h011yw00d

85 MY 5-speed.

For the life of me I can't figure out why this happens but when I'm driving aggressively, in the time between when I disengage one gear and engage the next the car will pull to the right. All other times the car tracks straight as an arrow.

I've had the alignment checked multiple times. I can't see any evidence of frame damage. I'm stumped.

Could it be from the engine torque causing the passengar tire to dig in first?

Must consult 928 font of knowledge

destructo_low

It could be a worn suspension component transitioning from the tire being pulled rearward during acceleration and then loosing that rearward pull and tweaking the alignment just slightly before the clutch is engaged again.

When I was learning to drive a manual vehicle, I wasn't 100% coordinated between steering, clutching, and shifting. During shifting, if the car had a tendency to pull, I would let my attention/ tension on the wheel relax, and the car would drift an inch or two, until I completed the shift and my attention returned to the wheel.

No HTwo O

I assume tires pressures are A-OK? Motor mounts (maybe not so much an issue on a 928 vs a 911 or Boxster, for example)? Tires all matched?

GlenL

Check for bad bushings or looseness in the rear suspension. That long stud that runs through the bottom of the shock and the arm can get loose and it'll make the car dart left/right with power.

h011yw00d

Good input guys. The motor mounts are original but good (don't know why), tire pressure is identical and new tires (>1000 miles) all around.

Hadn't checked the rear suspension as I just assumed it was a front issue. I know the alignment is good in the rear but I'll check for loosenes, all rear bushings and the long shock stud.

Thanks, Guys.

PorKen

A (working) LSD rear end will pull the back end around. Check your option codes for 220. (Run, or have someone run, your VIN through PET 7.x)


Come to think of it, I recall my (stripped down) S3 manual does something similar. The loss of torque during shifting unsettles the car.


With my S3 auto, the back end moves after it shifts at full throttle, because of it's LSD.
The manual moves after a shift too, when I do No-Lift-Shifts (option on my chipset).

Ducman82

i had a loose rear suspension pin, causing the passenger side carrier to shift. that was my problem with accel/decl steer

h011yw00d

Thanks, Ken... No LSD but I wish

Yeah, I'm starting to think I might not have got all those funky washers back on in the right order when I switched out the rear coilovers. Darn, things.

No HTwo O

Does a 928 have a Kinematic Toe adjustment in the rear, like the 993's? We see this with the 993's if the K.T. is not set right during a quality alignment.

h011yw00d

Hmmm... Kinematic Toe adjustment... good question...

PorKen

928s have the KTA's older brother, the Weissach axle.


Working Elasticities Integrated for a Systematic Stabilizing Alignment Change

h011yw00d

Thanks, Ken. He's our resident mad scientist.

Y'see No HTwo O, a lot of us (or me at least) can't really afford a high $ Porsche so we buy these cars, work on 'em like Hebrew slaves, love the dickens out of 'em and make 'em go like stink.

Googled 993 though and it's a very pretty car.

No HTwo O

Thank you, she's just a +15 year old Volkswagon. And I do the same as you!

h011yw00d

Awesome! Love the color...

White Lightnin'

Not certain if it was because the S4 had a staggered fitment from the factory -but my air pressure is not supposed to be identical:
36 psi front/44 psi rear.

You may want to check this on yours to be sure...