Slipping/dying transmission. How to get more time?

[SZR48207]

Well after 12 years and 150k miles, the 4R70W in my F150 seems to be on its way out. It started out as a groan at cold that I thought was worn engine mounts, then a vibration in the gas pedal between 40-50MPH, and finally a significant drop in MPG (5-7 MPG per loss city and highway). Now the gas pedal will vibrate very noticeably when lightly accelerating between 40-50 MPH and some slipping is felt when medium accelerating during that range. I can still WOT and it'll downshift for passing.

Quite a shame because I've been very finnicky about maintenance.

I've gone through the five stages of grief and have a new vehicle picked out to purchase in a month or two, but I think I'll keep this truck and in my idle time attempt to rebuild the transmission. I've found more than enough resources on doing so, and rebuild kits and parts are plentiful and fairly affordable.

So with that in mind, are there any things I can do between now and when I get the new vehicle, to put as little stress as possible on the transmission? Below is a list of my initial ideas:

1. Try not to drive it often. I can make this happen now that the weather is nice and ride my motorcycle for most trips.

2. I've put in 20oz of Lubegard Red but haven't noticed any improvement yet. I'm only 50 miles on it so far, though, so that could change.

3. If 2 doesn't work, I'm also going to try some Lubegard Dr. Tranny just for kicks ($5 tube.. no biggie).

4. Turn off OD when driving unless I need to go on the highway. Most of my driving in the area is on 45MPH roads.

5. Go light on the WOT? Or go heavy on the WOT? I was always under the impression that hard shifts were BETTER for a transmission because you engage quicker and cause less friction and heat.

 

[CharBaby]

Alot of folks will say(and I agree), change the tranny fluid and screen.

Have they ever been changed before?
Are there any bands that can be adjusted?

Others will chime in with some advise

 

[demarpaint]

I'd drop the pan and change the screen as Char Baby mentioned. It's a coin toss and you might get lucky and get a little more life out of the unit. I'd lay off the WOT.

 

[Wilhelm_D]

Originally Posted By: Reddy45
So with that in mind, are there any things I can do between now and when I get the new vehicle, to put as little stress as possible on the transmission?

The Hail Mary play:

- drop the pan, change the filter

- fill the transmission with Red Line High-Temp ATF

- don't use Lubegard

Red Line High-Temp ATF

The additional viscosity of the High-Temp may be helpful in getting some additional miles out of the worn tranny internals. If it's slipping you don't want Lubegard in there.

 

[David1]

Originally Posted By: Reddy45
Well after 12 years and 150k miles, the 4R70W in my F150 seems to be on its way out. It started out as a groan at cold that I thought was worn engine mounts, then a vibration in the gas pedal between 40-50MPH, and finally a significant drop in MPG (5-7 MPG per loss city and highway). Now the gas pedal will vibrate very noticeably when lightly accelerating between 40-50 MPH and some slipping is felt when medium accelerating during that range. I can still WOT and it'll downshift for passing.

Quite a shame because I've been very finnicky about maintenance.

I've gone through the five stages of grief and have a new vehicle picked out to purchase in a month or two, but I think I'll keep this truck and in my idle time attempt to rebuild the transmission. I've found more than enough resources on doing so, and rebuild kits and parts are plentiful and fairly affordable.

So with that in mind, are there any things I can do between now and when I get the new vehicle, to put as little stress as possible on the transmission? Below is a list of my initial ideas:

1. Try not to drive it often. I can make this happen now that the weather is nice and ride my motorcycle for most trips.

2. I've put in 20oz of Lubegard Red but haven't noticed any improvement yet. I'm only 50 miles on it so far, though, so that could change.

3. If 2 doesn't work, I'm also going to try some Lubegard Dr. Tranny just for kicks ($5 tube.. no biggie).

4. Turn off OD when driving unless I need to go on the highway. Most of my driving in the area is on 45MPH roads.

5. Go light on the WOT? Or go heavy on the WOT? I was always under the impression that hard shifts were BETTER for a transmission because you engage quicker and cause less friction and heat.



Did you try LUCAS Transmision conditioner?

I have been told by people with Fords and GM and Chyrslers Trucks that LUCAS Transmission Conditioner makes a big differnce.

1 guy was ready to have a rebuild done till he put in LUCAS.

I guess it help with the bands or something.

 

[msmoke00]

Originally Posted By: Reddy45
lightly accelerating between 40-50 MPH and some slipping is felt when medium accelerating during that range. I can still WOT and it'll downshift for passing.


Have it professionally diagnosed before assuming it's the trans. Well over 75% of the "slipping" transmissions we see at our shop is a misfire in a Ford. They won't throw a code for this type of miss and needs to be looked at via scan data or relative compression. The 40-50 mph range is when it shifts into OD and is most apparent for a miss. WOT is most always normal to not exhibit the miss. Get it looked at.

 

[Mud]

[/quote]

Have it professionally diagnosed before assuming it's the trans. Well over 75% of the "slipping" transmissions we see at our shop is a misfire in a Ford. They won't throw a code for this type of miss and needs to be looked at via scan data or relative compression. The 40-50 mph range is when it shifts into OD and is most apparent for a miss. WOT is most always normal to not exhibit the miss. Get it looked at. [/quote]

Agree, worth a check.

There are no adjustable bands on a 4R70W. The only bands are for OD and reverse, each of which are controlled by servo (accumulator) application. The clutch pack(s) activate and de-activate by a combination of shift solenoids and accumators. The shift solenoids are controlled by the ECM that monitors speed, throttle position, line pressure, etc. The solenoids have small screened orifices that can get clogged a bit over time, this can affect the shift patterns. Accumulators are like small pistons with rubber edge seals moving witin bores - the edge seals can harden with time/miles, causing a bit of luid to leak past, also affecting shifting durations.

The valve body itself can get debris over time, clutch material, stuff like that - the ONLY way to properly clean a valve body is to remove and manually clean, ensuring that all the spool valves move freely. Flushes don't do it because if you understand the operation/flow inside, there is no realistic way for junk to be moved out of it. I suggest that if the misfire does not show up on codes, then consider cleaning the VB and replacing the 2 gaskets used at the VB. There is one gasket where the VB attachs to the case and another that is a cover plate on the VB. Both can deteriorate over time and cause internal leaking, leading to another check - be sure that the VB bolts are tightened to spec - I always use an in/lb torque wrench to avoid warping. There is no screen, but there is a fibrous filter that needs replacement as part of normal maintenance.

I assume that you have changed the filter as part of maintenance and use MerconV fluid, which often helps with converter shudder. You may be experiencing that as part of the issue.

Don't confuse WOT "hard" shifts with valve body separator plate modifications, aftermarket tunes, etc. that result in less overlap between clutch pack applications at all speeds. The factory builds in a specific amount of overlap for comfort. Passenger cars typically have more overlap programmed than trucks. Overlap is the amount of time spent when one clutch pack engages and the prior clutch pack disengages. When you reduce this overlap the shift becomes faster and therefore firmer. Generally good for the tranny life, but can somtimes uncover hidden issues that were masked by the softer overlaps.

 

[SwampSurvivor]

Originally Posted By: Mud
[/quote]


Don't confuse WOT "hard" shifts with valve body separator plate modifications, aftermarket tunes, etc. that result in less overlap between clutch pack applications at all speeds. The factory builds in a specific amount of overlap for comfort. Passenger cars typically have more overlap programmed than trucks. Overlap is the amount of time spent when one clutch pack engages and the prior clutch pack disengages. When you reduce this overlap the shift becomes faster and therefore firmer. Generally good for the tranny life, but can somtimes uncover hidden issues that were masked by the softer overlaps.


That has to be one of the primary reasons the AW-4 in Cherokees lasts for ever. The 1-2 shift will jerk you around pretty good and the 2-3 shift is super firm.

 

[The_Eric]

Originally Posted By: msmoke00
Originally Posted By: Reddy45
lightly accelerating between 40-50 MPH and some slipping is felt when medium accelerating during that range. I can still WOT and it'll downshift for passing.


Have it professionally diagnosed before assuming it's the trans. Well over 75% of the "slipping" transmissions we see at our shop is a misfire in a Ford. They won't throw a code for this type of miss and needs to be looked at via scan data or relative compression. The 40-50 mph range is when it shifts into OD and is most apparent for a miss. WOT is most always normal to not exhibit the miss. Get it looked at.


Agreed.

 

[JHZR2]

I agree that fluid and filter is a reasonable step. But this is one time where DIY may not be the smartest. If the fluid is clean and clear, great. But if it has any indication of filings, junk, sludge, etc., you'll want a trans shop to see first hand to help make an assessment.

 

[Chris142]

transx fixed a slipping 727 Chrysler trans for me 20 yrs ago.

 

[eljefino]

These trannies are known for torque convertor shudder-- IIRC they were among the first for a modulated (half-on) lockup. Throw some fluid and a filter at it.

 

[SZR48207]

Thanks for the replies. Can't believe I forgot to mention the fluid change intervals.

At 36K (out of warranty) I did a pan drop, replace filter, refill with Motorcraft Mercon V...6 quarts or so.

At 75K I figured out how to do a cooler line flush so I exchanged 16 quarts for Castrol Mercon V, replaced filter.

At 150K (about a month ago) I did another cooler line flush with 16 quarts of Kendall Mercon V. Replaced filter. I found some (3-5 pieces) small pepper-flake metal shavings on the magnet. I cut open the old filter but didn't find much debris.

I'm kicking myself for not doing a cooler line flush at 110K but I drove this truck hard from mile 0 to around 45K. Between 50K to present, I was much lighter on the gas except on long stretches of highway.

 

[asand1]

If I had a transmission laying on its deathbed I would drain the atf for a fill of universal tractor fluid. It is said yo have less friction modifiers and slip less.

 

[01rangerxl]

Originally Posted By: msmoke00
Originally Posted By: Reddy45
lightly accelerating between 40-50 MPH and some slipping is felt when medium accelerating during that range. I can still WOT and it'll downshift for passing.


Have it professionally diagnosed before assuming it's the trans. Well over 75% of the "slipping" transmissions we see at our shop is a misfire in a Ford. They won't throw a code for this type of miss and needs to be looked at via scan data or relative compression. The 40-50 mph range is when it shifts into OD and is most apparent for a miss. WOT is most always normal to not exhibit the miss. Get it looked at.


I agree that further diagnosis needs to be done. Usually most any fatal trans issue in a Ford will set transmission specific codes. A lot of engine issues will not set codes, at least not for a while.

A coworker has an Expedition with the 4R70W with a little over 250K miles on it. Last total fluid change is unknown. It started to shudder a while ago...he recently put Lubegard Instant Shudder Fixx in it (2 tubes), and the shuddering almost completely stopped. He took it on a 500+ mile trip (one way, 1K mi + total) after adding the Shudder Fixx, and the Expedition did fine.

 

[artificialist]

My grandma had a slipping transmission on a Chrysler T&C van. I used Lucas transmission additive, and she was able to go for another year before selling then van.... to buy a new T&C van!

 

[hattaresguy]

TransX and baby it, keep your foot out of it and absolutely no towing, hauling, or 4wd!

Usually you can nurse a failing transmission along for awhile.

Firm shifting is actually good for an auto so when you rebuild it you might want to see if their is an aftermarket shift kit to firm the shifts up. Its a truck, so it doesn't have to shift like a Lexus.

 

[zzyzzx]

I would check for codes, and check the TPS, along with all the suggested fluid and filter changes already suggested. I really don't think 150K on a transmission is really that bad, unless you like to WOT. I have around 221K miles on my 1995 Ford Escort's original automatic transmission.