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Old 01-19-2016, 12:14 AM   #1
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4R100 shifting

I have a 99 Airstream on an F-53 ford chassis, presumably with a 4R100 4 speed transmission. When hitting long mountain up grades, my shifting goes something like this: I cruise at about 2900 rpm and 68 mph. Speed falls to about 61 mph and I get a shift that leaves me at 60 mph and 3600 rpm. Speed then falls to about 51 mph and 3050 rpm, when it shifts to about 50 mph and 4600 rpm. I have never had it fall enough after that to get another downshift, although I presume it would do so around 30 mph. Does the torque converter lock up on this transmission? I can never detect an unlocking. Since I have the early V10 with about 275 hp, does this seem about right? I presume later, higher hp models act about the same but take longer to fall off to downshift points-correct?
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Old 01-19-2016, 08:06 AM   #2
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We had the same set up in our 1999 34' Dutch Star. I can't remember how it shifted but since nothing seemed unusual I'll assume that it was for then somewhat normal.

I can not say for sure but I do know that cars did have TCLU and UL (That's torque converter Lock Up and Un-lock). We had a 1985 Pontiac Grand-Am that locked up at a way to slow speed and the 4-cylinder engine lugged down. Eventually they raised the lock-up speed from the 27 MPH to about 35 MPH and it didn't lug down.

At that time if the F-53 had TCLU it was only in high gear. So once it got into fourth gear at what ever RPM that happened eventually it would lock-up and you the driver would think that it actually had shifted into another gear because you would feel or see the rpms drop another 300-400. If you touched the brake it would un-lock the torque converter and the RPMS would again go back up.

As you reported you were in 4th and had 2 down shifts. At that point if one of those DS's was TCUL you could shift down one more gear into into 2nd and eventually into 1st. If you can't get but 3 DS's then maybe it does not have a TCLU & UL. My experience has been with the 5 speed that a TCLU and UL will usually see an RPM change of around 400-600 RPM's. A gear change will be around 900-1200 RPM's.

It's only been in recent years that the industry is using TCLU and UL in more than high gear. I have been told that they are using it in most gears. Today's shifting has gone from 4 speed to 10 speeds and many with a number of TCLU and UL in most of the other gears. The primary reason is improved fuel mileage.

Five Star TUNE has done wonders for the V-10 shifting patterns and improved utilization of more gears than Ford. I'm very happy with the 5-speed improvement and have also read how happy most are with the 2016 6 speed improvements from Ford and I'm sure that 5-Star will also improve what Ford had already done.

With the 5 and now the 6 speed transmission there are many more options for much smoother shifting, hill climbing and down shifting.

Give them a call and ask the techs what they have done for the 4 speed transmission. I'm sure it will be $$$$ well spent.

I'm sure others will chime in soon (once they wake up, get their coffee and get on the PC's) with a lot more information about the shifting patterns of these machines.

TeJay
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Old 01-19-2016, 08:28 AM   #3
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You do have the 4R100 transmission. It is capable of locking the torque converter in all four forward gears.

Fourth gear ratio is 0.71:1, third gear is 1:1, and second gear is 1.54:1. We'll need those numbers.

As you slow from 68 MPH and 2900 RPM, at 60 MPH your RPM if you remained in fourth gear with the torque converter locked would be 2600 RPM. Downshifting to third with the converter locked would give you 3600 RPM (that's 2600 * 1.29.) So that's about right. The first shift is a 4-3 downshift.

Now as you slow to 50 MPH and downshift to second gear your RPM should be about 4300. Since you say it's 4600 RPM, I think the torque converter unlocks during this shift.

The programming in the early 99s left much to be desired in my opinion. There might be a later factory program that could improve on this, or you might go aftermarket. What I would have programmed if I had done this (and I did this type of programming for many years at Ford, just not the F-53 in those years) would be to downshift from 4 to 3 at a higher speed. That might be enough to keep the second downshift to 2 from happening.

You can test this by pressing the OD OFF button either at the start of a hill, or as soon as you lose a couple MPH climbing the hill. Pressing the button will make the trans shift 4-3.
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Old 01-19-2016, 09:55 AM   #4
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Mark: Thank you very much! I was wondering if that approach would be OK. Would it be better to push the button to lock it out of overdrive 4th quickly (before I lose appreciable speed) or wait until I am at full throttle and have lost a couple of mph? I usually approach the hill in cruise control, then assist by stepping on the gas pedal after it loses 2-3 mph. The cruise control will cut out after the first downshift, somewhere around 55-58 mph so I do this "assist".
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Old 01-19-2016, 10:15 AM   #5
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Try it both ways and use the one you like better. Neither way is better or worse for the coach, it comes down to personal preference. If you press the button before you've lost speed you might not need to use the foot assist. Try it and see if it works for you.

Cruise is programmed to shut off if the vehicle loses 10 MPH from the set speed.
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Old 01-19-2016, 10:23 AM   #6
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Thanks, Mark-I will give it a try-after it warms up! I thought that must be the way the cruise control works.
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Old 01-19-2016, 10:47 AM   #7
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Quote:
Originally Posted by Mark Kovalsky View Post
Try it both ways and use the one you like better. Neither way is better or worse for the coach, it comes down to personal preference. If you press the button before you've lost speed you might not need to use the foot assist. Try it and see if it works for you.

Cruise is programmed to shut off if the vehicle loses 10 MPH from the set speed.
Is that cruise programming for F 53s.

I have a 1999 E450 that drops out at 40 MPH. Talk about a wake-up call.
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Old 01-20-2016, 09:20 PM   #8
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That's programming for all Ford cruise control systems. If the vehicle loses 10 MPH from the set point the cruise shuts off.
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Old 01-21-2016, 02:59 AM   #9
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Originally Posted by Mark Kovalsky View Post
That's programming for all Ford cruise control systems. If the vehicle loses 10 MPH from the set point the cruise shuts off.
Humm, OK, I guess I was never set over 50 mph when it happened.
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Old 01-23-2016, 07:31 PM   #10
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Mark: if you read this, could you recheck your figures on the downshift to second gear?? When I try the calculation it comes out like this-60 mph at 3600 rpm after dropping out of overdrive, dropping to 50 mph gives me 50/60 X 3600 = 3000 rpm at 1:1 ratio. Dropping to 1.54 ratio gives me 3000 X 1.54 = 4620 rpm at 50 mph. This seems to me to show the torque converter is still locked, or else it was unlocked all along. I don't quite understand what is happening and am seeking help!!
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Old 01-23-2016, 07:33 PM   #11
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Perhaps the torque converter does not unlock until some lower speed??
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Old 01-23-2016, 08:44 PM   #12
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Mark: if you read this, could you recheck your figures on the downshift to second gear?? When I try the calculation it comes out like this-60 mph at 3600 rpm after dropping out of overdrive, dropping to 50 mph gives me 50/60 X 3600 = 3000 rpm at 1:1 ratio. Dropping to 1.54 ratio gives me 3000 X 1.54 = 4620 rpm at 50 mph. This seems to me to show the torque converter is still locked, or else it was unlocked all along. I don't quite understand what is happening and am seeking help!!
I did have a math error. But in your original post you said 2900 RPM at 68 MPH. That's what I used here.

68 MPH @ 2900 RPM is 2559 RPM at 60 MPH, converter still locked and in fourth gear.
60 MPH third gear converter locked is 3300 RPM. 300 RPM when the converter unlocks is a reasonable amount.
50 MPH third gear converter locked would be 2750 RPM.
50 MPH second gear converter locked would be 4016 RPM.
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Old 01-23-2016, 09:10 PM   #13
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Ok, I see where I went wrong. I used 68mph/2900 rpm, dropping to 60mph/2558rpm. Then I divided 2558 by 0.71 and got 3602 rpm in 3rd gear at 60mph. However, 1/0.71 is 1.41, which would be a 40% overdrive. I should have done 2558 X 1.29 = 3300 rpm at 60 in 3rd gear, with 300 rpm added for the torque converter unlocking during that shift. then 50/60 X3600 = 3000 rpm, 50 mph, 3rd, unlocked times 1.54 = 4662 rpm after downshift to second, 50 mph, unlocked. Thanks for the help.
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