Dec 27, 2009

R35 GT-R Transmission and Clutch Upgrades

This needs an update. Added Forged/Dodson video 11/10/11
The R35 GT-R uses a completely new transmission for Nissan, the Borg Warner GR6 dual clutch transaxle gearbox.  The GR6 is an automated manual transmission, even though the misinformed masses call it an “automatic” transmission it is internally much more efficient and shifts faster than an automatic transmission.

This transmission has met with a lot of controversy in the automotive world, both in the real world and online. The first launch control feature(LC1), that was undocumented officially, but existed allowed the car to be revved to 4500 rpms before engaging the clutch. This caused a large amount of wheel spin on some surfaces, that caused wheel hop, and when abused broke gears.

I wrote up some of my ideas on how Nissan could fix this issue with transmission failures.  The people I spoke to at Nissan said the cars that broke had been abused, more than 20 launches in a row.
Setup switches. VDC Off= warranty issues

Nissan decided to initiate a software fix for the transmission that brought the launch RPM down to 3000 rpm(LC2). While this sounded like a step in the wrong direction, it actually had the opposite effect, the car got quicker.
The next issue that has come up several times is material getting stuck in the shifting solenoids. This material causes the transmission to go into a fail safe mode, and generally will only engage half the gears. This often shows up as a Code P0732 / P0729.

Another issue that has come up recently is with high horsepower/torque(700+hp) cars not wanting to shift gears. This is a TCM/ECM related issue that is being worked on. SP Engineering posted up some information on the problem. This issue has been pretty much solved thought tuning the ECM and TCM.

After any work to the transmission, and also as part of the performance optimization service, the clutches in the transmission generally need to be adjusted with a Consult III. The Consult III is a Panasonic Toughbook laptop with software to work with Nissan and Infiniti vehicles. However, to work on the Nissan GT-R, you need a special “GT-R card” .The Consult III and GT-R card are very difficult to get a hold of. Mostly only certified Nissan dealers have it. A few aftermarket companies around the world have Consult III’s, but they are not common, and they are expensive.  There are 15 different settings for the clutch touch point and capacity,which adjust how the car drives, and the firmness of the shifts.

At the factory clutch settings, the standard clutch starts to slip with the factory fluids at around 650 wheel horsepower. However, recently cars have done as much as 951 awhp on the standard clutches, with a Cobb tune on the engine(ECU) and transmission(TCU). At 951 awhp, the factory clutches were slipping at this level, but prior to the ECU tune, they would slip at a much lower level.  There are upgraded clutch pack, and OEM replacements available.

Cobb has released their new AccessPORT with TCM support.  It allows for DIY setup of the clutch adjustment, and launch RPM. Buy one here:

Installing the AccessPORT on the TCM starts with downloading the OEM TCM ROM for safekeeping, so the TCM can be returned to its stock configuration at any time. Once the OEM TCM ROM is stored, the AccessPORT flashes a new Level 1 map onto the TCM that is based on the Nissan LC2 logic upgrade, but increases launch revs to 3,300RPM and includes more aggressive clutch engagement and throttle curves than stock LC2 logic. The result is a positive launch that gets the GT-R off and running harder than the stock LC2 logic, but with smoother clutch engagement than the previous LC1 logic. Still not enough for you? A simple reflash of the TCM with the Level 2 map will have you experiencing the increased punch from raising the launch revs to 3,750RPM!


NEW AccessPORT TCM Flashing Features!
- ENHANCED LAUNCH CONTROL: Updates TCM to Nissan LC2 launch control logic with two user selectable launch control modes! Level 1 sets launch control revs to 3,300rpm (300 more than stock LC2) with more aggressive clutch engagement and throttle curve. Level 2 raises launch control revs to 3,700 rpm with the same clutch and throttle characteristics as Level 1.
- CLUTCH GEAR LEARNING: Perform this factory recommended annual optimization without a trip to the dealership. Shift quality degrades as transmission components wear. Performing this optimization recalibrates the transmission, resulting in smoother shifts and improved driveability.
- TOUCH POINT ADJUSTMENT: Use the AccessPORT to adjust the amount of clutch drag while stationary. Eliminate excessive creep or set clutch drag for the perfect launch responsiveness with +/- 7 levels of adjustment.
- CLUTCH CAPACITY ADJUSTMENT: An essential adjustment for higher horsepower GT-Rs to eliminate clutch slip during full throttle upshifts. Increase or decrease clutch clamping force with +/- 7 levels of hydraulic pressure adjustment.

 Updated 1-10-11

Clutch Packs

A clutch transfers the power from the engine to the transmission, and allows for the engine and transmission to be decoupled. As the horsepower of the engine is increased, the clutch will start to slip, and eventually fail.

Dodson/Exedy

Super Stock 650 ft/lbs $1750(NZD)
Dodson/Exedy Sportsmans 800 ft/lbs $8390(NZD)
Dodson/Exedy Pro Max 1000 ft/lbs $11500(NZD)
SSP OEM

$1199
700whp 700 hp $1599
Willall Racing WR35CP 30%up $995

 

While on the track, the transmission will get hot. The factory heat exchanger uses engine coolant as a fluid to try and cool down the transmission fluid. The problem with this is the coolant temperature will be high, and the temperature difference will be minimal.  The cooler the fluid the more protection for the gears.

Transmission Coolers

Dodson R35 cooler $1268
GR6 pan $1200
HKS Kansai Trans cooler $1840
SSP Pro Series $3199
Willall Racing WR35TC Complete $2995
Cooler only $1300

 

Transmission Fluid

Dodson +30 deg Liter $60

-30 deg Liter $60
HKS


SSP Pro Red Liter $75
Willall Racing WR35TM 10 Liters $600 (+130 shipping)USD

WR35TMVS 10 Liters $750 (+$130 shipping) USD

WR35TML 10 Liters $600 (+$130 shipping) USD

There have been several gearbox failures related to both seals, and to circlips within the transmission. PPG also offers both a 1st gear, and a 1-6th gear upgrade option for the transmission. Dodson have also started offering a 1st gear upgrade

Gearbox Internals

Dodson Input shaft Circlip $150
Magnet kit $50
O-Ring Kit $100
4wd gearlock Circlip $275
Uprated A Clutch Seal and Piston $1550
Uprated B Clutch Seal and Piston $1280
Uprated A Basket Output $1440
Uprated B Bastet Output $1440
Clutch shaft Piston Seals $100
PPG 1st gear $2200
Gear set 1-6 gear $10296
Willall Racing WR35CC Gear Fastening System $370
WR35PS Piston Seal Replacement $390
WR35CCL Clutch Retaining Clips $150



3 comments:

Chargeur de voiture pour nintendo ds said...

Nissan Motor Company Ltd. announced the launch of the Nissan GT-R, a new multi-dimensional performance machine that lives up to the concept of 'an ultimate supercar for anyone, anywhere, at anytime'. The Nissan GT-R features a newly developed Premium Midship package, including the worlds first independent transaxle 4WD developed independently by Nissan.

Jeff C said...

These are what I am waiting for, I want a proven formula for a 9 seconds street R35, it is getting there slowly :) I want to pull away from a stock Hayabusa with ease :)

Sean Morris said...

9's are there now Jeff...the recipe has been published. Now just have to follow it.