Table of Contents 4th Generation M3 Drivetrain Subject Page Introduction .3 GS6-53BZ Manual Transmission.4 Clutch.7 Propeller Shaft and Output Shafts.8 Final Drive.9 Fully Variable M Differential with Locking Action.10 Initial Print Date: 1/08 Revision Date: 4th Generation M3 Drivetrain Model: E90, E92 Production: 2/2008 After completion of this module you will be able to: • Identify the components used in the drivetrain of the M3 2 4th Generation M3 Drivetrain Introduction Via the self-adjusting SAC double-disc clutch, the power flow from the S65B40 engine is forwarded to the 6-gear manual gearbox (GS6-53BZ). This gearbox is based on the 6- speed transmission used in the E60 M5. In contrast to this gearbox, however, the M3 features electrically controlled transmission oil cooling. A further highlight of the M range is located behind the M3 drive shaft. This is the fully-variable limited slip differential transmission, which was first used in the E46 M3, and has now been adapted to the demands of the E92 M3. Appropriately adjusted output shafts ensure the distribution of power flow to the rear wheels. 3 4th Generation M3 Drivetrain GS6-53BZ Manual Transmission The following sensors are fitted on manual gearbox housings: • Zero gear sensor (selector gate) • Engine speed sensor, transmission input • Transmission oil temperature sensor. j , The signals of these sensors are monitored and evaluated by the MSS60. When reverse gear is engaged, the reversing light switch mounted on the gearbox issues an earth signal to the footwell module (FRM) to activate the reversing lights. The transmission oil pump is controlled by the MSS60 depending on the transmission oil temperature. Model E92M3 Gear Ratio (1/2/3/4/5/6) Gear Ratio (reverse) E92 M3 GS6-53BZ 4.055/2.396/1.582/1.192/1/0,872 3.678 E46 M3 Coupe S6S420G 4.227/2.528/1.669/1.226/1/0.828/ 3.746 E92 335i GS6-53BZ 4.055/2.396/1.582/1.192/1/0.872/ 3.678 4 4th Generation M3 Drivetrain Manual transmission oil circuit layout Index Explanation 1 Gearbox oil pump 2 Screw oil filter The activation threshold for the pump is approximately 130°C and the deactivation threshold is approximately 110°C. Should the transmission oil temperature rise above approx. 145°C due to a fault, the tem¬ perature value is gradually reduced in accordance with the engine speed in increments of 150-500 rpm, to a minimum of 5,000 rpm. 5,000 rpm is also the value in the event of a failure of the ATF temperature sensor. An electrical gear-oil pump is used to pump gear oil from the gearbox to the gearbox oil cooler. A screw oil filter is located below the oil pump. The transmission housing has been adapted for the oil cooler connection. The oil pump is mounted on the manual transmission housing. The gear oil is replaced and the screw oil filter is checked or cleaned during the running- in inspection, and later according to service specifications (estimated after every third engine oil change). Note: For fault symptoms with engine speed limitation, the gear oil temperature should also be considered as a possible cause. 5 4th Generation M3 Drivetrain Manual transmission system circuit diagram V Index Explanation Index Explanation 1 Plug-in connection for engine wiring harness 7 Engine speed sensor, transmission input 2 Plug-in connection for vehicle wiring harness 8 Zero gear sensor (selector gate) 3 MSS60 Engine control system 9 Transmission oil temperature sensor 4 Junction box/distribution box 10 Reversing light switch 5 Transmission housing 11 Footwell module 6 Electrical transmission oil pump 6 4th Generation M3 Drivetrain Clutch It is the first time that a double drive plate clutch has been used on an M3. The clutch and the dual-mass flywheel are based on the E60 M5 and E63/E64 M6 (manual gearbox), but their combined weight has been reduced by 4 kg. The contact plate and the transfer plate form a single unit with the integrated clutch driving plate. The following changes have been made: • The weight of the clutch and the dual-mass flywheel has been reduced. • The transfer plate is hollow cast and shaped, similar to an internally ventilated brake rotor/disc. This increases heat dissipation and hence the permissible thermal load of the clutch. Comparison of the S65B40 double-disc clutch and the S85B50 manual clutch Index Explanation Index Explanation 1 E6x M5/M6 SAC Clutch 2 E92 M3 Clutch Note: The clutch and the dual-mass flywheel are permanently connected and are balanced as a single unit. They can only be replaced in a set. 7 4th Generation M3 Drivetrain Propeller Shaft and Output Shafts The flexible clutch of the front propeller shaft is taken from the E6x M5/M6. The front drive shaft is hollow and has a graduated cross section. The rear propeller shaft is also a tubular construction and has an equal cross section along its entire length. The thickness of the tubing and the geometry of the front and rear propeller shaft have been adapted to handle the increased driving power. Both propeller shafts are fitted with the same constant velocity joints that are used on E92 M3 Axle drive components (Front propeller shaft with flexible clutch & rear) Note: The center bearing can be mounted in two directions. It is important that the bearing is mounted with the word "TOP" facing the body. Both output shafts are hollow and have a graduated cross section. The external axle shaft joint is new. The internal axle shaft joint is based on the joint used in the E60 M5. The left and right output shafts are different in length. Axle drive with output shafts 8 4th Generation M3 Drivetrain Final Drive In principle, the final drive is assembled in the same way as in the E6x M5/M6. It is, however, a separate new development. The bevel gear shaft bearing is a friction optimized, double-row, angular-contact ball bearing. The gear ratio between the bevel gear and the crown gear has been adapted to the engine speed and gearbox ratio of the M3. Index Explanation 1 Propeller flange 2 Front double-row angular contact ball bearing 3 Rear double-row angular contact ball bearing 4 Bevel gear 5 Crown gear The final drive ratio is 3.85:1. The 215 gear set (crown wheel diameter 215 mm) has been temperature and noise optimized. A friction-reduced gearing is used. The housing of the final drive has been adapted to accommodate the double-row angular-contact ball bearing. The flanges for the propeller and drive shafts are the same as those used on the E6x M5 and M6. Note: Due to their function, the shafts of the right and left stub axles in the final drive have different lengths. In an idle state, this results in a noticeably different vertical clearance of both flanges, which is a feature of the design. This does not affect the function and is not a cause for complaint. This uneven clearance applies for all models with fully variable M slip differential and may affect either the right or the left flange, depending on the version and model. 9 4th Generation M3 Drivetrain Final drive end cover The transmission housing end cover has been modified to ensure optimum gear oil cool¬ ing and bevel gear lubrication. The end cover has more ribs, which improves heat exchange. The internal styling of the end cover is adapted according to the size of the differential and the final drive ratio. This M final drive also has three bearings, with two front bearing and one rear bearing. Fully Variable M Differential with Locking Action This unique limited slip differential design is based on the E46 M3 and the E6x M5/M6 limited slip differential, where it is described in detail. The function of the limited slip differential has been adapted to ensure that the M3 develops the best traction at different engine speeds and in every road situation. 10 4th Generation M3 Drivetrain