On the Right Track

On the Right Track

The truly amazing thing about the little 318i was just how much fun I had driving it on the track and the fact that it just kept going and going despite weekly floggings on the local track. For a car with almost 200,000 miles on it, that had been mistreated most of its life, never had an engine rebuild, and was generally in questionable condition, it was an absolute pleasure to drive. On the street, however, the fact that it made its pathetically small quantity of torque way up at the tops of the revs made it not-so-fun to drive.

The car was running well, although there were small niggling issues, including a few failed track inspections that required a frenzy of Friday afternoon work to fix, slow oil loss, and tendency to lose a bit of coolant through the brand-new radiator cap – a problem I've heard other M10 car owners complain about. I also had a general concern about engine reliability – I simply couldn't believe that it kept on going and going and going… Making it home after a weekend on the track in Portland or Spokane, I was always especially thankful.

The car was what the experienced folks call a "momentum" car. This is a nice way of saying that it takes three laps to build up speed (0-60 in only three tries!). Stock the car had 101 hp. This car had an old and tired engine, a frankensteined exhaust, complete with plugged catalytic converter. Ninety horses was probably highly optimistic. It was also hampered by extremely long gearing – my gear limited top speed was, I calculated once, something close to three million miles an hour, thanks to the North American 3.64 ratio differential (that's the ratio of the "final drive". The higher this number, the quicker the car accelerates, but the lower its over all top speed) used in the '84 stick shift. This meant that from the time I entered 5b at SIR I had the gas completely floored to the braking zone for Turn 2 about a mile further down the track, with the exception of a brief lift and brush of the brakes for 8's turn-in. I came hauling into turn 2 at the blistering speed of 97 mph. On a good day. If I got a quick run out of turn 8.

This wasn't quite the same as my Extremely Shiny Purple Car, where I'd lift half-way down the straight, get back on the gas and still go through Turn 1 at 120 mph. A major difference between the two cars was that at 90 mph the 318i had a greater sensation of speed than the newer car had at 120 mph. The 318i, because of its lighter weight and less aerodynamic shape feels like its moving faster.

The 318i's stock suspension, while excessively soft and tall, was generally competent. The limits were low (and the body roll unbelievably bad), but ultimately it was predictable – although the massive body roll impacted my confidence a bit. The car understeered on turn-in (although this was mitigated by light braking to keep the weight forward), but once it was into the turn it was reasonably well balanced. The car was slow to respond to input, because of the softness of suspension.

In order to improve the body roll, and reduce some of the understeer, I decided to replace the rear anti-roll bar with a beefier one. I bought the used anti-roll bar from an E30 M3 for about fifty bucks. When I went to replace the old one, I found that there wasn't one present at all! After some online research I learned that the anti-roll bar was an option on the U.S. 318i. I mounted the new anti-roll bar in an afternoon's work. The next time I was out on the track, I took it quite easy initially, in order to carefully feel out the new limits of the car. As I incrementally pushed the car harder I discovered that overall understeer was significantly reduced, and body roll was reduced by about a third – definite changes for the better. I found that the car, with its very light rear-end occasionally wanted to get its tail through the corner faster than the front (i.e. oversteer). This wasn't a problem, however, because the lack of rear-end weight on the car meant that the tail had very little inertia, and thus was easy to bring back in line. This can be contrasted to a mid or rear-engine car: once a car like that begins to oversteer, the heavier rear-end, with its inherent inertia, is more difficult to "catch". Keeping firmly the gas on to balance the car through a turn solved my problem.

As my first suspension modification, I was happy to find a significant improvement in the drivability of the car from such a small investment of money and time. It was clear, however, that the car would greatly benefit from more complete suspension modifications in the future. My plan was to make these changes incrementally, so that I could learn the new limits of the car with each individual change over several track days.

As I slowly discovered, one of the greatest pleasures of this car is simply how light it is. In stock trim, the 318i with a driver and tank of gas weighs about 2500 lbs, compared to about 3500 lbs for an E46 3-series. Lightness translates to better acceleration and breaking. It also contributes to improved over-all cornering as the lateral forces acting on the tire decrease. The improvement in cornering is not linear since reducing the weight on a tire also reduces its coefficient of friction (i.e. how much it sticks to the ground). The biggest benefit of driving a light car is that there is less inertia to overcome. I think this is what people mean when they call a car "tossable".

I began pulling stuff out of the car to make it lighter, aka "adding lightness". This has included the easy stuff – removing the spare tire and rear seats, to more grungy work like removing the carpets, A/C, electrical fan and power steering components, to really tough stuff like removing the sound deadening tar. The whine of the differential, the hum of the fuel pump and rattle of road-gravel off the bottom of the car compounded by the lack of any radio can try my patience on long drives. Earplugs are an absolute must. But, the lighter the car gets, the more rewarding it is to drive on the track. I was able to reduce the car's weight by about 300 pounds.

In a lot of ways, I found that this car is the ultimate driving machine (for a novice), since it's not good at anything else! On the track, I really had to work hard to drive it well, but found it to be rewarding and practical. A complete lack of power means that I can't use gobs of torque to pull myself out of a speed-robbing mistake. When I mess up on a key turn, it impacts my speed on the following straight in a big way. To be quick in this car means driving well for every single corner. If I manage to pass someone I know it wasn't because I have a faster car!

The real measure of the car's performance is how much fun I have driving it. Not worrying about dings or dents is a big plus, but ultimately it's fun because I really have to work to look good in it! This can be contrasted with Extremely Shiny Purple Car I owned – which made me look like a good driver without much work (for that matter, I looked pretty good just sitting in it). After a day driving the old 318i car on the track I was exhausted, but happy – and a little more in love with the old BMW every time. There was just something absolute and perfect about drifting through a turn with the sun low in the sky and feeling complete concentration and relaxation. Moments like those are a reminder of why I do something so difficult to explain to the people that know me.