Nick,
Correct me if I am wrong, but wouldn't the lower control arm ball joint be
describing a different length arc to the tie rod when the arm is above the
horizontal position?
Cheers
Feral Errol
----------
From: abrahamk <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
Subject: Re: Strut spacers
Date: Thursday, September 28, 2000 11:49
Errol,
I don't think that the toe control rods/castor control affect the steering
characteristics of the car at all (or not much).
If Datsun got their suspension design right (they certainly kept it for
long
enough!) then the centre of the toe control rod bush and the centre of the
transverse arm bush should describe a line that is parallel to the
centre-line of the car and horizontal, and that also intersects the
steering
arm joint, i.e a virtual A-arm with no inherent bumpsteer.
If this line is not parallel with the centre line of the car, for anti-dive
etc.. this would certainly cause bumpsteer.
But I bet you've seen Ford Escorts and other 'gun' cars that have woeful
suspension geometry, i.e sway-bar acts as toe control rod etc.. They don't
seem to spear off the road and wrap themselves around trees and power
poles - much.
Therefore the speed limit should not apply for any modified Datsun - since
the handling and braking must be so good by comparison ;).
I have had a quick look/measure under my car with a bit of string and a
steel ruler (not very accurate +/- 5mm say), but the geometrical design
seems pretty good - at stock ride heights :).
Regards,
Nick.
----- Original Message -----
From: Errol Smith <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, September 28, 2000 8:26 PM
Subject: Re: Strut spacers
> Nick,
> I call them strut spacers!
> Your post is correct. Normally the arms are angled below horizontal so
that
> on bump the control arm length increases relative to the pivot horizontal
> plane and then starts to shorten relative to the pivot when over
> horizontal.
>
> The fact that the arms normally pass over the centre point of the plane
> means that they experience minimal length change (relative to th4
> horizontal plane) during bump. This means they maintain their lengths
> relative to the tie rods.
>
> If the control arm angles are horizontal or above then the relative
length
> to the tie rod will decrease during bump. This causes the wheel to turn
in
> towards the centre of the vehicle. This is bump steer!
> Cheers
> Feral Errol
>
>
> ----------
> From: abrahamk <[EMAIL PROTECTED]>
> To: [EMAIL PROTECTED]
> Subject: Bump Steer Spacers
> Date: Thursday, September 28, 2000 6:58
>
> Errol et. al.
> I have alluded to this in previous posts but I haven't been put straight
> (Yet!);
> Why are those spacers called 'bump-steer' spacers.
> By my reckoning they should be called 'scrub' spacers.
> A lot of people have talked about the front transverse arms being angled
> down-to-the-outside, in reality however, what is important is the
> hypothetical plane between the centre of the outside ball-joint and the
> transverse arm mounting bush. This should be horizontal, i.e parallel to
> the ground, presumably this is what the spacers achieve on a car that has
> been lowered.
> As you all know, scrub is the change in track, i.e the distance between
the
> front (or rear) wheels' contact patch.
> And the transverse arms move in arcs, obviously, so therefore the track
> will vary in pitch and roll - and it will vary least when the 'plane' is
> horizontal.
>
> Wadderurekon?
> Nick
>
>
>
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