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So... 997.2 GT3 alignments.....

PhilMorrison

Monza
Joined
30 Apr 2013
Messages
160
Always going to be an entertaining question this one.

I daily drive the car, but I am used to aggressive alignments on the road. I don't want to go through tyres every week though.

The rear engine thing is completely new to me. So the number one thing I'm going to change is learning how to drive it properly by doing some UK track days before hitting the Nordschleife. But with just the small amount of driving I have done on the road, I do find the has more 'safe understeer' than I need / want.

Do people here mess about with alignments themselves and understand the changes they are making? Or does everyone use experts? I'm not averse to either idea. I have the equipment to corner weight and align, but I may just have CofG do it, as they are localish and have 'a little' more experience with Porsches than me.

I'd love to know peoples settings (if they know them)

Am I correct in thinking 180*ing the front top mounts should give me about 2.5* neg camber?

I imagine rake is quite important on these cars. Visually the rear seems higher.

Anyway, thanks for entertaining me. I do know questions like these on forums can go one way or another, and I have done some research, but any help would be much appreciated.


While having a nose around what's adjustable, I felt obliged to take a snap, as it's so new to me I feel the need to stare at it frequently :D

Underneath.jpg
 
Riviera?

need more pics :)
 
Chris at CG did mine. I have -2.5 of camber on the front and -2.25 on the rear. I have not however had the top mounts flipped - it can be done with shims in the lower arms (thus doesn't mess around with the castor as much and leaves its road manners a bit more civilised). I have zero toe at the front, however I have a half at the rear. This is good for braking stability (with the less aggressive diff than that of the 996 it is tangible) but seems to be the cause of accelerated wear on the inner shoulder of the rear tyres so I reckon it needs dialling back at some point.

Ride height is 102mm at the front and 137mm at the rear from the correct datum points. ARBs are one notch below stiff at both ends and I have RS fit front tyres (245 wide instead of 235).
 
I do all my own alignment and know exactly what makes me and my car tick, but if you're unsure, I say single most important move is to take it somewhere that does, and that doesn't mean your local tyre fitter/alignment shop.

Most rep places will listen and adjust accordingly, but I can tell you now you need to make a decision between track or road. Unfortunately roads in this country negate any aggressive toe and camber, making the car a right handful as a DD.

are those cup tyres you're running there ??
 
markiii: Yes it is :)

Disco: Exactly the post I was hoping for, thank you.
Where are the Datum points front and rear?
How does flipping the top mount change the castor? the shock pivot point looks to be in the center (longitudinally) so shouldn't move the top of the shock any way but inboard / outboard. Surely lengthening the lower arm will change the castor if the castor arm isn't lengthened with it?

Bobsan: Yes they are Cup tyres. I hear where you're coming from. I'm pretty used to driving aggressive track aligned cars on the road, and I'm keen to see if I can reach a happy medium of track / road with the GT3, as I have with all of my other cars.
 
You don't flip the top mount, you rotate it, as its off centre it moves the strut out allowing an extra 2 degrees onto of existing shims in lower arm
 
Yeah sorry. Bad choice of word. I know you rotate it.
Does anyone make an adjustable top mount?
 
Search for rss and tarret.

I think you can get all the adjustment you need from the std part though.

Talk to Chris at CG, he knows all the options.
 
The very first thing you should do is convert the rear toe arm to something like the Cup adjustable arm or the RSS/GMG equivalent. This will allow you to remove the standard (and deeply flawed) eccentric bolt method of adjusting the toe. Get (or fabricate) the lockout plates & you will see much better tyre life & much longer between geo's. It's also worth fitting rubber boots over the rose joints if it's a daily driver as they get covered in road crap.

You need 15 minutes of toe in each side on the rear & about 25mm difference in ride height front to rear to achieve optimum rake.
 
PhilMorrison said:
Am I correct in thinking 180*ing the front top mounts should give me about 2.5* neg camber?

It's actually a 90 rotation into the so-called "Cup" position. You just knock the 3 studs out & re-insert. This will allow you a minimum of 2.5 degrees & a max of close to 5.

Nobody makes an adjustable top camber plate AFAIK; it's probably due to the mounting position not being flat like the earlier cars so it would be impossible to construct one that could be fitted without major surgery to the mounting plate.
 
NXI20 said:
The very first thing you should do is convert the rear toe arm to something like the Cup adjustable arm or the RSS/GMG equivalent. This will allow you to remove the standard (and deeply flawed) eccentric bolt method of adjusting the toe. Get (or fabricate) the lockout plates & you will see much better tyre life & much longer between geo's. It's also worth fitting rubber boots over the rose joints if it's a daily driver as they get covered in road crap.

You need 15 minutes of toe in each side on the rear & about 25mm difference in ride height front to rear to achieve optimum rake.

Spot on! Thank you. So the eccentric bolts: Are they known to move despite being torqued correctly? I'll have a look to see if I have the parts to make some arms and lockout plates this week. TBH the only reason I haven't started messing about properly yet is because I haven't bought a torque wrench for the stupid centre locks yet :D

NXI20 said:
PhilMorrison said:
Am I correct in thinking 180*ing the front top mounts should give me about 2.5* neg camber?

It's actually a 90 rotation into the so-called "Cup" position. You just knock the 3 studs out & re-insert. This will allow you a minimum of 2.5 degrees & a max of close to 5.

Nobody makes an adjustable top camber plate AFAIK; it's probably due to the mounting position not being flat like the earlier cars so it would be impossible to construct one that could be fitted without major surgery to the mounting plate.

Thanks again. I'm sure I'll have the car transformed by the end of the week :thumbs:. I might even give myself a deadline and book onto the Rockingham day this Saturday.
 
The eccentrics stretch their threads so that even when tourqed correctly, they don't hold position reliably. Added to which the nut is deep within the subframe and needs a crows foot spanner to reach it.
 

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