Project FD RX7 Restomod: Part 18 – Choosing a Transmission Upgrade

3. Dual-Clutch Transmission (DCT) – BMW GS7D36SG

BMW GS7D36SG DCT TransmissionThe BMW GS7D36SG Dual Clutch Transmission (DCT) is becoming a popular candidate for the FD RX-7 and many other platforms, enabling people to incorporate modern dual-clutch transmission technology into their builds.  No human can match the lightning-quick and seamless shifting of a DCT, or the 7-speed gear ratios.

These transmissions can be found in two gear ratios:

1.00 final drive ratio (Short gears) had ratios of: 4.78, 2.933, 2.153, 1.678, 1.39, 1.203, 1.00

  • 2009-2013 135i
  • 2008-2013 E9X, 2008-2016 Z4 (with a starter off to the side)
  • 2006-2013 E9X M3

0.671:1 final drive ratio (Long gears) had ratios of: 4.806, 2.593, 1.707, 1.277, 1.00, 0.844, 0.671

  • 2012-2018 F80 M3
  • 2013-2019 F82/83 M4
  • 2014-2019 F87 M2 (with a starter off to the side)
  • 2010-2016 F10 M5
  • 2011-2018 F06/F12/F13 6-series.

After purchasing all of the necessary coolers, transmission controllers, and adapter plates, a DCT will run roughly $10K to outfit a car.  But the demand for these transmissions is increasing.  There are still plenty of used transmissions available ranging from $1,500-2,500, but these prices are already $500 higher than what they sold for a couple years ago and are expected to increase.

The major downside of the DCT is its weight.  At 175lbs for the transmission alone, this option starts off at an 80lb weight penalty over stock, which will increase to nearly 100lbs after adding the necessary coolers, adapter plate, and components.

Another big issue is the programming.  The Transmission Control Modules (TCU) are getting better and are becoming more advanced, however, most DCT swaps that I’ve seen are quite jerky in operation at anything other than full-throttle shifts.  The initial clutch engagement from a stop and most part-throttle driving conditions, which is where you spend most of the time driving on the street, often has a harsh and inconsistent engagement, which is not an enjoyable experience.  Properly tuning these transmissions is far more time consuming and difficult than tuning an engine.

4. 6-Speed Manual Transmission – Nissan CD009 / CD00A

Nissan 350Z 370Z CD009 CD00A 6-speed TransmissionRising in popularity for 6-speed manual transmission options is the Nissan CD009/CD00A found in the 350Z and Infiniti G35.  This transmission has earned a reputation for reliably handling over 750lb-ft of torque, 1,000whp+, and for being arguably the best shifting synchronized transmission over 9,000rpm this side of a dog-ring, face-plated, or sequential gearbox.

Sharing architecture with the ’04-’15 Nissan Xterra and Frontier manual transmissions, the CD009 is a very stout gearbox and due to its strength and affordability, it has become an increasingly popular option for LS-powered vehicles and is a common upgrade for MKIV Supra owners to replace their factory Getrag V160 transmission.  At 134lbs, this transmission is 40lbs heavier than stock and 20-30lbs lighter than a Tremec T-56 Magnum.

The gear ratios for the CD009 are:  3.794, 2.324, 1.624, 1.271, 1.000, 0.794.

All-in, this swap costs just under $8,000 with a brand new $2,400 transmission.  The transmission is over $1K less than a new T-56 Magnum, and the rest of the components make this option over $2K less than the T-56 swap.  This was an added benefit to the major reason behind choosing this transmission, which is its reputation for handling high RPM.


Not all CD009s are the same and many are not even CD009s at all.  The history and application of the different variants is a bit of a mess that you can look into HERE.

In short, early versions of the 350Z’s transmission (CD000 to CD003 used in ‘03-‘04 cars) were known to fail the 2nd gear Double Cone synchros, and were just not as strong or reliable as the reputation the CD009 came to garner. Infinity G35s quickly implemented the CD003 through CD008, and the 2007 350Z HR, Infinity G35 HR, and G37s technically don’t use a CD009, but rather use the “JK400”, “JK40B”, “JK41A”, and “JK41B” transmission offshoots that have a different bolt pattern, internal slave cylinder, and different hydraulic system from the “CD” transmissions.

In its ultimate form, the CD009; which was superseded and upgraded by the CD00A (PN: 32010-CD00A) features triple cone synchros on 1st, 2nd, and 3rd (the Tremec T56 Magnum only equips 1st and 2nd with triple cones), and double cone synchros on 4th gear.  This transmission came on 350Zs built from 7/2004 to 11/2006 (not the “HR” versions), as well as G35s built after 11/2004 (except “HR” or G37 models).  They are also the fix and replacement for all ’03-’06 350Z and G35 transmissions with shifting issues.


While I am a big fan of the Tremec Magnum transmission, having had one in my daily driven Mustang, and racing them professionally in Mustangs competing in the Grand-Am series for many years, they are only rated to 7,800rpm and struggled with shifting above 8,000rpm without expensive, face-plated gears.  With our goals of a 9,000rpm+ redline, the high-rpm capable synchros of the CD009 makes it a better fit for our build.  It also does not hurt that the transmission and swap kit is far more affordable than the T-56 Tremec swap kit.


  1. All of the CD009 conversions, I’m a little bothered that the replacement bellhousing bolts to the relatively small bolts intended for that cover. Obviously it works, I can’t think of a better way that’s not a lot more work and cost, it’s done a lot, it’s not actually a problem, but it just bothers me a little.

    Nice to see the thoroughness of the upgrades – some of the other transmission options would mean the stock final drive ratios would be less than optimal, but that problem’s taken care of too.

    1. There are (11) M8 Bolts that hold on the front cover, and (now) attach the Fisch Racing Bellhousing adapter. These bolts are also close to the very outer diameter of the transmission. Fisch has numerous 1,000hp drag and drift cars that use this adapter design on various RX-7s, Supras, IS300s, LS engines and K-series engines. Based on the success of their extensive testing and customer base, there should be no reservations of this tried and true design.

      1. I know that any other solution would be a much larger casting, with a lot more post-casting machining and a lot more work to install. I know the design Fisch Racing came up with works and is well executed. I just wish there were a way to do it that fed torque loads into the case how it was originally designed; I’m really annoyed that design trends have gone away from separate bellhousings.

          1. If I were in charge of things, someone would make a front casing for the CD009/etc that had a T56/Magnum bolt face.

            I’m not though.

  2. I’ve never had the privilege to drive any of the mentioned transmissions above. Are any of them smooth like S2k or Miata 6spd? I have a 05 STi 6spd in my 00 2.5 RS and while its wonderful, I still find it awkward to shift super fast. Its not a skill issue on my part (at least in my opinion), because I was still able to do some 90s style drag shifts in a low mileage FK8 CTR.

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