Suspension

When giving such a small car double the horsepower, you need the handling to match.  Whereas the original ti is a great handler, adding twice the horsepower changes the characteristics of the car dramatically.  Even with it's modified suspension, further tweeks must be made in the future.

Front Shocks/Springs

The front of the 332ti uses the height ride adjustable coil over system from H&R Special Springs.  They are the front units from their E36 M3 kit.  The difference between the E36 M3 front and standard 318ti coil over suspension units is the following:

1. The E36 M3 spring is rated at 15 pounds heavier in spring rate
2. The E36 M3 coil over assembly has accomodations for connecting the swaybar to the strut

Having a heavier 3.2L M3 motor would make sense to use the heavier spring from the M3 system.  A nice feature of the coil over system is that it's spring is much more narrow than a stock spring, provide lots of inner clearance.   Therefore, running larger tires and wheels is not a problem.  Lowered to it's lowest position, the front sits 1.75" lower than stock.

The offset camber plates from a 96+ M3 were used in their stock positions.  Other M3 owners switch left and right plates to gain additional "negative camber" (where the tops of the wheels tilt inwards) so that aggressive, hard cornering gains the benefit of a "flatter" tire profile under load.  It's downside is that it wears out the inside edge of tires.  When purchasing the parts, the coil over front suspension is very complete and all you need to purchase is the offset plates (no washers, spring mounts, etc.).  The BMW part numbers for these plates are:

Left Guide Support	1 piece	31 33 2 227 897
Right Guide Support	1 piece	31 33 2 227 898
Self-Locking Collar Nut	6 pieces	31 33 1 092 887

Front Swaybar

Here are the specs on the different sway bars which BMW uses on their cars:

Car	Front Dia	Rear Dia
95 M3	23mm	19mm
96+ M3	23mm	20mm
95 318ti	25mm	14mm
95 318ti Active	26mm	16mm

Whereas the 318ti's bars are larger than the M3 bars, it should be noted that the 318ti swaybars mount to the control arm whereas the M3 bars mount to the strut.  Mounting the swaybar further outwards will make the swaybar more effective.

Rather than purchasing aftermarket swaybars, we mounted the stock 25mm bar to the strut (since we're using M3 compatible struts) using swaybar links from a stock M3.  The result is a front end which rides flatter when cornered, than a stock M3.   Unfortunately, stock ti strut mounts do not have the capability of attaching sway bars here.

After a few weeks of driving, we noticed that the 318ti bar does not have quite enough clearance for the M3 motor's oil pan as there is the slightest indication of rubbing of the swaybar and the oil pan.  For the time being, we'll be using an stock, 23mm M3 swaybar since it has plenty of clearance.

If using M3 compatible struts, puchasing a few inexpensive parts will make your car handle even better:

Swing Support	2 pieces	31 35 2 227 203
Hex Nut	4 pieces	07 11 9 922 856

Note that typically upgrading just the front bar would produce "understeer" (the car's tendancy to plow".   However, with the additional power at the rear wheels, the car normally wants to "oversteer" (have the rear end "come around").  In it's current form, the car's suspension seems fine.  However, we'll be experimenting with additional swaybars for the rear.

Rear Shocks/Springs

The matched rear suspension from H&R Special Springs is their 318ti spring and strut from their coil over set.   The rear is not height adjustable as is the front, so the rear height is set at 1.75" lower than stock.

Rear Swaybar

Since the rear swaybar is so small, the ability to upgrade to the stock, Active package rear bar which is 2mm greater in diameter.  The formula for effectiveness shows that the bar itself will be 70% stiffer than the 14mm bar.  What that will translate to in performance and handling will be determined.

Upgrading the stock rear bar to the factory optional 16mm bar would be in the hopes of dialing out the car's tendancy to understeer and perhaps make the handling more neutral.  The stock parts are relatively inexpensive (about $100 from the dealer) and easy to upgrade.

318ti Stabilizer Bar Rear (16mm)	1 piece	33 55 1 090 317
Stabilizer Rubber Mounting	2 pieces	33 55 1 129 700

We will be trying a M Coupe rear swaybar in the near future as it has a 19mm diameter, the largest for an E30 trailing arm style rear end.  This, with a stock M3 front swaybar may make the car oversteer a bit, but we always have the option of purchasing a 28mm aftermarket M3 front swaybar to compensate.  We'll post fitment issues when we try it.

Other Considerations

Other options for suspension include using stock E36 M3 struts/springs (probably pretty inexpensive compared to coil overs) or upgrading to an aftermarket strut/spring combination.  Popular aftermarket systems include Bilstein (they provide a complete strut) or Koni adjustables (they provide inserts only).   Be sure to that the front is made for the additional weight of a 6 cylinder, which typically means and M3 suspension.

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