How much negative camber f/r can you get out of a stock GT2? Any suggestions for easy ways to get up to -3 or so?

Running Hoosier R6s

I'm shooting for as much as possible, but balanced for a mostly track car.

Maybe just a hair of toe-in in front with a bit more in the back. Any other alignment suggestions or tips?

 

I am running -2.5 degrees in front and -2.0 degrees in rear.. With Hoosier R6's in 245/35-18 and 315/30-18, this is a perfect setting for track days and HPDE's but still leaves the Car driveable on the street without too much tire wear.

If it was track only, you would want to go to -3.0 front and -2.5 rear.

Hoosier's Web Site states -2.5 degrees minimum for R6's.


The way you get the camber is to go with Porsche factory Motorsports shims... You can get almost exactly -2.0 in the rear without shims, but you WILL need them for the front. Remember to watch out for the caster change that the shims create... you don't want too much more than 8.3 degrees caster in front, as it causes the tires to start touching the front inner fender.

I have tried toe-in and neutral toe.. Neutral was better for turn in, so I will try a tiny amount of toe out for my next track day. For the rear, try 1/16th toe in... it helps under braking as the rear wheels will tend to spread under hard braking and the toe in will basically have them pulling into a straight attitude under brakes.


Also, make sure you get your ride height set correctly and you have the Car corner balanced with whatever your weight is in the driver's seat to get the Car balanced as well as possible. Ride height can be measures two ways.. The official Porsche way is to measure 4 specific points under the Car.. The slightly easier way is to the top of the wheel arches. That figure should be 25 1/2" rear and 25 1/4" front.

Newly added:

GT2 ride height specs:

Measuring Points:

FRONT: Road contact surface to lower edge of hexagon-head bolt of cross-member screw connection to body.

REAR: Road contact surface to the locating bore in the rear-axle side section (between toe and camber eccentrics.)


Settings:

FRONT: 108mm to 113mm
REAR: 133mm to 138mm

Depending on whether you have the stock suspension or not, try your swaybars set at second from full stiff in the rear and at the softest setting in the front...

If you get all that done, you will have a PHENOMENAL handling Car...

See my sig for the other changes that are recommended to tighten things up.

Here's some video from a recent trackday... Apologies for the tapping sound, but you can see how precise the Car is and how well it holds a line and the freakish grip it can generate...

http://www.youtube.com/watch?v=XK6zhvTEbAM

 

Thanks very much 80shilling. Gives me some great guidance for alignment parameters. I picked up the same wheel/tire combo as you from Tirerack and am amazed at the light weights.

Toe-out front makes for a very fun car, but you have to be wary on the first long-straight braking zone you hit as the car will move around quite a bit under braking. It really dances around, not so much that you really have to correct (but you'll feel like you may have to).

It makes most people pretty nervous, but it isn't a big deal once you get used to it.

 

My pleasure.

I track my Sportbike, so a Car feels like it's stable and easy to control, even when it gets a bit squirmy under hard braking.. The Bike weaves, shakes it's head and bucks and lifts it's rear wheel off the ground under hard braking... The Car feels plush and soft in comparison...

 

Yep, be careful with the shims in front. Based on some rennlist discussions (and my own unfortunate experience), it seems that more than ~8mm of shims can lead to rubbing, even with stock wheel/tire sizes.

Camber in the front can be achieved one of three ways:
1. The holes in the body for the upper strut mounts are slotted. Loosen the three nuts and you can get somewhere up to -2 degrees. You may have to slot the holes even more to get that much though.
2. Swap the studs in the upper strut mount to put them into the 'Motorsport' position. This will get you anywhere from a minimum of -2.5 to over -4 degrees camber with no shims. You give up some caster, but that can be somewhat made up (on a track car) with additional -ve camber and larger tires.
3. The aforementioned shims. I used 13mm of shims to get to -2.6 degrees and the RF tire rubbed the fender liner and bent my front fender lip out on the test drive , even at stock ride height and on stock 235 PS2s. The caster bushing was in the center position to keep the wheel away from the fender. With the bushing in the alternate position, I couldn't even get the wheel on the car as it fouled on the front edge of the fender.

It seems that a combination of 1 and 3 is most common. To get to -3, I'm pretty sure you'd need 7 or 8mm of shims, and additional slotting of the upper strut mount holes. This apparently limits you to close to stock tire sizes though as strut and fender clearance are slim. I am going to switch to #2 since I plan to run larger tires and the fact that it has worked very well for some very fast people that I've talked to.

I was able to get -2.2 easily in the rear with the stock eccentrics. There was more available, but my car sees a lot of street miles and I felt that -2.2 was enough.

With stock suspension, I'd recommend starting the bar settings at one hole softer on the rear bar than the front, especially if you have modded the car for more power.

Lastly, if you don't have aftermarket rear toe links, get them.

 

I agree exactly with 80shilling and have run the same set-up on many tracks.
Nice vid!

 

+1 on 80 shilling.

Front needs a bunch of camber shims to get camber.
Rear already has a lot without shims (depends on ride height).

Front neutral toe is great on these cars, for track and street. If you have wider wheels front then also really NO need to do the 1mm toe out most Cup cars use.

For rear, up to appr 3mm total toe-in is good, actually closer to 3mm gives more corner exit traction than say 1,5mm.

 

I went with the EXACT same setup right down to the algerittas and R6s, mechanic got right at -2.5f -2.0r too. Front looks really tight?!?!

I assume as stiff as it is and with that much neg camber it will be OK, but first couple of laps i'll be listening for the front end.

 

What do you mean by tight? That the tires are close to the springs on the inside?...

You will really like the way it changes the Car's handling and makes the front end turn and grip better...

Where are your swaybars set? I recommend second from stiffest in the rear and full soft in front.

I have made a couple of changes last week.. I lowered the front end a bit more and went to 1/16th toe OUT in front and the Car is even better than it was... I am off to Laguna on May 31st and we'll see whether it helped or not, but I am expecting a decent improvement in my Lap time...

 

tires look close to edge of fender at the front, but i think it's ok

 

If you are worried about the tires rubbing.. look at this!! This is at the bottom of the Corkscrew at Laguna.. MAXIMUM compression, zero rubbing...

 

80, how exactly are you achieving your front camber numbers? If it's all shims, and you haven't slotted the upper holes or rotated the strut mounts, then your car is the exception to the rule. The details are in my previous response, but it is pretty dangerous to run more than ~8mm of shims without rotating the upper strut mounts. With 13mm of shims and -2.6 camber, my RF tire hit the bare metal edge of the fender. If that were to happen at speed on track and cut a tire...

Here's a link on rotating the mounts. Note in the pics that there are two sets of holes. http://forums.rennlist.com/rennforum...he-struts.html

 

I do have my mounts slotted and my upper strut mounts are rotated.. The guys that do my suspension work (SCARGO) are really, really good and have been doing suspension work for 30+ years for local racers, PCA guys etc. At present, I am running a 3mm and a 1mm shim on each side to give me my Camber.

My clearance on both my spring side and my outer fender side is still pretty good. I have no rubbing and no issues. As you can see from the picture I posted, if I had ANY issues at all, I would know it. Also, I have my suspension guys check and nut and bolt EVERYTHING before each track day I do, just because I am paranoid about having ANY component in my susension fail.... You are spot on with your observations.. at the track, suspension failure could result in not only the destruction of my Car, but severe injury or worse.

 

OK, that makes perfect sense. In your first response you said that the shims were the way to get camber, so I took that to mean that was how you got all of your camber

Unfortunately, from reading here and on rennlist, I mistakenly went down the road of thinking that only shims were required to get the camber I wanted (-2.5ish), and ended up damaging a fender in the process. Hopefully we can stop someone else from making the same mistake.

From my experience and subsequent conversations with a few people that know what they're doing, rotating the mounts is the way to go if you want to go with a lot of -ve camber in front. A small amount of shims are then used for fine-tuning of camber, and indirectly, caster. Your 4mm is exactly what I was told I'd need to get to -3 if I rotated the mounts. A side benefit of rotating the mounts is that you can run larger front tires without fear of rubbing. I talked to a guy that used to autox a GT2 and ran 265s on the front after rotating the mounts.

 

The guys that I meet at the track with GT3RS's are also running 265's...

I am running Hoosier R6's 245/35-18's at the moment, will be going to the 255/35-18 (it's the same exact width as their 275 and the perfect diameter as well)... I did a test fitting and it fits perfectly... The JRZ's have small diameter springs on them, so there is a decent amount of clearance with my setup right now.
Thanks for posting the info on here.. The more we know the better off we all are.

Cheers..