Dispatch20 Posted May 23, 2015 Posted May 23, 2015 Cliffnotes: The KCA313 extended length tie rods work OK at both stock height and lowered height! My car previously had RCE Tarmac coilovers with the Whiteline KCA313 extended length tie rod and ball joint kit. Due to the rough roads and construction in my area, I decided to go back to a mostly stock suspension. The KCA313 kit is not designed to maintain the factory alignment specs at stock ride height. I wondered if I would need to replace both the ball joints and the tie rods. Obviously, I'd like to replace the minimal amount of components while keeping a safe alignment. I decided to replace only the ball joints with OE ones and bring it in for an alignment at the Subaru dealer. It turns out the extended length tie rods are able to be brought into factory spec with an otherwise stock suspension. The gamble paid off! I figured I'd post this in case anyone else ever had the same question.
Underdog Posted May 23, 2015 Posted May 23, 2015 The KCA313 is not an alignment-related mod, rather it corrects the LCA and tie rod angles after lowering the car to restore the roll center height and bump-steer geometry. If you notice the car darting around as you hit bumps/dips then you may want to consider going back to a stock tie rod. The Crimson Dynamo
Code Posted May 23, 2015 Posted May 23, 2015 Do you still have the ball joints? I may end up needing one "Striving to better, oft we mar what's well." - Bill Shakespeare - car modder
Dispatch20 Posted May 23, 2015 Author Posted May 23, 2015 The KCA313 is not an alignment-related mod, rather it corrects the LCA and tie rod angles after lowering the car to restore the roll center height and bump-steer geometry. If you notice the car darting around as you hit bumps/dips then you may want to consider going back to a stock tie rod. Visually, it looked like the Whiteline tie rod has a longer arm length. Their description also says "...bump steer correction via extended tie rods...". Is the Whiteline tie rod 'extended' only in the ball joint height dimension? Or only the tie rod arm length? Or both ball joint height and arm length? My theory (assuming the tie rod arm is extended) is that the tie rod length will affect the toe angle adjustment range compared to a stock tie rod. The question in my head was: Will an alignment be able compensate for the extra Whiteline tie rod length when at the stock ride height? Am I way off on this? I am not an expert in suspension geometry. Pic for reference: http://www.rallysportdirect.com/user_submitted_content/photos/WHI%20KCA313_4.jpg
Dispatch20 Posted May 23, 2015 Author Posted May 23, 2015 Do you still have the ball joints? I may end up needing one Doh! It got sent to the trash on Thursday. My set had about 30k miles on it, and I would have gladly shipped them to you for free. I had no issues with them.
Underdog Posted May 23, 2015 Posted May 23, 2015 There is plenty of length adjustment in the stock outer tie rods to get the static toe within spec on lowered cars; it is the height of the spherical joint that puts the tie rod back into the correct position of it's swing. They may have added some length to the threaded end to allow extreme adjustment or added platform-compatibility. The Crimson Dynamo
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