Matt Alter

My 99 / 996 wallows in the land at speed. Not sure how else to describe it, but it does not stay straight. I had an alignment when I got the car.

It was suggested shocks could be causing this behavior. Any thoughts or suggestions?

Barn996

How are your tires? Can you verify which shocks you have. I noticed an improvement years ago when I switched from standard OEM shocks and springs to MO3O shocks and springs which firmed up the ride and eliminated the wandering.

Matt Alter

Shocks are oem I believe. I have replaced tires in Aug of 15, 225/40ZR18 Sumitomo HTR Z III. Was thinking of getting them balanced again as a start.

Slakker

Was it doing it before the alignment? Not all alignments are equal.

5CHN3LL

Wallowing sounds like it's not tracking straight. I'd take it to a different alignment shop and request an evaluation. Unless you can feel vibration from one or more wheels, there is no point in getting the wheels balanced at this stage.

rrtex1

I have the same issue and happen to have the same tires and notice it seems to do this more when there is a cross wind or next to another vehicle thus wind causing it to move. I know my camber is out of spec though and assume that is the cause and will address soon. Mine also has a slight tendency to pull to right even after two alignments two places. My plan is to get the car up and check bushings on all 4 corners, replace any if needed and then take in for alignment and camber resolution.

Question, if I know the camber numbers is there a way for me to adjust the camber without having the alignment shop do it? They state it requires parts or shim kits to fix thus an extra cost.

5CHN3LL

No parts are required to adjust the camber within the factory-supported range. Any more aggressive negative camber (or positive, I guess, theoretically?) requires parts or modifications to existing parts.

5CHN3LL

There are lots of ways to do this on the cheap. If you're gadget-minded, you can use your favorite prototyping platform (rp, arduino) and sensors; you can also go the "I have a Honda and $7" route like this guy:


Normally I'd post a LMGTFY link, but for some reason I'm not feeling the urge to be a jerk. Do some Googling for "DIY alignment videos" while I try to get an appointment with my primary care to see if we can find out why I'm being nice.

rrtex1

Thanks 5chn3ll. Now that I look at report it is both camber and caster with caster being the most out

5CHN3LL

That makes sense. Sounds like the car is set up to be really neutral, and you want it to track more.

If you asked for a "sporty" alignment, that could be the problem. The stock alignment has some impressively high numbers (like (neg) rear camber) to help overcome the pesky physics problems that come along when you cantilever the engine out past the rear axle. Anything more "sporty" or aggressive than stock can be very aggressive (camber) and unsettlingly neutral as far as tracking.

KoB

The report also says you're driving a 2004-08 Carrera GT. Did the alignment shop use the correct factory specs?

rrtex1

Nice Catch, I will be back to ask them to do it again. Correctly

Slakker

Your caster is fine. As long as both sides are within .5 degrees of each other it doesn't matter.

FRUNKenstein

Actually, it says 2004-2006 Carrera GT, but yeah, that might make a difference.

And I don't think Schnelly's $7 camber tool is gonna work because centerlocks.

Schnelly - I hope you get to feeling better soon.

Porschetech3

Toe-in of the front tires makes the car more stable going strait, toe-out (or negative toe) of the front makes the car turn in to turns faster but is not as stable. Toe-in of the rear tires makes the car more stable during braking.Toe-out of the rear tires (or negative toe) is not advised (except maybe on some wet tracks).Looks like your car had a lot (0.19 total) of positive toe before adjustment and a lot less ( 0.04 total) after adjustment.

0 camber is good for tire wear, negative camber is good for turns. Street cars 0-1.0 ,performance cars 0.5-1.5, track/race cars 1.5-3.5. It doesn't look like your castor was changed at all 0.2 before , 0.1 after, rear at 1.5 before and after,that little bit of change probably happened due to toe adjustment.

Castor is good for tracking at speeds. Low speed cars have 1-4 degrees castor , as you can see Carrera GT has 11-12, your car spec is about 8, yours is at 7.7 so your good. Castor is usually not adjustable and built into the design, but can be changed with redesigned or modified parts.

The most important part of an alignment is the set-up. Getting the car square on the alignment rack, and getting the equipment mounted correctly and precisely is KEY! If the setup is done sloppily the car will drive sloppily, even if the numbers look great it will not reflect the ACTUAL alignment and will show on the next alignment check (assuming correct setup) as out-of-spec.

And yes don't even look at those specs. they are WAY off.(big differance between a Carrera Gt and a 99 Carrera).lol .They probably don't have the correct specs to compare your car to, they have to pay or have the program updated I bet..