bump steer after disc brake upgrade

[turbotruck]

68 c10. installed the cpp disc brake kit. stock height spindles. after installing the upper ball joint angle seems more aggresive than before. also im getting way more bump steer than before. also using cpp 3' drop springs in front, cpp sway bar, viking double adjust shocks. any ideas on how to remedy the bump steer? is it a mismatch of components? An alignment was done.

[HO455]

I recommend you move this to the suspension section. Where bigger brains than mine will see it.
Then my first question is did you only change the spindles and brakes and then problem appeared or did other components get changed or added at the same time and the problem appeared.

[RustyPile]

The shorter springs are the cause of the bump steer.. The shorter spring places the upper ball joint at a higher location in relation to the upper arm pivot shaft.. As the spindle travels up and down going over bumps, the camber angle and toe angle changes drastically, which translates to bump steer.. The solution is to go with stock or maybe 1" shorter springs and dropped spindles..

[Jason Banks]

Is it possible you swapped the upper control arm side to side? The other thing that comes up is the center steering link can be put in backwards. Post some pictures of your setup.

[jonmc56]

+1 on the possibility that you installed the center/drag link backwards. Been there, done that myself.

Jon

[turbotruck]

control arms never left truck, drag link never left truck. truck has been lowered for 10 ish years on these springs with the drum brakes. i installed a full kit with spindles, rotors, tie rods, ball joints etc. its using the newer 73 plus style joints. the inner tie rod is on the back side of the drag link with the nut facing the front of the truck.

[turbotruck]

can and admin move this to suspension section if needed?

[HO455]

Originally Posted by turbotruck

control arms never left truck, drag link never left truck. truck has been lowered for 10 ish years on these springs with the drum brakes. i installed a full kit with spindles, rotors, tie rods, ball joints etc. its using the newer 73 plus style joints. the inner tie rod is on the back side of the drag link with the nut facing the front of the truck.

Bump steer (on our lowered rucks) generally is a result of the tie rod end at the spindle being higher than the center link end at ride height. The greater the angle of the tie rod the worst the bump steer will be. Do you have any photos of the suspension before you swapped the spindles that you can compare with the current spindles. Or even some measurements of the old spindles and the new ones will show if the tie rod arm on the new spindle is markedly higher. If that likely is the problem.
What are you using for bump stops?