Effect of RPM's on a 4L60E
Joined: Nov 2003
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From: Wichita KS / Rancho San Diego
Originally Posted by ChocoTaco369
but that's entirely contrary to what vince said. vince said it takes more work to do a 4-2 downshift and more stuff gets released.
Thread Starter
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From: Philly
Originally Posted by RPM WS6
Why, so we can be replacing clutches all the time rather than rebuilding trannies? 
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From: Schiller Park, ILL Member: #317
Originally Posted by RevGTO
I know ... that's why I made the calls today to double check. Vince said on the 4-2 the band releases and reapplies. I've understood that the band remains applied and the 3-4 clutches disengage. Both guys today agreed with that and disagreed with Vince.
I think I'm just gonna leave the car in OD for everything and forget about it. I plan to keep this particular car mostly stock anyway so I doubt it really matters; honestly it'd probably take 10s of thousands of miles to do harm to the stock tranny at stock power levels with either type of downshifting.
Joined: Nov 2001
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From: Schiller Park, ILL Member: #317
Originally Posted by ChocoTaco369
as promised, i watched when my car shifts into OD not locked up.
my car shifts into 4th gear at 35-36 mph. mind you, i have 2.73's. this means i was mistaken. even in a 2.73 car, a 4-1 kickdown is possible. you're at ~1100 - 1200 rpm's.
my car shifts into 4th gear at 35-36 mph. mind you, i have 2.73's. this means i was mistaken. even in a 2.73 car, a 4-1 kickdown is possible. you're at ~1100 - 1200 rpm's.
This info applies to a 2.73 geared '98 Camaro, and was gathered directly from my scanner (a-tap) and not the stock gages:
- Under very light continuous acceleration from a stop, the trans will shift into OD (4th) at as low as 32mph.
- If you release the throttle (coast) at or above 28mph, the trans will shift to OD (4th) by default (I assume this is for less gearing drag/improved fuel economy).
- Once the trans has shifted to OD (4th) it will remain in OD (4th) while coasting until the vehicle speed drops below 25mph.
So, taking all this into consideration, the 4-1 downshift actually happens probably a lot more than we think. Any time a 2.73 geared car punches it at or above 25mph all the way up to 36-37mph, it's possibile that the trans is already into OD (4th) and will be downshifting to 1st.
Either way, I honestly don't think it matters much (if at all) on a stock car which gear you downshift from and to. It may become more of an issue when the power numbers really start to climb. But at this point it seems that even the trans builders can't agree, so I'm just gonna go with whatever I feel like at the time.
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From: So.Cal.
Originally Posted by RPM WS6
So I guess we're still at a draw then. We have experts that are giving totally different answers. Guess it really doesn't matter what we do. If the builders can't even agree on what's best, then how can we ever decide?
I think I'm just gonna leave the car in OD for everything and forget about it. I plan to keep this particular car mostly stock anyway so I doubt it really matters; honestly it'd probably take 10s of thousands of miles to do harm to the stock tranny at stock power levels with either type of downshifting.
I think I'm just gonna leave the car in OD for everything and forget about it. I plan to keep this particular car mostly stock anyway so I doubt it really matters; honestly it'd probably take 10s of thousands of miles to do harm to the stock tranny at stock power levels with either type of downshifting.
The GEAR pid shows which gear (i.e. shift solenoid permutation) the PCM is commanding.
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Originally Posted by performabuilt
The right parts and design are the key
www.performabuilttransmissions.com
www.performabuilttransmissions.com
Are all the internals made out of titanium or something? Gold plated case too? Thread Starter
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From: Philly
Originally Posted by Marc 85Z28
$2500 for a built 4L60E? Are all the internals made out of titanium or something? Gold plated case too?
Are all the internals made out of titanium or something? Gold plated case too?the website says the level 2 can handle about 700hp. while that's probably a stretch IMO (since higher shift points can result in trans failure with substantially less power), it can probably take 500hp with high shift points, and how many people actually drive a 500hp car? very few. sounds like under $1700 gets you a pretty decent trans, which is on par with any other trans sponsor and performance rebuild.
you get a good warranty, also. the guy that builds these is on this site a lot and is very helpful, so i'll stick up for him. he seems like an honest guy. i hope some people start purchasing some of his transmissions so we can as a whole gauge how they perform. i know it's hard to be the guinea pig and go for the new sponsor, but i'm very anxious to see results as i have some high hopes. it's always good to have options for a new trans if the time ever comes. i also like the "no core charge". sweet deal IMO.
Last edited by ChocoTaco369; Oct 14, 2006 at 10:19 PM.
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From: Schiller Park, ILL Member: #317
Lets bring this thread back. It's got a ton of great info and personally I'd like to continue adding as we gather more facts.
From the logs I have run in the past, I can tell you that about 95% of the time, the trans is going 4-2 directly, not 4-3-2. For the other 5%, I have seen it go 4-3-2.
BUT, there is an explaination.
What I've noticed is, if I'm cruising at a steady speed and slam the pedal to the floor, it'll go 4-2. If I depress the pedal slightly more slowly (but still flooring it), I'll sometimes see the 4-3-2 situation.
Also, the 4-1 shift seems to be direct. I've never seen it go 4-3-2-1 or any other combo, just 4-1.
On occasion, if I punch it right in the 31-34mph range the trans will only go back to 2nd rather than 1st (in a 2.73 car, it should always go back to 1st at up to 36-37mph). But that's ONLY in the 31-34mph range. At 30mph or lower, or at 35-36mph it'll always go back to first if you go WOT. I think it has something to do with the fact that in the 31-34mph speed range is where the typical 3-4 upshift will occur in the 2.73 cars if you're at very light throttle input. I think there might be some confusion/freaking out in the PCM if you go WOT right when it's trying to pick between 3rd or OD, and by default it'll only go back to 2nd. This condition only occurs when the shifter is in OD, and I've noticed that this condition seems to happen more as the WOT 1-2 shift point is raised via custom tuning (not sure what that has to with it though?). If you run it in 3rd, then it'll always go from 3-1 even in that 31-34mph range, every single time.
Originally Posted by joecar
We should be able to tell what the PCM is doing during the 4-2 downshift by logging the GEAR and RPM pids; if the log shows the GEAR going 4-3-2 then the PCM is releasing the band and then reapplying it, otherwise if the GEAR pid is going 4-2 then the PCM is keeping the band applied.
The GEAR pid shows which gear (i.e. shift solenoid permutation) the PCM is commanding.
The GEAR pid shows which gear (i.e. shift solenoid permutation) the PCM is commanding.
BUT, there is an explaination.
What I've noticed is, if I'm cruising at a steady speed and slam the pedal to the floor, it'll go 4-2. If I depress the pedal slightly more slowly (but still flooring it), I'll sometimes see the 4-3-2 situation.
Also, the 4-1 shift seems to be direct. I've never seen it go 4-3-2-1 or any other combo, just 4-1.
On occasion, if I punch it right in the 31-34mph range the trans will only go back to 2nd rather than 1st (in a 2.73 car, it should always go back to 1st at up to 36-37mph). But that's ONLY in the 31-34mph range. At 30mph or lower, or at 35-36mph it'll always go back to first if you go WOT. I think it has something to do with the fact that in the 31-34mph speed range is where the typical 3-4 upshift will occur in the 2.73 cars if you're at very light throttle input. I think there might be some confusion/freaking out in the PCM if you go WOT right when it's trying to pick between 3rd or OD, and by default it'll only go back to 2nd. This condition only occurs when the shifter is in OD, and I've noticed that this condition seems to happen more as the WOT 1-2 shift point is raised via custom tuning (not sure what that has to with it though?). If you run it in 3rd, then it'll always go from 3-1 even in that 31-34mph range, every single time.
Last edited by RPM WS6; Nov 23, 2006 at 03:15 PM.
soo uhh
i just read the whole thread and yet we still dont have much haha
can someone say:
it is better for a computer controlled 4-1 or 3-1 or manually controlled 3-1 4-1 ect...
i started getting confused and for the sake of simplicity i would appreciate it if someone could just write that **** down haha
i just read the whole thread and yet we still dont have much haha
can someone say:
it is better for a computer controlled 4-1 or 3-1 or manually controlled 3-1 4-1 ect...
i started getting confused and for the sake of simplicity i would appreciate it if someone could just write that **** down haha
Originally Posted by RPM WS6
If you run it in 3rd, then it'll always go from 3-1 even in that 31-34mph range, every single time.
Good info on the 4-2 shift though.
Last edited by BlackHawk T/A; Nov 23, 2006 at 11:54 PM.
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From: Schiller Park, ILL Member: #317
Originally Posted by BlackHawk T/A
Not my car. The only way to kickdown to 1st is go slow down to around 25mph. Around 30mph, no matter if in 3 or D (Pontiac) it will not go to 1st.
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From: So.Cal.
Originally Posted by RPM WS6
...What I've noticed is, if I'm cruising at a steady speed and slam the pedal to the floor, it'll go 4-2. If I depress the pedal slightly more slowly (but still flooring it), I'll sometimes see the 4-3-2 situation...
when it does 4-3-2, what does the TPS say in your log as it goes 4-3-2...?
I did, I ran an STS kit with about 4PSI of boost. The tranny was stock with the exception of the converter. I had a fuddle 3400 stall with a 2.1 STR. I wouldnt think I was over 400hp at the wheels, but the shift points were adjusted to 6500RPM. Needless to say the tranny was smoked in about 2mos after i put the turbo kit on/ reflashed ECU. So i am gonna have to agree with what Chaco is saying.
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From: crossett, Arkansas
FYI the #1 failure on these transmissions is burnt clutches. And the #1 cause of burnt clutches is fluid problems. The stock EPC reduces line pressures significantly at higher rpms, especially over 5000rpms. Rather than drop the shift point to 5500rpms like you suggest, why not address the problem? Changing the pump spring will get you 95% of the way there.
Oooohhh... 550rwhp, through a 4l60e (obviously through a loose converter), and at 5500rpms.
My built 4l60e shifts at 6500rpm, and I make over 400rwhp through a loose converter. Never dyno'd on the spray. I beat the crap out of this trans on a daily basis, doing all the things people around here say you shouldn't (WOT in 4th lockup, 4-1, 4-2 downshifts, manually downshifting to D without throttle input) and its performed flawlessly.
Oooohhh... 550rwhp, through a 4l60e (obviously through a loose converter), and at 5500rpms.
My built 4l60e shifts at 6500rpm, and I make over 400rwhp through a loose converter. Never dyno'd on the spray. I beat the crap out of this trans on a daily basis, doing all the things people around here say you shouldn't (WOT in 4th lockup, 4-1, 4-2 downshifts, manually downshifting to D without throttle input) and its performed flawlessly.
your playing with fire and soon will be burned
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didn't read everything. transmissions are not a solid mass, they have many moving parts. there are several different common failure points. one cant say rpm caused a failure, because this discussion is not describing exactly what it is other than failure and thats a broad, vague statement.
the only way this question gets answered with any accuracy is to analyize 100's of failures, note each vehicles modifications.
its not cut and dry, rpm causes failure we found the problem, no.
take a t400 for example you might assume a transmission used mainly in light duty trucks could not end up in the core pile at a sponsors shop to be built into a transmission that can be shifted at 8000 rpm with mostly stock parts.
my answer is more power causes failure, thats quite obvious. aside from burning the 3-4 set which usually goes eventually even on stock cars, you're putting more stress on everything.
course of action. add more power, clutches slip; add better clutches and more holding pressure=no more slip=more power and stress placed on hardparts=first to break gets replaced first such as the sunshell, the input drum, the shafts. then you start breaking the best input drums and shafts, the upgraded parts. soon enough there are no more options.
stock transmissions last because they can hold stock power until they wear out which can be quick. add power to a stock one and it slips leading to burnt clutches, upgrade them, and so goes the process described above.
the only way this question gets answered with any accuracy is to analyize 100's of failures, note each vehicles modifications.
its not cut and dry, rpm causes failure we found the problem, no.
take a t400 for example you might assume a transmission used mainly in light duty trucks could not end up in the core pile at a sponsors shop to be built into a transmission that can be shifted at 8000 rpm with mostly stock parts.
my answer is more power causes failure, thats quite obvious. aside from burning the 3-4 set which usually goes eventually even on stock cars, you're putting more stress on everything.
course of action. add more power, clutches slip; add better clutches and more holding pressure=no more slip=more power and stress placed on hardparts=first to break gets replaced first such as the sunshell, the input drum, the shafts. then you start breaking the best input drums and shafts, the upgraded parts. soon enough there are no more options.
stock transmissions last because they can hold stock power until they wear out which can be quick. add power to a stock one and it slips leading to burnt clutches, upgrade them, and so goes the process described above.
