E46 M3 Track car mega build & development

[alclark]

Well I thought I'd put up my full development thread here as I figure some people might find it interesting. Or not! Who knows.





So winding back to February 2011 I had been looking for the right car for a month or so and when a car that I knew had been looked after and fitted with a couple of choice parts owned by Daniel, who was a member on here I think.







The very first thing to to was do a trackday, or four.






Bodyroll was good, brakes worked, it was all in all a decent car. I had no plans to modify it any further. :roflmao::roflmao::roflmao:

Went to the Germany to give it a test and it was brilliant.







Did more and more trackdays...







But then the tinkering bug started to set in. I changed the alignment to a far more agressive track biased setup, and lowered the car a bit more, and did the corner weights.






After a Bedford trackday I tweaked the settings a little more again to get the balance of the car right.


And then my day job is filming cars for adverts on tracks and roads etc, so I had a go with the M3:


It was time for a mega service and I went over the car with a fine tooth comb. I had a minor oil weep from the oil cooler which I replaced with a new one, and just generally went round finding bolts that needed nuts and holes that needed bolts all together.





And then and went and did around 85 laps in it over the course of a weeks trip to the Nordschleife.











And then it all started falling downhill. When I bought the car from Daniel, the car was fitted with KW v3's with it's normal soggy progressive springs which are around 84N/mm all round which whilst sort of comfortable never really offered the proper on track performance the dampers can offer. Fortunately, the car came also with KW spherical bearing top mounts (the car had non TuV Simpson motorsport rubber top mounts) and club sport front springs which are a linear 120N/mm spring.

However after a trip to Tom Schirmers in Kelberg and a decent chat (I say chat, more of a friendly one way lesson) I left with a set of proper springs - 160N/mm linears all round and some 20N/mm helpers. Basically nearly twice the spring rate as it had on before. Will it leave the car bone shatteringly stiff? Apparently not. I had to take Tom's word for it.

So three weeks after coming home from the 'Ring and umming and erring about ruining the perfectly acceptable ride on the car, I took advantage of a Monday bank holiday and Bon's free time.

The front springs are long conical jobbies, and we always knew they were too sloppy as the car was bottoming out in the foxhole at circa. 150mph through the compression, and leaving ever deeper grooves in the tyres. Raising the car wouldn't have necessarily solved this either apparently.



Wheel arch liner Nut damage to the tyre from the compression:


We fitted all the new springs and helpers and adjusters, and re-used a few parts from the original kit that we needed...


Set a basic geometry to get started with...


And then started dialling in a Schirmer alignment as best we could with the alignment gear we had (which unfortunately didn't quite work on a car that was now this low), so it needs a bit of tweaking at another alignment centre.


Once we did that, we started looking around at the corner weights. The car had a full tank of fuel, and with all that onboard and me not sat in the car we had a wet weight of 1580kg on the money:


So we began fiddling, and we found 15kg's straight away in the battery, which we swapped for a gorgeous Braile long life motorsport battery - 15kg's!!


Which took the car down to 1565kg.


Some more fiddling later we set up the corner weights properly based on the car with a driver and a front passenger, as my car almost never had an empty passenger seat on track these days.


So finally with two regular humans on board, we managed to tweak and nudge everything so that it was spot on 50:50. Final weight with passengers on board was 1724kg. We reckon straight away there is 50-55kg's to lose just in the front seats, and maybe 20-30kg's in the wheels alone, so those really are next on the project list. Slippery slope? Yes.


So how did it ride? The answer is extremely well - Tom was adamant that BMW's want stiffer springs as long as the dampers can keep up which the KW's can do no problem. The low speed 10-20mph ride is a little bumpy as you'd expect from any car running this sort of setup, but as soon as you hit 30mph and carry on to whatever speed you like the car is stable, quiet, rides perfectly (PERFECTLY) and I am nothing short of really really impressed.