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Discussion Starter · #1 ·
Hey all, hoping someone has some insight or similar experience. Having slip issues during shifts with a C800 setup making somewhere in the 825whp 625ft-lb range. It's making about 600 ft lb TQ at redline. Have solenoid current set at 1.72 in TCM table, and maxed the ECM Clutch TQ table. CC's are +3,+3, TP is +2,+2. Attached is a log with slips, pressures and temps. This is the best I could get, at one point it would just open the clutches up in 3rd and blow past the rev limiter. When that happens it's clear the clutch pressure command goes away first like it's a self protect mechanism. thanks
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Who is your tuner ?
 

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I can look at it more tomorrow, but you need to bump your solenoid amp values to 1.8 because you're not reaching 20bar of line pressure and your clutch pressure is bumping up against your line pressure in some portions of the log. That change alone might get the slippage under control because it should give you a bit more clutch pressure.
 

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Discussion Starter · #5 ·
I can look at it more tomorrow, but you need to bump your solenoid amp values to 1.8 because you're not reaching 20bar of line pressure and your clutch pressure is bumping up against your line pressure in some portions of the log. That change along might get the slippage under control because it should give you a bit more clutch pressure.
Forgot to mention, solenoid current values higher than this with the same clutch TQ table values result in a loud screech sound around 3rd that is closer pump cavitation than a metal on metal sound. Think the odd clutch might be toasted by now. Even shifts are crisp and firm. Odd soft like an OG auto.


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Forgot to mention, solenoid current values higher than this with the same clutch TQ table values result in a loud screech sound around 3rd that is closer pump cavitation than a metal on metal sound. Think the odd clutch might be toasted by now. Even shifts are crisp and firm. Odd soft like an OG auto.


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The other way to increase the line pressure on your Odd basket is to go back to the TCM tune under the folder "Line Pressure" and change the last value in the table "Target Line Pressure Related B" from 84% to 100%. The stock tune for TCM runs 100% line pressure for Basket A and 84% line pressure for Basket B and you will notice in your logs that Basket B is always a lower pressure vs Basket A. I have not personally done this so I don't know if there is a potential risk to making this change, but it should raise your Basket B clutch pressure.
 

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Forgot to mention, solenoid current values higher than this with the same clutch TQ table values result in a loud screech sound around 3rd that is closer pump cavitation than a metal on metal sound. Think the odd clutch might be toasted by now. Even shifts are crisp and firm. Odd soft like an OG auto.


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Would you mind posting a log of a 1st gear start from a dead stop with 100% throttle off the line? I am trying to tune out my new clutches so I am just trying to see how much slip there is. I would not need you to rev it past 4K RPM in 1st to get the necessary data. In the log you posted you were initially at ~33% throttle so I was surprised the clutch slip was so high and perhaps I need to actually lower my clutch pressure on initial start.

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Discussion Starter · #8 ·
The other way to increase the line pressure on your Odd basket is to go back to the TCM tune under the folder "Line Pressure" and change the last value in the table "Target Line Pressure Related B" from 84% to 100%. The stock tune for TCM runs 100% line pressure for Basket A and 84% line pressure for Basket B and you will notice in your logs that Basket B is always a lower pressure vs Basket A. I have not personally done this so I don't know if there is a potential risk to making this change, but it should raise your Basket B clutch pressure.
I had put it up to 90 and didn't notice any changes so I put it back. No reason not to try 100 now. trans is going to Shep soon anyway. In this log I see B press from 265-278 and A pressure 230-277. where are you seeing a difference?
 

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Discussion Starter · #9 · (Edited)
Would you mind posting a log of a 1st gear start from a dead stop with 100% throttle off the line? I am trying to tune out my new clutches so I am just trying to see how much slip there is. I would not need you to rev it past 4K RPM in 1st to get the necessary data. In the log you posted you were initially at ~33% throttle so I was surprised the clutch slip was so high and perhaps I need to actually lower my clutch pressure on initial start.

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This was with LC enabled and APP at 100% which resulted in 33% throttle to achieve my 3600 RPM launch target. are you asking for a log without LC and just punch it? I will log APP% next time so we know what my foot is doing vs the TB's.

EDIT: just looked at other LC logs and they all have 33-35% throttle until vehicle speed increases. Definitely LC holding it there until i release brake. I will try the standing stop and punch it method and post up a log.
 

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Discussion Starter · #10 ·
Tried taking off both ways. logged APP so you can see where my foot was. I changed the B clutch press map in the TCM to match the A map for 100% pressure and CC's+2,+2, TP +1, +1, Sol Current 1.72 both. On LC the launch felt good, the 2-3 shift was still spongey. I have 91 Oct in there now BTW, which the trans has always done better on since it makes so much less power
 

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I had put it up to 90 and didn't notice any changes so I put it back. No reason not to try 100 now. trans is going to Shep soon anyway. In this log I see B press from 265-278 and A pressure 230-277. where are you seeing a difference?
Both Clutch Pressures (A&B) peaked at 278psi, but in 3rd gear you are consistently running lower clutch pressures (vs 4th Gear) because it appears the Clutch Pressure is bounded by the Line Pressure. You will also notice your 3rd Gear Line Pressure is also consistently lower than your 4th Gear Line Pressure. I have attached a graph below.

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Tried taking off both ways. logged APP so you can see where my foot was. I changed the B clutch press map in the TCM to match the A map for 100% pressure and CC's+2,+2, TP +1, +1, Sol Current 1.72 both. On LC the launch felt good, the 2-3 shift was still spongey. I have 91 Oct in there now BTW, which the trans has always done better on since it makes so much less power
Thank you and the foot launch was perfect and gave me what I was looking for.

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Discussion Starter · #13 ·
Seems to better after upping the B pressure table. At this point I think I've probably put more wear on B. Time for some trans upgrades
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A few months back I was part of a conversation discussing TCM tuning and one of the items that was discussed was clutch pressure crossover point and that to be mindful of keeping the crossover point at or below 10 bar or the clutches could fight or bind against each other causing accelerated wear.
 

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Discussion Starter · #17 ·
A few months back I was part of a conversation discussing TCM tuning and one of the items that was discussed was clutch pressure crossover point and that to be mindful of keeping the crossover point at or below 10 bar or the clutches could fight or bind against each other causing accelerated wear.
I actually found and used that post for decision making. But at some point slipping the crap out of the B basket was more of a concern than a cross-over drag to me (with knowledge I was taking this out soon anyhow). I think if I had started with the much higher TQ table in the ECU map combined with what 240Z mentioned here about the B line pressure in the TCM map I might have prevented some wear and now could possibly hold the torque. I had higher TQ table values and higher solenoid currents than Cobbs maps, just too conservative on that. Side note: enjoyed your post about the radium fuel hanger. I ripped out the hacked up stock basket with WB 485's and put in a triple brushed Radium. Works awesome and I still have duty cycle control on the primary!
 

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It is the R mode launch log I posted above
I don't understand what is going on with your line pressure, but despite your commanding 278psi, in most cases the line pressure falls well short. The 290psi reference in the chart is just a reference to 20bar. You mentioned earlier that trying to tune for 1.8a caused what you thought was pump cavitation so perhaps you have a pump issue. The erratic behavior of your line pressure vs what I see on my car gives me some concerns.

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This is how my trans looked with a similar log and this was a few days ago before lowering my clutch pressures. I am now only running about 210psi of clutch pressure at full boost with the new clutches to hold [email protected] The point of the graph is to show that line pressure should be a fairly constant value.

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Discussion Starter · #19 ·
I don't understand what is going on with your line pressure, but despite your commanding 278psi, in most cases the line pressure falls well short. The 290psi reference in the chart is just a reference to 20bar. You mentioned earlier that trying to tune for 1.8a caused what you thought was pump cavitation so perhaps you have a pump issue. The erratic behavior of your line pressure vs what I see on my car gives me some concerns.

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This is how my trans looked with a similar log and this was a few days ago before lowering my clutch pressures. I am now only running about 210psi of clutch pressure at full boost with the new clutches to hold [email protected] The point of the graph is to show that line pressure should be a fairly constant value.

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This was insightful, thank you. Car has 31k miles and based on what I saw elsewhere, the previous owner only did engine oil changes. Old fluid with a partial clogged pickup and/or line filter would give erratic pressure. I used to have a 2015 that I bought new and this trans has never felt as solid as that one and the ETS has never felt as good (despite take 18nm to break loose). Its getting a Shep 1.5k plus billet B basket and brace. But now I feel like I know why. Thanks again for the dialogue
 

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Discussion Starter · #20 ·
I went ahead and pulled the trans, it's currently on a pallet. Notable observations were that the fluid looked pretty dirty but didn't smell burnt, very light "clutch dust" particles could be seen in the oil as it swirled into my container, much like a wet clutch on a motorcycle. And the fluid level was not one bit over serviced. I'm convinced now that old dirty oil and filters with the possibility of being underserviced were causing my erratic line pressure. Will post logs and tune results after I get it back from Shep. Also, for anyone considering DIY trans removal, its MUCH easier/faster than the engine. It was a pleasant surprise after reading some of the horror stories.
 
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