on the front or the rear.
    Since the rear wheels do not steer the truck, rear caster would have very little if any effect on the handling.
    Since the rpm arms do not allow for any adjustment of caster, the front caster angle would be +7 degrees, rear would be 0 degrees.
    Here’s a good link that explains Toe, Camber and Caster very well.
    http://www.ozebiz.com.au/racetech/theory/align.html
    No slipper/tall gearing/power = broken parts.

  8. #8
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    Sweeeet @Snook Man is Awesome thanks so much you and Wildman4910 and nitronaught now your S stuff well, I hope I did not leave anyone out if so I will be sure to mention ya soon
    Thanks again Im going to read this very moment
    T-Maxx 3.3 :)

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