transam19

iTrader: (1)

Looking to see what everyones 4l60s are shifting at, when at wot. What are im having a 2-3 shift problem. And have every table matching. Kinda sumped.

Philip Pugeau

Have you tried lowering the 1-2 shift? Try 4500 rpm @ 20mph, then work your way up. I had the same thing, WOT 1-2 made 2-3 hit limiter way past shift point. Once 1-2 was lowered enough under WOT, shifted 2-3 like a champ street and strip.
_______________________________________
2001 NBM Formula A4 T-Top DailyDriver
383ci b&b | 230/236 114+4 | AR 1-3/4" LT | 3" Y-pipe | FTI 3500 | Built 4L60E | BMR k-member | BMR F&R U&L control arms | torquearm | panhard | S60 4.10 | 315/35R17 555R
393rwhp / 377rwtq

mrvedit

Is the shift occurring just late or is the shift occurring slowly?
"Just late" is a tuning problem.
A slow shift could indicate low pressure due a problem with the Pressure control solenoid, or a bad tune.

Sorry, what Philip Pugeau says makes no sense to me, but I'm no expert and always happy to learn something new.

I have built and track tested several 4L60E which always shift within 100 rpm of the tuned value. I use the Transgo HD2 shift kit, build sub 0.050 3/4 clutch clearance and have 150/225psi line pressure for [D]rive/max.

I tune the WOT 2-3 shift speed at 84mph (3.42 rear) which is about 6000 rpm for me. I then set the WOT rpm anywhere from 6400 to 7000 and that is within 100 rpm of where it shifts, according to my logs.

Philip Pugeau

Yeah it doesn't make any sense. But it has been my experience that was resolved in this particular way.

transam19

iTrader: (1)

adjusted 2-3 and tested on the street and worked fine. went to the track and car bounced off the revlimter. adjusted alittle more at the track and bounced even worse. have 2-3 rpm at 6000 at 52mph. i lowered it to 48 and bounced off bad. should i go up on the rpm.

transam19

iTrader: (1)

mrvedit, no its not slow its just too late. i have a 3.73.

Philip Pugeau

I'm not even a first day on the job novice when it comes to working on transmissions. In my specific case it is the 4.10 gear that I'm running. I researched the heck out of this issue all over this forum for several months.

After reading what all the sponsored trans builders had to say (and then some), it turns out that anything making a faster revving engine, like shortening up the gear, made the rpms come up faster, which offset the timing for the shift. This effect is multiplied by a higher stall, cam, valvesprings, etc.

Given that the trans was working properly, it was always the 2-3 shift for most people, which as I understand, moves the most amount of parts taking the most time to actuate. This requires a more aggressive adjustment to the mph and rpm, while satisfying the mph first, letting it command off rpm. My tuner and I tried several combinations of scaling back 2-3 only, leaving 1-2 at 30mph@6000. Even with 2-3 set at 57mph@5500 it still hit the limiter set at 6500 with WOT 1st and 2nd. If no WOT 1st, shifted 2-3 every time.

It wasn't until scaling back 1-2 that it magically started working as expected. First adjustment was a big one setting 1-2 to 20mph@4500. It worked first time out and many more after. Then adjusted it to 23@5000. Worked on the street but not on the strip. So, we scaled it back to 4500. I have verified this by many, many test runs street and strip.

Here is a quote from Performabuilt:

post # 39 https://ls1tech.com/forums/automatic...sh-more-2.html

"Bear in mind that while the shift may be commanded at 5100 it could indeed take to 6200 for the trans to make the shift . You see while the electronics are instant hydraulics are not and several things come into play.

One thing is a constant at WOT it always takes the same amount of time for the trans to complete the shift. This time will of course vary from trans to trans depending on condition, Shift kit set up. Line presure.

What does change is the rate the RPM are climbing under various conditions. These numbers are off but bear with me.
Lets say it takes 1 second to complete a shift from 1-2 and at 340 hp NA the RPM climb 300. Ok same time period at 600 hp the rpm might climb 600 RPM during the same period. Other variables would be for instance gear ratio and engine with 4.10 gears behind it is going to climb in RPM much faster that lets say a 3.23 would so then again you might have another 300 or more increase in the RPM during the same time frame between the two gears.I think this is why many times you hear of people boucing limiter after going to lower gears even though they did set up the PCM for the hear change. They failed to compensate for the RPM rate increase. With the stock converter and stock power the PCM can adapt but once you get outside those it cannot do so on its own. Add a shot and the RPM rate increases again even though the time for the trans to shift is still a constant.

I think this is why you hear so many people talk about bouncing the rev after mods they changed something wether it be power or gearing that changes the rate of the rise and fail to realize that all of these things have to be compensated for. Its not as simple as I want it to shift at 6000 rpm and set it that way because to acheive and actual shift at 6000 RPM where you would actually have to command the shift would be different for virtually any mods you make that can affect the rate the RPM rise during the shift.

So realistically every car would be different depending on the POWER/GEAR RATIO/SPRAY.
Then a converter with a high stall is still a further complication and the RPM due to the slip in the converter may be higher that expected for the MPH and this again would vary again with the addition of power adders such as Nitrous or even rear end would affect this too.

So the conclusion I have come to is there can be no one size fits all when it comes to tuning for shifts it would be unique to each set up. A car with 4.10 might take 500-800 or whatever to complete and shift and a 2.73 car might do it in 200-400 and power adders change these numbers around more. So its kinda a trial and error system I would conclude would have to be used.

Also you have to beware looking at the shift completion times with the 4l6x units since the PCM uses the engine rpm verse output speed to determine when the shift did happen and with a stall these numbers can be way off so are useless. The exception would be the late 4lxx with the input speed senor 07 up with these you would get a true time since the converter is not part of the equation.This would be true of the 4l80e also since it does have input speed sensor.
Ramble over lol "

transam19

iTrader: (1)

i understand what u mean. im just trying to see what more i can try before i hurt the trans and by hurt i mean the 2-3 band. trying to tune this on my own. if not than i will have to get it tuned by a local tuner.

mrvedit

Thanks for re-posting that excellent thread from Frank at PerformaBuilt. His posts answer about 90% of the questions that keep arising here.

transam19: I'm sorry, I just don't have the experience to help you further. Any chance you could get a log file made and posted here?
I'm wondering if it is a flare. But mostly, I don't want to give bad/wrong advice.

joecar

transam19,

Philip is saying to lower your 1->2 shift point and see if your 2->3 shift comes in without bouncing the rev limiter.

transam19

iTrader: (1)

Ill give it a try. Thanks.