Overdrive: How to use correctly. (MT guys do not read!)

I've had a couple 5R55's in explorers and I learned the hard way that heavy throttle 5-3 downshifts kill these transmissions. I did a lot of 2 lane highway driving and lost a transmission in my 2002. After reading about many failures in mustangs caused by a 5-3 downshift, I adjusted my driving to click off the O/D with the button and then get on the throttle to pass. My 2005 had 230,000 km when I sold it and the fluid never had a hint of a burned smell and the shifting felt as good as it did when I got it.

I'd do a pan drop and a filter change on the transmission and make sure you have the correct amount, I didn't put enough fluid back in when I did a pan drop and it shuddered until I added more.

tw557 said:

I also have a TCI shifter and how do you have the handle work with a button in it. My OD button is located on the base of the TCI shifter. Not very convienient. I would like the button on the handle.

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I purchased a universal handle from Jegs or Summit, can't remember. Then I just cut the wire going to the OD button and ran it to the button on the handle. The button placement by TCI is a joke. I think I clipped the wire on the harness in but I don't remember which wire it was but a quick look at a wiring schematic should reveal the answer.

It’s simple, I always turn off the od every time I start the car. The ONLY time I turn the od back on is on the highway or backroads with sustained highway speeds and even then I only turn it on once I get up to speed. Second you drive a Mustang why are you afraid to give it the gas! It is NOT a Honda it’s a Mustang man drive it as such!

fdjizm said:

Hey just stopped in to say fuck your automatics.



k bye!

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Good one made me laugh, still can’t pass up a chance to say

Laga said:

Unless there's a problem in the transmission itself, and it doesn't sound like there is, you simply do not know how to drive the car properly. You are not applying enough throttle to make the trans downshift. Just give it more gas.

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I experience that in my 2008 GT. I'll give it maybe 1/4 to 1/2 throttle and it's accelerating, but not all that well. I'm thinking "Come on, man, let's go!", then I give it more throttle, I get the downshift.

Terry said:

Hi esteemed Forum members.

Manual overdrive (O/D) in my 07 has had me flummoxed ever since I bought the car over a year ago. Now I understand it is probably a locked converter situation or 1:1 ratio

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In the 5R55S, 4th is 1.00:1 and 5th is 0.71:1, thus an overdrive in 5th. Overdrive means it's taller (higher ratio, lower number) than 1.00:1.

I did have an old 89 Chevy Caprice with a 700R4 that would struggle when accelerating after slowing down from higher speeds. It would spark knock really badly unless I floored it, then it would finally downshift. I'm guessing the lockup clutch on the torque converter didn't unlock properly. It turned out that the 5-year-old battery in it didn't quite have enough to unlock the torque converter clutch, and a new battery fixed the problem.

So, it's POSSIBLE that your torque converter lockup clutch is not unlocking. I don't know enough about the Mustang transmissions to hazard a guess.

fdjizm said:

Hey just stopped in to say fuck your automatics.



k bye!

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Yeah, fuck these automatics. I thought I wanted an auto because of the shitty traffic around here and the heavy clutch pedal in the 05-09, but I miss the stick shift now. The precision just isn't there with an auto.

Terry said:

If I applied your approach of not selecting O/D until 70 mph then I'd never need to select O/D since our speed limit nationwide is limited to 60 mph. Perhaps that's the answer. 60 mph dose seem a little slow for O/D. Maybe I jsut keep O/D off unless I deem flat road conditions allow it, and just switch select it on and off as needed. I might see how that works out for me!

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What I do (and anybody correct me if I'm mistaken, please), I'll leave OD off until I'm on flat ground at a steady speed. Sometimes I'll be in 5th (OD on) at 55-60 mph, but I never have to accelerate hard. If I get into a situation where traffic on the highway backs up and I'm dropping below 45mph or so, I'll turn the OD off again so it's not hunting up and down as much.

RED09GT said:

I've had a couple 5R55's in explorers and I learned the hard way that heavy throttle 5-3 downshifts kill these transmissions. I did a lot of 2 lane highway driving and lost a transmission in my 2002. After reading about many failures in mustangs caused by a 5-3 downshift, I adjusted my driving to click off the O/D with the button and then get on the throttle to pass. My 2005 had 230,000 km when I sold it and the fluid never had a hint of a burned smell and the shifting felt as good as it did when I got it.

I'd do a pan drop and a filter change on the transmission and make sure you have the correct amount, I didn't put enough fluid back in when I did a pan drop and it shuddered until I added more.

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I appreciate that info. Do you happen to know what the mechanical process is behind the transmission wearing out faster due to dropping 2 gears?

I'm picturing a situation where the car is cruising in 5th, full throttle gets applied, and it drops to 3rd. My car has a noticeable hesitation when I do that (2008 GT auto), as if it's needing to get itself downshifted before it puts the power back on. It feels like it closes the throttle during the downshift as well. I'm pretty diligent about leaving it out of OD when I'm on surface streets or in slow traffic on the highway, and generally I'll leave OD off even if I get up to speed on the highway but the engine isn't warmed up yet. Someone also posted earlier to not let the transmission do a 4-2 or 3-1 shift as well, is that the same principle as the 5-3 downshift, as far as wear on the transmission? I'm also comparing it in my mind to a manual, where a 2-gear downshift would require the synchros to spin up the lower gear more, whereas a sequential downshift would increase the input shaft RPM incrementally, thus less wear on the synchros.

I partially tore down the failed transmission and the 2-5 band was burnt up. The 2-5 servo bore had a groove in it as well so whether it was the leaky servo bore or the band adjustment is kind of a chicken or egg scenario.
I had replaced a failed solenoid block on that transmission and would get the o/d light flashing. It worked good for maybe 5,000 miles then it started doing a 2-3 flare. I tried doing a band adjustment at that point and the 3-4 band was in spec but the 2-5 one just seemed to turn without the torque wrench ever hitting spec. When it finally went, I lost 2nd and 5th gear.
It seems that if the downshift is 2 gears on the same band, it is just fine but if you are jumping from one band to the other, it seems like the design can't handle that scenario.

Blue Roads said:

I appreciate that info. Do you happen to know what the mechanical process is behind the transmission wearing out faster due to dropping 2 gears?

I'm picturing a situation where the car is cruising in 5th, full throttle gets applied, and it drops to 3rd. My car has a noticeable hesitation when I do that (2008 GT auto), as if it's needing to get itself downshifted before it puts the power back on. It feels like it closes the throttle during the downshift as well. I'm pretty diligent about leaving it out of OD when I'm on surface streets or in slow traffic on the highway, and generally I'll leave OD off even if I get up to speed on the highway but the engine isn't warmed up yet. Someone also posted earlier to not let the transmission do a 4-2 or 3-1 shift as well, is that the same principle as the 5-3 downshift, as far as wear on the transmission? I'm also comparing it in my mind to a manual, where a 2-gear downshift would require the synchros to spin up the lower gear more, whereas a sequential downshift would increase the input shaft RPM incrementally, thus less wear on the synchros.

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These transmissions are just delicate. You can't put bigger beefed up parts in there. Our Synchronous transmissions have a lot more going on inside during gear shifts than your standard automatic. It's great for clean smooth shifts and great fuel economy but do not stand up well to abuse. So when you go from 5th to 3rd it actually shifts through 4th and then down to 3rd. But it does it all at once and that is what messes up and burns out your clutch bands. I was trying to pay attention to what I was doing when I get it to go from OD to 4th without hitting 3rd. Not sure if I'm going to explain this properly but I'll try. When cruising in 5th I will depress the throttle hard and as I feel it start to down shift I actually lift on the throttle ever so slightly. Like I said before, gear selection is based off a a bunch of tables but throttle position is one of them. By lifting slightly on the throttle after the downshift has begun lets the computer believe there is less demand so it only kicks down one gear instead of two. Originally this was not a thought out process but was just instinctively developed over time by my right foot and I'm not sure I was really aware I was doing it. But after this discussion rose up I decided to pay attention to what I was doing.

If you know u will be passing on the hwy, or want to screw around, shut the OD OFF. For a smoother 5-4 downshift (when u hit the OD button), let off the gas pedal for a split second 1st.... then hit the OD button.

The poor 5r55s gets worse, when a blower + LT's are added to the mix. My 5r55s temps would rise from 170 F to 200 F in 5-8 secs..with blower on. I installed a JDM engineering catch can, PA deeper pan (holds an extra 4 qts, plus locking dipstick, big enough to easily add ATF if required. Also has a drain plug on bottom of pan), + 13 k BTU, B+M tranny cooler, in series with oem cooler. Then 100% synthetic ATF. (I used RP 'max atf' ). Now temps only rise to 171-172F with blower on. Without the catch can, the 5r55s will puke ATF all over the road. Without the dipstick, u have no clue what the level is.

After ceramic JBA LT's installed, + hi flow catted H, + 94 tune, it pulls like a mofo... even when not in boost, just putting my foot into it, without dropping from 4th to 3rd. Even 5th, uphill, no lugging.

RED09GT said:

.
It seems that if the downshift is 2 gears on the same band, it is just fine but if you are jumping from one band to the other, it seems like the design can't handle that scenario.

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Thanks for the info.

07 Boss said:

By lifting slightly on the throttle after the downshift has begun lets the computer believe there is less demand so it only kicks down one gear instead of two. Originally this was not a thought out process but was just instinctively developed over time by my right foot and I'm not sure I was really aware I was doing it. But after this discussion rose up I decided to pay attention to what I was doing.

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Thanks for the info, I'll keep your technique in mind.

Is this real life?

Also your car needs a tune up, Motorcraft plugs and replacment ignition coil boots