Looks good, very clean. So you aren’t planning to change the damping in the paddock? What about ride height?
I think it’s fair to say you have the most track ready s4 on the boards, maybe qua77ro being the only equal. How comfortable is your car on the street?
Adjustment sounds like a pain in the ass.
In emails with Bryan Hise at JRZ, I requested he design the system to stay at OEM ride height. I really didn’t believe it until I saw it. It’s probably 10mm lower than I had though visually it looks the same. We’re roughly at 25.9" to 26.2" fender height all around. I have a full 6.0" of ground clearance rocker panel to ground. The springs are still settling and I haven’t corner balanced it yet. I’m anticipating a 3700 pound empty weight, and low 39xx with the driver and fuel in it (track weight). The tech working on the car is an expert and the craftsmanship in this custom job is all his. He even made nice caps for the front towers out of recycled BMW gaskets (that’s Berkeley for you). He made mention that this ride height didn’t move the roll center (or else it would dive excessively under braking). He also mentioned the wheels have over 7" of droop when the car is raised, which means the suspension can travel freely.
Setting these dampers on 12/24 (which I now know is a race setting), I can say they’re in an entirely different league than a Bilstein/KW/HR street kit. I honestly might revert the front to 0/24 and the rear to 4/24. I want to leave it at one tuned setting. Finding the balance where I like the low speed rebound and I like the high speed rebound is going to be key. Obviously I only have one adjustment, with the ability to bias it front to rear. It’s enough rope to hang myself with for now. I can’t imagine starting with 2 way or 3 way if you hadn’t gone through this beginner’s exercise.
If I’m right this will be one of the most track ready S4’s. If I’m wrong it will be expensive for me to inch my way there. I have 3 track weekends scheduled in Jan/Mar/May. We’ll find out. Though I’ve put a bit of cash into this I feel it’s less expensive to keep my low miles S4 than purchase a 2015/2016 sports sedan, which runs over $70k at least.
http://tapatalk.imageshack.com/v2/14/12/14/83d63dd7ff2832c6b2c9afd3303e18f3.jpg
http://tapatalk.imageshack.com/v2/14/12/14/953726d822b2ae80528bb904b7243bc7.jpg
This isn’t specifically about the B8, but shows what a next level suspension has in terms of componentry: http://www.elephantracing.com/tool-box/specs/991/Cup/991-GT3-vs-991-Cup-Car-Suspension-Comparison.htm
I read through that and some of it is pretty cool to see the differences. Certain things have been out for a long time either with other OEMs or with aftermarket companies.
I like the adjustable caster link. Most cars have caster locked in place from the factory and the only time that it is off is when you get into an collision or something bends the control arms. Don’t see why the GT3 needs a rubber bushing there since a solid adjustable puck probably wouldn’t transfer much NVH to the driver.
They use spherical bearings basically every where instead of rubber bushings. Certain people like me want to do that anyways just to not have rubber bushings.
The sway bars have blade ends that allow much finer adjustments compared to the normal two to three hole adjustable sway bars that are sold now. Very cool.
I haven’t seen so many double shear bolts/nuts. Never seen a single shear end break but apparently it happens enough that Porsche felt it was worth the time and aggravation.
My final settings on the JRZ are 0/24 front and 4/24 rear, which is close to “maximum soft”. It’s highly competent both at low speed around town and stable/connected at high speed over expansion joints in the highway, drainage grates, and other obstacles. You can be more confident than stock on almost any surface.
Now it’s a question of how many miles these will last. If I can get 14,000 miles and 2 years out of them before a rebuild I will be very happy. If I could get a second set of the dampers for $2400 I’d consider doing annual rebuilds, to keep them at peak performance and avoid having them leak or blow out when they naturally expire. I’ve seen some Stasis/Ohlins kits go at 8000 miles and a dozen track days - they start seeping fluid.
@boro92 - I dropped off the OEM dampers with 39,500 miles and 30 track days on them (!) for a shock dyno. I won’t get the results until next week. I had to double check my track calendar but it is actually 30 days. Obviously I’m going to discard those dampers as they have exceeded their useful service life.
August 2014 Hooked On Driving Laguna Seca 1
July 2014 HOD Thunderhill-West 1
May 2014 Audi Thunderhill 2
March 2014 Audi Laguna Seca 2
Jan 2014 Audi Thunderhill 2
Oct 2013 Audi Sonoma 2
Aug 2013 BMW Laguna Seca 3
June 2013 BMW Buttonwillow 1
May 2013 Audi Thunderhill 3
Jan 2013 Audi Thunderhill 2
Nov 2012 BMW Thunderhill 2
Oct 2012 Audi Sonoma 2
May 2012 Audi Thunderhill 2
Apr 2012 BMW Buttonwillow 1
Feb 2012 BMW Laguna Seca 2
Nov 2010 BMW Thunderhill 2
http://tapatalk.imageshack.com/v2/14/12/24/5763e7ee9799d58a84bbd93af3eb7ebc.jpg
With me in it and half a tank of fuel:
http://tapatalk.imageshack.com/v2/14/12/24/f37e9dfeef0c16ecf8b026185a17159d.jpg
Looking more closely at the specs, it appears my rears were not pushed out by 5mm per side swapping in RS5 hubs. So while my front 5mm spacers were not necessary to even that out, I’m going to keep them as a wider front track by 10mm (0.4") should have desirable traits for turn in and control.
It is slightly concerning that the wheelbase is off, but I think that is attributable to the difference in caster rather than a serious issue.
One other note - the tech thinks my rear sway bar may be bent. Fucking eurocode. Should have gone H&R. I have to keep an eye on it.
Wow! Thank you!
This is going to be pretty cool. No one has documented stock shock curves anywhere.
This’ll give so much insight into how much Audi cares for tuning the car “properly” out of the box, and whether or not they spec good units. I will expect the rebound settings to be pathetic on the stock units 
Nice alignment specs.
Curious to know - why so much camber out back? Are you fighting a tire wear issue? The camber curve on the rear end of the B8 is way more aggressive than the front. As for running spacers–you will actually take away turn in response due to the increase in scrub radius. But, the trade off is you have much more room to run a bigger tire…so that is a good trade off if you are running some big rubbers all around (see camaro Z/28 for example of this :D). A total of 20mm difference on track width is a noticable difference in turn-in (a reduction in turn in response). I ran 12mm out of necessity on my previous E36 track car, and the drop in steering response made me sad 
YMMV
I run the high camber to mitigate outer tire edge wear at track events. The B8 also has a tendency to roll the tire edge (you can tell when it happened because the pavement will remove the lettering from the side of the tire). Camber is the only thing I know that addresses this.
It’s only a 5mm spacer. In any case I may pull it off. Don’t fix it unless it’s broken is the smartest modding advice I know of.
Exactly if it’s not broken don’t break it. If it’s working stick with it.
Do you by any chance have a picture of the rear sway bar mount on the S4.
Makes sense, I was only curious due to the car’s tendancy to understeer.
I tracked last year with bone stock alignment, and had minimal tire wear concerns with my rear tires.
It’s actually the fronts that have the big problem of killing the outer edge of the tire.
FWIW tire pressure will help combat the tire wear issue. I actually run around 38psi f, 42psi r hot pressures. The higher pressure reduces the side wall roll over issue…but also, having such high rear pressure reduces grip out back…in my attempt to balance out the handling of the car. It’s okay for big tracks. Smaller, street style tracks really pwns the rubbers. The stock alignment, springs, dampers, EVERYTHING is very ill-suited for a tighter circuit (read: non GP style).
FWIW also, I ran -1.8 rear on my E36 M3 (yes, I know, different platform) and did not have rear tire wear issues. Again, it was the front, and that car I was running -2.5 and it was insufficient. I am hoping I can get more than -2.6 with camber arms up front next season…but seeing that you can get -2.6 on stock ride height, that’s awesome. I will be a little lower, so may be closer to -3 (fingers crossed!).
Glad to see you are doing this up all hardcore. No one else is that serious about this platform. It’s neat to see.
Some interesting data in here, @boro92, that conflicts with the rear motion ratio of 0.6 that you estimated for the rear. I’m not sure this is accurate, as many several people think the B8 has the same motion ratio front and rear.
"The ratio between the front shock body motion and wheel motion is about 0.65 to 1 and the rear is 0.80
to 1. This means that the wheel travels about 1 inch for every 0.65 inches of shock body travel on the
front and 0.80 inches of spring travel on the rear. Therefore, for example, if you wanted to lower the car
½ inch from its current ride height at the right front wheel, then you would have to lower the lower spring
perch on the right front shock body by ½ x 0.65 = 0.32 inches. The rear motion ratio is calculated the
same way. "
Interesting. I actually calculated the motion ratios based on information from Stasis!
Using the formula to calculate motion ratio (Wheel Rate = Spring Rate * (Motion Ratio ^ 2)), I just got the #'s using the spring rate figures given by Stasis for the S5. If you also do the math based on the Stasis verified OE spring rate of 480f/440r, you’d get the same wheel rates as I have.
I wish the motion ratio out back was 0.8. But it isn’t. Easy test: Push down on the car (with stock suspension) from the front. Note how stiff it is. Now, push down on the car from the back. Note that it is softer.
Based on the known spring rates of 480f/440r, if the rear motion ratio really was 0.8, the back should actually be stiffer due to geometry. But it infact is not.
BTW thanks for posting the OE dyno. I was chuckling when I saw it, but it’s pretty much expected. Stock shocks are noooooo gooooood for road course duty. The rebound is really not there at all. But what’s interesting to see is that Audi put in a digressive curve. Definitely made to soften large impacts at speed. The difference between front and rear in both rebound and bump stiffness is huuuuuuuuuuuge. Totally looks like Audi made the stock configuration very understeery on purpose. The only saving grace is the sport diff–but that is only helping on corner exit in most cases @.@
@boro92 the distinctions you made were helpful. Now I see quite clearly how the rate of increase decreases with force (digressive), in the OEM struts. I also notice how linear the JRZ is at the stiffest setting, and how the rate of increase increases (progressive) on the softer clicks. It’s impressive.
Additionally, the OE struts have a compression bias. I’m now seeing clear as day the rebound bias on the JRZ.
One concern - I’m at 0/24 front and 4/24 rear, which seems like it has much lower compression and rebound across the entire curve than OEM (comparing the pounds of force at any given velocity like 3 in/s or 10 in/s). It seems to control the chassis quite well without rattling everyone on board too badly, but is it a regression? The wheels feel like they’re glued to the ground. Maybe what I’m noticing more in the ride is the linear springs at their stiff rates, over the big soft progressive springs Audi shipped with?
There are a couple things going on with the factory setup. Road cars with stock suspension is usually going to have a bump stiffness bias (rather than rebound bias). This is because the factory springs are so soft, too much rebound can overpower the spring and cause it to pack down after hitting a series of bumps.
I wouldn’t sweat your JRZ’s at 10 in/s. That’s like, probably never happening in the real world. 10 in/s is like getting airborne and slamming back into the ground (probably). 3 in/s and under is what counts for road course duty, so those are the areas you want to care about.
The JRZ’s are definitely regressive. All proper coilovers are. This allows you to run a stiff spring, but yet allow the tire/wheel to maintain contact with the ground on high speed impacts. That said, if your current config has actually less rebound than stock, you are in for a treat when you dial it up at the track 
More rebound out back = much less brake dive (because the back of the car is resisting lifting). You can then brake deeper/harder with more traction in the back. A higher rear rebound setting will also yield more mid corner/corner exit rotation.
Similarly, more rebound in the front = less front end rise under accelleration. Also, more bump in the front = better immediate turn-in response. Of course, there’s a balance you want to achieve to all this, as you in general are dealing with an understeery platform.