Project R35 GT-R, What is inside our 1200 lb/ft Capable GR-6 Transmission!

A Dodson anti-surge baffle was installed in the pan to further reduce the chances of the transmission oil pump sucking up air.  We are also installing Boost Logics breather tank overfill kit which will allow us to add two more quarts to the oil capacity which makes sucking air just about impossible.

Sheptrans adds 4 more magnets to the transmission pan to fortify the two that come stock with the car.  The selector piston magnets tend to collect metallic debris which can prevent their sensor from detecting piston movent which causes the transmission to go into limp mode and these magnets will help collect the magnetic particles before the piston magnetic strips will.

To give the rear wheels of the car positive locking, we replaced the stock differential with an Overtake Saikou 1.5-way rear limited-slip differential from Bulletproof Automotive.

The Overtake Saikou differential is a Salisbury style that uses a combination of cone washers and ramps and cams to apply force on multi-plate clutches inside the diff to provide limited-slip action. The more one wheel wants to slip, the more locking force is applied by the differential.  The differential is made to Overtake Saikou’s specs by Drexler Motorsports, a maker of diffs used in DTM, FIA GT, prototype, and formula cars.  It is calibrated to have aggressive locking but not to freak out the GT-R’s electronics.

6 comments

  1. Are you sure you want to add “super-strong ARP bolts” in the blind holes machined in to the cast aluminum differential cover? Higher strength bolts means more clamp load to achieve the same stretch which in turns leads to shearing the threads in the non-serviceable transaxle. Those holes don’t look to deep so it would be a good idea to triple check the thread engagement calculations.

  2. Is there some reason that they don’t go with straight cut gears? Seems like noise and vibration wouldn’t be a serious consideration in this application.

    Personally, I kind of enjoy a bit of gear whine in a race car.

    1. The helix of the gears is changed for more strength. Helix gears can be stronger although they do waste more power.

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