Shopping list for making a E88 135i handle like a Porche Boxter on the street

[xQx]

I know, it can't be done. They're completely different cars. But who doesn't love clickbait?

So I'll rephrase, what's the best shopping list of improvements to make a 135i handling predictable and neutral so when it's driven hard on the street you can feel before it lets go, predict how it's going to let go, and be able to drive it predictably at the limit and retain control?

Also, we all know the biggest influence on a car's handling is the interface between the seat and the steering wheel - so what exercises (on the track, on the road, on a skidpan or in the dirt) would you recommend to get the experience to know how the car handles at the limit?

Finally some background - I've got car envy. I tried and tried to buy a E46 M3 vert before giving up and buying a 135i. I live in a country area and the nearest M3 was 1,000km away and required interstate transfer of registration. Every one I looked at had accident damage, subframe issues or ludicrous pricing. So I got a stock 135i and made it FBO. Now, I'm happily doing 0-100kph in under 5 seconds, and love the low-down torque. I love the small chassis, the comfort access, the gearbox, the MHD exhaust burble etc. I've reached the point where any more engine mods would be pointless - I can't get the power that I've got down on the road in under 100kph (ie. 1st or 2nd gear) due to excessive wheel-spin. Honestly, I think if I traded in the 135i and got an E46 M3 now, I'd wish I had a 135i. ... But every time I see someone say "you just can't compare a "m" BMW with a tuned "non-m" BMW, or "the m3 handles like it's an extension of your own body" - I get car envy... and driving my car near the limit - I find it unpredictable.... I need practice, yes, but from what I read, the stock chassis is unpredictable for the best drivers - so I'm willing to spend money to make it more forgiving, more predictable.

I have years of practice driving Subaru's, and have absolutely no qualms driving around a street corner with four wheels loose - I know how the throttle and the brake affects the balance near the limit. When I come into a corner, I know which end is going to let go, which gear I need to be in to have enough power to pull myself out but not run out of rpm - I don't always know _when_ it's going to let go, but I know how to get it back when it does. But I love the convertible. I love the comfort levels of the BMW (seriously, a WRX feels like a Hyundai excel by comparison). I'm trying to practice - but after 6 months of practice in the 135i - I think I'd be more comfortable at the limit in a VL Commodore.

It's easy to find a list for the track. Coilover, subframe bushes, control arms, quaife. But I don't actually need _more_ grip, I need progressive, predictable grip.

Any help would be greatly appreciated!

[drunkenup]

Here's what I would do in your application had I known everything I knew about my car when I first bought it.

Front suspension
-camber plates (dinan or otherwise)
-stiffer tension arm bushings
-front sway bar

Rear suspension
-toe arm bushings (easiest via manzo or megan arms)
-upper strut mounts (i.e. monroes)
-limited slip diff AND rear sway bar. Reason behind this is after my relatively stiff springs, stiff front bar and -3 deg camber, the car still leans on the outside tire very hard. mcpherson strut has a propensity for this but it can be dialed out as I have witnessed first hand. Whether or not the diff is necessary is your decision. I believe the car is not neutral as could be until the rear bar is addressed.
-RSFB, though I would almost consider optional with the addition of the other parts that are very simple installs.

coilovers/springs of your choice. Though I wouldn't even bother with one way adjustable coilovers if you don't have stiff enough of a tire to feel it (ie 200tw, MPSS and similar won't really take advantage imo). Also consider a square setup, whether it is 8.5 or 9". Throw apex's recommended 1er fitments out of the window, the staggered fitments don't lend to rotating, and you'll eventually try to stick too wide of a tire on the front.


I know I basically rattled off a track functional setup BUT the crux of the situation is that the M3 and other out of the box sports cars are equipped with all of these uprated bushings and hardened arms that are usually only upgraded by the most competitive (and sometimes with spherical, full metal stuff that is only good for a season or two). That said, tire is very important, stiffer sidewalls go a long way (common theme here all around is **stiffer**). I had my whole suspension setup and genuinely did not feel like I was getting anywhere until I added some square setup dunlop z2 star spec.

That said.. maybe try front and rear sway bars, more front camber and some better tire to start with. Those are probably the best changes to making the car more neutral though the upgraded rear toe arms and bushings aid rear stability enough to justify the cost

[Eyeman]

http://www.bimmer-mag.com/issues/101...ndling-machine

[xQx]

Thanks, that's more than enough to get me started