Propulsive Dynamics 6HP21 Upgrade/Dynamic Calibration Procedure and Data


Nov 6, 2016
New Market, AL
335i e92 6MT
I wanted to post this write-up over here in its own thread. I had originally posted something similar, albeit not as detailed, up on one of the other forums but that thread has since been zapped after I recently decided to leave that forum.

After reviewing this information, it will be easy to see why Propulsive Dynamics has formed an exclusive partnership with EuroTrans to provide reliable, high value, high performance transmissions to our customers. EuroTrans is also a BMW certified transmission refurbishment facility, meaning that most of the transmissions that are replaced under warranty at BMW dealerships in the US have been re-manufactured by EuroTrans. It also means that there are strict non-disclosure and proprietary intellectual property protection contracts in place mandated by BMW in order to achieve this level of certification and possess the calibration and testing equipment outlined in this article.

Every transmission is completely disassembled and cleaned to remove contaminants that result in premature wear to gears, bearings, shafts and other precision components like the valve body. Transmission cleaning includes individual component hand washing. Individual parts are inspected and bushing/bearing surfaces are polished to micro finish for durability.

Valve bodies are tested on a $31,000 O.E.M. level valve body tester a unit which simulates actual vehicle operation at the elevated line pressures required to compliment the high performance G3 clutches. Vehicle speed and driver demand are varied hydraulically. The test unit quickly locates cracks and imperfections and verifies accurate shift points. Valve bodies are disassembled, cleaned and re-manufactured to O.E.M. specifications. All components of the Valve body are inspected for wear and the valve body is resurfaced for correct mating and sealing with the transmission case. Case and valve body resurfacing along with profilometer inspection of shaft smoothness enables us to maintain exact standards and precise tolerances in all phases of transmission re-manufacturing.

Below is the calibration test results of one of our customer's units showing the pressures at which each clutch drum combines to form the respective gears.




Here is a video of how this test is conducted on a 6HP19 valve body which is the same as a 21...

Regarding dyno calibration to the higher power capacities, every transmission is loaded dynamometer calibrated and tested under live engine power with recorded inspections to shift patterns and shift pressures on the same criteria and against the same standards as a new transmission but with a higher load capacity. Adjustments to shift durations and adaptation parameters are also made at this time to compensate for the increased dynamic coefficient of the G3 friction material. A stall test, fluid leak test, lock-up test and park test are also performed. Tests are made at varying speeds and at full and closed throttle positions to ensure optimum performance at all driver input conditions. This is a $85,000 O.E.M. level piece of equipment.


Consistent quality is maintained through a continuous control system managed by German Master mechanics and re-manufacturing experts with statistical process control (Six Sigma). All areas of the transmission are scrutinized for cleanliness, surface finish quality, lubrication, clearance and wear patterns. Assembled to ISO 9001 specifications, maintaining all clearances and tolerances as specified by O.E.M. GD&T (Global Dimension and Tolerance).

You simply are not going to find a higher level of quality and reliability in an upgraded high performance 6HP19/21 transmission.
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