Effect of RPM's on a 4L60E
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From: Philly
Originally Posted by RPM WS6
I have logged 4-1 downshifts with a-tap, so I know it can occur. But I can't remember now if it was with my 2.73 geared Camaro or the 3.23 geared WS6. I'm pretty sure it was with my 2.73 geared car though, as I recall under very light throttle it would shift into OD at just above 30mph, yet the tables would allow for a downshift to 1st at up to 36/37mph.
Originally Posted by staringback05
how big a difference are we talking about in rpms between a 2.73 and a 3.23 at that low of a speed?
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From: Schiller Park, ILL Member: #317
Originally Posted by RevGTO
4-1: release the band and disengage the 3-4 clutch pack. 3-1: disengage the 3-4 clutch pack. But with the 4-1 downshift, the overun clutch is not applied; manually downshifting from 4-3 applies it, and then the 3-1 automatic downshift releases it. Although I don't think one is "safe" while the other is "destructive" to your tranny, on balance, I'd probably lean toward the manual 3 - automatic 1.
- PCM controlled/automatic 4-2 downshift from a higher speed WOT roll when already in OD.
and
- Manual 4-3 downshift (under no load), then PCM controlled/automatic 3-1 downshift at WOT for lower speed rolls where the trans will want to hit 1st gear.
Is that correct?
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From: Schiller Park, ILL Member: #317
Originally Posted by ChocoTaco369
honestly, i don't know. it's not really a question of RPM's, though. it's a question of shift points. i could guess, but i don't want to throw information out there i haven't verified.
Originally Posted by ChocoTaco369
honestly, i don't know. it's not really a question of RPM's, though. it's a question of shift points. i could guess, but i don't want to throw information out there i haven't verified.
Originally Posted by RPM WS6
This is why I think the 4-1 will be seen more often in a 2.73 car, because of the shift points. I think that both the 3.23 and 2.73 car will hit OD right near 30mph under very light throttle, but the 3.23 car will only go back to 1st up to ~30mph, vs ~36mph for the 2.73 car.
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From: Philly
Originally Posted by staringback05
so your saying a 2.73 car will shift into 4th around 36?
hopefully i'll remember to do this.
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You guys are starting to go against everything i've learned about this subject...let me post what was advised to me:
But the question still remains though, the car is set up so that the average user wouldn't even think twice about this. He would nail it from overdrive, being an automatic that you normally don't mess with yourself. GM surely must have accounted for this in their design, you would think, but I could be wrong. I just don't see why they would design it so that 4-2 would burn up the transmission if thats how its driven by default, but that's what seems to be the general consensus among transmission builders on here.
I was reading this the other day, got side tracked and forgot about this pm. I really don't have a problem with you doing wot upshifts. I know that people say 3-4 at wot is bad but with a properly built unit with a properly adjusted band I think it is probably ok. As far as manual shifting not a big fan of that. If you want to pull it into 3rd before punching it to force a 3-2 shift I think that this would be best. The problem with doing a direct 4-2 is that the band must relaese for 3rd, then the 3-4 clutch must release and the band must reapply to give you 2nd. I think that this can possiably cause a tie-up between the shifts and this is what causes these things to burn up. I hope that this makes sence. I hope I answered your question. Good luck, Vince
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From: Wichita KS / Rancho San Diego
Originally Posted by RPM WS6
So in summary, you'd recommend: PCM controlled/automatic 4-2 downshift from a higher speed WOT roll when already in OD. and - Manual 4-3 downshift (under no load), then PCM controlled/automatic 3-1 downshift at WOT for lower speed rolls where the trans will want to hit 1st gear. Is that correct?
The problem with doing a direct 4-2 is that the band must relaese for 3rd, then the 3-4 clutch must release and the band must reapply to give you 2nd. I think that this can possiably cause a tie-up between the shifts and this is what causes these things to burn up.
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From: Schiller Park, ILL Member: #317
Originally Posted by RevGTO
As everyone has been saying, a 4-1 downshift is rare if it happens at all and so I honestly think it's a non-issue.
So I'd still like to know if the 4-1 is better, or the manual 4-3 + auto 3-1.
Originally Posted by staringback05
i just dont see how you could run 4th at that low of a speed, i could be wrong....hell though in 4th at speed your doing only 2k rpms at like what 70-80 something with 2.73s...guess i just dont get the concept
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From: Philly
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.
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Originally Posted by Rokko
Same here. I only put it into OD on the highway. Never around town. That's just way too much lugging on the motor for me to be comfortable with. Even more so with 2.73's. IMO anyway. 70mph is 2000-2100rpm's in my car.
Loading the motor is better than a high-rev/low load. I think GM proved that in their oil-useage TSB.
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From: Schiller Park, ILL Member: #317
So once again I ask, can we get a final answer from the pros on what's the best WOT downshifting pattern to follow?
Manual 4-3 at no load, then auto 3-2 at WOT? Or just auto 4-2 at WOT?
- AND -
Manual 4-3 at no load, then auto 3-1 at WOT? Or just auto 4-1 at WOT?
It'd be great if we could solve this once and for all, because I'm tired of constantly doubting myself, as I'm sure others are as well.
Manual 4-3 at no load, then auto 3-2 at WOT? Or just auto 4-2 at WOT?
- AND -
Manual 4-3 at no load, then auto 3-1 at WOT? Or just auto 4-1 at WOT?
It'd be great if we could solve this once and for all, because I'm tired of constantly doubting myself, as I'm sure others are as well.
Originally Posted by RPM WS6
So once again I ask, can we get a final answer from the pros on what's the best WOT downshifting pattern to follow?
Manual 4-3 at no load, then auto 3-2 at WOT? Or just auto 4-2 at WOT?
- AND -
Manual 4-3 at no load, then auto 3-1 at WOT? Or just auto 4-1 at WOT?
It'd be great if we could solve this once and for all, because I'm tired of constantly doubting myself, as I'm sure others are as well.
Manual 4-3 at no load, then auto 3-2 at WOT? Or just auto 4-2 at WOT?
- AND -
Manual 4-3 at no load, then auto 3-1 at WOT? Or just auto 4-1 at WOT?
It'd be great if we could solve this once and for all, because I'm tired of constantly doubting myself, as I'm sure others are as well.
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From: Schiller Park, ILL Member: #317
Originally Posted by BlackHawk T/A
However pulling it back to 3 to get it out of overdrive, with foot still on the gas at cruise speed, was the way to go I was told.
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From: Wichita KS / Rancho San Diego
Originally Posted by RPM WS6
So once again I ask, can we get a final answer from the pros on what's the best WOT downshifting pattern to follow?
Manual 4-3 at no load, then auto 3-2 at WOT? Or just auto 4-2 at WOT?
- AND -
Manual 4-3 at no load, then auto 3-1 at WOT? Or just auto 4-1 at WOT?
Manual 4-3 at no load, then auto 3-2 at WOT? Or just auto 4-2 at WOT?
- AND -
Manual 4-3 at no load, then auto 3-1 at WOT? Or just auto 4-1 at WOT?
Anyway, that's my story and I'm stickin' to it.
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From: Philly
Originally Posted by RevGTO
I checked today with a couple of tranny builders that I know locally. Both unequivocally affirmed that on a direct 4-2 downshift, the band remains applied and it is just a matter of releasing the 3-4 clutch pack. Thus it is a simpler operation than the 3-2 downshift which must both release the 3-4 clutches and apply the band. So regarding your first question, it seems the simple 4-2 downshift is best. When it comes to the >1 downshift, as I said, I lean toward the manual 3 to automatic 1 because in that case, the 3-4 clutch pack simply disengages. 4-1 must disengage the clutch pack and release the band. But overall, I just don't think that the difference between any of these options is a matter of life and death to your tranny.
Anyway, that's my story and I'm stickin' to it.
Anyway, that's my story and I'm stickin' to it.
i honestly don't think anyone knows 100% what happens inside the tranny when you're moving and exactly how detrimental these things are. all i can say is, if your tranny blows because of a WOT downshift, it was gonna blow anyway. transmissions just don't blow on stocklike rides - it's a long time coming. as for highly modded cars, your 4L60E will have to be beefed up enough to hold the power anyway so if it's built right, it really shouldn't matter as your bands/clutches will be beefed up. if you're running a stock 4L60E in a highly modded car and it blows, it deserves to anyway
if you're gonna race the car nonstop, something will eventually go. you may as well go out there and have fun. for me, i'll stick with the manual downshift to 3. even if it's harsher for that 1 second of downshift, it's definitely easier on the transmission for that WOT pull.
