‘87 Coupe - front end tracking & drift issue
 

Thoughts on where & what to look at please.
‘87 3.2 Carrera coupe; Euro ride height. I bought the car 9 months ago fully sorted. Driven it 5k miles in 9 months - 89k miles now.

When I punch the throttle, the front seems to lower a bit and jump slightly to the left and when I depress the clutch to shift gears in a more aggressive drive, the front seems to lower a bit and jump slightly to the right. So, opposite movements when accelerating or decelerating. There is also a mild drift in the steering that wasn’t there before this started.

I’ve looked under the car and don’t see anything that appears to be broken or out of place as far as I can see; but have not been able to get it on a lift yet.

What should I be looking for and where?
Thanks much!

Sounds like the "thrust line" is off center. That means the rear wheels are pointed off to one direction or the other relative to the front wheels. Given your "accelerate goes left, decelerate goes right" I suspect the rear wheels are pointing more to the right.

Do this: Car on flat floor. Point front wheels straight ahead. Get down on the floor behind the car and sight down the edges of each rear tires to the front tires. The sight line should fall outside the front wheels by the same amount. then roll the car forward one half wheel rotation and check again. Report your results.

Corrected this for you so it might make more sense?

Two things jump out at me - first off, you might try new motor mounts. Be aware that the quality of then vary quite a bit - don't get the cheapest ones available as they'll transmit an incredible amount of engine noise. There's 5 or 6 hundred pounds of motor and transmission hanging off these and it can move around uncontrollably without good/fresh mounts.

Secondly, every time I read "euro ride height" I question if it really is or is it much lower. Over time everybody's eyes have gotten used to lower, and lower 911's. A wise man once said (OK I admit it was me) "Low is cool - And you can never be too cool.' But there's a price to pay. Many 911's are running around on the bumpstops.

The 911 has a pretty horrific rear-steer problem which gets worse and worse the lower you go. It's particularly bad on a car with the overly soft stock rear torsion bars, as the suspension is allowed to move and steer the car. If the thrust angles are off, or you're turning, it gets even worse. It can be compounded by bad rear trailing arm bushings.

Just something to keep in mind.

How are the spring plate bushings? If those are roached it can change lanes from the torque of acceleration and deceleration

^^ This too, in addition to checking the rear wheel alignment.

If it was fully sorted with new bushings etc. then you should check all suspension hardware to see if something has came loose. The first place to check is the rear spring plates. Perhaps the toe and camber adjusters and the bolts attaching the spring plates to the trailing arms.