Confused about fluid coupling issue

[N2BRK]

What can cause poor fluid coupling, other than the converter?

My old PI ML converter was slipping like mad, yet when locked up it was solid and had no slip. I just swapped my converter to a Goerend K, and I expected tons of fluid coupling, based on their data and my research, yet it slips like my old converter.

For example, I’m in 5th gear and I give her about 1/3 throttle and watch her slip 1800rpm for a sec and then just hang in the 1000rpm area of slip. If I don’t lift it won’t go into lockup until deep into mph in 6th. Yet, like the old vert, once locked there’s no slip.

My fluid is always fresh and clean and my filters are always changed with Allison filters.

Am I off base in my expectations, or is there somewhere else I should be looking to fix my problem?

Thanks,
Wally

 

[Chevy1925]

K is a high stall, you have to go past stall to start heavy coupling. You will still have “stall” even when cruising down the road. This is how/why you can spool up a big turbo quickly with the converter unlocked. Let’s you hit high rpm fast before power is multiplied heavy through the converter and sent through the trans.

What rpm are you at while doing this? I’ll bet you are not pushing the converter hard enough to actually get into heavy coupling.

You are a little askew about how coupling works vs stall.

 

[N2BRK]

Thanks James. I thought that was the case but I got confused when Mike always says stall gets you out of the hole and then coupling takes over. So, I figured I was in coupling when I was loafing along in 5th. I’m going to go take a ride and get into it deeper and see. Thanks.

 

[Chevy1925]

He’s right but the whole concept of stall and coupling goes much further. That is the simplest way he can explain it as it takes out the variable of not being full throttle, not launching from a dig and so on.

This is where calling and talking with him or other experienced trans builders can help you nail things down farther. Not a dig at you by any means though! Hard to know what is best without experiencing it, ya know

 

[N2BRK]

I talked to my trans builder, Goerend, Mark my tuner, and someone with the same setup as me they had an R and then went to a K (Mike is his builder) so I did homework, lol.

I did a quick romp in between dodging drunks. I let it rev higher. I’m calling out slip in 100’s like 15 is 1500 etc. I rolled on from 3rd gear. Approx 40% throttle. I would have expected more coupling, but maybe that’s my
mistake.

https://youtu.be/Wo8hPkbsytw

 

[gmduramax]

Damn that thing is slow :hug:

 

[N2BRK]

Of course it is. All the power is going out the tailpipe lol.

 

[Chevy1925]

those numbers aren’t bad at all. My precision ML would see 2500-3k slip difference in 3rd gear at WOT on my tow tune.

What’s the slip difference at wot on the biggest tune?

 

[ZeroGravity58]

You can put a lockup box on it. That's on my list of things to do also

 

[N2BRK]

those numbers aren’t bad at all. My precision ML would see 2500-3k slip difference in 3rd gear at WOT on my tow tune.

What’s the slip difference at wot on the biggest tune?

Not sure. I haven’t given it WFO in that scenario. I whacked it in 3rd in tune 4 and it melted the tires.

I showed the video to Mike’s customer with the same setup and he said his K doesn’t sit there like that, it couples. I asked him to make a video - I’ll update.

Is there anything else for me to consider?

 

[ZeroGravity58]

There's alot to consider with converters. Power, vehicle weight, gears, tire height, ect can effect stall speeds. It took me a long time when drag racing to figure out converters. Just because you buy a converter that says it's a 2500 rpm stall doesn't mean it's going to flash to 2500 rpms. The only way to see the true stall is to use a transbrake.

 

[Bdsankey]

Not sure. I haven’t given it WFO in that scenario. I whacked it in 3rd in tune 4 and it melted the tires.

I showed the video to Mike’s customer with the same setup and he said his K doesn’t sit there like that, it couples. I asked him to make a video - I’ll update.

Is there anything else for me to consider?

The torque converter is the main thing that controls coupling, fluid is a variable but nowhere near as big of a contender. I'm with James, I don't think you've pushed it into heavy coupling.

Mike's statement is 100% true, but I believe he is talking about a drag/dig scenario where you're at full throttle and using the converter to get onto the charger(s). A Goerend K is an amazing converter but definitely needs power fed into it to get the benefits.

 

[N2BRK]

So you’re saying that this converter will couple harder with more power applied. So if I hit the unlock button, toss the truck into my 700hp tune, and whack the shit out of it, I should feel it grab instead of what I’m seeing now? Maybe that’s what I’m doing wrong - Kevin (the guy I’ve referenced as having mike do the k on his same-equipped truck) is always in tune 5 at 758hp and says his couples instead of that slip I videoed.

I’ll play some more and see thanks

 

[Mike L.]

The K is a performance converter that is very streetable. It will stall about 2400/2500. It needs power to couple. Driving it like an old lady on the street will keep it in torque multiplication ( slip ) and that can not be helped. There is always a trade-off and that's just the way it is. The angle of the fins and stator are set so that the engine rpm's will rise quickly to spool the turbo; therefore more slip at low rpm's.

 

[Chevy1925]

So you’re saying that this converter will couple harder with more power applied. So if I hit the unlock button, toss the truck into my 700hp tune, and whack the shit out of it, I should feel it grab instead of what I’m seeing now? Maybe that’s what I’m doing wrong - Kevin (the guy I’ve referenced as having mike do the k on his same-equipped truck) is always in tune 5 at 758hp and says his couples instead of that slip I videoed.

I’ll play some more and see thanks

Do not expect slip to become less that you have been monitoring though.

Kevin’s interpretation of coupling could very will be different than yours regardless of how you guys describe it to one another. Your looking more at the torque multiplication of the converter at part throttle/low power input than you are the true coupling of the converter. Stall and coupling are based on WOT we’ll more than what you are looking at. If you want more coupling at 40% throttle, you need an R or G converter

 

[N2BRK]

ok - perfect sense! I get it. I think the problem was when I read that this couples like mad, I was remembering my old 777 Suncoast that was damned near like lockup. I was imagining this converter would roll out to 2600’ish and then clamp down nearly locked up and go.

I am very happy to ignore the slip numbers and drive the hell out of this converter. Funny enough it feels exactly like my tightened ML did once it was broken and slipping hard. Hahahahaha. Which is great on the street. No waiting for spool.

My near future goal is a mild build and have mark ditch the de-torqued tune in favor of letting the 68 boogie - like Kevin. He’s on a stage1 build and marks tuning.

Thanks for all of the help guys. Knowledge is rarely free, and I appreciate every bit that I gain here!!

Happy New Year!

 

[Bdsankey]

ok - perfect sense! I get it. I think the problem was when I read that this couples like mad, I was remembering my old 777 Suncoast that was damned near like lockup. I was imagining this converter would roll out to 2600’ish and then clamp down nearly locked up and go.

I am very happy to ignore the slip numbers and drive the hell out of this converter. Funny enough it feels exactly like my tightened ML did once it was broken and slipping hard. Hahahahaha. Which is great on the street. No waiting for spool.

My near future goal is a mild build and have mark ditch the de-torqued tune in favor of letting the 68 boogie - like Kevin. He’s on a stage1 build and marks tuning.

Thanks for all of the help guys. Knowledge is rarely free, and I appreciate every bit that I gain here!!

Happy New Year!

I guarantee that's also part of it, he isn't trying to protect a stock motor.

 

[N2BRK]

I have had a little more time behind the wheel. I put in the big tune and gave her time to learn. I did some pulls and it makes no difference. She will not go into lockup unless I have less than 20% throttle. At 27% it locks at 79mph. I went the other way and worked up to 57% throttle and it never locked. I went up from there harder and harder on the throttle and it won’t lock. I dropped to 4th on a roll and went full throttle and it never locked - I lifted over 90mph.

I did notice that playing around town in 2nd and 3rd I did get it to fluid couple with a lot of throttle and I thought it was in lockup because it felt so good. But that was shortly followed by wheelspin. lol.

Kevin (Mike’s customer) and he said his locks up just fine at light to mid throttle etc. he opined a solenoid problem. I have no codes.

Any other thoughts on this? I can’t believe that this is normal. Especially since this is exactly how my Precision has been acting lately - making me think it was hurt.

Thanks

 

[Chevy1925]

Lock up is not solely distinguished by the converter and it’s fluid coupling. Some trucks will command a lock up as it should, some won’t even if at the correct slip limit.

You really gotta take your mind off this fluid coupling thing. It’s not that. Your statement about it pulling like it’s in lock up in 2nd and 3rd gear says that converter is working as it should.

Time to start searching else where if the truck is falling on its face in taller gears and more throttle. That usually leads to fueling/draining rail. You may be spiking high rpm, rail drops because cp3 can’t keep up and power falls off. Converter never locks because the torque isn’t matching up in the ecm so rpm never drops to make rail catch back up and you go into an infinite loop till something changes like backing out of the throttle.

Converter not locking under light throttle is either a tune issue or internal issue but you would set a code very quickly if the computer is commanding lock up and the converter doesn’t lock so it may be tune related. Since we don’t know what’s in there, I can only assume the tune moved lock up much higher in the speed/throttle point to try to make the turbo come up faster before lock up.

No lock up at part throttle vs no lock up at full throttle are, imho, two separate issues based on how the tcm works with them

 

[N2BRK]

I’m not stuck on any theory - please don’t think that’s the case.

The truck does not fall on its face and I do not lose rail pressure. I’ve had no tune change in over 4 years. The only change was going from stock cp3 to 12mm a couple years ago.