This is a general guide in stages for those interested in tracking their RS5’s on a road course. If anyone has an experience with a particular product which worked or did not work, post up about it and I can amend the top of the thread.
This’ll mostly focus on suspension and brakes although I’d like to include engine and transmission tunes/modifications as well.
BRAKES AND SUSPENSION
Let’s start with the basics, assuming you’re going to make no changes to the car and track it as it came off the showroom floor. The RS5 is track capable as-is and will run comfortably up to a certain point. It’s also driver dependent, particularly relying on the owner’s driving style. If you’re hot in and hard on the brakes all the time, those along with your tires will become a limiting factor. Try to drive smoothly and keep the car in shape at all times and those components are going to last longer. With that said, there are aftermarket components available which can take advantage of improved driving skills and allow the car to perform at a higher level while still maintaining a bit of mechanical cushion.
-The car should have a mechanical once-over to ensure all fluids are at the correct level as specified by Audi. There should be no leaks and the car should be in excellent mechanical shape with no mechanical issues or stored codes for the drivetrain. If you have a small nagging issue, fix it before hitting the track.
-The brake fluid should be fairly new, definitely less than two years old. It’s a good idea to do a full brake bleed prior to the track day. Do not do it the night before. I’ve found it often takes a second attempt to fully get all the air out.
-Brake pads and discs should be well within factory specifications for wear.
-The oil should be fairly new. If it’s towards the end of it’s change interval, it’s probably a good idea to swap it out for fresh oil.
-Maintenance up to date including the transmission and rear differential fluid.
-Tires should be inflated to the manufacturer’s recommendations. Experiment with tire pressure to suit your needs and tire wear.
-Tires should not be towards the end of their life.
-Most sanctioning event bodies will NOT allow you to run with spacers. Keep that in mind if you’re using them with the OEM or aftermarket wheels.
-All bodywork, including panels underneath, should be securely attached.
If you’re worried about paint chips, the old fashioned method is painter’s tape. There’s a lot of new offerings from clear protection films, spray-on and even roll on protection films that you can later peel off.
Paint shield is one such product. https://generalchem.com/product/paintshield-5720
Ok so now that you’ve been to the track and officially have the “bug”, you want to step things up and see how fast you can safely go. My advice is to start from the bottom up. This means tires, the best tires you can afford and are comfortable running on the track and the street. Tires will help other components perform at their optimal level as well as help you find any perceived weaknesses in other areas and components. For many, a set of sticky max performance tires is enough. Just remember you’ll need to drive home on them.
Wheels, tires and brakes. Maybe you want to run different tires on the track than you do on the street. At this point you’re looking at aftermarket wheels which are hopefully lighter than the OEM wheels. The OEM rotor wheels, 20" size, come in at about 35 pounds each and are 9" wide. Most aftermarket forged wheels will run 25 pounds or even less in a 20"x10" width. It IS possible to bend a wheel nailing the rumble strip at certain tracks, even forged wheels.
A tire/wheel package will generally run you at least $2,000 and can climb quite quickly. It’d be easy to drop $5500 on a set of forged wheels and say Michelin Cup2 tires.
-Before making a decision on wheels, make a decision on tires and check the available sizes and cost.
-Consider going to a wider 10" or even 10.5" wheel if you have a tire that will work with that rim width.
-Wider isn’t necessarily better! You can “over tire” a car if it doesn’t have other components to take advantage of the increased grip.
-Consider the tire’s weight in your equations. The OEM 275mm width will weigh less than a tire with a 295 or 305mm width, sometimes by as much as five pounds per wheel. Look at the weight of the tire AND the wheel as a combined package. Different brand tires will also weigh different amounts. Tire Rack has the weight for all of the tires listed on it’s page.
-Use several criteria for tire choice. In addition to all-out performance, consider how often you’re willing to replace your track tires. Is three tenths more important than having a set of tires that’ll last four track days a year? Tires are consumables. How often can you afford to replace them?
With stickier tires, the RS5 can now take advantage of an upgraded braking system. The bare minimum is to run a brake fluid with a higher WET boiling point vs. the OEM fluid. Forget dry boiling point numbers, that goes out the window the moment you crack open the container. That wet boiling point will be a good indicator of how long the fluid will last. The “best” in my opinion is Castrol SRF. It’s EXPENSIVE. But it really is the best option. There are others which are less costly and perform almost as well. So do your research and don’t be afraid to experiment with different brands. Most will perform really well as long as everything else is within specification.
Pads. Pads are a very personal choice usually based on initial brake bite, modulation and a number of other subjective criteria. Bottom line, a dedicated set of track pads will always outperform a street-biased pad AND you brakes will most likely run cooler overall. This isn’t a super technical breakdown of pad materials although we can add that later. You can use track-biased pads with the OEM rotors. Realize you may have to bed-in the new pads to the rotors and do it again if you swap the OEM pads, or a street pad back in. Some manufacturers tout the compatibility of their track and street pads, with a re-bed procedure not needed. Just swap the pads and you’re done. One such company is Carbotech and I’ve used their pads with great success in the past. They also have a helpful guide on their web page and will answer any questions you may have. https://ctbrakes.com
Understand the pad’s braking power comes from material transfer to the rotors. Pads and rotors which are not bedded in can wear more quickly and not perform as well. The RS5 weighs in at more than 4,000 pounds. Take that into consideration when choosing pads.
The standard iron disc front brake setup on the RS5 uses the same caliper and rotor as the Audi R8 equipped with the iron front brakes. Pads, rotors and calipers are interchangeable.
What if I have ceramic front rotors? The carbon ceramic front brakes on the RS5 are fantastic. The rotors, pads and calipers are identical to the ceramic brake setup on the R8V10 and Lamborghini Hurican including the Performance and new Evo. In fact, the rotors are the same as the Gallardo front ceramics too. The rotor is 380 x 38mm and the caliper is a Porsche 19Z.
Their big advantage is less rotating and unsprung weight. They’re pretty much fade resistant and can handle anything you throw at them.
With that said, they are extremely expensive to replace. Carbon ceramic rotors wear when they overheat and aren’t give a chance to cool properly. The resins outgas and that’s what is holding the matrix together. While there can be visual indicators concerning wear, rotors could look absolutely fine visually but not be within specification. The only way to truly tell is to clean and weigh the rotors or by using a special tool imported by Porsche NA to digitally measure the wear with a laser-guided tool. It cost about $7,000 so it’s not suitable for the DIY’er.
Replacement ceramic rotors can run anywhere from $6,000 to upwards of $10,000 depending on where you’re shopping. You CAN track a ceramic-equipped RS5 but it’s also possible to go through a set in as little as four track sessions. On the street, they’ll most likely last well past 100,000 miles.
CCB RS5’s do not have to forsake the track. It is possible to replace the CCB rotor with an iron rotor. Both JHM and ECS Tuning makes just such a rotor. It’s a 380x38mm unit with the proper offset used on their big brake kit.
I believe Racing Brake out of Australia also has a suitable rotor for the CCB-equipped cars. They also have replacement CCB rotors which are generally less expensive than the Audi OEM-marked discs.
The RS5 does not have a dedicated brake duct pointing cool air at the inside of the rotor hat for either the iron or ceramic front brakes. To my knowledge there is no “kit” readily available. Each brake type would require a different duct due to differences in caliper size and backing plate design. The suspension linkage doesn’t make it easy to add one either.
For ceramic-equipped cars, there are pad options, most notably from Pagid. Pagid has their RSC brake pads, the RSC1, RSC2 and RSC3, with the “1” being the least aggressive (but more aggressive than OEM) and the “3” being the most aggressive. http://www.pagidracing.com/en/products/racing-brake-pads/product-family-rsc.html
Moving past a simple pad swap, rotors are the next step up. You’re pretty much locked in on the front CCB-equipped cars but the rears can be upgraded. For the iron rotor-equipped cars, there are upgrades for both front and rear rotors.
When looking at rotor upgrades, owners have the option of one or two-piece as well as OEM vs. larger diameter. Two piece rotors come in semi and full-floating specifications with full floating allowing for thermal expansion in two directions for better rotor to pad alignment under duress. Most of the two-piece designs also weigh less than the OEM rotors. Most choose to go with an aluminum hat, two-piece rotor design and most offerings are actually less expensive than the factory OEM discs.
The stock front rotor size is 365mm in diameter and 34mm in width. Multiple manufacturers offer a 380mm x 34mm rotor which also includes a new caliper spacer. The additional diameter and mass will improve overall braking performance all other specifications being equal. Those same manufacturers also sell lightweight two-piece rear rotors.
Manufactures which make two-piece rotors include Girodisc, JHM, Racing Brake, ECS, EBS, Brembo, AP Racing and others. There have been reports from both RS5 and R8 owners that the ECS two-piece rotors do not last on the track.
Springs, dampers and sway bars.
-The least expensive and easiest retrofit is sway bars. I am of the opinion they need to be replaced in pairs, front AND rear, not just the rear as the RS5 will slightly oversteer out of corners when pushed. It’s pretty balanced and I wouldn’t swing the pendulum to the rear with the addition of just a rear bar. With that said, I’m also more inclined to go up in spring rate first. Why? It’s an independent suspension and sway bars effectively “tie” each side to one and other. But…it can be a quick, relatively easy mod which can improve handling. Larger sways increase the effective spring rate and the car’s body will generally tip over less and feel more controlled. This can be a detriment on rough pavement/tracks.
Companies that offer matched sway bar sets include GMG (hollow), H&R, and Eurocode Tuning.
-Springs would be next on the list. There are many, many manufacturers who offer spring kits in various drops. And while they will lower the car, the center of gravity and change the roll rate, they often put the OEM damper piston in a less than optimal position in the damper’s stroke and can cause premature wear. Many have had great experiences with lowering springs however so I’ll leave it up to the end user. The labor cost of replacing just the springs is quite high and I’m of the opinion that you should make the jump to a dedicated set of coil-over adjustable dampers. There are aftermarket shocks designed to be used with lowering springs too. Bilstein makes a set. https://www.bilstein.com/us/en/product-search-detail/?ItemId=6608359963564712073&YearId=8477382149529100437&MakeId=1879536789086600307&ModelId=5467366457346913821&SubModelId=4194908274341715756
-Moving on to full damper or coil-over kits, these offer matched springs and dampers where the damping characteristics are mated to the effective spring rate. There are two types of springs; linear and progressive. Linear springs, for the most part, maintain the force needed to compress the springs through the entire spring compression and rebound. Progressive springs generally start out a bit softer and progressively become harder to compress, hence their name.
Without a doubt, linear springs are more predictable on the track and offer a slightly more “locked in” feel with less squirm. Progressive rate kits generally offer a better ride on the street due to the initially softer compression force and their ability to absorb road irregularities. A linear rate kit with a very high quality damper and appropriate spring rates can ride very well on the street.
The big three are Bilstein, KW and Ohlins. KW offers multiple kits, from non-adjustable to two-way adjustable. Unfortunately the two-way adjustable requires the rear dampers to come out if you’re going to adjust the compression damping. Ohlins offers one kit which features linear rate springs. Bilstein has two kits, one featuring in-cockpit adjustment over three settings and a manually 1-way adjustable kit with supposedly 10 clicks of adjustment. I find mine have eight. All three kits feature height adjustment via the spring perch. The fronts are true coil-overs with the rears featuring a separate damper and inboard spring.
My big problem with all of the full kits is they’re for not only the RS5 but also for the S5 and A5. Are they all therefore a compromise? The A5’s weight distribution and indeed its overall weight, is different from the RS5. Or do they make it specifically for the RS5 noting that it’ll work with the S5 and A5?
Irregardless, a quality kit can drastically improve handling and how well the tires stay glued to the pavement and will take advantage of the increased traction offered by better tires and wider wheels. Some kits are a bit lighter than the OEM components as well.
Bushings, inserts and braces. Truth be told, most of us, myself included, have already purchased all the available bushings, braces and various inserts available for the RS5. Overall they’re not that expensive and are relatively painless to install.
Inserts and bushings are designed to limit movement in parts designed to move. So expect a slight increase in noise, vibration and harshness (NVH) as a result. They’re often solid, milled pieces of aluminum which are pressed into voids within various factory mounts from the transmission to the differential to the rear subframe. The solid pieces limit movement allowed by rubber inserts on the original pieces. 034 Motorsports and ECS Tuning are the big two companies that make most of the inserts.
There are two readily available chassis braces. One is called the Alu Kreuz and it replaces the under brace which sits below the oil pan. It’s vaguely shaped like a boxed in X and is milled out of billet aluminum so it’s a bit lighter than the OEM stamped, welded and extruded piece. Two companies make them, the original inventor is Eurocode Tuning and 034 has a slightly different knockoff version.
Then there’s the Canyon Run CR-15 bar. This is a cleverly engineered bar which fits behind the firewall and provides some support between the strut towers.
Both units are reported to reduce chassis flex and improve steering feel/turn in.
Here’s a link to the CR-15 plus an installation video; https://eurozonetuning.com/products/canyon-run-cr-15-front-strut-tower-brace-b8-b8-5-a4-s4-a5-s5-rs5?variant=2687223201820
The rear differential can use up to three inserts/bushings. There is a big bushing which sits in front of the rear differential and two bushings behind and on either side of the rear differential. Those two take inserts. Again, Eurocode Tuning, 034 Motorsports and ECS Tuning make a majority of the inserts and bushings. Apikol also makes a poly insert for the main rear differential busing and I’m a big fan of it as it can be customized to fit your needs and still allows a bit of movement.
Links to other bushing inserts:
There’s also a transmission insert as well as a more stiff transmission bushing to eliminate slop at that point and provide crisper shifts. 034 Motorsports sells both the lower insert as well as the main unit which features a high durometer rubber mount.
This last stage includes aftermarket big brake kits, roll bars, additional chassis bracing and at least, double adjustable motorsports-grade dampers.
Currently, as far as I know, there is only one double adjustable motorsports-grade kit and that is from Öhlins. PSI Shock in Sonoma can put the kit together for you and I know of one individual who runs these shocks. It is a big step up from the Öhlins R&T dampers.
Other manufacturers include JRZ, Moton(AST), Penske, etc…but you’re going to spend big, big bucks on a completely one-off custom setup through those vendors. I’m talking $5K on up. It looks like AST has a single adjustable kit for the B8 but honestly, I’d go with Öhlins over AST. Aragosta is a company out of Japan and I’ve run their dampers on multiple cars over the years including a road race RX7. Unfortunately, at this time, they don’t offer anything for the RS5.
I would avoid any of the Korean/Taiwan brands like Fortune, K-Sport, BC Racing, Megan Racing, etc…they’re all made in one of two factories either in S. Korea or Taiwan and are definitely a big step below offerings from Bilstein, KW or Öhlins. Yeah, they “look” great but often have sub par tolerances, piston designs, shim stacks, valves, etc…
ENGINE AND TRANSMISSION
Thanks to JH Motorsports here in the United States, we now have a viable, powerful, reliable tune for the RS5’s engine and transmission. Stage 1 is an engine tune and it does unlock considerable hp. I personally saw a 25hp gain after testing on a dynamometer and the car was much more enjoyable overall.
Stage 2 is primarily a transmission (TCU) tune although changes are made to the engine tune (ECU) as well. Besides the dramatic increase in acceleration abilities, stage 2 improves shifts up and down, a more aggressive launch control, as well as reworked drivability characteristics in D and S mode. It also unlocks even more horsepower. The difference is simply night and day and either option is definitely worth the rather modest price of admission. The full stage 2 completely transforms the driving experience and it will definitely transfer over to the car’s on-track performance. S mode in particular is far more aggressive and the throttle calibration is also changed for improved engine response. It’s really a must-have for even street-only weekend cruiser RS5’s.
Unfortunately there are no aftermarket oil coolers for the RS5 but as is, the RS5 comes with a giant Setrab oil cooler which is actually larger than anything Setrab offers independently off the shelf. The RS5 also has a main radiator along with two auxiliary radiators on either side below the headlights. They’re up to the job for the most part with, in my opinion, the ECU-controlled thermostat being the weak link. It can actually vary your coolant and ultimately your oil temperatures by manipulating the main coolant thermostat.
What isn’t up to snuff is the OEM transmission cooler. It’s a liquid to liquid heat exchanger which uses your rather hot radiator fluid to “cool” the fluid (automatic transmission fluid or ATF) on the clutch/mechatronic/TCU side of the transmission. The gear side, which is filled with gear oil, has no cooler although there appears to be heat transfer between the gear and clutch/mechatronic side of the transmission.
The ATF fluid is responsible for cooling the mechatronic, electronic components such as the PCB and TCU as well as the clutch packs. It also provides hydraulic pressure for the solenoids and lubrication for the clutches and various other mechanical parts.
Luckily, this past year, saw the development of the RMR transmission cooler which solves and greatly improves upon the cooling performance this car so desperately needs. It’s a fully-divorced system meaning it no longer interfaces with the car’s radiator. This is beneficial for two reasons. First, it removes some of the heat shedding burden from the radiator and gives you more capacity to cool the engine and the oil. Second, it allows the transmission to run at a lower overall temperature along with all of the associated components, including the main computer. The kit also comes with a new cross bar which allows more air to be forced through the radiator. Here’s a video on the RMR transmission cooler; https://youtu.be/KHkgBHrraeI
Plugs, Filters & Oil
For plugs, you’re fine with the OEM offering. No need to change heat range or anything crazy like that. I have tried a few plugs and recently switched over to the NGK 92400 Ruthenium HX which has a slightly different electrode design and I’m quite happy with them.
Filters. K&N offers a drop-in replacement filter for the RS5 which seems to produce as much power as a $2500 carbon fiber intake. They should be just fine for track days and you can, of course, clean and reuse them.
Oil. There are many, many offerings and it’s really a rabbit hole endless debate. I like to use a Group 4 full ester synthetic. There are very few “true” group 4 oils being sold. Make sure it meets the Audi specification for the RS5 (502.00). I like to look at the oils viscosity index amongst other things as well as what it’s made of. There is literally a ton of information out there yet, in reality, it’s almost not enough to make an educated decision without proper scientific testing, used oil analysis and so on. Oil change intervals should be every 5,000 miles. Don’t go the full 10,000 miles especially if you’re tracking the car.
Motul has a readily available, ester-based full synthetic in 5w40 called Motul Sport. I have yet to try it but will use it on my next oil change. But there are a number of super high quality oils available. Consider taking the time to send in samples to a testing lab after a track day. They may help point you in the right direction. Be sure to share the information here!
More to come…