M3 Suspension Bits, Part 2

Now that I've had some time to drive the car with the M3 bits (front control arms, front and rear sway bars, and rear subframe bushings) attached, I can give some feedback about how it is to drive.

The first thing I noticed -- and continue to notice -- is the steering effort is higher.  It's been a while since I drove an E90 M3, but I don't remember the steering being so tight on that car.  I'm not sure if this is a side effect of the 335i's narrower track, or of the revised front end alignment (more camber and caster), or both.  But it's significant.  It's not exactly bad, and there's still plenty of feel, but I definitely have to use more effort on the wheel, especially on-center.

The second-most-significant change is the the back end of the car feels far more planted and secure than it used to.  The stock suspension, although comfortable, always gave me a feeling of being a little floaty in the back, especially in throttle transitions and/or during cornering.  Now it's very planted, with none of the float I used to perceive.  The tradeoff is that it's a firmer ride back there now -- rear seat passengers could detect the different if they jumped from a stock car into a modified one.

Finally, the whole car corners flatter, thanks to the stiffer sway bars, and the front grip is improved, thanks to the increased front camber and the stiffer bushings in the control arms.  It seems like it's impossible to un-stick the front end on the street.  In fact, overall grip is high enough now that the only time I get the car to slide around is under power with the tires spinning.

Overall I'm delighted by the change the M3 components make to the suspension.  It's still a perfectly comfortable car to use every day, but it is SO much more confidence-inspiring in the corners.  If you've been thinking about these parts, do it now!

M3 Suspension Bits, Part 1

The M3 is the top dog in the E90 pack, but since the 335 and the M3 share the same floorpan, there's nothing to prevent a 335i owner from applying the M3 suspension goodies.  Most of these parts are available in the aftermarket, but the original-equipment M parts are nice because they are readily available, they fit perfectly, and they're relatively affordable.  Plus, the sway bars are hollow.  More on that later.

Our Mach V car came equipped with the OEM Sport Package springs and shocks, and we like the ride height and feel of those a lot, so for now we have left them alone.  We focused instead on the suspension bushings and the sway bars.

For the front of the car, the lower control arms can be swapped out to M3 bits.  These have two benefits.  First, they incorporate stiffer bushings, reducing slop and squirm when they are loaded.  The second benefit is that the arms are slightly different lengths from the 335i pieces, giving about 0.5 degrees extra camber, and perhaps a bit more caster. 

While we had the front suspension apart, we also installed the M3 front sway (or "anti-roll") bar.  The M3 version is the same diameter as the stock 335i bar, with the exception of one six-inch section in the middle of the bar.  The 335i version has a neck-down section that's much smaller in diameter.  The M3 bar has no such neck-down.  Along with the M3 sway bar, we swapped in M3 sway bar bushings, which are a more solid bearing style bushing, instead of the softer 335i bushing.

The rear control arms in the 335i can also be replaced with M3 units, but we opted to leave our stock parts in for now.  We did choose to replace the rear sway bar with the M3 version.  Since the rear subframe has to be dropped down to replace the sway bar, we also took the opportunity to replace the very soft 335i rear subframe bushings with the firmer M3 units.

After observing the similar front sway bar diameters between 335i and M3, the huge size difference in the rear bars was a bit of a shock!  The stock 335i RWD rear sway bar is 13mm thick.  The M3 bar is 20mm thick!  Now, that's not quite a directly comparison, because the 335i unit is a solid bar, while the M3 unit is hollow.  But in any case, the M3 bar is FAR stiffer.

While we're talking about hollow versus solid sway bars -- the stiffness of a sway bar in terms of resistance to twisting it proportional to the 4th power of the diameter.  That means the stiffness goes up very fast as the diameter gets larger.  It also means that the very outer part of the bar is the most important in terms of the overall stiffness.  The result is that a hollow bar is very close to a solid bar in terms of stiffness, since the center of the bar does very little of the work.  Of course, hollow bars are much lighter than equivalent solid bars.

The rear sway bar install/subframe bushing replacement is a pretty involved job, taking the good part of a day even for our experienced mechanic.  Besides being time-consuming, it takes some special tools to press the bushings in and out of the subframe.  It's not something we would recommend tackling on jack stands at your home unless you're a pretty experienced mechanic.

So after a good long day on the lift, it was time to set the car down on the ground and see how everything worked.  We'll give our subjective opinion in our next blog post.


M3 suspension bits -- buy them here.

Cosmetic Tidbits: Grills and Caliper Paint

We did a couple of subtle appearance modifications on the 335i this past summer.  The first was a set of matte black kidney grills for the nose of the car.  Although it would be easy enough to paint the existing grills, from experience we know that little rock chips will immediately peck holes in our black paint, revealing the chrome underneath.  A better solution is to install grills that are black plastic all the way through.  As it happens, we sell those, so we grabbed a set off the shelf and popped them on.

Install is extremely simple -- the grills just snap into place in the bumper.  Pre-LCI (facelift) cars will have an additional "eyebrow" that attaches to the hood, but our 2009 car doesn't have that.

The other cosmetic change was to paint the brake calipers.  We didn't want anything overly flashy, but the original brake parts were looking very scabby and rusty, so we decided to freshen them up with a coat of silver paint.  Since brakes see a substantial amount of heat, we didn't want to use just any paint -- we used our brake caliper paint kit, which includes a two-part epoxy paint that cures hard, glossy, and heat-resistant.  Since we were already painting, we also painted the rotor hats.  Our silver calipers and rotor centers look a lot better than the old rust color from before.  If you don't like silver, the kit also comes in red, blue, black, yellow, and even orange.

The brake caliper paint kit comes with a handy can of non-chlorinated brake cleaner spray, which we used to soak down all the extremely dusty brake bits.  As you can see, it's still a plenty messy job; gloves would be a good call.

Tech tip: Once you mix up the epoxy paint, use it right away, because it immediately starts to thicken, and in a few hours it'll be set up.  We had one customer who didn't understand that and left it overnight... Also, hang the caliper from a coat hanger or bungie cord so it's not hanging from its brake line.

If you have the time and room, get the car off the ground on a lift or jack stands, paint all four corners, and leave it to cure overnight.  By the next morning, everything will be nice and hard, and you can assemble it all back together without worrying about leaving thumb prints in your new paint.

CP-E Intercooler Upgrade Ups Power and Torque

We installed a CP-E intercooler upgrade.  The CP-E core has a volume that's around double the volume of the stock core, and is more efficient as well.  Cast end tanks make for smooth flow in and out of the core.  The kit also comes with an additional oil cooler, which is invaluable if you're going to run the car at the road course.

We followed the instructions CP-E includes with the kit, and everything fit together nicely.  Note that plumbing clearance is very tight on a car equipped with an automatic transmission (like ours is), since there's an extra water-to-oil transmission cooler that's not present on the manual-trans cars.

You've probably noticed the CP-E logo on the intercooler core.  I wasn't super excited about the logo -- not that we don't love the guys at CP-E! -- but decided to fit the core up and see how it looked before doing anything drastic like removing the logo or spraying the core black.  It turns out that you can hardly see the core OR the logo when everything is back on the car.  If you are REALLY looking closely -- like crouching down and putting your face right at the bumper -- you can see the logo.  Otherwise, you'd never know it's there.  So it'll stay.  If anything, it's kind of nice because it's an indicator the intercooler core is not stock, if someone does end up peering in there.

We did some minor trimming of the plastic vanes on the inner bumper plastic to make installing the oil cooler easier, but we didn't have to cut or trim any of the outer bumper skin.

Once done, we strapped the car back on to the dyno and ran it.  We gained another 15 hp and 21 ft-lbs of torque.

We're very happy with the results from the intercooler upgrade, and with the fit and finish of the kit.


The massive power gains we've achieved at each stage of this project are addicting.  We're now considering a full turbo-back exhaust, despite our earlier vow to keep it stock...

In other news, the AccessPort now works on all 335i models, including 2007 model years.  We expect to hear soon about the latest maps, which will include Stage 2 maps for cars with full exhaust systems.  We also expect the release of the Cobb ProTuner software, which will allow us to develop custom maps here at Mach V Motorsports.

Wavetrac LSD: 100% More Driven Wheels!

We installed a Wavetrac limited-slip rear differential in the shop 335i, and it really changes the way the car drives.  By no means does it eliminate tire spin or slip -- it can't perform miracles -- but when the rear end does give way, both wheels are spinning, not just one.  Those annoying one-wheel burnouts, which seemed to happen every time I drove the car, have been replaced my much-less-frequent small episodes of rear-end-hip wiggling as the tires struggle a little before hooking up together.  Another benefit is the elimination of the strange left-right-left jerkiness that was the result of the stock "e-diff" braking action attempting to get control of the one-wheel tire spinning.

By now we're getting pretty good at the differential swaps on these cars.  Give us a call and we can put one in for you. It takes about a day.

Note that there are two types of differentials on these cars.  Most of the automatic-equipped cars have bolt-in differentials, and some of the early manual-transmission cars do, too.  Replacing the differential on those cars is a straightforward affair.  Other cars have weld-in diffs, and that requires a bit more work and cost, since we have to have ring gear machined off the old differential.


In my next post, I'll talk about a CP-E front-mounted intercooler upgrade.  Check back in a few days.

Summer Tires! New Wheels, Too

Betting there won't be any more snow storms this year, we took off the Continental all-seasons and the OEM BMW wheels they were sitting on, and we bolted up a set of Hankook Ventus Evo V12 tires, with some VMR V701 wheels.  The wheels are 19x8.5" in the front, 19x9.5" in the back.  The tires are 235/35R19 front, 275/30R19 rear.


The visual difference is striking.  The large wheel diameter combined with the spoke profile of the wheels gives a nice sense of depth, and the 20mm wider rear tire fills out the wheel wells.  The V701 style seems like a good visual match for the car.

As you might expect, ride comfort is reduced.  The thinner and stiffer sidewalls transmit more harshness into the car, and sharp expansion-joint style bumps make themselves known more than the softer 18" Continentals.  I thought I might sense an increase in steering feel, but it doesn't feel that different.  The car does tend to tramline a little more, following troughs or grooves in the pavement more than before.

Weight-wise, the new setup is actually lighter than the old, despite being both wider and larger in diameter.  The stock wheels with 225/40R18 Contis on the front were 50.5 pounds for the package.  The new fronts are 49.5.  The stock rears with 255/35R18 Contis were 55 pounds even, while the new ones weigh in at only 51.5.  I didn't get a chance to weigh all this hardware separated from each other, so I'm not sure how much of the difference is wheel and how much is tire.  Still, it's nice to know the new rollers are actually saving weight.

On the ECU front, we're continuing to test new maps from Cobb tuning.  I should have some updates on that in the near future.

A desperately-needed limited-slip differential from Wavetrac is on the way, and should be installed in the car in the next couple of weeks.  Stay tuned.

Downpipes Yield Still More Power; Winter Tires Handle the Weather

We picked up some take-off catless downpipes from a customers, and decided to put those on the car.  The install is a little tedious because of the tight work space, but it's straightforward other than that.  If you do it yourself, plan to replace the rear gaskets.  The front gaskets are a hard ceramic type that can be re-used.

The rest of the exhaust is still stock, including the remaining main catalytic converters.  The car picked up still more power -- another 12+ hp and 10 ft-lbs, with no change in the ECU mapping.

After showing the "uncorrected" numbers in my last post, I have switched back to "SAE" correction on this one.  I figured I'd have to list out the weather conditions if I did uncorrected numbers, and with three different runs it's starting to get complicated to list all that out.  So...SAE correction just takes care of that, attempting to normalize over the different weather conditions.

In the near future Cobb Tuning will have "Stage 2" ECU mapping intended for cars with modified exhaust systems.  At that time we'll re-flash the car and get the car back on the dyno with the new ECU logic.  We expect still more power from that change, and more when we upgrade the intercooler further down the road.

If you were looking closely at the picture of our shop staff working on the 335i above, you'd see the new Continental ExtremeContact DWS tires (in stock Sport Package fitment of 225/40R18 and 255/35R18) we put on earlier this winter.  As you probably know, the Bridgestone RE050A Sport Package tires are...downright hazardous in cold weather.  The Continentals were a HUGE improvement in the snowy weather we had, with decent grip in sub-freezing temps and snow or slush.  They're fairly quiet, and they have a very comfortable ride.  The price isn't bad, either.  The one trade-off is that they are not run-flat tires, so in that sense we're flying without a net -- the 335i does not include a spare tire.  We carry a small air pump and tire plug kit, although depending on where/when we broke down we might just call for a tow if it comes to that.