E46 M3 - Kumho Championship Race Car Build
 

So this is a somewhat belated build thread. Which is apt, because the build is also somewhat belated! When we are finished this will be the Track Tek / Braille Battery e46 M3 entry in the Kumho Championship.

This is my personal car but as Track Tek we have 15 years’ experience in building, supporting and racing various Japanese race cars, drift cars and turbo engines in various stages of tune before moving across to BMWs in the past couple of years. I’ve spent the past 6 years campaigning a heavily modified Nissan 200SX in the Nippon Challenge. Affectionately known as “The Hag” she has now been put out to pasture to make way for the e46.

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So here’s where it started back in October last year:

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A completely standard 50,000 mile 2 owner e46 M3 with full BMW history, no accident damage, perfect boot floor and generally mint throughout. Seems like a bit of shame really…. Oh well on with the build :-)

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We will only be using top end, race proven products on the car. This does not make for a cheap build but it pays back dividends over the course of a season. With race weekends costing the best part of £2k, we’ve learned this lesson the painfully expensive hard way. So here’s some of the kit:

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Motec M600
Motec PDM30
Motec CanBus Swtichpanel
Custom Race Loom
AIM MXL Pista Dash Logger
AIM Smartycam
More sensors than you shake a stick at
Custom Cages FIA Cage + Track Tek Diff Mounts
Alcon brakes
Turner Motorsports Solid Bushes
Mocal Diff Cooler and Pump
GSR Airbox
Drexler type Diff
We are also working with a number of suppliers to bring some seriously trick suspension parts to the e46 for the first time. Watch this space…

So firstly we stripped all underseal off the car. We did this the hard, manual way rather than dipping the shell. This allowed us to get up close and personal with the chassis so we could identify any cracks, issues or opportunities to make things lighter and/or stiffer. The Kumho rules are pretty strict when it comes to altering the chassis, so there’s a load of weight reduction that we’ve identified but sadly won’t be able to do on this occasion.

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It was then on to the seemingly endless task of seam welding every chassis join and junction, of which there are many on the e46!

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Next up was the FIA Custom Cages cage. Just one or two bits and pieces to be getting on with here:

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As we all know the e46 is somewhat structurally challenged around its hind quarters, which is why the FIA cage ties in to the rear floor. However, we identified an opportunity to create an even more robust solution and machined up our own diff mounts and welded the cage directly to them. Just take a look at the standard mounts vs the Track Tek mounts. Beefy.

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Track Tek diff mount on the left, standard diff mount cut out of the floor on the right
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So with the cage finished it was off to paint.

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And then it sat for a few months as the workshop filled up with customer cars, so we had to put the project on the back burner for a while.

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As you can see from the pictures our new unit is still not quite yet finished but we've decided to crack on with this build instead of finishing the ceiling.

Sensible choice I hope you agree :-)

Updates to follow

Nice.
Love a good build diary...

THANX for sharing :beer: a MONSTER M3 in the making :supz: keep it coming :thumbs:

So a bit of an update with trial fittings of various light weight panels today:

GTR bonnet

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Fibreglass Doors

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Single skin CSL style boot

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Carbon roof

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And light weight e36 type dash (makes for easier mounting of switch panel)

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Not pictured but also going on are fibreglass front wings and CSL style front bumper with twin air scoops which we'll use for brake ducting.

All the panels need quite a bit of work to get them properly aligned but we at least know where the issues are.

Anyone know of anyone that does half decent (but cheap!) fibreglass rear bumpers? The standard rear bumper is outrageously heavy given that it's plastic.

Job for tomorrow, get some pictures up of the suspension...

Awesome build. Keep it coming.

Very cool Build. Looking forward to updates.

Thanks for the words of encouragement :-)

So we're now ready to start bolting bits to the car. However, before we could get started, Nick insisted that the suspension arms and various undercarriage bits had to be shot blasted and repainted. This is for no other reason than Nick is a tart and likes things to be all shiny.

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Next up was pressing bushes into the newly painted bits. For this we used Turner Motorsports solid or ball bearing bushes and standard BMW for the upper and lower trailing arms as they're ball bearing bushes as stock.

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We also took the opportunity to replace the wheel bearings before refitting the hubs.

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So this is what the underside looked like a couple of days ago:

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And now with the subframe, arms and rear coilovers fitted:

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You may notice that the nearside upper arm isn't nice and shiny. Sadly the painted arm had too much play in one the bearing housings so had to be binned. We'll get a another painted up but I'm itching to get this thing finished and tested so we're going to have to live with it for now.

So onto the first of the new suspension parts we are developing for the e46. We have been working with Quantum Racing Suspension and Cornering Force for the past year to develop the QRS X Series range for the M3. These are 4 way adjustable recirculating shock absorbers that generate far greater damping forces than traditional mono-tube dampers. The design of the adjusters allows for far more accurate control of damping forces and Quantum have the expertise and flexibility to build shocks to a specified damping curve. They are also much lighter than the 3 way adjustable dampers we have used previously.

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So far we have the prototype set of rears on the car but the fronts will be a few months away. In the meantime, Quantum are making up a set of monotube dampers for the front end so we can get out and race this season. The X series will go on the front over the winter ready for the start of the 2015 season.

We will be using suspension potentiometers on all 4 corners linked in to the AIM datalogger*. So we'll be able to analyse compression and rebound speeds against a whole host of other parameters to help us fine tune damping and spring rates. By the end of some rather intense testing and calculations by people far cleverer than me, we should have a pretty decent base set up.


Info on the X Series if you're interested:

The X Series is a modern gas-pressurised recirculating shock absorber with in-line valve head permitting independent adjustment of high and low speed bump and rebound damping.

The recirculating design passes oil around the outside of the shock absorber — as opposed to through the main piston as is the case with mono-tube shocks. In both bump and rebound, oil is compressed between the main piston and the valve head. The floating piston — separating the oil from the gas pressure charge — is behind the valve head and is never exposed to the high pressure on the ‘damping’ side. This means the shock can generate significantly greater damping forces than are possible with mono-tube shock absorbers — with significantly less gas pressure, too — as it is not necessary for the gas pressure to be greater than the peak operating pressure in order for the shock to function.

What sets the X Series apart from similar designs is the unique method of adjustment. In place of the traditional needle-and-jet, the X Series employs a trademark drilled bleed adjuster.

Every X Series low-speed bleed adjuster has exactly eight positions corresponding to eight drilled bleeds. At position one, one bleed is open. At position eight, all eight are open. Each bleed can only ever be open or closed — there is no in-between.

Four different bleed adjusters are available, ranging from fine to coarse adjustment. The design offers a significant improvement in usability, with almost ‘digital’ operation and clear and precise adjustment; and because the eight positions are well defined, there is no need to ‘clock’ or ‘set’ the zero position.

Where specified, high-speed damping adjustment is achieved by preloading four ball bearings against valve seats cut into ‘pistons’ inside the valve head — not to be confused with the piston on the end of the shaft. Each ball bearing has its own spring. There are no shims.

Each high-speed adjuster has two full turns of adjustment affecting the ‘digressive’ part of the damping curve. Once the pressure behind the piston is sufficient to overcome the force applied by the springs, the adjuster ‘blows open’ and the rate at which damping force increases with velocity is significantly reduced.

Exhaustive testing has proven the ball bearing design to be an effective and reliable method of achieving a digressive damping curve with a broad range of adjustment.

The X Series will be available with two, three or four ways of adjustment.

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*Well we will have them plumbed into the AIM until Nathan from Race Data Systems finally wears me down and we buy a proper Motec logging setup :-)

Found a few more cage pics just after it was painted, seemed rude not to post them...

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