[JCviggen]

Driving on track with Cup 2's I needed more camber, easily solved with some GT3 LCAs or adjustable top mounts, I know, but the easiest and fastest thing to get out here was some PU Powerflex bushings that are eccentric for camber adjustment. They're supposed to give .75 degree in each direction. For about $200 shipped, I figured more camber is more camber. https://www.powerflex.co.uk/road-se...+Arm+Inner+Bush,+Camber+Adjustable/10953.html

I had previously maxed out the slots in the front suspension, giving me about -1.8 degrees with my X73 suspension. Somehow didn't feel like quite enough when doing time attack laps on Michelin Cup 2s.

Here are the alignment numbers stock - stock with max camber - Powerflex with max camber.

On the whole, they don't seem to have reached the advertised adjustment, but an extra .55-.60 degrees on the front axle is still pretty good for the money. One thing I've noticed is that the caster has increased significantly, unlike when the strut tower slots were used the first time around. The car still felt fine on the road on the way home so it's probably within reason, but it may be a side effect of increasing camber this way. Will see if I can feel a difference on Sunday, last time out I had a lot of understeer on new tires. I did also add a Rennline subframe brace now together with the front bushings so any effect of that will be mixed in to the experience.

 

[lovetoturn]

I think you will enjoy the upgrade. I run -2.4 in the front and -2.8 in the rear. Next alignment will be -2.5 in front with a little toe out for more front end bite. The increased caster is a by product of widening the track whether it is from eccentric bushings or the shims on the GT3 LCAs. I am about 9 on the caster as well. You should be ok with those numbers but the 9.28 is a little high.

 

[JCviggen]

A little post-rack analysis if anyone's interested.

Going from about 1.8 to 2.4 negative on the front axle is definitely very noticeable. Finally it's starting to get past the point where you always feel you're driving on the outside shoulders of the front tires. I think a few tenths extra would be nice, but -2.4 seems pretty good and I suspect there will be diminishing returns when pushing further.

I can't tell if it's mainly the extra camber, or the rennline subframe brace at the back, or my Cup 2's not being what they used to be, but corner entry oversteer is becoming a little excessive. It was always there with the X73 even fully stock, but it's hard to do an entire lap and not screw up somewhere as the car is on a bit of a knife edge with rear grip. Traction is still decent, but trailbraking is a lot trickier than it was last time out. Admittedly I had too much understeer in the car then.

Maybe I just need to adapt a little more to it, the car is faster and that's what you want in a time attack format. As you're pushing the limit, you're going to find it eventually either at the front or the back and I do prefer the front end being pointy.

Oh, and finally, braking felt VERY good. Don't know if the stiffer LCA bushings had any effect on that or simply the slightly altered toe angles but stability under braking was excellent and confidence inspiring.
Here's a few examples https://youtu.be/sPqf-GGHwoM (the last one was a stubborn right foot kind of thing, not exactly relevant)

Overall the car did very well and was very very fast relative to the other stuff out there, so I'm looking forward to next season.

 

[lovetoturn]

Everything you are saying is right on as compared to my impressions when I first went to -2.5 front and -2.2 in the rear. Great front end bite, but not enough in the rear, which does slow you down a bit. Then I went back to more rear camber at -2.4 front and -2.8 rear by adding rear eccentric monoball joints for the rear LCAs. Everything was great after that. Now as I push the car even harder we just went to -2.7 front and -2.8 rear with the toe out in front going from 2 minutes to 6 minutes on each side. Can't wait to get out this weekend and try it out. RE-71Rs are almost done, so it should move around a bit more.

Maybe you can try some of those eccentric bushings on the rear to bring up the negative camber as well to balance everything out.

 

[lovetoturn]

Wow, just saw the video, great driving to keep on the road. Looks like a handful. No nannies there it would appear. Definitely looks like you need more negative camber in the rear.

 

[JCviggen]

Wow, just saw the video, great driving to keep on the road. Looks like a handful. No nannies there it would appear. Definitely looks like you need more negative camber in the rear.

Thanks, the first one was with PSM on in sport+ mode which is lenient enough to get into a bit of trouble. Last one everything was off obviously.

Ideally I'd like to soften up the rear ARB a bit but it's non-adjustable so maybe the extra camber at the back is the way to go. Stock Porsche puts a lot more camber at the back than the front so maybe it makes sense to stick with the intended balance of the car.

 

[lovetoturn]

Stock set up is (-.5 front and -1.5 rear) but (-1.5 front and -2.0 works) much better. If you add -.6 camber to the rear with some bushings you would end up with (-2.4 front and -2.8 rear). Humm... that is exactly what has worked very well for me over the last year.

 

[JCviggen]

Brilliant, one last thing though, you didn't run out of toe adjustment going that far negative at the back?

 

[lovetoturn]

Yah, you are going to need adjustable rear toe links to get that much camber. Tarret and others carry those, and they are on my car. With 6 mm of added track from eccentric monoballs at each rear corner, some readjusting of the rear subframe to make everything even, you can get a max camber of -2.8. Rear LCAs are the better way to go, but eccentric bushings or monoballs are more cost effective.

 

[lovetoturn]

Just had a great weekend at the track. The -2.7 front and -2.8 rear camber worked excellent with a little toe out in the front. Ninth and tenth day on a set RE-71Rs which are done due to heat cycling, but so much fun. The pace was about 3 seconds slower from about a 1:23 to a 1:26 lap. It feels a little like being in the damp cause the tires move around so much. A little understeer slide, some oversteer slide, or a neutral 4 wheel slide. You can pick your poison and work the slip angles as you like depending on the corner. I still leave PSM on most of the time and can have plenty of fun within its restraints. These camber numbers are probably above what most are contemplating unless your car is mostly for the weekends and or the track. Just an FYI to let anyone know that these numbers can work well and the car drives just fine on the way to and from the track.

 

[JCviggen]

I wish we could get those tires here, I get like 3 days out of the Cup 2's before performance drops off too much to compete properly. They don't seem to be sold at all in Europe by Bridgestone.

The camber is interesting because I know my closest competitor in a 981S is running -3 front -2 rear. Even so his car isn't as edgy as mine with more relaxed camber settings. Main difference: he's on PASM. Of course just because he can run more camber more easily doesn't necessarily mean it's faster than my X73 but still, there seems to be a significant difference there. When running lots of camber I do feel the rear ARB on X73 is too aggressive so I suspect the main difference is there and not necessarily the shocks themselves. I'll have to see what to do for next season, I've put my 20" with winter tires back on, as it started freezing and snowing. 7 months of winter whoopee.