FRS Understeer Issues - Rear Drop Knuckles

[deadr0ze]

[U]Hello everyone!
Looking to see if anyone can provide some input on some interesting steering issues I am having that I have never had before;

- upon turn in the traction control absolutely loses its mind and activates about 6 times before finally being stable again. This is on 90% of turns around 50-65 MPH, these are the same turns Ive taken before at upwards of 70 MPH

- with traction control off, the car has grip and only has mild stuttering around the same speeds and steering angle

I did a few suspension mods all together but mainly it was spherical bushing arms rather than poly, the most impactful mod that was done was the GKTech Rear Drop Knuckle/RUCA combo. Really at a loss as to how to remedy this current so looking forward to any and all input. Below are suspension mods/specs and a photo of the car for more info. Thanks in advance!!

Suspension:
Annex Club Spec Pro (7k F, 8k R)
GKTech Tie rod end (15mm RCC)
RacerX FLCA
RacerX Endlinks
Hotchkiss Front Sway (tested both settings with minimal difference)

PBM Diff Riser Bushings
VooDoo13 Subframe Bushings
GKTech RUCA
GKTech Rear Drop Knuckle
Stance 60mm Drop LCA
VooDoo13 Toe Arm
VooDoo13 Trailing Arm
MCA Traction Mod
Stock Rear Sway
Spherical Endlinks

18x11, 295/35 Michelin PS4S Squared

Front:
2.5 Deg Camber
0 Toe
6 Deg Caster

Rear:
1 Deg Camber
1/16 Toe (1/32 per side)

Aero:
75” Wide Front Splitter
Professional Awesome Large Diffusers
Voltex 1800mm

[whataboutbob]

1) Is the rear toe value toe-in, or toe-out?
2) You might check your rear wheel speed sensors to make sure they aren't damaged. I have damaged mine in the past when swapping rear axles when I forgot to remove them from the rear knuckle. There's not a ton of clearance between them and the axle, and the tips can get damaged easily.

[deadr0ze]

Originally Posted by whataboutbob

1) Is the rear toe value toe-in, or toe-out?
2) You might check your rear wheel speed sensors to make sure they aren't damaged. I have damaged mine in the past when swapping rear axles when I forgot to remove them from the rear knuckle. There's not a ton of clearance between them and the axle, and the tips can get damaged easily.

Toe value is toe-in, and I would like to say that they are in good condition, done axles a few times and never forgotten to remove them but there is definitely always a chance so Ill check those asap

[Opie]

Did you recalibrate the steering angle sensor after the mods....if not. start there.

[deadr0ze]

Originally Posted by Opie

Did you recalibrate the steering angle sensor after the mods....if not. start there.

I never would have thought of that!! SAS have never been recalibrated to my knowledge. I will do so tomorrow and report back

[marco_mc22]

Had a similar problem once and it was a lack of rear droop travel, due to lowering LCA's design. Changed the arms with standard ones first and then with pillow ball hard race model and the problem was solved.