It’s not all too often in DIY wrenching that something requiring very little effort makes a big impact, which is why I’m so thrilled with the transformation of my beloved 2002 Audi S4.
I picked up my example of this iconic late-’90s/early-’00s German sports sedan at the end of 2022. Just $925 plus fees from Copart put my name on its pink slip. Previously, I wrote about some of its lovable/hate-able foibles at The Drive; long story short, there have been plenty of signs indicating deferred maintenance before it got to my driveway. Plus, the fact that its twin-turbo V6 is crammed between its narrow, compact car frame rails makes any degree of wrenching a bit more complex than other cars. It’s been a heck of journey nursing it back to health—or keeping it barely alive, depends on how you look at it.
Which is why I was over the moon when these three recent, simple fixes paid off so well. Here’s how spacing out its wheels, installing an aftermarket front sway bar, and fixing a boost leak made my S4 look, handle, and perform better than ever.
How It Should’ve Come From the Factory, In My Opinion
Alright, maybe this doesn’t necessarily classify as a fix, but it sure did make a big aesthetic impact: Installing 10mm H&R wheel spacers.
Cars often show up on the dealer floor with wheels deep in their arches. But it doesn’t look as good, and I didn’t realize how much of a visual difference it’d make until I did it.
Throwing on wheel spacers is a very easy modification to perform. In fact, I like to think of it more as a mild alteration than a modification. Step one: Acquire spacers from a reputable brand. H&R’s are legal in the eyes of Germany’s ultra-strict vehicle parts legislation—known as TÜV—so they’re good enough for me. Step two: Acquire longer wheel bolts. Step three: Safely jack up and support the car and install at each corner, and it’s a good idea to very lightly coat each spacer with anti-seize along the way. Done!
Even at stock ride height, my very factory S4 looks so much better. Its OEM 17-inch Avus wheels are more prominently displayed and line up better with its sleek sedan shape. Though, there are also downsides to keep in mind, such as the tires throwing more dirt and debris onto the fenders, doors, and rear bumper. Then, moving each tire closer to the inside of its respective fender could result in rubbing and potentially tire damage, so it’s important to make sure there’s ample range of motion. My car isn’t lowered and I haven’t experienced any rubbing across all degrees of suspension movement since installing them, so I’m in the clear.
[Ed Note: Here’s suspension-engineer Huibert Mees’ take on wheel spacers (it applies to lower-offset wheels, as well). There are some significant drawbacks worth noting. -DT]
Cleaning Up Its Handling In the Twisties
Next up, I installed an H&R front sway bar on my very front-heavy little Audi. And boy, do I mean heavy; to accommodate the massive Quattro all-wheel drive system, the S4’s entire engine sits ahead of the shock towers. This doesn’t bode well for overall handling—usually, the farther an engine sits behind the shock towers, the better.
Installation was almost as easy as installing the wheel spacers: Safely jack up and support the front end with jack stands, unbolt the old bar and brackets, install new bar and brackets … done!
Sway bars help reign in body roll under cornering, and this did exactly that. A more substantial improvement in this department often comes from installing a rear sway bar on this chassis, but this made a very nice difference, too. On stock springs before the bigger bar, the front end felt vague and downright sloppy on twisty roads. Now, it feels a lot more taut and confident, and steering weight loads up a tad more in corners. I haven’t noticed an increase in understeer, either. As far as downsides go, well, I have yet to find any. Bumps are more pronounced through the steering wheel, but not to any annoying degree.
Chasing Boost Leaks
Ask any B5 S4 owner, any real B5 S4 owner: It doesn’t matter if your car has 50,000 or 200,000 miles, boost leaks are boost leaks.
After fixing some light boost leaks over a year ago, throwing in fresh spark plugs and coil packs, remedying boost solenoid-related codes, and installing a new mass airflow sensor, I started to feel a general loss of power, plus some stumbling under wide-open throttle. One day while out running errands, the potential cause revealed itself quite prominently: the unmistakable sound of compressed air escaping from boost piping while driving alongside parked cars.
I’ve had to reinstall and tighten the connection between the right-bank turbo and right-bank intercooler before, but that wasn’t the issue this time. After popping the hood, thankfully, the issue was easy to find: The OEM throttle body boot finally tore. It happens to every B5, I’m surprised that it took this long for mine to die.
As luck would have it, a beautiful Imola Yellow B5 S4 was sitting in a local junkyard 30-or-so miles from me down in Orange County, so I headed out to see if I could pull anything useful off of it. The luck continued: I grabbed its sturdier-than-stock aftermarket Samco throttle body boot, plus better-condition bi-pipes—those are the two pipes connecting the intercoolers to the throttle body. Plus, all the clamps holding it all together, as they seemed to be in better shape than mine.
Upon returning home, I swapped it all in and went for a test drive. The mighty twin-turbo 2.7-liter V6 not only ceased stumbling with my foot to the floor, it felt stronger than ever. In fact, stronger than I thought it would. I’m wondering if my old clamps were possibly a little weak and letting a teeny amount of boost pressure out, though I had previously tested it for leaks and everything looked good. Regardless, I was over the moon.
Despite having a turbo on each cylinder bank, the US-spec B5 S4 only makes around 250 horsepower and 258 pound-feet of torque from the factory. That’s not nothing, especially for its era, but these things are a bit heavy at 3,600 pounds. Mine’s also a five-speed automatic, so it’s not the quickest-shifting box out there. Yet, I clicked off a 0-60 mph run in just over five seconds while merging onto the highway, which seems awfully healthy for an auto with deferred maintenance and 135,000 miles on the clock.
Maybe it’s a testament to my attentive restoration, but I think it may have more to do with its tuning; there might be a tune on its ECU that ups the boost pressure a tad. One way to find out is installing a boost gauge, which I plan to do very soon.
But Can I Rest on My Laurels?
The days following all of this were such a treat: My dear rescue Audi was not only more powerful than ever during my ownership, but also looking and handling great to boot. While I’ve spent a lot of time, money, and effort on the ol’ steed—more than simply buying one used from a fellow enthusiast like a normal person—I’m proud to have put it back on the road. Thing’s helped me become a more confident and capable wrench.
However, a new issue cropped up about two weeks later: Its light tick upon startup turned into a constant tick. Boy, the fun never stops with this thing. Listening closely with the hood open, I could tell it was driver-side valvetrain related, and not the injectors or a cashed rod bearing. I attempted to remedy it with an engine flush, followed by fresh oil and a Liqui Moly hydraulic lifter additive, but to no avail. Pulling the valve cover instantly revealed the issue: Several caved-in lifters, though every camshaft lobe thankfully looked to be in good shape. I guess that’s what happens when deferred maintenance meets frequent peak boost.
I’ve ordered new lifters and other miscellaneous parts, and just have to find the time to accomplish this lengthy job. It’s a great learning experience, I’ll just keep telling myself.
What are some quick fixes that transformed your car, and that you perhaps wish you’d done sooner?
Adding an aux port to my Mazda 6i. I had one of the lower trim models that didn’t include an aux port. It still had the aux button though, so the head unit actually supported it. Just a quick removal of the glove box door, and a couple of bolts to get the head unit out, then cut an extra aux cable and bridge a couple of connections on the back of the head unit. Drilled a hole to mount the aux port and put it back together.
The fact that they left the aux input button and everything was functional with the cable added is such a joke, because it means there is no functional difference between trim models except what they remove for the lower end. So it isn’t a cost savings, just a feature delete to entice customers to spend more to get the feature that already exists.
12′ PHEV Prius…
new touring shocks/struts and oem replacement springs at 200k + At the same “while I’m in there” time; I installed a quality 1.5″ lift, basically metal platforms installed as well. And michellin tires (Defender T+H)
These changes made a huge difference, no longer have to worry about potholes as the Prius seems to have rather low ground clearance stock now handles like I think it probably should have stock. For peace of mind I also added an emergency compact spare tire from a regular Prius since the PHEV version omitted a spare due to the larger hv battery pack. Oh I also switched to quality led low beam headlights from Headlight Revolution which have a crisp horizontal light cutoff and are probably 5x brighter than the stock halogens too.
98′ Jetta TDI, performance chip added 25 ‘screaming mini horspowers’ and 50 more ‘torques’. Which doesn’t sound like much, but stock it was I think 90 hp. Post chipping, it made it at least feel pretty peppy. Also replaced oem shocks, struts and springs with HD Bilstein shocks, struts and new oem springs + quality all seasons (spring, summer, fall) and separate winter tires (blazzaks) on separate steel rims for winter traction
90 Jetta GLI
K&N intake and free(er) flowing car back exhaust.
Sport bilstein struts, shocks and sport eibach springs; dropped the ride height 30mm and along with grippy summer tires (some kind of Yokohammas) for +45 F and winter tires (I had some Coopers which were fantastic in the ice and snow on separate steel rims) for below 45 F, made for a spirited 150(ish) hp, 2200 lb 4 door sedan
Spacers are on the list for my 335ix, the stock appearance is sub par.
Best mod for my 2003 Honda Accord was adding a wiring harness and 3.5mm input jack that tricked the factory stereo into thinking my old cell phone was the optional CD changer. Probably the last project I’ll ever do, car or electronic, that was sourced from Radio Shack (RIP)
I feel you, my best ever mod was on my E36 when I soldered an aux cable onto the tape deck. My favorite part was that I had to put a tape in there to trick the deck into using the signal. Found a tape of “number 2” by Butts and pulled out its guts.
One overlooked item on my 2014 Passat 1.8T that made a nice improvement in performance was replacing the PCV (aka Oil Separator), an easy DIY as it is right on top of the engine. The car drove much smoother afree replacement, and also an oil burning issue was cut in half from what I have seen so far. Given that the car was not throwing any codes before replacement at 130k, I would say this is a preventative maintenance in any of these VW turbos at about 100k miles. The rubber diaphragms in the part slowly degrade and leak, but apparently reduce performance even before they get bad enough to throw a check engine light.
Replacing the clutch pedal on my Infiniti G37 with a aftermarket unit made a world of difference. The factory clutch pedal has a spring in it that causes the pedal to work like an on/off switch, which made the car tricky to drive and detracted from the fun. It took a few hours spent in an uncomfortable position, but, if I can do it myself, it counts as easy.
Repeatedly and across multiple vehicles, better tires.
The biggest difference was probably in a half-ton Silverado, replacing the Wranglers with Michelin Defenders. The diff lockup on it was kind of late but abrupt, and it’d squeak a tire just giving it a hint of gas on a left turn with the Wranglers. Changed tires and it drove normally, and did great in all conditions.
Volt made a pretty big difference as well. Replaced the stock tires with CrossClimate2s and it no longer spins one front tire just from a little extra acceleration on damp roads.
Notice any economy difference with the new tires on the Volt?
Not really. Other people apparently have, but I haven’t measured precisely enough or driven consistently or often enough to really notice. If it makes a difference, it’s a much smaller difference than using the heater. I also live someplace just hilly and snowy enough that I need 4PMSF tires but not enough for winters to make sense, so I’d take the range hit even if it were bigger.
Fair. Boy does that heater really does go through the electrons!
This applies to all BMW 5 and 3 series with a manual transmission: Remove the “Clutch Delay Valve”. It’s a small fitting inline with the hydraulic line with a tiny orifice that limits the speed at which the slave cylinder will move. They install it to prevent drivers from dropping the clutch and damaging driveline components, but the side affect is that it is nearly impossible to shift smoothly. It takes 5 minutes to remove, then bleed the line and it’s done.
When Car and Driver first reviewed the E39, they recommended buying one with an automatic because their manual equipped test car shifted so badly. And this is why.
Add the 1 Series to this list as well, it made a world of difference in mine. The other thing I will add is getting rid of the stock run-flats. HUGE difference in ride.
I used to have a B5 A4, and while I didn’t get a chance to upgrade a lot of things I really wanted to (mainly an S4 rear sway bar), I did get to make one upgrade that made an enormous difference: Bushings. These cars have a thousand and one suspension bushings, and each one of them introduces flex that dampens the driving experience, especially as they age, irrespective to mileage.
I installed urethane bushings and spherical endlinks on the front sway bar when the factory bushings went bad, and they made made as much of a difference as an all-new bar.
If you get a chance, I’d strongly recommend eliminating as much rubber as possible in favor of urethane (PowerFlex is a personal favorite and offers almost every possible mount and joint), with the exception of the subframe mount pucks, as those can benefit from being solid billet instead of urethane.
This was once a luxury car, so eliminating 1 or 2 of the dozen or so layers of NVH won’t make it a track-only beast, it should still be more comfortable than a same-year economy car. Many road cars of the era had hard-mounted subframes or no subframes at all, with suspension bolted straight to the body, and any bushing, no matter how hard, is a huge upgrade over floppy quarter-century-old rubber.
Bushings are addictive, so tread carefully. Start small, sway bar bushings are easy, control arm bushings can require a press to remove and install. Stiffer bushings can cause worn ball joints to fail faster, but they’ll certainly improve steering and seat-of-the-pants feel.
05-12 Pathfinders come from the factory under-damped in the rear. Add some age and sloppy springs and it will frighten you in corners while making passengers sick.
Bilstein 5100s and Moog HD springs makes it corner less like a beached whale and more like a cavorting Orca.
Or, seriously, it is a different vehicle.
My 66 Dodge Sportsman van has the 225 slant-six with a three speed manual. Ran fine but gas mileage wasn’t great and it was slow at low RPMs. I just assumed the weight of the van was the culprit. While changing the points, I noticed the vacuum advance was stuck. Turns out the diaphragm was cracked. Twelve bucks and fifteen minutes later, it was amazing. Gas mileage went from 9 to 17 and it pulls like a champ.
My 2.5L Boxster came with a completely lifeless clutch pedal, I was stalling routinely and then it started to squeak. A bit of scrolling through the forums tipped me off to the existence of a clutch helper spring, presumably placed there to make the car more approachable to those who bought it as a luxury car. It came off in less than a minute with no hardware (only needs a nail and a pry bar), and now the clutch feels like a proper sports car, shifts are way smoother and no more stalling.
Finding anything useable for less than $1000 from Copart these days is a miracle in itself. Last I did that was my 2007 S-Type I picked up from them in 2018.
Great article, awesome car. Would love to see more of it.
I’ve had a B9 S5 for a little over two years now. Felt tape to fix some rattles and some Kilmat in the hatch area and under the rear seat really quieted it down on the highway. A billet transmission mount insert really stiffened up the shifts. Of course the ECU/TCU tune really woke everything up, but that kinda feels like cheating. I too installed some wheel spacers for a flush look and it does indeed make a massive difference. VCDS provided many easy QOL improvements, like changing the lane change signal from 3 blinks to 4 and disabling the Soundaktor. The only thing I’ve done that I’m not sure I like is replacing the stock Akebono pads with Hawk ceramic pads. It’s really nice not having an inch of brake dust on my wheels after driving around the block, but the Hawk’s don’t do a damn thing unless they’re warm and slogging through traffic just doesn’t get them hot enough. I miss the bite the stock pads provided.
Thanks!
Great stuff, but good call on the very underrated usefulness of felt tape
I forgot to mention, the best hack by far was getting a day pass to erWin and downloading every manual, TSB and SSP for both my cars I could find. The SSP’s are great for learning how the things work, and not having to ask forums or FB groups for torque values or “how do you unclip this trim” is worth wayyyy more than the $30 Audi charges.