HELP NEEDED!! 2-3 shift on limiter still...RPM
Thread Starter
Teching In
Joined: Oct 2011
Posts: 17
Likes: 0
From: Springfield,Mo.
I know the line pressures are all stock.... And I'm sorry my tuner has the passes we logged....So I'm not Sure what mph@5900 rpm... Thank Gilbert. I will let my tuner know. I do know RPM builds some awesome stuff, so I'm by no means saying it's the tranny.. I do think it's in the tune somewhere... At this point I'm just willing to try anything..... Thanks again.
My tranny started off as a Level 4 back in late 06", it went behind my GF's H/C Z/28, and I posted up about the issues we were having right after install here...
https://ls1tech.com/forums/automatic...ft-points.html
it turned out to be a bad EPC solenoid... Once fixed the tranny was flawless and never gave us another issue until....
My GF put a 427 in her Z/28 and it did not like it at all.... it was slipping a little and would not shift, again....out it came and back to RPM for a re-fresh and an upgrade to level 5 specs...In the mean time a FLT level 7 went behind the 427 and when the RPM came back it went behind my stock SS with a 4K stall and has run great until...
I just threw on a set of heads and cam that I had in the garage on it and now it won't do the 2-3 shift again...lol. We are going to replace the above solenoid next week and hope it fixes it.
https://ls1tech.com/forums/automatic...ft-points.html
it turned out to be a bad EPC solenoid... Once fixed the tranny was flawless and never gave us another issue until....
My GF put a 427 in her Z/28 and it did not like it at all.... it was slipping a little and would not shift, again....out it came and back to RPM for a re-fresh and an upgrade to level 5 specs...In the mean time a FLT level 7 went behind the 427 and when the RPM came back it went behind my stock SS with a 4K stall and has run great until...
I just threw on a set of heads and cam that I had in the garage on it and now it won't do the 2-3 shift again...lol. We are going to replace the above solenoid next week and hope it fixes it.
Solenoid is fine. You need to redo trans tune since with those mods motor revs faster and car accelerates faster. Up the limiter by 200 rpms and take 2MPH out of both tables. Bet it fixes it
80 percent of the time the tune is the cuprit on these 2-3 shift problems. Verify gear and tire height are correct and then start on speed,rpm and rev limiter in the trans tune
I had this EXACT same issue with my car....until this past weekend. Just for the hell of it I left it in OD instead of D and it made the 2 to 3 shift without hitting the limiter. Try leaving it in OD when launching and after it shifts into third (hopefully without hitting the limiter this time), shift it back into D.
First you must understand that when speaking of and auto trans at WOT"Max line pressure" the time from command to shift is a constant regardless of power it will remain the same, The trans when commanded to shift must either make the shift or slip. It cannot just say no
.
Now there is however something that does change with lower gears sets and power adders that must be considered. RPM-Since both power adder and lower ratio change the rate at which RPM rise it must be taken into consideration. Since the shift time is a constant if the RPM rises at a faster rate more time must be allowed between desired and actual shift, Which is why for instance with ratio changes simply changing the ratio in the PCM may not be enough to stop the bouncing the rev limiter. Consideration must be allowed to the faster RPM increase this would also have to be considered with power adders such as N2O which is why you will hear people say that there trans shifts perfect N/A but hots the limiter on N2O.
And example and these numbers are random just for explanation. Lets say that with a 2.73 gear ratio it takes 200 RPM to complete a shift from command to actual (6200 commanded-6400 actual) with lets say 4.10 gears it may take 400-500 rpm and possibly more to complete the same shift(6200 commanded-6800 actual) Now if in addition you have a power adder like N2O this could e pushed even further not because the trans cant make the shift but again because the RPM are increasing at a greater rate in the given amount of time.
So when making gear ratio changes or power adding this must always be considered.
Also of note generally more time must be allowed for the 2-3 than for the 1-2 shift , The reason is on the 60e the shift to 2nd is very simple fluid is sent to the intermediate servo it moves and applies pressure to the band stopping the REVERSE INPUT DRUM and creating second gear where on the 2-3 shift more is o curing. Fluid must travel to both the 3-4 clutch set and simultaneously be fed to the back side of the servo to release the 2-4 band. So basically you have two chambers being filled at the same time with a given amount of fluid so it takes longer to complete this shift.
Additionally you may also note a small difference in the shift timing in D3 over D4 on the 2-3. Again in D3 something is different the OVERUN CLUTCH is also turned on during the 2-3 shift in this position so now you have 3 components being moved by a given amount of fluid further increasing the time from command to actual shift. This also must be considered when allowing the car to auto shift in the D3 position from second to third gear and would need to be allowed for.
Now all this time may e measured in 10th or 100th of a second but can make a considerable difference when trying to set a shift point near the rev limiter
So in sumery if you change the gear ratio, power,even weight or stall and yes tire size even this can change your shift points.
.Now there is however something that does change with lower gears sets and power adders that must be considered. RPM-Since both power adder and lower ratio change the rate at which RPM rise it must be taken into consideration. Since the shift time is a constant if the RPM rises at a faster rate more time must be allowed between desired and actual shift, Which is why for instance with ratio changes simply changing the ratio in the PCM may not be enough to stop the bouncing the rev limiter. Consideration must be allowed to the faster RPM increase this would also have to be considered with power adders such as N2O which is why you will hear people say that there trans shifts perfect N/A but hots the limiter on N2O.
And example and these numbers are random just for explanation. Lets say that with a 2.73 gear ratio it takes 200 RPM to complete a shift from command to actual (6200 commanded-6400 actual) with lets say 4.10 gears it may take 400-500 rpm and possibly more to complete the same shift(6200 commanded-6800 actual) Now if in addition you have a power adder like N2O this could e pushed even further not because the trans cant make the shift but again because the RPM are increasing at a greater rate in the given amount of time.
So when making gear ratio changes or power adding this must always be considered.
Also of note generally more time must be allowed for the 2-3 than for the 1-2 shift , The reason is on the 60e the shift to 2nd is very simple fluid is sent to the intermediate servo it moves and applies pressure to the band stopping the REVERSE INPUT DRUM and creating second gear where on the 2-3 shift more is o curing. Fluid must travel to both the 3-4 clutch set and simultaneously be fed to the back side of the servo to release the 2-4 band. So basically you have two chambers being filled at the same time with a given amount of fluid so it takes longer to complete this shift.
Additionally you may also note a small difference in the shift timing in D3 over D4 on the 2-3. Again in D3 something is different the OVERUN CLUTCH is also turned on during the 2-3 shift in this position so now you have 3 components being moved by a given amount of fluid further increasing the time from command to actual shift. This also must be considered when allowing the car to auto shift in the D3 position from second to third gear and would need to be allowed for.
Now all this time may e measured in 10th or 100th of a second but can make a considerable difference when trying to set a shift point near the rev limiter
So in sumery if you change the gear ratio, power,even weight or stall and yes tire size even this can change your shift points.
__________________
Additionally you may also note a small difference in the shift timing in D3 over D4 on the 2-3. Again in D3 something is different the OVERUN CLUTCH is also turned on during the 2-3 shift in this position so now you have 3 components being moved by a given amount of fluid further increasing the time from command to actual shift. This also must be considered when allowing the car to auto shift in the D3 position from second to third gear and would need to be allowed for.
The overrun clutch purpose is to allow engione braking in lower gears when manually downshifted. And yes that is correct on OD vs D
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Well if preformabuilt is correct which i would assume is true since they build these things for a living...i would say yes race in D in ur case..in theory it should shift quicker that way, how much quicker idk, but it might just be enough to not have u hitting the limiter....ive always just raced in 3 as well never had an issue even on the bottle but it sounds like OD is just cheap insurance that allows u a little bit of breathing room.
So was this ever solved? I'm looking at buying a built trans from a member but his does the same thing, just hits the limiter in second and stays there till you get out of it. Is this just a tuning issue or could it be something internal?
His has done it since he bought the car and has had 3 different transmissions all do the same thing
His has done it since he bought the car and has had 3 different transmissions all do the same thing
Staging Lane
Joined: Dec 2011
Posts: 72
Likes: 0
From: Orlando, FL
Mine is tuned to shift at 5500, rev limit at 6500. Not sure what the speed points are at, but I see the tuner tomorrow. I haven't tried this with the shifter in "3" yet.
OP, take a look at this thread....may help with your issues:
http://www.njfboa.org/forums/showthread.php?t=57922
http://www.njfboa.org/forums/showthread.php?t=57922
Thread Starter
Teching In
Joined: Oct 2011
Posts: 17
Likes: 0
From: Springfield,Mo.
Thanks deezl ss,,,I actually never have fixed the issue. Tore it apart this winter, and just now finishing it up. I will get to my tuner asap I will let ya guys know if that fixes it.
