"Bump Steer" is just that. If your front suspension geometry is not
properly set up and your front wheel moves up after hitting a bump, the
front wheel changes its direction left or right, steering the car away from
the desired direction. It is caused by the steering arms not being
geometrically in alignment with the suspension arms as the wheel moves up
and down after hitting a bump.
This often happens when cars are lowered excessively and the suspension and
steering arms are operating at angles outside their designers intended
travel positions.
On a 1600 you have to compensate for the lowered ride hight either by
lowering the outer end of the radius arm by bolting an appropriately thick
block between the steering arm and the base of the strut, or raising the
inner pivot point of the radius arm by using an early model cross member or
repositioning the inner pivot bolt higher in the crossmember. This
repositions the radius arm so it then operates over its "longest" arc, from
just below horizontal too just above it on full compression. Under this
condition the relative change in distance from the steered wheel to the
inner pivot point of the radius arm remains relatively unchanged, minimising
bump steer.
If you dont do this mod on a lowered Datto, the radius arm may start above
horizontal, and continue up under bump. This will effectively shorten the
distance from the steered wheel to the inner pivot point of the radius arm.
However, the steering rod which is also connected to the same wheel does not
shorten as much, so it moves the steered wheel out, causing the wheel to
"steer" as it moves up from the bump.
Sorry this is a long winded explanation.
----- Original Message -----
From: "David Andrews" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, 20 June 2000 13:05 PM
Subject: handling question
> g'day all,
>
> been reading this mailing list for a few months but this is my first post:
>
> with regards to the handling problems topic i was wondering if anyone
> could be bothered enlightening a total amateur as to what bump steer is?
> btw.. planning to (eventually! when i know just a lot more) to do a s15
> sr20det
> conversion.. or probably a s16 by then!.. and one of the blokes from sss
told
> me that the six spd turbo g/box will fit under a 510. anyone have any
thoughts
> on this?.. i'm guessing as theres another gear in there it'll be weaker
> than the
> 5-spd turbo g/box.. any if anyone knows the 6th gear ratio i might be able
> to run
> a mid-to-tall diff to get some 'pull' and not rev hard on the freeway..
> thanks,
>
> dave
>
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