BMW SMG and M DCT Transmission Guide
S6S 420G (SMG), GS7S47BG (SMG, 7-speed), GS7D36SG (M DCT, 7-speed twin-clutch) · US-market M cars and a few others · E46 M3, E60 M5, E63 and E64 M6, E9x M3, F80 M3, F82 and F83 M4, F12 and F13 M6, E89 Z4 35is
Part of the BMW transmission guide. To find the gearbox in a particular car, use the E-series lookup or the F and G series lookup.
BMW sold two kinds of clutchless performance gearbox in US cars. The first is the sequential M gearbox, called SMG: a manual gearbox with an electro-hydraulic system that works the clutch and the gear changes. The second is the twin-clutch gearbox, which BMW calls DKG and M owners call M DCT, with two clutches in an oil bath and gear changes without a break in drive.
The two behave differently in service. SMG gearboxes have a hydraulic system filled with a special hydraulic oil that is not brake fluid, and BMW's M-model schedule changes the gear oil and cleans a filter on them. The twin-clutch gearbox has a lifetime-fill oil, and BMW's M5 and M6 schedule says its gear oil is not changed as part of maintenance.
Quick read
- Ownership position: Not established yet. We are still researching how these gearboxes age in service.
- Reliability: No family-wide verdict. BMW documents in our files cover one E46 M3 SMG complaint and towing and service rules, listed below.
- Cost to own: Not established yet.
- Power potential: BMW designed the E60 M5 and E63 M6 SMG for up to 550 Nm and 8,500 rpm, and describes the twin-clutch gearbox as configured for up to 520 Nm and 9,000 rpm.
- Main watch item: Using the right fluid. SMG hydraulics take Pentosin CHF 11S, not brake fluid, and the twin-clutch gearbox takes BMW DCTF-1 or DCTF-1+.
SMG and M DCT At a Glance
| Question | Practical answer |
|---|---|
| BMW designations | S6S 420G (SMG) for the E46 M3, GS7S47BG for the E60 M5 and E63 and E64 M6, and GS7D36SG for the twin-clutch gearbox. BMW lists the first as Getrag D SMG, the second as Getrag J SMG with seven speeds, and the third as the Getrag DKG, seven-speed, type 436. |
| Which BMWs have them | SMG: E46 M3 (option 793), E60 M5, E63 and E64 M6. Twin-clutch: E92 and E93 M3 in BMW technical data and in NHTSA recall 08V595000 (2008-2009 M3), E89 Z4 35is, F80 M3, F82 and F83 M4, F12 and F13 M6, and F10 M5 and F87 M2 in BMW technical data. |
| SMG fluid | Gear oil: MTF LT-2, 83 22 2 339 219. Clutch and shift hydraulics: Pentosin CHF 11S hydraulic fluid, 83 29 0 429 576, which BMW says is not brake fluid. |
| Twin-clutch fluid | BMW DCTF-1 (83 22 2 148 578) until 12/2015 cars, DCTF-1+ (83 22 2 446 673) for the F87 and all cars from 01/2016. BMW says cars up to 12/2015 can also take DCTF-1+. |
| Fill | SMG GS7S47BG: 2.55 liters, 2.75 liters on a first fill or replacement. Twin-clutch: 7.8 liters on the E9x and E89, 8.4 on the F80, F82, F83 and F87, 8.6 on the F10 M5 and 8.8 on the E92 M3 GTS. |
| Towing | BMW says E60 M5 and E63 M6 SMG cars with a gear engaged should only be towed with the rear axle raised, even for short distances. |
| Service schedule | SMG: change the transmission oil and clean the SMG oil filter at the 2,000 km check, around 52,000 km and 127,000 km, then every third engine oil change, on the ECE basic interval for the E9x M3, E60 M5 and E63 and E64 M6. Twin-clutch: BMW says the gear oil does not need changing as part of maintenance on the M5 F10 and M6 F06, F12 and F13. |
Technical Specifications
| Specification | Detail |
|---|---|
| SMG, E60 M5 and E63 M6 (GS7S47BG) | Seven gears, 11 Drivelogic programs, four shift rods, designed for up to 550 Nm and 8,500 rpm. BMW says gear changes are about 20 percent faster than the second-generation SMG, and about 65 milliseconds at best. Launch date 09/2004. |
| SMG, E46 M3 | Called the sequential M transmission, option 793, with the S6S 420G (SMG). One bulletin covers E46 M3 cars with it built 10/2000 to 07/2002. |
| SMG oil, S7S 47BG | 2.55 liters, or 2.75 liters on a first fill or replacement gearbox |
| Twin-clutch design | Seven gears, two oil-bath clutches, one for gears 2, 4 and 6 and one for gears 1, 3, 5, 7 and reverse. BMW describes it as configured for up to 520 Nm and 9,000 rpm and weighing 89 kg with the dual-mass flywheel. |
| Twin-clutch oil | BMW DCTF-1 and DCTF-1+, lifetime fill, with a green label reading Lifetime Fill near the filler plug |
| Gear ratios | Not established yet |
| Six-speed SMG variants outside the US | BMW also built SMG on the ZF GS6-37BZ (GS6S37BZ, up to 370 Nm) and GS6-53BZ (GS6S53BZ, up to 600 Nm). BMW's E46 document puts that SMG at 03/2003, worldwide except the USA and Canada. US availability on the E60 and E63 is not established. |
Which BMWs Have Them
Rows below are from BMW parts data. The E46 M3 SMG and the E9x M3 twin-clutch cars are not in that fluid table; they are listed after it from BMW technical data.
| Chassis | Models | Engine | Built | Gearbox | Fill (L) |
|---|---|---|---|---|---|
| E60 | M5 | S85 | 09/2005-12/2009 | GS7S47BG | 2.55 |
| E63 | M6 | S85 | 03/2006-07/2010 | GS7S47BG | 2.55 |
| E64 | M6 | S85 | 09/2006-07/2010 | GS7S47BG | 2.55 |
| E89 | Z4 35is | N54T | 03/2010-08/2016 | GS7D36SG | 7.8 |
| F12 | M6 | S63N | 03/2012-05/2018 | GS7D36SG | 7.8 |
| F13 | M6 | S63N | 07/2012-08/2017 | GS7D36SG | 7.8 |
| F80 | M3 | S55 | 03/2014-10/2018 | GS7D36SG | 8.4 |
| F82 | M4, M4 GTS, M4 CS | S55 | 03/2014-12/2019 | GS7D36SG | 8.4, 8.6 |
| F83 | M4 | S55 | 07/2014-12/2019 | GS7D36SG | 8.4 |
| Car | Gearbox | Note |
|---|---|---|
| E46 M3 | S6S 420G (SMG) | Option 793; BMW parts data lists the manual S6S 420G for this car |
| E90, E92, E93 M3 | GS7D36SG | BMW technical data: 7.8 liters on a first fill for the E92 and E93 S65, 8.8 liters for the E92 M3 GTS; BMW service information lists the E90, E92 and E93 |
| F10 M5 | GS7D36SG | BMW technical data: 8.6 liters on a first fill with the S63 |
| F87 M2 | GS7D36SG | Named in the F80, F82, F83 and F87 capacity table, 8.4 liters; BMW parts data lists the F87 M2 with a manual only |
Variants
- SMG (E36 M3 and E46 M3 generations): BMW service information says the sequential M transmission was introduced in the E36 M3 from 01/1997. US availability of the E36 version is not established.
- SMG, third generation (E60 M5, E63 and E64 M6): a seven-speed unit described by BMW as a fundamentally new development. It uses four shift rods, each selected by a hydraulic cylinder.
- Twin-clutch GS7D36SG: used from the E9x M3 (S65) through the F80, F82 and F83 M3 and M4 (S55) and the F12 and F13 M6 (S63N), and in the E89 Z4 35is.
Service Parts at a Glance
These BMW part numbers were looked up in BMW parts data (December 2019 data date).
| Part | BMW part number | Catalog lists it for | Status |
|---|---|---|---|
| Hydraulic fluid CHF 11S, 1 liter. The catalog lists it for many models, including uses outside the gearbox | 83 29 0 429 576 | E46 320i, E46 323Ci, E46 323i, E46 325Ci, E46 325i, E46 325xi and others | current |
| MTF LT-2, 1 liter, SMG gear oil | 83 22 2 339 219 | E36 318i, E36 318ti, E36 320i, E36 323i, E36 325i, E36 328i and others | current |
| BMW DCTF-1+, 1 liter | 83 22 2 446 673 | E82 1 Series M, E82 128i, E82 135i, E88 128i, E88 135i, E89 Z4 35is and others | current |
| BMW DCTF-1, 1 liter, earlier twin-clutch oil | 83 22 2 148 578 | superseded to 83 22 2 446 673 |
Known Failure Points and Service Items
Only items a BMW document or an NHTSA recall backs are listed. Frequency is not established.
01 Clutch does not engage, E46 M3 with SMG
BMW service information says some E46 M3 cars with the sequential M transmission built from 10/2000 to 07/2002 could fail to move off because the transmission control unit did not see the bonnet as closed. The cause BMW names is a failed or damaged microswitch in the lower bonnet lock. Watch for the R or 1 gear indicator flashing while the engine runs and the car does not move or only pulls away with the indicator flashing.
02 Towing an SMG car (service item)
BMW says that on an E60 M5 or E63 M6 a fault can leave a gear engaged in a parked car and block the start enable, and that towing it with the rear wheels on the ground can drive the engine through the rear axle and damage it. The rule is to tow with the rear axle raised, even for short distances.
03 SMG hydraulic fluid (service item)
A 1997 BMW bulletin written for the M3 with SMG says its clutch hydraulics hold Pentosin CHF 11S hydraulic oil instead of brake fluid, and that the brake bleeding equipment must never be connected to them, since even a trace of this oil in the brake system can make the brakes fail.
04 Downshift software recall, E9x M3 twin-clutch
NHTSA recall 08V595000, filed in November 2008, covers about 2,500 2008-2009 M3 cars with the optional double-clutch gearbox. Under rapid deceleration the gearbox software could make a multi-gear downshift, and at low speed the engine could stall. Dealers reprogrammed the engine and gearbox control units. Watch for a stall after hard braking on a car that has not had the update.
Reliability Verdict
Not established yet. We are still researching these gearboxes.
Power Potential
Not established yet beyond BMW's design figures: up to 550 Nm for the E60 M5 and E63 M6 SMG, and up to 520 Nm for the twin-clutch gearbox.
Cost of Ownership
Not established yet.
Common Questions
What BMWs have SMG?
In BMW parts data the seven-speed SMG, GS7S47BG, is in the US E60 M5 and the E63 and E64 M6. BMW service information also names the E46 M3 with the sequential M transmission, option 793.
What BMWs have the M DCT?
BMW parts data lists the twin-clutch GS7D36SG in the US F80 M3, F82 and F83 M4, F12 and F13 M6 and E89 Z4 35is. BMW technical data also names the E92 and E93 M3 and the F10 M5.
What fluid does the M DCT use?
BMW specifies DCTF-1 for cars to December 2015 and DCTF-1+ for the F87 and all cars from January 2016, and says earlier cars can also use DCTF-1+. The current BMW part number in parts data is 83 22 2 446 673.
How much oil does a BMW twin-clutch gearbox hold?
BMW technical data gives 7.8 liters for the E9x and E89, 8.4 liters for the F80, F82, F83 and F87, 8.6 liters for the F10 M5 and 8.8 liters for the E92 M3 GTS.
What hydraulic fluid does an SMG take?
BMW specifies Pentosin CHF 11S hydraulic fluid for the SMG hydraulic system, not brake fluid. The BMW part number in parts data is 83 29 0 429 576.
Sources
- BMW service documentation: transmission designations and maker table.
- BMW Service Technology 23 01 04 (088): sequential M transmission E60 M5 and E63 M6; 23 01 03 (002) and 23 03 03 (044): SMG.
- BMW Service Technology: functional description of the twin-clutch gearbox.
- BMW Service Information SI 28 01 08 (001): twin-clutch gearbox oil; SI 23 02 96 (142): manual gearbox oils.
- BMW Service Information 21 01 02 (917), 00 01 06 (254), 1 15 97 (211), 00 10 09 (593) and 00 24 11 (729).
- BMW technical data: transmission filling capacities, groups 23 and 28.
- BMW parts catalog data, December 2019 data date: fluid table, fitment and part numbers.
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