Review: Wavetrac Front Limited Slip Differential for DQ500 Transmission (2018 Audi RS3)

Abstract: The Audi RS3 (and TTRS) are plagued with under steer in all phases of the cornering process. The 68% nose weight prevents the car from ever actually being balanced, and the front wheel drive bias of the car’s all wheel drive system means that the emphasis on front traction is mandatory. Audi tried to “help” this in a few ways, however this specific review will discuss my experiences with the Wavetrac limited slip differential to help increase the front traction at mid-corner and corner exit.

The Decision and Aquisition

Working with the folks from #oneof250 as well as some other friends that have done events such as One Lap of America (OLA), and have much more experience in modifying cars for handling, I decided to purchase the Wavetrac for the DQ500. This is supplied by AutoTech in the US, however they aren’t the direct distributor. I reached out to USP Motorsports, and spoke with Justin via their website’s chat function (support and info was available immediately) about some issues that earlier Wavetrac’s had seen, and then decided to place the order. He estimated about 14 days to arrival, and it was delivered to me in 12. Total cost for the Wavetrac from USP was 1799.00

The Install

I chose Black Forest Industries in Cary, NC to handle the install for a multitude of reasons:
1) They are close to me (about an hour each way)
2) They have a machine shop on-site, so if something went wrong, the likelihood of them being able to correct it was extremely high
3) They have experience with Wavetrac
4) Their ability to source Audi parts directly, especially the hard to find ones, is great
5) Open, Honest, and transparent communication

We had an initial false-start on the install due to a delay on a few parts coming from Audi. Due to Covid-19, Audi has ceased all overnight shipping of any parts, and is shipping all parts 100% FedEx Ground. Also, all Audi parts must go to a dealership before they can go to an independent shop or a consumer, further delaying things.

To do this install, I recommend having the following already on hand:
– DQ500 WaveTrac (1799)
– Upper radiator hose (if your car has over 30,000 miles) (150)
– Clutch pack seal (80)
– Axle seals (25 for the pair)
– Billet oil tubes (129)
There are a few other miscellaneous seals and gaskets, however they are standard size and not specific to the RS3. Please note that you will need to do a transmission flush after about 500 miles of install on the Wavetrac.

Once the process was started, things went fairly smoothly with a few exceptions. The upper radiator hose and one of my heater hoses delaminated, and needed replacement. Most of the ‘extra’ time was spent waiting on the upper radiator hose, and the difficulty in getting this has caused me to go ahead and order a spare to keep on hand for future use. The heater hose was able to be shortened and re-used for the time being, however we’re *still* waiting on it. The overall install was smooth and no additional shimming was necessary, however this does involve dropping the engine to get to the transmission, pulling the transmission and splitting it open. If a shop has never done a DQ500, that’s fine, however if they’ve never done deep transmission work on any VAG car, I would not trust them to accomplish this.

We hit our first real snag when putting the drivers side axle back in. We’ve heard reports that some of the earlier Wavetrac’s were engineered with incorrect specs, however did a test fit on the bench to ensure that this wasn’t one of them. BFI did this test without the circlip installed on the shaft, and the splines fit perfectly. Once the circlip went on, it did not want to seat on the drivers side. Passenger side went perfectly. Further, not only did the drivers side not seat, it actually got stuck!

We’ve now reached the point in this article where I simply state that I’m extremely glad that my car was at Black Forest Industries. This team knows their trade, and knows what they can do. Trying to force the axle out was not an appropriate solution and they did not want to harm anything in the process. These guys actually engineered, and CNC’d a custom tool to extract it while it was still installed in the car, and then were able to carefully sand down the offending piece to reinstall it. Any other shop that I had consulted with would simply not have been able to accommodate this, and I probably would still be without my car while they figured things out. In addition to that tool, I heard that they also had engineered a few other tools to press certain pieces back into place exactly as they were intended to fit. None of this “well, that bearing is close enough to this place” stuff that you sometimes see (or that I would do in my own garage). This is next level, to say the least.

Once they had it released and milled down, everything went back together smoothly. When I picked up my car, I not only had a report on the Wavetrac, but also a report on a few other maintenance items I should look into (brake pads were low… not surprising 🙂 and a wheel hub/bearing on the rear needed replacement). Overall, I could not be happier with the transaction. They communicated sometimes three to four times a day, with pictures, and called me the second there was a problem. Even if nothing was up, Adam still gave me daily updates. A shop shows their value through transparency, accountability, and simply doing things the right way. I trust them. So should you.



Results (you know, the fun part!)

I’ll cut right to the chase. I shaved 4.2 seconds per lap at Carolina Motorsports park, no other changes to the car save a small ride height change in the front. The events were 2 weeks apart. I have *never* had a modification impact me this much. The only modification that I’ve done that had the same $ per second drop was moving from all season tires to 200tw track tires. The car simply pulls through corner exits now. I still have to enter slower than I’d like to prevent the plowing, however once I get to mid corner I can get back on the throttle and head out. Straight line speed was up 4-5 mph at the end of each straight. I’ve got a fair amount of experience at CMP, and I was using my ‘normal’ lines. This is effective in low speed technical corners, don’t expect a miracle at higher speeds where you’re more momentum and suspension dependent.
Car configuration for SCCA Track Night in America (only different between events was Wavetrac) matches the SCCA Tuner 2 TimeTrial class.

Street manners are no different than stock, you can’t even tell it’s there.

Total cost: Budget for 5,000 and you’ll be happy.

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