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Thursday 28th June 2012


BMW E46 M3 BUYING GUIDE: ROLLING CHASSIS

Dampers, wheels, brakes - what to look for and possible upgrades


The M3 uses a steel monocoque shell with MacPherson strut front suspension and a multi-link set up at the rear. For the M3, BMW widened the front and rear tracks compared to the standard 3 Series Coupe and fitted unique 'bat wing' forged aluminium lower control arms with bearings and bushes developed solely for the M3.

Convertible roof needs lubrication to stay sweet
Convertible roof needs lubrication to stay sweet
For the M3 Convertible, a stronger rear subframe was added to carry the larger half-shafts and uprights to cope with the extra power. BMW also used thicker anti-roll bars, with a 26mm item at the front and 21.5mm at the rear. In February 2002, the Coupe and Convertible gained an M Racing strut brace for the front suspension.

A set of 18-inch alloy wheels were standard for the M3, with the option of 19-inch alloys. Michelin Pilot Sport tyres were original fitment in 225/45 ZR18 front and 255/40 ZR18 rear, with the 19-inch wheels using 225/40 ZR19 and 255/35 ZR19 tyres front and rear respectively. The CSL has unique 19-inch alloy wheels with Michelin Pilot Sport Cup tyres in 235/35 ZR19 front and 265/30 ZR19 rear sizes.

Behind the wheels reside 325mm ventilated discs front and rear with ABS as standard. The power assisted rack and pinion steering of the standard M3 needs 3.2 turns from lock to lock, while the CSL quickened this with a 14.5:1 ratio rack for 3.0 turns between the stops.

CSL got special Cup tyres and other mods
CSL got special Cup tyres and other mods
The CSL also benefits from firmer suspension with front springs that are shorter by one coil and different rate shock absorbers. Thicker front and rear anti-roll bars, 30.8mm and 22.5mm respectively, are supplemented by aluminium rear suspension links and firmer bushes all round. Larger 345mm front brake discs are used for the CSL.

Upgrading the brakes for track use is worthwhile and Pagid Yellow compound pads are a good first step. AP Racing's 335mm front discs with six-pot calipers are the next logical step for greater stopping power.

As with all E46 3 Series, the M3's front ball joints wear and spoil the feel of the car, but they are a straightforward repair. The front wishbone bushes and rear trailing arm bushes are also likely to need replacing on any car with 60,000 miles or more on the clock. Rear coil springs and dampers will most likely need replacing by 80,000 miles.

Aftermarket suspension kits are widely available for the M3, but cheap ones can ruin the ride and handling balance. Eibach or H&R springs are worthwhile, while AC Schnitzer kit is better still but expensive.

Last point to look for is a cracked boot floor. BMW will replace it for free on cars less than 10 years old, but it will be very expensive to fix on cars where no goodwill is offered.


Owner's view:
"Only thing my M3 had of interest were the six-pot AP Racing calipers up front and the four pots on the rears - they are ace. Really good brakes."
Paul Milne


Buying Guide contents
Introduction
Powertrain
Rolling chassis
Body
Interior
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