[Cobra #3170]

This is what I did on CSX3170 to get acceptable bump steer:

The original cars were a ***** to set rear toe on because changing the drag link changed toe but it also effected the caster angle of the rear upright. You had to adjust the rear inner pivot with those two large nuts on either side of the spherical bearing to correct the bump curve every time you changed the drag link. That would then effect toe so it was an iterative
process that could take hours to get right because you had to check both toe and bump steer after an adjustment. Moving the location of the drag link could help bump steer on a car with stock ride height.
This is what I did with my 18" race tire set up.

I set rear ride height at 3.75" from the rear of the frame tubes to ground and front height at 2.87" from the front frame tube to ground. I fabricated two new drag links using left and right NMB rod ends so that all you had to do was loosen the locking nuts and rotate the drag link tube to change its length. I bought two new lower rear A arms from Kirkham and then revised the inboard ends to get rid of that crappy spherical joint that moves around
because the fit is so bad. I set it up with a 3/4" NMB rod end so that I could also adjust the length of the lower arm. Initially I used a bunch of washers on either side of the rod end to locate it fore and aft in the frame double shear bracket. I then screwed around for days trying different caster angles by shifting washers back and forth on either side of the 3/4" rod end. I would then set the proper toe angle from .00 to - .090 and check the bump steer or toe change for the full range of travel about 1.8" down to 2.0" up.
I made up some charts and then picked my ideal caster angle from the data. I then fabricated 4130 spacers at the correct dimension to replace the ideal washer arrangement.
I found that I could get really good bump steer with this approach at that ride height.
If the car has a street ride height it might be beneficial to lower the the forward drag link pick up. I am not really sure, the best thing would be to fabricate a movable pick up point
and try it. If you don't have a good suspension analysis program and VERY accurate measurements of all the suspension points in 3 axis the program gives you garbage. I tried it both ways and found that my ability to measure locations in space on the car were not good enough. You really need a computerized measuring system to do it right. A bonus with my set up is I can adjust track width slightly by resetting the upper and lower arm lengths for minor tire clearance issues. I use less toe in the rear on an autox course and more in the rear on road courses to avoid the dreaded oversteer monster. .