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BMW E36 Three Series - Mechanicals

Engines

BMW m40 engine

M40 M43

Four cylinder 8 valve

1.6, 1.8 and 1.9

1988 - 2001

BMW m42 engine

M42 M44

Four cylinder 16 valve

1.8 and 1.9

1989 - 1998

BMW m52 engine

M50 M52 M54

Six cylinder 24 valve

2.0, 2.2, 2.5, 2.8 and 3.0

1989 - 2004

BMW m51 diesel engine

M41 M51

Four and six cylinder turbo diesels

1.7 and 2.5

1991 - 1999

BMW s50 engine

S50 S50B32 S52 S54

Six cylinder 24 valve

1992 - 2007

 

BMW E36 cutaway

Cutaway drawing of an M3

Suspension

The E36 used the Z-axle multi-link rear suspension which had been pioneered on the the Z1 roadster. This was much more complicated that the semi-trailing arm system which preceded it but it gave the advantage that the angle of the rear wheels under hard cornering could be designed for optimum handling. This was a notable flaw in older systems and led to poor grip, especially in wet or icy conditions. I can testify that the E36 is a much better winter car than an E30 and is less likely to loose the back end.

 

BMW E36 z-axle

The Z-axle multi-link rear suspension

To save money and take advantage of easier packaging they Compacts and the Z3 did not use the Z-axle but employed the older E30 semi-trailing arm rear suspension. They had the same front suspension and other systems as the normal E36s including five bolt hubs. Compact parts are often used to convert E30s to five bolt in order to fit larger brakes.

Front suspension wasn't that different from the Macpherson strut arrangement on the E30, in fact E30 owners often use E36 struts to convert to five stud hubs. A cross brace was fitted under the front subframe of the M3 and Z3 to make the front suspension track better, it's a common upgrade for track cars.

 

BMW E36 front cross brace

Front cross brace.

The stock E36 suspension was supple and not overly stiff. It made for a good drive but wasn't sporty in nature and tended slightly towards understeer. The sports upgrade was standard on Coupes and was a good deal firmer but still not as hard as the M-Tech version had been on the E30 by quite some margin. Some might say the E30 option was actually too stiff and compromised the motorway cruising ability of the E30 and they'd be right. So the new "stiffer" suspension was designed more for an all rounded grand tourer perhaps.

Later M-Tech suspension packages were stiffer than on early cars. My '96 328i touring which I'm fairly sure had the original sport suspension was a lot firmer than my '93 318iS coupe and really handled well on all types of road. It understeered a little when pushed but the fitment of an M3 Evo rear anti-roll bar soon sorted that.

Steering

The rack and pinion steering was power assisted as standard on all models which reflected the heavier nature of the E36. The assistance was not overdone and was well weighted, unlike early E46s. The rack was a lot quicker than the E30 and the whole driving experience benefited as a result.

There were several racks with subtle differences over the years. The M3 Evo rack was very slightly quicker with 0.2 turns less lock to lock. M3 racks of all types also had limiters to prevent wider tyres rubbing the arches. The M3 3.0 rack had a non-linear ratio and was slower in the middle to promote high speed stability.

 

BMW E36 rear brakes

Rear disc brakes with a good view of the shock and spring.

Brakes

Non-M3 Front brakes were 286mm and were vented on six cylinder cars and the 318iS. The Compact and 8 valve four cylinder cars had solid non-vented discs as did four cylinder Z3s. Rear discs were slightly smaller at 280mm and were non-vented. However all 323i and 328i's had 276mm vented rear discs. E36 brakes were well up to the job even for spirited driving, they felt positive and had good power.

Four cylinder 8 valve cars in the UK and europe had rear drum brakes, all 318iS and 318ti's had rear discs as did 1999 UK 318i saloons. I believe that in some markets 8 valve cars may have had rear discs.

Almost all E36s had ABS. It was optional on very early four cylinder cars but in practice I've never heard of an E36 without ABS. The handbrake was the usual Porsche style system with two shoes operating on the inside of the rear brake disc's hat.

The larger M3 brakes are described on the M3 page.

 

BMW E36 M43

M43 four cylinder in a later 318i.

Drivetrains

All manual E36s were five speed using the S5D gearbox. Some S5D's were ZF and some made by Getrag. Fitment depended on model year and engine power also some engines, such as the M41 diesel, had differing gear ratios to better suit their torque characteristics. Top gear was always a direct drive 1:1.

Most E36s used the five speed A5S transmission. Four speed A4S were fitted to all four cylinder models as well as early American M50 325i's. This is actually a French General Motors THM-R1 "Strasbourg" gearbox. ZF made a compatible transmission for BMW that was also called an A5S but it tended to be fitted to larger or later vehicles. That said it's not impossible some E36s got the ZF version. These supposedly had lifetime fluid but they really need to be changed every 60k miles.

Drive shafts were two part with a centre bearing and a nylon Giubo flex disc at the gearbox end to reduce vibration. Neither the flex disc not centre bearing last forever but they often last the life of the car except at very high mileages.

Differentials came in small and big case versions. Four cylinder cars had the small type with a 168mm ring gear and the sixes got a large case unit with a 188mm gear to handle more torque. The 318iS originally had a 3.45:1 and the 325i 3.15:1 ratio but various minor changes around these figures took place over the years. A limited slip diff with a 25% locking action was optional on the 318iS, 318ti and six cylinder cars. It's much less common on later cars with ASC+T traction control but can still be found.

There were four wheel drive E30s and E46s but no E36 alas. Up until 1995 you could get an E34 525iX but then your choices were curtailed by the lack of a follow on E39 4x4.

 

BMW E36 M52

M52 engine with second ASC+T throttle plate.

Technology and Systems

ASC+T All Season Control + Traction was BMW's first traction control system and was initially offered as an option on the 325i. Alpina had actually made a nice system for the 1989 E34 B10 3.5 which used an electronic throttle body from the M70 V12. My B10 had this and it worked really well but perhaps it was too expensive for mass production at the time.

Oddly BMW's approach on the M52 was to fit a second throttle plate under the control of the computer. This could be used to reduce engine power but it added extra pumping losses to the intake, perhaps not a problem on the already restricted M52!

If one wheel slips on an open differential the other will get no power. To prevent this the computer used the ABS sensors to detect if wheels were slipping and could apply the brake to ensure power went to the wheel which wasn't. Previously cars could have an optional limited slip differential but after the introduction of ASC+T in 1995 LSDs were less common.

1995 onwards cars with the M52, M44 or diesel engines had the first version of the EWS anti-theft system. This had a transmitter in the key which passed a code to a loop aerial around the ignition barrel. The code changed every time the system was used and if it was correct the EWS unit enabled the DME to start the engine. It wasn't possible to spoof the signal to the DME to hot wire the car.

Most manual E36s had dual mass flywheels which were designed to reduce driveline vibrations and harshness. These are a bit of a curse because they can fail and replacements are expensive, mine died at 160,000 miles which wasn't too bad.