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Old 09-14-2017, 08:27 AM
at the beach's Avatar
at the beach at the beach is offline
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Default "Minx" Spindles and Bump Steer

Recently, in another thread on this Forum, a member was looking for a set of "minx" spindles. He eventually located a set.

My question is, "What does installing a pair of these do to the car's Bump Steer?"

bt
at the beach
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Old 09-14-2017, 06:42 PM
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0neoffive 0neoffive is offline
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Cool Hmmmmmmm ?

Quote:
Originally Posted by at the beach View Post
Recently, in another thread on this Forum, a member was looking for a set of "minx" spindles. He eventually located a set.

My question is, "What does installing a pair of these do to the car's Bump Steer?"

bt
at the beach
Simple geometry would infer that the wheel center now being further from the lower wish bone's movement, bump steer will be slightly affected by the more rapid angle change of the short arm upper. Just sayin' . . . .
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Old 10-23-2017, 04:36 PM
MT Roads MT Roads is offline
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Default Re-Minxed

Since the Drop spindles are direct replacement for the Alpine/Tiger [except for the vertical location of the wheel, of course], the location of the upper & lower ball joints is the same. The distance between the upper & lower ball joints is not changed, & so the angles made by the upper & lower A-Arms will be the same at ride height [+/- production tolerance, maybe].

This means that the angle of the A-Arms remains the same & so the "Instant Center" extension of those angle lines is the same. The Steering rack is not changed or affected, so the location of the tie rod ends is the same, so there should be no change in the bump steer configuration. The wheel/tire is just located farther up or down in a flat plane, but the geometry of the suspension is not changed.
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Old 10-23-2017, 08:08 PM
spmdr spmdr is offline
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Default It changes

The Minx/Dropped spindle moves the wheel up compared to the lower ball joint/ A-arm.

Along with the wheel, the brake caliper and steering arm are moved as well.

When you change the relationship between the A-arms and the steering arm/ outer tierod end, bump steer changes (and other things change bump steer).

So, yes, the bump steer needs to be FIXED with the Dropped spindles.

If you want an extreme TEST/example of BAD bump steer, swap the steering arms on the spindles from side to side.

Reset the Toe in and take the Wild ride for a test!

The car will have a MIND of it's own, as far as direction control!
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Old 10-23-2017, 11:08 PM
MT Roads MT Roads is offline
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Default Oops!

Haven't worked on the Tiger is a while & also not had the opportunity to compare stock spindles with the Minx Dropped variety [& the current project car is set up differently, lets see, can I think of any more excuses?].

So yep, if the drop spindles mount the steering arm in the same absolute place on the upright, as opposed to moving it relative to the change in height, then the tie rod angle changes dramatically relative to the A-Arms & introduces significant bump steer. Thanks for the clarification.

Here's a quote from someone who has done the install & confirms the bump steer issue:


Quote:
Originally Posted by mwood View Post
I was able to find a set of the Hillman "drop" spindles recently (thanks, Jim!) and installed yesterday. Total drop was 7/8". I had also taken 1/2" off of the isolators Rick sells, which gave another ~1" (so, now I know our MR is around .5).

Only thing with the spindles is that the steering arm angle steepens a good amount, so I'm looking for the hardware to adjust. In the past, I've done a combo of a stud and Heim joint. Does anyone make a kit for the Tiger? Jim did point me to Speedway, which has adjustable tie rod studs, but I was curious if anyone is currently selling a kit with all needed parts. Don't know if there would be a market, because the Hillman spindles are so rare and I don't know that stock cars really need to be bump steered.

Thanks
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