It’s strange the path that automotive technology takes sometimes. Typically, it’s a trickle-down effect. Top-tier race vehicles and techno-packed supercars are first in line for the latest and greatest gadgets. In the case of the dual-clutch transmission, it was a VW Golf (well, technically an R32) that was responsible for the trickle-up of the modern DCT into sports cars, like your F8X M3 or M4. Even with a non-conventional path to the M3, the Getrag paired with the S55 still needs to regulate temperature to operate to its true potential.
Why does the transmission temperature on the F80’s DCT matter? Simply put, the excess heat can wear the oil in the transmission prematurely, which diminishes the oil’s lubrication properties. The DCT is, in essence, a clever combination of an automatic and manual transmission. However, instead of a torque converter, there is a pair of clutches that split duties between the gear ratios, most commonly split between odd and even gears. These clutches are commonly wet clutch packs and utilize oil to cool the clutches, given the immense friction. The clutches continually switching gears, not to mention the constant gear meshing between the two gear sets, already generates plenty of heat, but a spirited track day on top of that could lead to issues down the line.
This isn’t BMW’s first rodeo, though, and their engineers already equipped the DCT-optioned M’s with liquid-to-air cooler for keeping the transmission fluid temperatures in check. BMW incorporated a single-pass cooler that measures in at 21.75x3x1”, giving it an adequate core volume to contend with most daily driving duties. They also made sure to utilize hard lines for a secure connection to the transmission lines and implement the use of internal fins to promote more efficient heat transfer.
We still saw room to grow, though, and started our design process with a full 3D scan of the stock unit with the help of our Faro Design Scanarm. With the scan completed, Jason got straight to work on our new design. There was limited space to expand into; however, Jason was still able to add an inch to the height and bumping out the thickness to 1.25” which equates to a 42% increase in core volume over the stock unit. Also, Jason made adjustments to the external fin design, adding three additional rows, that put our cooler at a 69% increase in external fin surface area for improved heat dissipation.
Our new design is more than just skin deep as well. We were able to carry over the use of internal fins that promote increased heat transfer to the external fins. We also adjusted the layout of our inlet and outlet to accommodate a dual-pass flow through the core while retaining a direct fit on your Bimmer. With these features combined, we were able to record a 15% increase in heat rejection and improved heat regulation over the stock unit during our bench testing.
While BMW already knew that transmission temperature regulation was imperative, they were still aiming for a more common cooling approach. With our cooler, you’ll spend less time worrying about transmission temperatures in your M, and more time just enjoying the Ultimate Driving Machine. Get yours today:
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