pete95zhn

I just got done some suspension mods to my C2, which already had M030 suspension and KW V3 coilovers. Now it got GT3 adjustable wishbones to all four corners, GT3 front strut supporting mounts and GT3 stabilizers. And some brake mods too, but that's not the issue here. A local shop did the installation ( I just didn't have noe time for that ), but I took the car to the alignment myself.
While rears were easy to adjust to Kussmaul settings, fronts weren't. And aren't set. Now to the questions....before I start to check the installation myself, I need to know few things:
1. Should front wishbones be installed control arm attachment holes aligned like this / \ or this \ / , when the direction to travel is ^ ?
2. At which camber values one shoud start using outer ( = not the center ) attachment holes? WSM only states "racing circuit values"...
3. What kind of camber values have you got with strut mounts modified to increased camber, ie. bolts switched over?

What I got from the alignment was L camber 3.5, caster 7.8, R camber 3.0, caster 9.2. Strut mounts switched ( and set to minimum camber position ), 7mm shim at RH wishbone!, LH none... When I got home, I checked data sheet from the previous owner ( from year 2005 ), cambers were at 1.0 but casters had almost a 1 deg difference, similar to present. Something's not right, but I'm ( among with the shop ) pretty sure that the car's not been hit.
Rears are aligned beautifully at 2.3 deg camber with 4mm shims.

TIA, Pete
'00 C2, Factory Aerokit with some GT3 goodies

NJ-GT

The GT3 doesn't have wishbones, it has control arms & trust arms at the front, control arms, toe arms and trailing arms at the rear. The Gallardo, R8, F430 have wishbones.

1) Please clarify your question. Are you referring to the holes in the bushing, is the bushing stock or custom (provide the brand or a pic), are you referring to the trust arm?

2) Never, always use the center one, unless you have adjustable ones (see 1) (ERP/RSS/Sharwkers/GMG).
3) -2.2 minimum up to -3.5 depending on ride height, before adding shims, with the strut tops set to minimum camber (toward fenders). These values are car dependent, every car is different (height, tire profile, shock life, spring life, etc).

From your camber readings, it looks like the car is too low, in which case you need to dial out the bump steer front and rear.

pete95zhn

PET Illutration 401-01 996 341 122 90 wishbone /L . Number for right wishbone is ...121 90.

The holes in the bushing, std Porsche part, #s few lines above.

OK.

Checked.

IMO not, measured per WSM Group 4 / 44 Wheels, tyres, suspension alignment / Vehicle height, p.144 . And that's the really worrying part. EDIT: Rear is about 5mm higher than factory recommended height, front is about 20mm higher.

NJ-GT

Wrong translation from the Germans. Wishbone (very popular in chicken):



A wishbone as last used in the 993. 996/997 don't have one anymore. Notice that a wishbone has three attachment points instead of two as a regular control arm.



One thing I noticed is that the front strut tops might not be rotated on both sides. Your caster is off by 1.4 degrees. The other reason on why this could happen is that they used the eccentric hole in one side control arm bushing, and the center hole in the other. It has to be in the center for both. Another reason why caster would be off, is an incident that results on bend suspension parts.

Check that (A) in the following picture positioned to the inside of the car at both front corners.

pete95zhn

Whatever...

This was the first thing I checked, mainly because I rotated them myself and I wanted to be sure that there were no alterations made in the shop.

This thought is the main reason for this post altogether. BUT could this also cause that difference to caster too??

The local Porsche center has checked the car too, and they are pretty sure that this is not the cause. At least all chassis metalwork seems to be of same age and without damages.

NJ-GT

When you switch to the eccentric holes in the front control arm bushings, the following values will change: drastic change on toe, towards toe-in, easily adjusted back with steering rod, drastic change on caster not adjustable, moderate change in camber, easily adjusted with the tops or shims.

pete95zhn

Back to the original question:

1. Should front wishbones be installed control arm attachment holes aligned like this / \ or this \ / , when the direction to travel is ^ ?

According to the WSM alignment should be \ / ( outer holes in the bushings forward of center holes ). OTH I have a copy of a 2004 911 GT3 RS Technical info/ service information bulletin, where in a illustration 4_25a_04 fwd ones are set / \ and rear ones \ /. I'd be attempted to believe in the WSM...

Just checked my first post to this subject, if the basic setting is like / \ and the left one is installed incorrectly to center eccentric hole, but right one to the outer one, your quote
would explain why left camber value is within
without the shims ( and with less caster = L camber 3.5, caster 7.8), but the right one is measured: R camber 3.0, caster 9.2. Strut mounts switched ( and set to minimum camber position ), 7mm shim at RH wishbone!

Or am I totally wrong? Anyway, I'm going to jack up the car tomorrow, and check by myself how those are installed.

pete95zhn

OK, the car's been up on jackstands for two days. Findings and things done:

1. Front control arms were installed eccentrics facing front and in ( / \ ), thrust arms in center holes. As stated in the WSM for street driving.

2. I rotated strut mounts back, gives now significantly less camber, I even might get that 2,5 deg.

I'm going to get scales tomorrow for few days,it'll be interesting to see the corner weights. And more interesting to adjust them...

I had a long conversation over the phone with a senior Porsche mechanic ( he was kind to answer from his vacation ) about these caster/camber issues, and he was quite sure that one of the thrust arms is slightly bent. New ones are in order.