Worst time to go WOT
Joined: Nov 2003
Posts: 6,216
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From: Wichita KS / Rancho San Diego
Originally Posted by Transguy
Basically, going from 4th {OD} to 3Rd is as simple as releasing the 2/4 band, enlighten me, and explain how this hurts the transmission?
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Joined: Sep 2005
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From: 415 Northern CA
Originally Posted by Gary98Z
I talked to Carl Rossler and Rodney at RPM, and they both told me one of the worst things you can do to the 4l60e is to floor it on the highway while in OD. They said that if you're going to roll with someone on the highway, drop it down to D first and then punch it.
Good Advice.
yea i also read somewhere that when u go top end speeds u should drop it in D or for us T/A guys, put it on "3" so it will have less stress on the tranny...if u dont it messes up the 3-4 stuff and eventually will mess up alot more than that
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Joined: Apr 2002
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From: So.Cal.
Originally Posted by BlackHawk T/A
Also is it better to tap the brakes first to unlock the converter, or is this necessary?
TCC apply/release is based on the MPH vs TPS tables.
Originally Posted by joecar
Tapping the brakes will not release the TCC;
TCC apply/release is based on the MPH vs TPS tables.
TCC apply/release is based on the MPH vs TPS tables.
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Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
Originally Posted by Transguy
If I had an application chart loaded on my computer I would show you very clearly what is on and what is off in every gear, It is pretty simple when you see it on a chart. Basically [ without getting into a tremendously long reply ], going from 4th {OD} to 3Rd is as simple as releasing the 2/4 band, enlighten me, and explain how this hurts the transmission?
Edit: Here's a hosted image so it is more legible...
Last edited by joecar; Mar 21, 2006 at 03:57 PM.
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TECH Senior Member
Joined: Apr 2002
Posts: 6,080
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From: So.Cal.
Originally Posted by BlackHawk T/A
Tapping the brake does unlock the converter...I can lock/unlock mine at will by doing this. As soon as I let off the brake, it waits about 1 second before locking up again.
Edit: I'll go out and log data just to be sure...
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Joined: Oct 2005
Posts: 595
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From: Miami, FL
So, if I know my car will automatically downshift to 2 from a 65 punch, should I have it in "2" on the gear selector before I nail it? And if so, would it be better to immediately kick it back into 3 or D?
Originally Posted by mpe488
So, if I know my car will automatically downshift to 2 from a 65 punch, should I have it in "2" on the gear selector before I nail it? And if so, would it be better to immediately kick it back into 3 or D?
IMO the only reason you should ever select your own gear is when you do a burnout in 1st. Other than that it's OD from a stop, D from a roll...
This seems to be the consensus so far, from what i've gathered from the tranny builders here. I'm no expert myself though.
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Joined: Apr 2002
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From: So.Cal.
Originally Posted by joecar
Tapping the brakes will not release the TCC;
TCC apply/release is based on the MPH vs TPS tables.
TCC apply/release is based on the MPH vs TPS tables.
Originally Posted by BlackHawk T/A
Tapping the brake does unlock the converter...I can lock/unlock mine at will by doing this. As soon as I let off the brake, it waits about 1 second before locking up again.
Originally Posted by joecar
I can't do this on mine...
Edit: I'll go out and log data just to be sure...
Edit: I'll go out and log data just to be sure...
Originally Posted by BlackHawk T/A
It may depend on speed, I don't know. But I can do it on the highway, which is 40-50mph.
Anyway, I don't think you need to tap the brakes because when you punch it to WOT the TCC unlocks anyway (there's TCC Throttle Release tables for this).
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When you have it in "OD" 4th gear, and the you floor it, and the transmission downshifts to "D" 3rd gear, the only "thing" that happens is the 2-4 band releases, no overrun clutches to apply, nothing else. So how is this bad?
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It is not bad, It just seems like everyone is convinced that it is. The only advantage to putting it in 3rd from a roll before whacking the throttle is that you dont have to wait for the transmission to down shift. I have been building Transmissions for about 25 years, and have a pretty good idea of how they work.
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Joined: Apr 2002
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From: So.Cal.
That's right, the 3-4 clutch is already applied and the 2-4 band releases.
In WOT/PT downshift, the forward sprag holds when 3rd hits (engine is driving car).
In manual downshift, the overrun clutch is applied in 3rd, and...
the overrun clutch is preventing the forward sprag from overruning, which is what the sprag is trying to do (car is driving engine) before the throttle is punched; so the overrun clutch is holding back the vehicle at 70MPH (say); the overrun clutch has 2 friction plates, so I wonder if they end up getting burnt from repeatedly doing this...?
i.e. it may actually be bad to manually pull back to 3rd at freeway speeds,
but it's only the overrun clutch so engine braking is lost.
Any comments ("you're all wet, kid")...?
In WOT/PT downshift, the forward sprag holds when 3rd hits (engine is driving car).
In manual downshift, the overrun clutch is applied in 3rd, and...
the overrun clutch is preventing the forward sprag from overruning, which is what the sprag is trying to do (car is driving engine) before the throttle is punched; so the overrun clutch is holding back the vehicle at 70MPH (say); the overrun clutch has 2 friction plates, so I wonder if they end up getting burnt from repeatedly doing this...?
i.e. it may actually be bad to manually pull back to 3rd at freeway speeds,
but it's only the overrun clutch so engine braking is lost.
Any comments ("you're all wet, kid")...?
Last edited by joecar; Mar 22, 2006 at 10:47 AM. Reason: Fixed it better...
Originally Posted by Pro Built Automatics
When you have it in "OD" 4th gear, and the you floor it, and the transmission downshifts to "D" 3rd gear, the only "thing" that happens is the 2-4 band releases, no overrun clutches to apply, nothing else. So how is this bad?
Originally Posted by Pro Built Automatics
Yes, you can downshift a 4L60E, but you must do it as downshifting a manual transmission (double clutching). You have to give it throttle when you backshift the lever, once the engine rpm's match the gear you are in, (less than 1/2 a second) you can let off of the throttle, and let the engine do the braking now. If you back shift the lever without giving it throttle, you can ruin the transmission.
Now another question...is it worth doing this? Is it better to do this than just punching it from 4th?
Last edited by BlackHawk T/A; Mar 22, 2006 at 11:15 AM.
Originally Posted by Pro Built Automatics
When you have it in "OD" 4th gear, and the you floor it, and the transmission downshifts to "D" 3rd gear, the only "thing" that happens is the 2-4 band releases, no overrun clutches to apply, nothing else. So how is this bad?
Also i thought i read in one of the earlier post, that some one said leaving the car in OD when racing say at the track, was good, as in less chance of slipping when shifting into 3rd, is that correct?
