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Discussion Starter · #81 · (Edited)
Before I touch the TCM tune I’m going to see if I can tune this out using the touch points and clutch capacities.

After some reading, the clutch capacities control the ramp in rates for line pressure and allow for more slip on start as well as gear shifts. I was under the impression that clutch capacities raise the overall clutch line pressure, but they have a minimal affect on overall line pressure and largely affect ramp in rates. I also have some forward creep on level ground so I’ll lower the odd touch points to slightly disengage the clutches at idle while in 1st gear.
 

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Discussion Starter · #83 ·
240 is the seal you used correct?
View attachment 399960
That part number matches the part number for the OEM seal for the FWD driveshaft flange that I used per my previous post. Make sure the case is completely clean and do a final wipe with acetone and then lightly coat the seal with NissanBond (Threebond) on the sides and the underside of the lip before inserting. Remember, NissanBond has a 5min working window.
 

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Discussion Starter · #85 ·
I've been swamped with work and home related projects so haven't had time to touch the GTR since last week. I finally installed all of the underside panels and found a spot for the drain valve.

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Cool, but what about vibrations? You are connecting two different parts of the car...just asking for the case :)

J.
 

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Discussion Starter · #87 ·
Cool, but what about vibrations? You are connecting two different parts of the car...just asking for the case :)

J.
I'm not sure I understand what your referencing
 

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Me and my propper english :)

I try: You bolted the drainline on the cover, as you posted on your last two photos.
What I meant: Gearbox is vibrating, the cover is vibrating and that could loosen bolts or destroy weldings.
Maybe mount it with rubberparts to avoid vibrationtransfer.

J.
 

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Me and my propper english :)

I try: You bolted the drainline on the cover, as you posted on your last two photos.
What I meant: Gearbox is vibrating, the cover is vibrating and that could loosen bolts or destroy weldings.
Maybe mount it with rubberparts to avoid vibrationtransfer.

J.
Hose/drainline is flexible, so it should be ok.
 

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Discussion Starter · #90 ·
Me and my propper english :)

I try: You bolted the drainline on the cover, as you posted on your last two photos.
What I meant: Gearbox is vibrating, the cover is vibrating and that could loosen bolts or destroy weldings.
Maybe mount it with rubberparts to avoid vibrationtransfer.

J.
It will be fine and there is no transfer of vibration. Not sure what welds you're referencing, but again it will be fine.
 

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Discussion Starter · #91 ·
Before I touch the TCM tune I'm going to see if I can tune this out using the touch points and clutch capacities.

After some reading, the clutch capacities control the ramp in rates for line pressure and allow for more slip on start as well as gear shifts. I was under the impression that clutch capacities raise the overall clutch line pressure, but they have a minimal affect on overall line pressure and largely affect ramp in rates. I also have some forward creep on level ground so I'll lower the odd touch points to slightly disengage the clutches at idle while in 1st gear.
I'm going to start tuning the TCM today and I've spent about and hour watching the clutch slip and line pressure. I am also trying to understand the small amount of chatter when starting in 1st gear, which I think the issue is actually too little line pressure on initial clutch engagement. When I run TP/CC at 0,0,0,0 I get about 500rpm of clutch slip in all gears except 6th when just cruising around. If I run the TP/CC at 2,2,2,2 I don't experience any clutch slip when just cruising around. This will be tuned out in the Torque lookup table and/or the table that controls line pressure as a function of requested torque. I'll explain this in a subsequent post when I start tuning those tables. I don't think the general tuning will be very complicated since you don't have too many tables to play with.

The first order of business is to up the overall line pressure from 16.5bar to 20.0bar, which requires that you modify 3 TCM tables. The values may change based on how my logging develops, but this should do the trick and I'll update if necessary.

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Discussion Starter · #92 · (Edited)
Going from 16.5bar to 20bar for the Maximum Clutch capacity did help with most of the clutch slip with CC/TP set at 0,0,0,0, but did not resolve slip for all conditions. I wanted to understand how increasing the Clutch Capacities affects the actual Clutch pressure so below is using the 20bar setting and comparing 0,0,0,0 vs 2,2,2,2 for CC/TP. You can see from the graph that for a given Clutch Torque and Line pressure, increasing CC by 2 increased the Clutch Pressure by ~5psi. This is consistent with what I saw Shep post many years back that increasing CC by 4 resulted in an increase of ~10psi in Clutch Pressure.

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Below is how the Clutch Torque Table in the ECM relates to the Line Pressure table in the TCM. Basically, you have a table in the TCM that adjusts the line pressure as a function of Clutch Torque and the current basket (A or B), depending on the gear. So if you are in 3rd Gear (Basket B) and have a Clutch Torque of 111ft-lbs, you will have a Line Pressure that is 57% of what I assume would be full line pressure.

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When I raised the Target Line Pressure Related (A & B) by 5% for all values from 0ft-lbs to 111ft-lbs, I get the results shown below. Although I successfully increased the line pressure by 15-20psi, for a given torque this had seemingly no effect on clutch pressure. What I can only assume at this point is that as long as Line Pressure Target is higher than Clutch Pressure, then the ECM Clutch Torque Table I showed above is what actually controls the Clutch Pressure. However, there is no table that I see that actually correlates Line Pressure with Clutch Pressure or Clutch Torque with Clutch Pressure.

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I am out of time today, but tomorrow I will revert back to the stock values for Target Line Pressure related (A&B). I will then create a baseline log using the stock Clutch Torque table and then increase the Clutch Torque table by 20% to see how it effects the Clutch Pressure. If I simply log Clutch Torque as a function of Clutch Pressure B I can see the coorelation, which I guess means that all Clutch Pressure tuning is done in the ECM after you up the TCM max Clutch Pressure to 20bar.

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Great thread. Lots of interesting info.

One thought on your catch can. I drag race and run one also. You may want to rethink the placement of the can. When you overfill the trans you want to keep it overfilled. Mounting the can higher than the trans allows fluid to flow into the can when you launch the car. It then returns to the trans after. That keeps the trans filled and there is no need for a drain. I have the one T1 offers. It was originally mounted in the left rear wheel well, which is something I didn't like. When I had my car at Cicio's he moved mine to the passenger side in the area between the trunk and taillight so it is out of site. I would post a pic but I don't have my car here at the moment.
 

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Discussion Starter · #94 ·
At 2 quarts over filled, my trans did not spit any fluid out the vent like you seem to experience. My issue was the vent lightly coated the top of the trans with a thin layer of tranny fluid vapor that mixed with the surrounding dirt. Perhaps if I was drag racing with slicks it would start shooting out the vent tube, but for what I do that didn't happen. My main objective was just to keep the top of the trans clean since you can't access it without dropping the trans.
 

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One interesting fact when you started is this is the first DCT oil change? You have much more power than stock and never until now, installed the new TSB clips......... Your DCT never failed...... This is great news .....
 

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Discussion Starter · #96 ·
One interesting fact when you started is this is the first DCT oil change? You have much more power than stock and never until now, installed the new TSB clips......... Your DCT never failed...... This is great news .....
Indeed, but I thought I was playing with borrowed time. However, the fluid looked to be in decent condition for ~29K miles and the clutches actually looked very healthy.
 

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Discussion Starter · #97 ·
I've been tuning the clutches, but I might need some help to understand how some things should look based on the stock trans. For now I'll simply focus on starting from a dead stop in 1st gear. Can someone with a stock trans please log a 1st gear start from a dead stop with throttle around 50%? You can see all of the parameters I selected at the top for logging purposes. I am trying to understand how slip is ramped out as my car still chatters upon start because I believe it is slipping too much. Below is an example of a 1st gear start showing how the clutch slips relative to RPM and how quickly (or not quick enough) it locks the clutches (zero clutch slip).

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The other thing I am wondering is can someone log a 1st gear WOT punch so I can understand if there should be any clutch slip in 1st gear. I have about 100rpm of clutch slip, but I added about 40psi of pressure and it didn't seem to affect clutch slip. Perhaps I need to add more, but just curious as to how the stock clutches are logging.

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You should of sent me a text last night, I would of gotten the log for you when i took the car out!
 

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Discussion Starter · #99 ·
You should of sent me a text last night, I would of gotten the log for you when i took the car out!
I thought of you, but you have a build trans so was hoping to see how the stock stuff looked. However, would love to see how your clutch slip looks on move out.
 

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Discussion Starter · #100 ·
I was able to find some stock clutch slip data online for 1st gear. Thanks for the help.:rolleyes:
Clutch Slip?

It verifies there is indeed about 50-100rpm of clutch slip in 1st gear, which is what I have been consistently seeing despite raising the clutch pressure. I have been playing around with clutch pressure to eliminate the minor 1st gear slip, but even after raising the pressure 65psi, it seemed to have little to no effect on 1st gear slip and is consistent with the data provided in the link above, which I have provided pictures below.

This is how much slip is allowed in 1st gear from a dead stop with the stock clutches, which is about 300rpm. This is the info I wanted because I can now adjust the slip to reach a target.

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You can then see how much slip is seen in 1st gear on stock clutches once the car is going and under constant acceleration, which is around 50-100rpm. This is consistent with the data I have been seeing on my setup.

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Finally, here is my car today after about 6 runs of steadily increasing clutch pressure by +65psi, but it having little to no effect on clutch slip in 1st gear. I will note that 2-6th gear show no clutch slip prior to my increasing the clutch pressure. At this point I am going to revert back to my lower pressure map and start tuning the slip from a dead stop.

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