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Thread: oversteer problems high speeds

  1. #1
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    Default oversteer problems high speeds

    Not a real "off roading" question, but on the Defender 90, at street PSI (call it about 35 right now), I get wicked oversteer, floaty feeling when letting off the gas on the higway at about 55/60 mph.

    Nothing bad has happened, but I'd like to know if there's anything I can do PSI wise or other to get a more solid steering feeling on the higway. Bar that, an explanation to why the feeling is there.

    I've had a new swivels (all parts and pieces), steering box worked over, new front diff, and new tires on it at this point. I think it's just a matter of having a small lift kit and having a short wheel base. Would dropping it a few inches lose that feeling a little?

    Thanks

  2. #2
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    Lightbulb

    Probably alignment, caster specifically ;)
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  3. #3
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    Quote Originally Posted by nobletrout View Post
    Not a real "off roading" question, but on the Defender 90, at street PSI (call it about 35 right now), I get wicked oversteer, floaty feeling when letting off the gas on the higway at about 55/60 mph.

    Nothing bad has happened, but I'd like to know if there's anything I can do PSI wise or other to get a more solid steering feeling on the higway. Bar that, an explanation to why the feeling is there.

    I've had a new swivels (all parts and pieces), steering box worked over, new front diff, and new tires on it at this point. I think it's just a matter of having a small lift kit and having a short wheel base. Would dropping it a few inches lose that feeling a little?

    Thanks
    You could try higher tire pressure, but Id be looking for something to be out of whack. Alignment is always a good place to start as a good shop will check everything before doing anything.
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    Default

    Quote Originally Posted by Rubicon View Post
    Probably alignment, caster specifically ;)
    ^This. Also check tie rod ends and steering linkage.

    Highest probability item will be caster though. Options to correct caster on a radius arm suspension are caster bushings, caster plates, cut and turn, or replacement radius arms that have correction in them. Cheapest options from that list are bushings or plates. For wheeling, bushings don't tend to flex well because they are typically made of poly instead of rubber. Plates typically require some cutting and welding. I went with plates on my Land Cruiser and am happy with the results.
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  5. #5
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    Quote Originally Posted by nobletrout View Post
    <snip>I think it's just a matter of having a small lift kit </snip>
    Quote Originally Posted by Rubicon View Post
    Probably alignment, caster specifically ;)
    I'd bet dollars to donuts that it's caster related
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  6. #6
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    Default Flaoting down the road

    First, make sure all your bushings are good and the nuts torqued tight. Look for any light powdered rust coming out of any bushing. That means it's bad. Track bar (2) Radius arms (4 each) 4 tie rod ends, anti-sway bar (2 links, 6 bushings), and that's the front. The rear has 2 trailing arms (3 each), upper control arm (2 bushings and 1 ball joint). You and I have the same suspension, and i just went through my front susp, and am starting on the rear. If you like, drive over and we can slide under and take a look and discuss what we see.
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    Default

    Nice, a fellow solihull suffer in amherst.

    PM me and maybe we can find a time to meet up?

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    Think I got this figured out. Looka like the caster isn't adjusted correctly. Many thanks to ratchets for giving it a look today.

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    Quote Originally Posted by Rubicon View Post
    Probably alignment, caster specifically ;)
    Quote Originally Posted by nobletrout View Post
    Think I got this figured out. Looka like the caster isn't adjusted correctly. Many thanks to ratchets for giving it a look today.
    You got it figured out? I think we told you and someone else fixed it :p Haha!
    Traction, articulation, and gearing make a good off-road rig. Just a big lift, wide mud tires, and a winch simply do not.
    ~Shawn(the correct spelling ;)

  10. #10
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    Not sure yet, looks like the solution is going to be more complicated than the diagnoses.

    Since I bought the car with a lift kit, is there a way to eyeball measure what the lift kit is currently doing?

    Looks like I'll need a terra firma set of castor correcting forks. Or maybe I'm wrong?

    https://www.roverparts.com/Parts/TF529

    something like this. maybe it's too much?

  11. #11
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    Quote Originally Posted by nobletrout View Post
    Not sure yet, looks like the solution is going to be more complicated than the diagnoses.

    Since I bought the car with a lift kit, is there a way to eyeball measure what the lift kit is currently doing?

    Looks like I'll need a terra firma set of castor correcting forks. Or maybe I'm wrong?

    https://www.roverparts.com/Parts/TF529

    something like this. maybe it's too much?
    Did Ratchets give you the current castor number? Be curious to see what that compares to the expected stock value. It should be a positive number and the same for both sides. Usually castor issues also introduce a vague or non-existent "return to center" condition coming out of corners. Did Ratchets have any specific suggestions?
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  12. #12
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    It was a quick visual inspection, I wasn't there for inspecting the caster specifically. That said, I think I was told that it was "not enough for the lift" about 2 or 3 degrees for now and should be more than that.

    I hope that helps. I think the previous owner lifted it, but didn't change the OEM caster. The only adjustment available was with a washer. I think that's why the forks from terra firma are also available.

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