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Is my A43D auto transmission slipping in overdrive?


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I’m new to this forum, but I’ve been reading a lot of the information available here.  It’s very useful and quite extensive.  Until now I’ve been able to answer all of my questions with the available posts, but now I’m stumped.  
The Issue:  I’ve collected RPM/gear/speed data illustrating that gears 1,2,3 are not slipping but OD/4th is slipping up to 15%
My Question:  Is OD (4th) gear slipping because the transmission or torque converter is compromised or is this just the way that the A43D behaves?
My Rig:  ’88 Sunrader on a ’87 Toyota frame, 22RE, A43D transmission, 4.10 gear, 6-lug 1-ton rear axle, 85k miles
Brief vehicle history:  This camper was bought at 22k miles by my dad, handed down to me at 72k miles, now at 82k miles.  I recently had the pleasure of doing a head gasket job after I discovered a very minor coolant leak to the outside.  I took the opportunity to change the timing chain, oil + water pump, and put a new engnbldr head on along with ‘new’stock fuel injectors, a hedman shorty header and new 2.25” open flow exhaust all the way back. The engine is generally running very well and, I think, has generally as much power as a stock 22re is going to get.
My driving habits:  This is my first real experience with trying to understand an auto transmission.  I drove it the last 10k miles with OD on and I’ve been struggling to understand why it is so difficult to wrestle this beast down the road.  I understand now that  if I just treat it as a 3 speed auto trans with OD off that it behaves just fine.  Unfortunately it took me quite a while to figure that out.   Could I have hurt the A43D by pushing it  in OD for 10k miles?
Here is a brief table of data I collected recently after I installed a tach.  (example typical/average data shown, I collected >40 data points):

Gear

RPM

MPH, GPS

MPH, calc.

Grade

%slip

1

3000

22

22

flat

0%

2

3000

36

37

flat

3%

3

3600

63

65

flat

3%

3

3700

63

66

uphill

5%

4

2600

60

68

flat

10-14%

4

2500

56

65

uphill

15%

4

2500

62

65

downhill

5%

How I determined slippage percent:  
I use an online calculator at http://www.grimmjeeper.com/gears.html using the stock gear info for the A43D.  I have 25.5” diameter tires (Thunderer 8-ply) but I measured the actual radius from the ground to the center of the axle and the ‘tire squash' at 65 PSI is ¾” and thus the radius I used to determine speed and RPM in the calculator is based on a 24.75” ‘effective radius’ rather than the 25.5” ‘theory’ radius.  FYI, my speedometer is off by about 4 mph at highway speeds (too high); I’m not sure why.  I used GPS to determine the speed.  I’ll order a compensating gear to correct it unless someone knows why it’s off.
Data summary:  
The transmission works well in gears 1, 2, and 3 where slippage is minimal.  Even up a hill in 3rd the max slippage is only 5%.  However, 4th/OD is a disaster.   The slippage is high (10 to 15% typical) and it “feels” terrible on the road.  No power, no torque.    The data in the table is biased towards higher RPM for gears 1-3, but it performed about the same at RPMs in the range of 2500 to 3000 too.   
In short, everything ‘feels’ fine in gears 1-3, but OD just has zero to give and just don’t see the point of even using it.  Is this normal or is my transmission have ‘issues’ with OD?  I know that 3rd is a 1:1 input:output and 4th is 0.688, but jeez, is the way that the OD is implemented in this transmission really that much of a compromise so that it results in the weak performance I'm experiencing?
Further, I still don’t understand how a 20-ish percent change in the rear gear (going to 4.56 or 4.88) will alter the behavior of 4th/OD so that it suddenly becomes useful.   But since others report that, indeed, the OD does actually become useful with a gear change, I would ask that if anyone can tell me how this is possible I’d be very appreciative.  If my torque converter is the culprit then that would make sense I guess, or perhaps there is a factor I have not even considered…?

 
I have been seriously considering a gear swap to a 4.56 or 4.88 from my stock 4.10 but now I’m really skeptical of that idea based on my transmission behavior.  If I get 15% slippage at, say, 2400 RPM in OD, why would it suddenly behave better at 2800 RPM?  Sure, it could be a little better, but I don’t want to be relying on an OD gear that is behaving so inefficiently.  I’d rather take the approach of convincing myself that I really have a 3 speed automatic and use the OD only for special occasions.


All of my ‘angst’ on this issue is compounded by my (likely groundless) bias towards wanting to run at lower RPMs on the highway.  Maybe if I can just get over it and drive it wound up and forget that OD is even an option (except downhill with a tailwind) then I’ll be just fine and totally ready to roll.  I hear so many people say that the 22re likes to run at high RPM and so maybe my key to happiness is simply accepting that fact and winding her up and letting it go. 


Based on my current limited knowledge on the topic I plan to keep the transmission and gears just like they are and learn to drive in 3rd gear on the highway. I'm open to any corrections in my approach to wrestling the A43D auto down the highway...
 

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Random disconnected thoughts

Yep its slipping, thats why most toy owners NEVER use O/D. The were/are a zillion older Toyota pickups flogging along with just 4 sp trannies  without O/D. Many with 250,000 mi .

So you ain't going to hurt it in 3rd, but in fact your killing it in O/D. All that slip your seeing is being converted in to HEAT. Can you guess what the biggest killer of transmissions is?

Its the load that causes the slippage and your moving a full size barn door through the air at 60 mph and thats a real load. To maintain speed your using a lot of throttle.

By going to a 4.88 or a 4.56 you let the engine rev a little higher and produce the power you need @ a lower throttle setting, putting less strain on everything. Most of the time there is no change in MPG. Yes the engine is turning faster with the rear ratio change but with a lower throttle setting.

What ever you do, you need a larger transmission cooler.

, There is a long techno babble explation of HP vs rpm vs manifold vacuum vs load.

 

 

Edited by WME
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I only drive in third. Never use overdrive even when going down hills. A member of another group did a vacuum check with installed equipment and the vehicle is most efficient in 3rd. I have done a few runs on a long flat stretch of highway and my mileage was always better not using overdrive. Stop using it and you'll be fine for many miles to come. I must add my trannie didn't shift well when I got it. Changed the fluid and added some Lucas trannie stuff and 14 years later it still runs fine. I have change the fluid since then but never needed the Lucas stuff again.

Linda S

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Thanks for the replies.  I didn't have my notification settings set up so I only just now realized that I had a couple of replies (such a newbie).  I think I have it set up to email notification of all replies now.

Both of the comments reinforce the idea that if I simply drive it in 3rd gear then everything will be fine.

I'll do some reading about how to change the transmission fluid and what to replace it with.  Although I abused the auto trans in overdrive for the last ~10k miles, hopefully with some care and attention it should be ok now that I plan to just run in 3rd gear.  It sounds like my transmission is behaving normally and the amount of slip is nothing to be alarmed about.  Clearly the simple fix is to simply not use O/D.  

I have what I believe is the stock transmission cooler - the fluid goes through the engine radiator and then trough the small transmission cooler mounted in front of the radiator.  I've got a mechanical transmission temp gauge that I plan to install in-line in the hose going to the transmission cooler.  I'll monitor my transmission temp this way and plan on an upgrade to the size of the transmission cooler.  I'll try and do some reading to determine if a fluid change at this point is a good idea or if that's overkill.  

I think I'll abandon the idea of changing rear gears for now and just get comfortable using the stock power train in 3rd gear.    

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The external cooler maybe an add on. My 86 did not come with one. I added one and a gauge, things were all good after that.

The stock transmission pan does not have a drain plug. I just used a vacuum extractor and pulled a couple qts every oil change. That way I was adding fresh additives all the time. I had to flush the transmission when I got the Toy as the fluid looked like mocha, after that it stayed good. After 5 years the fluid looked pristine.

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I can't tell if the cooler was an add-on or stock - maybe added by Sunrader?  Once I get my temp gauge installed I'll have a better idea of what the temp is and if it seems remotely high I'll increase the size of the cooler.

I do have a drain plug shown in the attached image.  

FYI, mine is labeled Asin-Warner Model 03-71 35333, serial 87EF 041745.

My fluid is nice and clean (red, don't know specifically what is in there).  I noticed that my fluid level is _very_ high when level with engine cold.  Level shows way above the hot level (in the middle of the 'Dextron II' label on the dipstick).  This can't be right.  I'll check it again later after I've done the procedure pasted below; however, if things are clearly wrong here feel free to let me know.

-------------------------- Transmission level check procedure I found:

1. Drive the vehicle to get everything up to operating temperature.

2. Park the vehicle on a level area.

3. Shift the vehicle through drive and reverse letting the tranny fully engage in drive and reverse. Remember to put it in park before you get out.

4. Leave the engine runniing.

5. Pull the tranny dip stick out and wipe it off.

6. Push the dip stick all the way in so that it is fully seated.

7. Pull the dip stick out and check the level.

If you don't bring it up to temp, don't shift through the gears, don't park on the level, or otherwise skip any of those steps, you will not get a good idea of what your fluid level is.

Capture1.JPG

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By all means use the procedure you posted

BTW to much fluid is almost as bad as not enough

 

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On ‎3‎/‎26‎/‎2017 at 8:15 AM, WME said:

The external cooler maybe an add on. My 86 did not come with one. I added one and a gauge, things were all good after that.

The stock transmission pan does not have a drain plug. I just used a vacuum extractor and pulled a couple qts every oil change. That way I was adding fresh additives all the time. I had to flush the transmission when I got the Toy as the fluid looked like mocha, after that it stayed good. After 5 years the fluid looked pristine.

My stock 86 transmission pan has a drain plug.

Linda S

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I have a 6 cylinder.  about every 10k miles, I drain the tranny pan (about 2 quarts) & replace. Even though this is only about 1/5 of the tranny fluid, I feel it is a workable procedure.   When I was at 50k, I did this procedure repeatedly (with driving between drains) until I used 3 gallons.  Every subsequent change was removing less and less old fluid and more of the new, but I would not do a "flush". The other alternative was to remove a cooler hose and let the fluid pump out (of there) and try to add equal amounts "real time" ( with engine running).  T 50K I did drop the pan and changed the filter too.

 

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Why not do a flush? My 85 also has a drain plug.

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3 hours ago, markwilliam1 said:

Why not do a flush? My 85 also has a drain plug.

If the fluid has changed every 30K (as it should be in an over taxed trans) that's no issue but usually people think that "well it's never been changed" in 80,000 miles lets do a flush that's when the trouble begins.  

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On 3/26/2017 at 11:55 AM, AtlantaCamper said:

I can't tell if the cooler was an add-on or stock - maybe added by Sunrader?  Once I get my temp gauge installed I'll have a better idea of what the temp is and if it seems remotely high I'll increase the size of the cooler.

I do have a drain plug shown in the attached image.  

FYI, mine is labeled Asin-Warner Model 03-71 35333, serial 87EF 041745.

My fluid is nice and clean (red, don't know specifically what is in there).  I noticed that my fluid level is _very_ high when level with engine cold.  Level shows way above the hot level (in the middle of the 'Dextron II' label on the dipstick).  This can't be right.  I'll check it again later after I've done the procedure pasted below; however, if things are clearly wrong here feel free to let me know.

-------------------------- Transmission level check procedure I found:

1. Drive the vehicle to get everything up to operating temperature.

2. Park the vehicle on a level area.

3. Shift the vehicle through drive and reverse letting the tranny fully engage in drive and reverse. Remember to put it in park before you get out.

4. Leave the engine runniing.

5. Pull the tranny dip stick out and wipe it off.

6. Push the dip stick all the way in so that it is fully seated.

7. Pull the dip stick out and check the level.

If you don't bring it up to temp, don't shift through the gears, don't park on the level, or otherwise skip any of those steps, you will not get a good idea of what your fluid level is.

Capture1.JPG

Simply answer read the low side of the stick that is the most accurate.

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On 3/21/2017 at 8:49 PM, AtlantaCamper said:

I’m new to this forum, but I’ve been reading a lot of the information available here.  It’s very useful and quite extensive.  Until now I’ve been able to answer all of my questions with the available posts, but now I’m stumped.  
The Issue:  I’ve collected RPM/gear/speed data illustrating that gears 1,2,3 are not slipping but OD/4th is slipping up to 15%
My Question:  Is OD (4th) gear slipping because the transmission or torque converter is compromised or is this just the way that the A43D behaves?
My Rig:  ’88 Sunrader on a ’87 Toyota frame, 22RE, A43D transmission, 4.10 gear, 6-lug 1-ton rear axle, 85k miles
Brief vehicle history:  This camper was bought at 22k miles by my dad, handed down to me at 72k miles, now at 82k miles.  I recently had the pleasure of doing a head gasket job after I discovered a very minor coolant leak to the outside.  I took the opportunity to change the timing chain, oil + water pump, and put a new engnbldr head on along with ‘new’stock fuel injectors, a hedman shorty header and new 2.25” open flow exhaust all the way back. The engine is generally running very well and, I think, has generally as much power as a stock 22re is going to get.
My driving habits:  This is my first real experience with trying to understand an auto transmission.  I drove it the last 10k miles with OD on and I’ve been struggling to understand why it is so difficult to wrestle this beast down the road.  I understand now that  if I just treat it as a 3 speed auto trans with OD off that it behaves just fine.  Unfortunately it took me quite a while to figure that out.   Could I have hurt the A43D by pushing it  in OD for 10k miles?
Here is a brief table of data I collected recently after I installed a tach.  (example typical/average data shown, I collected >40 data points):

Gear

RPM

MPH, GPS

MPH, calc.

Grade

%slip

1

3000

22

22

flat

0%

2

3000

36

37

flat

3%

3

3600

63

65

flat

3%

3

3700

63

66

uphill

5%

4

2600

60

68

flat

10-14%

4

2500

56

65

uphill

15%

4

2500

62

65

downhill

5%

How I determined slippage percent:  
I use an online calculator at http://www.grimmjeeper.com/gears.html using the stock gear info for the A43D.  I have 25.5” diameter tires (Thunderer 8-ply) but I measured the actual radius from the ground to the center of the axle and the ‘tire squash' at 65 PSI is ¾” and thus the radius I used to determine speed and RPM in the calculator is based on a 24.75” ‘effective radius’ rather than the 25.5” ‘theory’ radius.  FYI, my speedometer is off by about 4 mph at highway speeds (too high); I’m not sure why.  I used GPS to determine the speed.  I’ll order a compensating gear to correct it unless someone knows why it’s off.
Data summary:  
The transmission works well in gears 1, 2, and 3 where slippage is minimal.  Even up a hill in 3rd the max slippage is only 5%.  However, 4th/OD is a disaster.   The slippage is high (10 to 15% typical) and it “feels” terrible on the road.  No power, no torque.    The data in the table is biased towards higher RPM for gears 1-3, but it performed about the same at RPMs in the range of 2500 to 3000 too.   
In short, everything ‘feels’ fine in gears 1-3, but OD just has zero to give and just don’t see the point of even using it.  Is this normal or is my transmission have ‘issues’ with OD?  I know that 3rd is a 1:1 input:output and 4th is 0.688, but jeez, is the way that the OD is implemented in this transmission really that much of a compromise so that it results in the weak performance I'm experiencing?
Further, I still don’t understand how a 20-ish percent change in the rear gear (going to 4.56 or 4.88) will alter the behavior of 4th/OD so that it suddenly becomes useful.   But since others report that, indeed, the OD does actually become useful with a gear change, I would ask that if anyone can tell me how this is possible I’d be very appreciative.  If my torque converter is the culprit then that would make sense I guess, or perhaps there is a factor I have not even considered…?

 
I have been seriously considering a gear swap to a 4.56 or 4.88 from my stock 4.10 but now I’m really skeptical of that idea based on my transmission behavior.  If I get 15% slippage at, say, 2400 RPM in OD, why would it suddenly behave better at 2800 RPM?  Sure, it could be a little better, but I don’t want to be relying on an OD gear that is behaving so inefficiently.  I’d rather take the approach of convincing myself that I really have a 3 speed automatic and use the OD only for special occasions.


All of my ‘angst’ on this issue is compounded by my (likely groundless) bias towards wanting to run at lower RPMs on the highway.  Maybe if I can just get over it and drive it wound up and forget that OD is even an option (except downhill with a tailwind) then I’ll be just fine and totally ready to roll.  I hear so many people say that the 22re likes to run at high RPM and so maybe my key to happiness is simply accepting that fact and winding her up and letting it go. 


Based on my current limited knowledge on the topic I plan to keep the transmission and gears just like they are and learn to drive in 3rd gear on the highway. I'm open to any corrections in my approach to wrestling the A43D auto down the highway...
 

There is a huge difference between converter slip and clutch slip. The trans will shift down when it needs to but prolonged use of OD can cause over heated trans fluid if you don't manually shift out when it's struggling. Brown trans fluid is a bad thing.

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Since you seem confident you have heated fluid I'd change it. Cheap insurance.

It's my understanding that today's Toyo trans fluid spec is 100% synthetic. Synthetic offers superior resistance to heat degradation. I believe I used Valvoline Import Trans fluid that showed it met Toyota spec purchased at Walmart. Price was reasonable. This was for my car. My RV is manual.

The newer Toyo cars use a fine mesh screen filter. Not sure what the 87 has. If you got red fluid I think you could pass on filter change.  

When will I85 bridge repair be completed?  

Edited by vrocrider
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I've had my rig 1 year. Imagine my stupidity when I just found out I've had her in OD the entire time! The OD light on the dash was not illuminated so I figured it was disabled. Was so concerned about no power and manually down shifting to 2nd all the time. So I finally pushed the OD button and the OD light lit up saying OFF. What a difference! Feel like I'm turbo charged now. I see why nobody recommends driving in OD with the 22RE!

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  • 5 months later...

A quick question for all of you. My friend has an 86 Dolphin, 22re with A43D auto tranny. His tranny shifts all the way into Overdrive with no problem, but when pushing the overdrive button on the shifter on the steering wheel column to kick the tranny down to 3rd for instance, nothing happens. The tranny just stays in overdrive. So the button on the shifter is useless. Do you think this is a possible fuse issue, overdrive solenoid issue, or something going on with the overdrive button itself. If I remember correctly, no overdrive light ever comes on or off neither. 

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If you drive the toy home like you would drive a stick shift (turn off the OD) on hills or if it shift up and down you can still use it without issues. The trans is pretty tough but like anything heavy it is important to add a cooler, and change the fluid (30K at least) it applies to any MH. If it has high miles and never been changed drive it until it starts to have issues putting new fluid in a high mileage trans will have you walking in short order. I have seen these things with over a 100 grand going along just fine with virtually no problems. As far as OD use what's worse shortened engine life or transmission life?  You can probably guess I use OD in mine and it's still on the road.

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Tranny shifts through all gears just fine. Just when pushing the OD button on the shifter nothing happens. Meaning, pushing the button, the OD will not disengage. The tranny is obviously engaged to shift into overdrive when needed, just no way to take it out of overdrive and keep it out of overdrive via the button on the shifter. So I assume the button is not working correctly? Any thoughts? 

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Hey Maineah is your rig a 4 banger? I also use OD on occasion. I just had my tranny completely flushed, new gasket, filter and filled with Dextron 4 all synthetic. The supervisor @ the transmission shop (familiar with Toyota RV) recommended a complete flush and fill every 20K due to the strain on the tranny for the 4 cylinder. Expensive but I think I'll follow his advise!

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3 hours ago, markwilliam1 said:

Hey Maineah is your rig a 4 banger? I also use OD on occasion. I just had my tranny completely flushed, new gasket, filter and filled with Dextron 4 all synthetic. The supervisor @ the transmission shop (familiar with Toyota RV) recommended a complete flush and fill every 20K due to the strain on the tranny for the 4 cylinder. Expensive but I think I'll follow his advise!

Yes mine was a 4. I am not a fan of syn oils but I do agree with syn trans fluid it does stand heat better. 20K maybe be a bit excessive but it won't hurt a thing. The 4 cyl does not have a lockup converter but people who own a 6 may not know that when there is a bit of strain on the trans the first thing that happens it goes out of lockup a good bit before it downshifts to 3rd and now is just like a 4 cylinder so regular trans service is just as important.

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