Gary Pinkley wrote:
>
> Theoretically, all a dropped spindle does is relocate
> the tire vertically with respect to the rest of the truck.
> It doesn't change the suspension geometry so bump
> steer isn't affected. The current gen Daks can't use
> the stock rim diameter when you go to a dropped
> spindle. To get a two inch drop, you probably have to
> increase to at least a 17", most likely an 18". This is
> due to clearances between the wheel and the upper
> and lower ball joints. On older suspension designs,
> the ball joints resided inboard of the wheel. Modern
> suspensions are migrating towards positive offset
> wheels. This tucks the ball joints inside the wheel.
> My experimenting has shown me that bump steer is
> not a big issue on a 2" drop (via coils) as long as you
> aren't running a low profile tire. The larger sidewall
> of the stock tire profile absorbs a lot of the impacts that
> would cause bump steer. One advantage to dropping
> with a coil is you can change the rate of the spring,
> allowing the designer to fine tune the performance
> characteristics.
>
> Gary Pinkley
> 97 Reg Cab V-6 5 spd
> lowered monochrome red
> 255/50-17 BFG Comp T/A ZR4
> Budnik 17x8 wheels
>
> -----Original Message-----
> From: Michael Z-Sykes <msykes@su.edu>
> To: dakota-truck@buffnet.net <dakota-truck@buffnet.net>
> Date: Wednesday, November 11, 1998 2:43 PM
> Subject: Re: DML: BUMP STEER attn Gary
>
> >You seem to be the Guru on this, so I ask, would a dropped spindle
> >correct bump steer?
> >
> >-mike d.
> >
> >>>> Gary Pinkley <gapinkley@earthlink.net> 11/08/98 01:08pm >>>
> >The Western chassis dropped A-Arm does not correct
> >bump steer.
> >
> >Dakotas have bad bump steer when lowered beyond
> >2". This is caused by the angle of the steering tie rods
> >with respect to the rack. The factory designs steering
> >geometry to cause slight understeer. In this condition,
> >the tie rods point slighly downward from the rack at ride
> >height. This allows the wheels to point slightly outward
> >during cornering. Subjective testing by automakers has
> >shown that normal drivers feel more comfortable with
> >slight understeer versus oversteer. Slight understeer can
> >be corrected by simply lifting off the throttle on a rear wheel
> >drive vehicle. This is a natural reaction when your car is
> >pushing towards a guard rail. Lowering beyond 2" on a Dak
> >angles the tie rod upwards. This gives oversteer, i.e. the
> >truck's steering seems to be overly sensitive and twitchy
> >when cornering. Also if you encounter a bump during that
> >corner, the truck will seem to dart to the inside, seeming
> >to change lanes without warning.
> >
> >As I stated above, the dropped A-Arm DOES NOT correct
> >bump steer. The only way to correct bump steer on a lowered
> >Dak is to change the angle of the steering tie rod. The dropped
> >a-arm only lowers the spring pocket, changing the pre-load on
> >the spring, allowing the vehicle to sit lower. Only by relocating
> >either the rack (can't be done without major surgery to the Dak)
> >or by lowering the outer tie rod ball joint can you return your Dak
> >to the factory geometry. Changing the outer tie rod location can
> >be accomplished in several ways, all of which require increasing
> >the rim diameter above the factory 15" size. You can cast a new
> >spindle which has it's steering arm lower than stock, you can try
> >to put spacers between the tie rod and the spindle, or install a new
> >tie rod end that has a longer stud. Looking at the factory spindle
> >with 15" rims, you will see that there is no room to play with the
> >vertical height of the ball joint.
> >
> >Gary Pinkley
> >97 Reg Cab V-6 5 spd
> >lowered monochrome red
> >255/50-17 BFG Comp T/A ZR4
> >Budnik 17x8 wheels
> >
Gary, Whos spring would be the best choice for a 2" drop in the front?
And whos hangers for the rear? Bob
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