95 Explorer Engine Braking / Coast Clutch issue ? 4R55 Transmission

[lighttech]

I am hoping someone can tell me if their 1995 explorer does the same thing:

When driving in OD (50MPH or above, fourth gear) I make note of the engine RPM. I then take my foot off the gas pedal and the engine RPM drops just a tad (maybe 100 RPM), telling me that engine braking is going on, and obviously TCC unlocks. In all other gears, (with gear shift in the D position) there is no engine braking (RPM drops significantly when taking foot off the gas) unless I press the O/D cancel button.

I have looked at the ATSG manual for the 4R44 / 4R55 (4 speed, which is mine) and it says no engine braking when in OD (fourth gear). This is contrary to what I am experiencing.

I also looked at the ATSG manual for the 5R55 for comparison (5 speed), and it noted that in OD (fifth gear) there is engine braking.

I am just trying to figure out whether there is a problem in my Tranny, or there may be a mis-print in the book.

Any help or experience would be appreciated.

 

[lighttech]

I just did some more reading and found a contradiction in the ATSG 4R55E manual.

According to page 5 in the "Band/Clutch Application Chart" it clearly says no engine braking in fourth gear.

According to page 18 in the Solenoid Operation Chart, Engine braking is on for fourth gear all the time.

Typo I guess somewhere.

Not going to worry about it. There is more to life than obsessing on this.

 

[imp]

I just did some more reading and found a contradiction in the ATSG 4R55E manual.

According to page 5 in the "Band/Clutch Application Chart" it clearly says no engine braking in fourth gear.

According to page 18 in the Solenoid Operation Chart, Engine braking is on for fourth gear all the time.

Typo I guess somewhere.

Not going to worry about it. There is more to life than obsessing on this.

Here's what's confusing about this: You are right, get off the gas, and TCC unlocks. You're thinking the rpms should go UP due to engine braking, that's where the hard to understand part comes in. There IS engine braking. With NO throttle, unlocked TCC, rpms LOWER than with TCC engaged, the wheels are DRIVING the engine, through the torque converter fluid, so some rpms are lost in swooshing the oil around, only backwards from how it happens during acceleration, when rpms are HIGHER as engine drives wheels through converter. Make any sense? imp

 

[lighttech]

I understand exactly what you said, there was never any confusion there. My confusion was simply whether there is "supposed to be" engine braking in 4th gear on the 4R55. Mine does. It does exactly what you said. I am going to assume for now that this is normal, and there IS engine braking in 4th gear.

Thanks !

 

[imp]

I understand exactly what you said, there was never any confusion there. My confusion was simply whether there is "supposed to be" engine braking in 4th gear on the 4R55. Mine does. It does exactly what you said. I am going to assume for now that this is normal, and there IS engine braking in 4th gear.

Thanks !

My apologies if my terse approach offended. I never know what level of understanding exists between two conversants on a technical point, so try to explain what I think I know in advance.

The thing about the converter causing eng. rpms. to DROP when "gearing down" only lit up for me after a lot of thought, some of which I included.

I would think if there is NOT engine braking in 4th. gear, by design, it would be through a fluke in the actual mating of the planetaries method used, rather than an INTENDED effect designed in. imp

 

[lighttech]

Hey Imp,

Thanks for replying. I agree, you never know the level of understanding of each person when communicating.

I guess what I need to do to know for sure (like it really matters in the grand scheme of life) is to find several other people with the same year and model as my explorer and ask them what happens when they let off the gas when in OD (4th gear). I would ask them the following question:

After establishing a constant speed at 65 MPH, when letting off the gas, does your tach drop just a little bit (100 RPM or so), or a lot (down to just over 1000 RPM) ?

For the record, my vehicle DOES have engine braking in fourth gear. The tach drops only about 100 or so.

By the way, I was impressed with your explanation concerning what happens when engine braking is working. I had already understood all that, but to a newcomer to all this, it would be great for them to grasp the concept.

Thanks !
Craig

 

[Justme63]

:scratch:

Hey Imp,

Thanks for replying. I agree, you never know the level of understanding of each person when communicating.

I guess what I need to do to know for sure (like it really matters in the grand scheme of life) is to find several other people with the same year and model as my explorer and ask them what happens when they let off the gas when in OD (4th gear). I would ask them the following question:

After establishing a constant speed at 65 MPH, when letting off the gas, does your tach drop just a little bit (100 RPM or so), or a lot (down to just over 1000 RPM) ?

For the record, my vehicle DOES have engine braking in fourth gear. The tach drops only about 100 or so.

By the way, I was impressed with your explanation concerning what happens when engine braking is working. I had already understood all that, but to a newcomer to all this, it would be great for them to grasp the concept.

Thanks !
Craig

Now I will have to look into this, I have an early 96 with a 4R44E.