Last month we noted it took too many months for suspension (or any parts for that matter) to become available for the F30 BMW 335i, and when they did arrive, several options were available.
The first parts to arrive for our Mineral Grey Project 335i were a set of Street Performance coilovers from H&R Suspension, so we added 20" HRE Wheels and Nitto Invo tires to kick off our new build series.
The parts were fitted by LTMotorwerks in El Monte, CA as they simultaneously worked on their own 335i. It also had 20" HREs and Invos but KW Variant 2 coilovers. This set us thinking: how often does anybody directly compare suspension systems on near identical cars?
Admittedly, the most empirical way to do this would be on a track with a stopwatch. However, the LTMW car had some engine mods and auto transmission, which would make that infeasible. And the 20" wheels really aren't ideal track wear. So we'd test them on the freeway and local canyon roads instead: the natural habitat for cars and components such as these.
LTMotorwerks 335i with KW V2 coilovers, HRE P43sc wheels and Nitto Invo tires was marginally the winner on this occasion. StopTech brakes, Juice box and downpipe were a nice addition but factored out of the equation
Project 335i boasts H&R coilovers, HRE C100 wheels and Nitto Invo tires but narrowly came second in this coilover comparison, where the softer, more compliant ride was deemed a disadvantage. It's hard to imagine such a scenario...
Comparing the two cars wasn't going to be straightforward. One of the biggest problems was that while our H&R Street Performance coilovers were fixed rate, LTMW had adjustable KW Variant 2 coilovers. Our solution was to put the V2s on their middle setting to give us the best compromise.
Before we set out, the ride height was adjusted so both cars had the same suspension travel. Measured from the ground to the top of each fender, both cars were 25" front, 25.5" rear. Again, this is very low for daily street use but it's our preference.
Both cars use Nitto Invo tires; 245/30 R20 front but slightly different sizes on the rear. Ours had 295/25s while LTMW used 285/25s. That said, tire pressures were set to 28.5psi all round at 62?F ambient in the morning. Being relatively cold, they would reach about 30psi as the day warmed up.
So with tires and suspension travel equalized, we were ready to hit the road. However, another difference became apparent. Although both cars used the same size HRE wheels, the offsets were different.
As we examined last month, our project car had 20x9" ET36 front and 20x10.5" ET54 rear HRE C100 wheels. The LTMW 335i used the same dimensions but their HRE P43sc offsets were ET35 front and ET44 rear. "We asked HRE to build ours with aggressive offsets," explained Long Tran from LTMotorwerks. "Your set was a development from ours with less offset designed for people who don't want clearance issues."
In reality, our rear wheels rubbed on the inner fenders and needed 5mm spacers. Since then we've had no rubbing whatsoever, despite the huge tires, lowered height and even with passengers in the rear.
The same can't be said of the LTMW car. Every hard corner was greeted with the familiar sound of tires rubbing against fenders, which initially affected our test, as you'll read...
Remember, the wheels on our cars were among the first sets built for the new F30 chassis. HRE can build you a set of wheels to your specification and will ensure a good fit based on your requirements. Our cars, being for promotional purposes, tend to be more aggressive than you might otherwise choose.
With both cars prepped, we headed to the freeway network north of Los Angeles for our journey to the nearest canyon roads. As a daily driver, I was intimately familiar with our Project 335i in these conditions and set about assessing the LTMW car on its KW V2s. My impressions were supported by Ivan Madrigal from LTMW: a co-owner of the business and track-day regular.
Our first impression was that the H&R coilovers seemed a little more refined on the freeway. They damped the concrete sections slightly better. In fact, they seem to echo the stock ride quality, only firmer. This meant they had the tendency to "bounce" gently in order to absorb low-frequency imperfections, where the KW coilovers had less movement, causing them to feel slightly flatter and mildly harsher.
We should point out here that we're talking about very small differences. What surprised us was that despite the limited suspension travel and minimal sidewall flex, both cars were actually surprisingly comfortable on the freeway. They were inevitably firmer than stock but not uncomfortably so.
Very happy with the H&R coilovers, I found myself liking the KWs equally. They didn't have the same cosseted feel, but certainly weren't jarring. In fact, I started to enjoy the flatter response from the dampers that controlled the movement slightly quicker than the H&R dampers, which started to feel fractionally "floaty" in comparison. Obviously, this is subjective since neither could be considered soft. And again, we've been very happy with the H&Rs for several thousand miles.
With similar 20" HRE wheels and Nitto tires, the major difference here is the coilover suspension
With similar 20" HRE wheels and Nitto tires, the major difference here is the coilover sus
As we peeled off the freeway, I was hesitant about the decidedly uneven surface and tight turns on the country roads. They would be a harsh test for these cars.
Immediately, the LTMW 335i started protesting. It's wider offset caused the tires to rub on corner entry and exit. The mechanical suffering was hard to ignore. After checking we were doing no damage to the tires or paintwork, we proceeded.
At this point we need to commend the rigid BMW F30 bodyshell. It feels superior to even the excellent E90 and the longer wheelbase gives it greater composure. At high speed on uneven roads there was no indication of flex.
With stock sway bars, both cars rolled slightly on initial turn-in. It was considerably less than stock and was to be expected, but both did it equally.
Despite its horsepower advantage over our standard car, the LTMW 335i was putting the power down consistently, rarely resorting to traction control interventions. Whereas the H&R suspension allowed greater suspension travel, which would sometimes leave a wheel dangling without weight on it for traction.
At lower speeds, this greater wheel travel gave better comfort but, as our velocity increased, we found the H&R car became slightly more unsettled, making it more challenging to control. It had a fluidity that again resembled the stock 335i, but the KW V2 seemed more planted and secure in this particular situation.
The low-frequency "bouncing" from the H&Rs that we'd noticed on the freeway, while not unwelcome in isolation, was less acceptable here when compared to the KWs. The Variant 2 coilovers would damp the oscillation more rapidly, but without jarring the ride. In contrast, the H&R Street Performance dampers would allow that oscillation greater travel and time. The damping simply wasn't as abrupt, and while this increased freeway refinement, it didn't really help the canyon behavior.
Another advantage of the KW suspension is that the Variant 2 units have adjustable rebound damping. This would allow the driver to tune the shocks to his taste: perhaps softer for regular freeway work, harder for canyons and occasional track days. It's fair to say that if we'd adjusted the damping for the conditions during our test, the KW benefits would be amplified.
We must also mention the tires since this was our first opportunity to use the Nitto Invos in anger. We'd previously mentioned that the low-profiles were rather noisy, which we had attributed to the stiff 25-series sidewalls needed for this application. And while it's still a factor, the level of grip offered in the dry was a surprise.
During our canyon runs, several decreasing radius turns caused butt clenching but the tires never let go. They allowed sharp, precise turn-in with good feedback through the steering. Power application was also exemplary, resulting in no traction issues once under load, even in the lower gears.
The Invo has been around for several years and was a conscious effort by Nitto to target our premium European market with a high-performance product at a competitive price. And while we've not tested them in the wet, the square shoulders and wide tread blocks performed well on the dry canyon roads.
Next Month: We hope to have either a cat-back exhaust or some aerodynamic spoilers for the car, depending on what we can get our hands on...