Just did a full suspension refresh on my 1987 W124. The entire subframe came out and I did all of the bushings, links, control arms, brakes, rotors, springs and shocks. For the front, I did new springs and shocks, new control arms/ ball joints, with their matching bushings, new pads and rotors, and new sway bar bushings. Put it all back together and got it aligned. When out on the highway, I noticed that under acceleration, the car would sort of drift to the left, then when I got off the gas, it would come back to the right, so I got under the car and checked all the torque specs and took it out and drove it again. Same issue.

So this time I placed jack stands at the center of each wheel hub and measured the distance on either side. One front wheel looks to be about a half inch further forward than the other, so my guess is that either they didn’t know what they were doing when they set the caster or the new suspension is still settling and it has changed. When I checked the bolts in the front control arm, the adjustment bolts were definitely looser than they should have been on the driver’s side, so who knows what happened.. As I was trying to avoid - the likely scenario is that I’ll have to do the caster myself. I imagine there isn’t a full half inch of adjustment and that I’ll have to adjust one wheel forward and one wheel back.

Just wondering if anyone has ever experienced this drifting issue and whether the caster is the likely culprit, or I should look elsewhere.

I would take a hard look at the rear suspension. There is a link there which is more or less horizontal which if loose will make the back end dance around under lift throttle or applied throttle.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

The banana looking camber link?

Ditto, it sounds like the thrust angle/rear toe is changing under acceleration. If you have access to a drive-on rack, loosen every fastener you touched and settle the suspension by bouncing it a few times. Re-torque everything and see if the issue goes away.

Good call. I don’t have a drive on rack but I do have a set of ramps and a floor Jack and Jack stands. I can’t put pressure on all four wheels at once but I can do the rear all at once by putting the rear on the ramps and the front on stands on the Jack pads. Will that work?

It can't hurt

Is there any way that the differential/driveshaft could be causing the issue? All of my bushings were totally shot, so I replaced everything, but now that all the bushings are tight and new, maybe slop in the transmission mount, or something could be causing it?

I've noticed that the directional change happens when there's a hard upshift, and it gets worse as I go higher speed.

I took care to align my differential bushings like the old ones, and the differential is sitting in front mount nicely...

Just updating the thread. Ordered fresh bolts all around. Loosened and removed everything, put everything back in, and retorqued with the axle level. Issue gone. The alignment is still whack (thanks Les Schwab) but I've got a string setup I use for my other cars that I will use and get it all sorted.