What’s it like to have upgraded Clutches, new gear(s), and a TCM Reflash?
I knew that I’ll be noticing new weird noises from the upgraded clutch/gears…as if the OEM GR6 wasn’t enough lol. I’m typing this on my 5th day driving my built GT-R (in the 1000km break-in process).
First of all, when upgrading to any power level over 600whp/600wtq, your clutches will start to slip. You will have to upgrade your clutches, and your gears (depending on how and where you’ll be driving). By doing so, your tuner will have to “Reflash TCM”, so re-calibrating your transmission/clutches, clutch capacities, and touchpoints. This will allow your car to run as smooth as possible, and shift as it should be.. (hold on “smooth”?? .. don’t expect that haha)
For my Alpha 9+ turbos & built 3.8L short block, I upgraded to a the Dodson Superstock with an 8 plate clutch kit (DMS Superstock, plus added parts from my build shop MC Performance, to handle 860+whp safely). I also replaced my 1st gear with the DMS heavy duty & input shaft. Many advised to replace all gearsets, mainly because 4th seems to be the most gear that fails. It all depends on the purpose of the car: Street, drag, track etc.. In my case, it’s street driven. The shop was confident to keep my stock 2-6 gearsets, and promising that it won’t break. The owner actually dared me to break 4th lol (that made me confident). So if you have an extra $9,400 laying around .. go for the full set. I don’t need it now, and you probably won’t under 1000whp.
TCM Reflash: Required!
Example: Cobb AccessPort V3 from 005 to 006, which includes the TCM reflashing. Apart from the 1st to 2nd, the car really shifts & downshifts smoother at the right speed. Before reflashing my TCM, and even factory TCM settings, had the up shifts way too early.
On Auto, and normal acceleration, it Finally shifts right. It no longer shifts to 6th at 30mph lol (tree-hugger). I’m on 38B0B stock style LC5 V103
It feels like Trans “R” mode, just less aggressive, but very responsive. When cruising normal, it now shifts to 6th at 50mph (80kmh)..if I let off and drop to 49mph, it would downshift to 5th and so on. If I slowly accelerate, it would downshift like it needs to, allowing you to accelerate on higher RPMs. Finally feels like a sports car even when driving on Auto.
Gear Learning and Clutch adjustments
Gear Learning: What, When, and Why?
Clutch Gear Learning helps the transmission to verify the location of the clutches in the transmission and how thick they are. This enables the computer to make adjustments to clutch engagement as the transmission wears over time.
With modified GT-R’s putting down more power & torque, the clutches need to hold better and avoid “Slipping” and wearing out. There are no exact whp/wtq numbers that indicate when the clutch would start slipping. Many FBO GT-R, pushing 600+, have had clutch slips, and many had no issues (including me).
A good tuner will always advise you on this, but based on my experience, I would definitely go with an ECU version that includes TCM Reflashing. My Cobb AP3-NIS-006, includes the TCM flashing, gear relearn, and clutch touchpoint adjustments.
Clutch Capacities and Touchpoints
Depending on your power levels, and driving style (street/track etc..) you are able to adjust the clutch capacities and touchpoints and adjust how your GR6 transmission behaves. So what does each setting do?
When increasing your Odd/Even clutch capacities to positive values, and your touchpoints to negative values (e.g. +2, +2, -1, -1), this would provide a quicker clutch engagement, with smoother shifting. This works best for sports driving. (Factory settings are: 0, 0, 0, 0)
Again, there are no right settings that can be applied to all. Each GT-R clutch and transmission, especially with a tune behaves differently. The best option is to have your tuner set a baseline for you to adjust.
In my experience, with the Alpha 9 power level, Dodson 8 plate clutches, and 1st gear & input shaft.. I’ve kept the clutch capacity settings to +2,+2 for pump gas, and a maximum bump to +4 while using C16 (which I still haven’t). For my touchpoints I tried “Zeros” and negative values (-1,-1 & -2, 2).
0 or positive touchpoints shifts faster, but more rough, from 1st to 2nd. On negative TPs, such as -1 or -2, a minor lag is felt when shifting to 2nd, but much smoother shifting feel.
How to perform a Gear Learning & Clutch adjustments
1) Make sure you’re on a flat surface, with the engine running, and Handbrake engaged.
2) Make sure the trans fluid temps are at 65c (150 F) or more.
3) Set your desired Clutch Capacities & Touchpoints
4) Run the Clutch Gear Relearn
If you search online, most say to set CC/TP before running a gear relearn. It’s not required. The steps above work, as you can see in my video. Just my 2 cents, always go with what your tuner advises.
First driving impression
Long story short: It’s jerky & slightly noisy. In reality, all these upgraded heavy duty clutches/gears are noisy and normal. Some might be louder or more “jerky” than usual, and that all depends on the Clutch Capacity & Touchpoint adjustments set by the tuner. As of now, I’ve been playing around and testing 3 different touchpoints, until I find the right one.
All my feedback below are on normal AUTO driving, minimal boost, below 4K rpms.
My first settings were set at: +2, +2, -2, -2.
I noticed the a lag coming off slowly from 1st to 2nd, like from a light. Slow RPM picks up until it shifts to second (best example: imagine rolling off first, forgetting the handbrake up lol).
I then adjusted the touchpoints to +2, +2, 0, 0.
This cancelled out the lag, however made 1st to 2nd shifting more “Jerky/Rattle”. It would kind of hesitate once before shifting to 2nd harshly. (Best example: image having a gear 1.5 lol.. shifting from 1st to 1.5 to 2nd).
I re-adjusted the touchpoints for a 2nd time to +2, +2, -1, -1. (as advised by my tuner).
Immediately noticed a bunch of odd NEW noises. Louder gear cranking, heard a tiny grind while shifting from even to odd gears , clutch whistling noises on 2nd at low speeds, and a terrible constant clutch grinding while hooked on 1st or R at standstill.
Solution:
The shop adjusted the clutch basket spacings between each plate, hoping to reduce the jerky takeoffs/gear shifts and noises. A few days later I noticed heavy and constant clutch noises when hooked on 1st or R at standstill. Had the shop re‑adjust the clutch basket spacings back to OEM clearance (3.4mm Clutch A and 4.1mm Clutch B), which now improved the jerky shifting and eliminated the clutch friction noise.
Understanding Clutch Baskets
The baskets are filled with clutches (frictions) and steels that couple together when pressure is applied to the basket. When pressure is not applied to the basket, you have a gap between each steel and in this gap is the clutch (friction).
If the gap between the steels is 5mm and your friction is 2.5mm thick, then your clearance is 2.5mm. You can increase or decrease this clearance by varying the steel thickness, but it has to be within a range to function properly. It could be the gap is too small so the clutches are dragging despite setting the touchpoints to the lowest settings.
MAJJ GARAGE 