Rose jointed LCA

totta crolla
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Rose jointed LCA

Postby totta crolla » Mon Dec 19, 2016 11:53 am

Image

Installed a pair, adjusted to standard length.
Increased bump steer.
Any ideas anyone ?

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jondee86
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Re: Rose jointed LCA

Postby jondee86 » Mon Dec 19, 2016 2:56 pm

Interesting question :) As I understand it, bump steer is a product of the disparity
between steering arm and suspension arm geometry. Therefore, the only way that
the arm itself could affect bump steer would be if the relative positions of the centre
of the inner fixing bolt and the ball joint pivot centre were changed. If the arms have
the same centre distance as a stock AE86 LCA, this is not the issue.

Looking at your pic I would not be certain that those arms are made from OEM AE86
arms. So the attachment point for the tension rods could be different, and this might
have changed your caster angle ? I don't know if caster affects bump steer, so maybe
not an issue either.

Cheers... jondee86
Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.

totta crolla
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Re: Rose jointed LCA

Postby totta crolla » Tue Dec 20, 2016 12:51 am

After some investigation it appears that the caster arm now has full control over the LCA. i.e when the caster arm goes through its arc the LCA does nothing to resist being pushed backwards (and forwards) towards the track rod end and I think that this maybe what I'm feeling through the steering wheel.
Just to clarify, the picture was a generic one I found online but I will look closely at my LCA's anyway. Thanks for that idea Jondee.

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Jeonsah
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Re: Rose jointed LCA

Postby Jeonsah » Wed Dec 21, 2016 12:57 pm

Could you explain what you are feeling through the steering wheel?

Thanks
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davew7
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Re: Rose jointed LCA

Postby davew7 » Thu Dec 22, 2016 5:23 am

Chances are that you can not feel it in the steering wheel, but in the vehicle as it travels down the road. It will be most noticealbe when the car runs over an undulation on one side, the car will want to wander to the left or right. The higher the speed the more the wandering effect will be noticeable. DaveW

totta crolla
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Re: Rose jointed LCA

Postby totta crolla » Sat Dec 24, 2016 12:33 pm

Some further investigation shows that my LCA's are not standard length after all, they are adjusted 12mm longer.
I have been using caster arms that have been adjusted to 5mm shorter than standard length. What actually needs to happen is the caster arm should be made longer by the same amount as the LCA, this brings the triangulation points closer to where they should be. My steering is much better after doing so.

totta crolla
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Re: Rose jointed LCA

Postby totta crolla » Sat Dec 24, 2016 12:34 pm

Jeonsah wrote:Could you explain what you are feeling through the steering wheel?

Thanks


A kind of pulling sensation through the steering wheel.

assassin10000
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Re: Rose jointed LCA

Postby assassin10000 » Wed Feb 15, 2017 8:41 pm

Yeah, just too much caster. Not a bump steer issue.

Andrew

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Re: Rose jointed LCA

Postby 4agshoob » Sun Mar 12, 2017 10:02 pm

I can attest to this:

If you are using the t3 style caster rods, youve now moved theyre "pivot point" towards the wheel about 2". This allows greater arc deflection through the suspension stroke.

Sounds crazy.

Bolt on your oem caster rods with urethane bushings, and i bet it goes away. If so, then look towards cusco's style caster arm brackets, and arms.

I love t3's products and currently use them, but i did stray away from their and megans castor rods, because of this very issue. The pivot is moved closer to the control arm, meaning an even more aggressive arc through the suspensions travel. This is why i went cusco.

Also, are you running rca, or nrca?
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