8L90 Transmission parts, repair guidelines, problems, manuals
Transmission general data
The RWD automatic transmissions with longitudinal positioning Hydra-Matic 8L90 (M5U) and 8L45 (M5N, M5T) were designed in 2015 for Cadillac CT6 with new engines (3.6 liters) and also suitable for 6-liter engines V8. The design of this modern transmission is similar to 8HP by ZF and has a lot of same "features", like Start-Stop system on at traffic lights, used to save more fuel.
| Number of gears | Transmission Type | Drive | Torque (Nm) | ATF (full capacity) L | ATF (change) L | ATF type |
|---|---|---|---|---|---|---|
| 8 | AT | RWD/AWD | 1000 | 11,7 | 6 | Dexron HP |
Technical issues and repair guidelines
The transmissions has much higher reserve on components than its German competitor and should operate at least 200-300 thousand kilometers before the first overhaul ( under the condition of well-timed ATF change). In case of frequent “kickdown” usage with a switch-on of controlled slipping of the lock-up clutch, the wear-out of friction elements occurs quite rapidly and contaminates the valve body, fluid and filter. The filter is made of plastic with a two-layer felt membrane and its better to change this part in a timely manner.
The oil and filter should be changed when there are any suspicions related to oil transparency. Such situations may occur after travelling 40 thousand kilometers or 80 thousand kilometers depending on driving style and adherance to the transmission warm-up rule before driving in winter time. Removal of the pan allow specialists to estimate the level of components wear-out and valve body contamination.
Which cars run with this gearbox?
| Brand | Model | Year | Type | Engine |
|---|---|---|---|---|
| Cadillac | ATS | 15-16 | 8 SP RWD | V6 3.6L |
| Cadillac | CT6 | 15-16 | 8 SP 4WD | V6 3.0L |
| Cadillac | CTS | 15-16 | 8 SP RWD | V8 6.2L |
| Cadillac | ESCALADE | 15-16 | 8 SP R/4WD | V8 6.2L |
| Cadillac | ESCALADE ESV | 15-16 | 8 SP R/4WD | V8 6.2L |
| Chevrolet/GM | CAMARO | 15-16 | 8 SP RWD | V8 6.2L |
| Chevrolet/GM | CORVETTE | 14-16 | 8 SP RWD | V8 6.2L |
| Chevrolet/GM | SIERRA | 14-16 | 8 SP R/4WD | V8 6.2L |
| Chevrolet/GM | SILVERADO | 14-16 | 8 SP R/4WD | V8 5.3L 6.2L |
| Chevrolet/GM | YUKON XL | 06-16 | 8 SP R/4WD | V8 6.0L 6.2L |
Instruction manuals and useful links
| Link type | Source | Description |
|---|---|---|
| Atra | Introduction 8L90 | |
| web | gmauthority.com | Specification 8L90 |
| web | sandyblogs.com | Harsh Shifting on the 8L90 |
| web | sandyblogs.com | Reprogramming Procedures for the 8L90 |
| web | sandyblogs.com | All-New 8L90 8-Speed info |