Challenge Car: Bump Steer Issue

[StromSpeed]

Yes, I'll apologize now, another bump steer question. After going through tons of threads and reading Longacre and other bump steer set-up sources, it appears I have a larger problem, and it is this: I have 1:1 ratio in travel to bump steer. So if I droop the suspension 1", I get 1" of toe-out, and vice versa. And a professional alignment HAS been completed, with caster, camber, and toe-in set and verified. Yet this is the result which is very disturbing. This is a NEW build and I have not driven the car at length to find out how unstable it is. Because this car will be raced heavily, I need to make sure the car is stable in the turns, and I DO NOT want to find out after the fact and crashed into a wall!

My question: Per my attached pictures, do I have the bump steering linkage installed correctly per my build?

Here's my build info to help answer the question:

1. Challenge Car, Mark IV frame, 7789SP
2. Zero donor parts, all new parts supplied from FFR
3. Manual Steering rack new from FFR (believe it was the Flaming River rack that was shipped)?
4. FFR bump steer kit installed; rod end placed on top of the steering arm per instructions (due to manual steering)
5. Alignment settings: Caster +3.0, Camber -2.0, Toe-In 1/16 inch total

Note: Pictures are of Passenger side linkage (same issue on Driver side too); notice the angle of the tie rod to the upper/lower A-arm. Shouldn't that be parallel?

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[Hankl]

Speed,

To answer your last question first, yes, according to all that I have experienced, the tie rod should be parallel to the lower A-arm. Not having the newer FFR spindles,
could the removable tie rod arms be installed on the wrong side, in other words, are the arms side specific? If there is a slight bend in the arms, you could move them side
to side and have a different impact on the geometry. Your alignment setting don't look out of place for the intended use.

Hank :cool:

[Mike N]

The tie rod should be roughly parallel to the lower control arm. You need to have the tie rod end attached to the bottom of the steering arm on the spindle and not the top.

[Mark Dougherty]

put the heim joint on the bottom side of the steering arm.

Run 4.5 deg pos castor ( If you are going to track the car then you wont mind the slightly heavy steering when putting it in the garage )

flipping the heim and adding castor will decrease the bump.

Next WHY manual steering
It has been proven time after time that the power steering is the best and safest. You should reconsider the use of manual steering.

[StromSpeed]

Speed,

To answer your last question first, yes, according to all that I have experienced, the tie rod should be parallel to the lower A-arm. Not having the newer FFR spindles,
could the removable tie rod arms be installed on the wrong side, in other words, are the arms side specific? If there is a slight bend in the arms, you could move them side
to side and have a different impact on the geometry. Your alignment setting don't look out of place for the intended use.

Hank :cool:

Thanks for the feedback. I doubled checked the arms and they are correct per side and per the instructions.

[StromSpeed]

The tie rod should be roughly parallel to the lower control arm. You need to have the tie rod end attached to the bottom of the steering arm on the spindle and not the top.

That's what I orginally thought, but the FFR instructions specifically call out with manual steering that this should be on-top. Looks like it needs to be below. Looks like the FFR instructions need updating?

[StromSpeed]

put the heim joint on the bottom side of the steering arm.

Run 4.5 deg pos castor ( If you are going to track the car then you wont mind the slightly heavy steering when putting it in the garage )

flipping the heim and adding castor will decrease the bump.

Next WHY manual steering
It has been proven time after time that the power steering is the best and safest. You should reconsider the use of manual steering.

Mark thanks for the feedback. Some answers:

1) Will do on the heim joint. I just want to make sure its not going to cause any other steering/linkage issues? This is a track only car, no street use.
2) Will try that castor on the next alignment.
3) Why manual? One: cost. Two: minimize system complexity. Three: reduce weight. And finally: want to go as old school as I can get and see if my arms will last! :D

[Mark Dougherty]

This is a NEW build and I have not driven the car at length to find out how unstable it is. Because this car will be raced heavily, I need to make sure the car is stable in the turns, and I DO NOT want to find out after the fact and crashed into a wall!

With this being said
These car are very hard to catch at the limit. There are very few people who can race a FFR at the limit on track with the manual rack. The car will oversteer and snapback faster than you can physically turn it back. This means you will spin, or be forced to slip the steering wheel between your hands ( letting go of the wheel )
I have worked on many challenge cars and power is the way to go.

[Jason Lavigne]

To expand on Mike N's comment, your tie rod is nearly parallel but off in a direction that will probably hurt performance (tire will toe-in under bump/compression). It's better to have toe-out in a bump scenario, so having the tie rod under the steering arm should help.

Regarding the instructions, the note about above or below the steering arm is more of a principle to follow than an absolute rule. It can vary slightly by spindle type, too (Fox, SN95, Mk4). Lastly, I do agree with Mark's comment about his preference for power steering. Manual steering setups are certainly lightweight and clean, but you can be much more precise in normal driving conditions and in situations when you have to make corrections.

Jason @ FFR

[StromSpeed]

Mark/Jason,
Thank you for your feedback and appreciate your experience on this. I'll add PS to the punch-list and Christmas list. :D

[FFRSpec72]

So I added PS when I went to the MkIV spindles as part of the upgrade, I went from +2 to +8.5 camber and no way was I going to fight the wheel, it was bad at +2. So it took me almost a season to unlearn how to drive the car w/o PS, so if you can start with it you will be much better off. With all the brackets, pulleys and ways to run the belt you will have to find a belt that will fit your configuration, and that was the hardest part of the conversion