OD confusion

[Svashtar]

Thought I had this all figured out. I know when I am at freeway speeds and want to punch it to take the OD off. For that matter, if the car is moving at all and I want to go WOT I take it off. No problem.

But what about from a dead stop? What do you guys do at the track? The OD has not kicked in yet obviously at that point so the same stresses should not be on the tranny correct? I went WOT the other day from a stop and at 5 seconds and 50-55 MPH the car was screaming and the tach was close to 6K RPM. The car was close to shifting up but I was afraid of going over 6K so backed off a bit. I mentioned this to someone and he pointed out that whether the OD is on or off at a dead stop it makes no difference to the tranny. (?) I assume I would have had lower RPM's with the OD on.

Sorry for the dumb questions, but the shifting stuff is still a bit of mystery to me and I know just enough to be dangerous.

As a general rule when I am at a stoplight at my private track and want to go WOT, I take the OD and traction control off first.

Thanks as always,

Norm

[grampaws]

OD off any time you put a heavey Load on the TRans..
Good rule of thumb
The shift points change slightly for better power..
and the weaker componenets of the OD are not used..
The rpm limiters and shiftpoints are set well within the engine.
capabilities unless you've reprogrammed it..
OD of and matt it..

[Tallboy]

At the track, I click the O/D off so it won't shift into 4th on me at the end of the run. If I'm just punching it from a dead stop, and will let off soon, [like when I'm punishing the rear tires] I don't bother clicking O/D off. Sounds to me like you're doing all the right things...

[Blackened300a]

WOT launches from Dead Stops I always click the O/D off, If Im crusing about 65mph and I want to get up to say 100 in a hurry, I click off the O/D wait for the RPMs to jump up and hammer down. The O/D band is the Weakest link in the Transmission.

[SergntMac]

At the track, I click the O/D off so it won't shift into 4th on me at the end of the run...Sounds to me like you're doing all the right things... With the grand variety in tranny programming we see here, shifting into OD before the end of the 1320 can happen, and it will happen on my MM if I don't shut it off. Norm, you're doing fine.

[TripleTransAm]

The shift points change slightly for better power..

Is this really the case on this car? Has someone actually determined the exact change in shift points when OD is on or off? I ask this because all documentation seems to indicate that there is no change in mechanical element application in the transmission between having the OD disabled or enabled. This is not the case with all transmissions (the RWD GM transmissions applied an overrun clutch in D versus OD to provide extra engine braking) but for this transmission, I haven't seen any indication of the OD button doing anything other than telling the PCM not to ask for 4th gear when the time comes.

If it was the case, it would have to be controlled by the PCM and I haven't seen anyone with tuning experience indicate that there are two shift schedules, one for OD on and another for OD off.

As for shift firmness, the older hydraulic brain trannies saw extra fluid paths being fed when the selector was in OD versus D, so it was possible to see higher pressures if those extra fluid circuits were blocked off by keeping the tranny in D (same fluid amount, less distance to feed, more pressure).

Nonetheless, if I was leaning on the car a little, I'd want OD off. Even though 4th gear should only kick in at a very high speed if you're keeping the pedal down, sooner or later you're going to lift off and I wouldn't feel comfortable having the PCM suddenly decide that conditions were now right for grabbing 4th gear when the car was still under acceleration as you're still lifting off the gas.

[Lidio]

On a MM that’s stock, it will not go into OD at WOT till about 113mph if its an ’03… and 120mph if it’s a ’04.
So for the most part it wont go into OD in the ¼ if it’s a relatively stock MM with only bolt-ons and a maybe a few extra’s. But its still a good thing to go down the ¼ with OD off because to me it’s a little awkward to go into OD at high speeds at the end of the ¼ as you lift off with the gas pedal. Plus its easier to slow down from high speeds and offers better compression braking while slowing down in 3rd gear with OD off. As far as I know when you turn off OD in a MM, it does nothing else to the trans as far as shift feel and shift timing… it only turns off OD.

The OD band in the AOD’s and 4R70W’s is inherently the weakest thing in these transmissions. The newer ones like the 4R70W have a much better and improved OD band and surface. But I still recommend going into OD at moderate throttle/loads or lower, not at WOT.
As I’ve said before, the most damaging thing you can do to a AOD or 4R70W is down shift from OD back to 3rd or even worse directly from 4th back to 2nd.
Because a flare can happen under these conditions, I always recommend turning off OD first manually then proceed to hammer it. On the last few years worth of Fords including the MM we can tune them to reduce TQ during 4-3 or 4-2 downshifts which greatly reduces flaring and increases trans life, and also configure them to grab 3rd for a few mili seconds first as it attempts to perform a 4-2 down shift. Most of these downshifting out of OD problems I’m mentioning here are experienced mostly on Ford’s with looser then stock TQ converter’s and above all with a supercharger.

Most Fords that are EEC-5 shift entirely based on throttle vs MPH. The newer Power PC based Fords like the ’04 and up F-150, 2005+ Mustang and many other newer Fords use TP and MPH only till you go WOT, then its strictly a RPM based shift point which is an unbelievably awesome feature on the newest Ford’s.
The newer computers are very fast and accurate now days when it comes to shift timing at WOT.

On the new 5R55S 5-speed auto trans like in the 05 GT I got earlier this year, I no longer recommend turning off OD while racing because the OD system isn’t as weak as it is in the older 4-speed OD’s because it’s a non-synchronous shift and also doesn’t have as much of an RPM drop because the OD ratio isn’t as steep either. Even though I earlier mentioned the new 5-speed automatic in the 05 GT is physically smaller and potentially weaker then previous 4-speed auto’s, I’ve gotten quite used to it this past season and got my 05 GT to make just under 500 RWHP and go low 11’s in the ¼ mile with no problems yet, and have not dropped the trans pan for any mods at all. Its all been done through tuning. No shift kit or any mods what so ever, nor will ever be needed from the looks of it for right now.


Thanks

[CRUZTAKER]

As I’ve said before, the most damaging thing you can do to a AOD or 4R70W is down shift from OD back to 3rd ......... I always recommend turning off OD first manually then proceed to hammer it.

Damn.

I have always been in the habit of manually dropping out of OD when exiting the freeway or handling sharp ramps at high speeds. I mean...I do this alot. Always have.

I'm actually not sure if I can break the habit at this point.

Damn.:depress:




I always recommend turning off OD first manually then proceed to hammer it.


Even at highway speeds just before WOT?

[grampaws]

Is this really the case on this car? Has someone actually determined the exact change in shift points when OD is on or off? I ask this because all documentation seems to indicate that there is no change in mechanical element application in the transmission between having the OD disabled or enabled. This is not the case with all transmissions (the RWD GM transmissions applied an overrun clutch in D versus OD to provide extra engine braking) but for this transmission, I haven't seen any indication of the OD button doing anything other than telling the PCM not to ask for 4th gear when the time comes.

If it was the case, it would have to be controlled by the PCM and I haven't seen anyone with tuning experience indicate that there are two shift schedules, one for OD on and another for OD off.

As for shift firmness, the older hydraulic brain trannies saw extra fluid paths being fed when the selector was in OD versus D, so it was possible to see higher pressures if those extra fluid circuits were blocked off by keeping the tranny in D (same fluid amount, less distance to feed, more pressure).

Nonetheless, if I was leaning on the car a little, I'd want OD off. Even though 4th gear should only kick in at a very high speed if you're keeping the pedal down, sooner or later you're going to lift off and I wouldn't feel comfortable having the PCM suddenly decide that conditions were now right for grabbing 4th gear when the car was still under acceleration as you're still lifting off the gas.
It was a general statement and is based more on the older hydraulic..Trans..
At WOT it probably doesn't change much..the computer would assume max load..I would have to actually test it to see if actually does work on this
specific trans..

[cyclone03]

Damn.

I have always been in the habit of manually dropping out of OD when exiting the freeway or handling sharp ramps at high speeds. I mean...I do this alot. Always have.

I'm actually not sure if I can break the habit at this point.

Damn.:depress:




Even at highway speeds just before WOT?

Cruztaker if I'm not mistaken the problem is not in "power off",like you do jumping off the highway,It's in "power on" automatic pedal to the floor downshifts that tend to jump from OD to 2nd at high throttle settings.
I've been retuned so long now I don't remember if the trans ever stopped at 3rd when stock,it does now because of the tune.

[Svashtar]

Wow, thanks very much for all the great info! The only thing I have had hard coded in my brain is that when I am doing 60 or 70 on the freeway and want to go WOT to pass someone I set the OD to OFF and floor it. As soon as the button goes off he RPM jumps of course, and then I hit it.

As far as coming off the freeway if I am slowing gradually I just keep it in OD and come off slowly, so that has not been a problem I don't think.

Thanks as always for your input.

Norm

[Blackened300a]

Damn.

I have always been in the habit of manually dropping out of OD when exiting the freeway or handling sharp ramps at high speeds. I mean...I do this alot. Always have.

I'm actually not sure if I can break the habit at this point.

Damn.:depress:

Join the Club, Guilty as charged here as well. I like using the engine to slow me down to save the brake wear

[SergntMac]

Join the Club, Guilty as charged here as well. I like using the engine to slow me down to save the brake wear Guilty three, and I enjoy the exhaust rumble as well.

[Hotrauder]

Me 4 for both reasons but as my friendly Porsche DT instructor told me in my youth, " brake pads are a hell of a lot less expensive than engine and tranny parts." Dennis:beer:

[TripleTransAm]

Could there be any correlation between that infamous retaining clip weakness in our trannies and "sporty" driving styles such as manually cutting out 4th gear to reduce road speed? I'm trying to figure out why we seem to have so many reported incidences of that clip problem versus the rest of the Panthers out there. This is one reason I've held off on blipping off OD to reduce speed at higher revs, even though it's a pleasant sound to hear.

Maybe it's the custom torque converter applications in some aftermarket programming that's applying unforeseen reverse torques on the tranny innards from not unlocking during deceleration, whereas the stock programming would unlock the TCC anytime you lift off?

These are two items that used to interest me until I began to worry about the root cause for these failures. I still would like to know the real reason, so that I can eliminate any or all of the above suppositions.

[grampaws]

Me 4 for both reasons but as my friendly Porsche DT instructor told me in my youth, " brake pads are a hell of a lot less expensive than engine and tranny parts." Dennis:beer:
Me 5..guess the brakes are easier to replace!!