A43D rebuild in progress

[Bodybagger]

I read spungo's thread about the 4 speed automatic (A43D) and limping home when researching the Toyota Motorhome.

Not long ago, I had a little hint that something could be wrong...

It didn't really want to go into 3rd. Then one day, it didn't want to get out of first. I decided to change the really dark fluid and filter and look for other signs of trouble while under there, rather than risk getting stranded in another part of the country.

While I was under it, I noticed a sling pattern of automatic transmission fluid in the plane of the extension housing seal.

So grabbed hold of the U joint and gave it a shove. My heart sank when it wiggled considerably.

I removed the extension housing and measured about .042" of clearance in the bushing. I also noted excessive wiggle in the output shaft.

I decided to bite the bullet and pull the tranny. I have a very nice large place to work. Unfortunately, it was colder than a walk in refrigerator. Temps have been in the single digits at night and the garage never really warms up since it's on the north face of a hill.

Anyway, it looked something like this:

With the tranny off, I set out to find out if the 3 oil sealing rings were the culprit. Unfortunately, the transmission has to be completely disassembled to get to those rings. After getting to them, I found a worn bushing for the output shaft (about .008" clearance). But the bore that the oil rings sit in was in good condition and I found that the rearmost ring was JUST starting to polish into the case. There was only about .001" of wear there.

The rings were still in very good condition.

These rings spring outward and are supposed to hold themselves stationary inside the bore of that tranny. There is a hole for fluid going in and for fluid going out(which gets directed through the shaft to and from the governor, which controls shifting!)

So now that it's apart, it's getting new bushings, seals, clutches, o-rings, and oil sealing rings.

I think the culprit could be the fact that the fluid is getting so hot in this application that it can no longer effectively lubricate the bushings.

To make a long story short, I was lucky I caught this before it ruined the tranny case. I'm REALLY lucky that I addressed it now instead of finding out the hard way this spring.

You may not avoid the extension housing bushing failure and the trouble it bring, but you can fix it without removing the transmission IF you catch it before it wears the case bushing.

I've been hearing good things about synthetic ATF and I can't help but wonder if it would have provided better lubrication under the high temperatures involved. Also, I believe a larger tranny cooler is in order. I'm going to weld a fitting on transmission pan to install a temperature sensor. Per Toyota, ATF will last 100,000 miles if it never gets hotter than 175 degrees Fahrenheit. Every 20 degrees above that cuts its lifespan another half. I have no doubt some of these rigs are seeing 300 degrees.

BTW, huge thanks goes out to spungo for his help and his original post.

Edited March 6, 2009 by Bodybagger

[motoyhomme]

Great post! Always love to see pictures.

Allen

[WME]

If I remember from other transmission posts the rear tailshaft bearing is replaceable, without a new tailshaft.

[Gulfstream Greg]

I have heard great things about redline (not sure that's the correct name) synthetic oil. The oil just can't be killed from what I gather. For those who want to swap whats in there though I also hear you can't get all the old out, so you end up with a partial blend. A mechanic told me that a couple more drain and refill is best but thats a costly procedure. If I remember what he said its because what gets left in the torque converter.

Good luck with the rebuild. And if I had that garage to do my repairs I would not complain about a little cold, try gravel in the rain on a tilt! When I need a floor I pull out the 1 inch plywood.

[Maineah]

There is a bushing kit that is made to repair the governor ring damage to the case if you can feel any thing in the surface you need to put a bushing kit in it. Any good transmission shop should be able to help you out with that mind you they are pretty old now they may have to dust them off. That was a common problem regardless weather of or not it was in a motor home Toyota's Volvo's Jeep's etc..

[FIRSTYODA]

I read spungo's thread about the 4 speed automatic (A43D) and limping home when researching the Toyota Motorhome.

Not long ago, I had a little hint that something could be wrong...

It didn't really want to go into 3rd. Then one day, it didn't want to get out of first. I decided to change the really dark fluid and filter and look for other signs of trouble while under there, rather than risk getting stranded in another part of the country.

While I was under it, I noticed a sling pattern of automatic transmission fluid in the plane of the extension housing seal.

So grabbed hold of the U joint and gave it a shove. My heart sank when it wiggled considerably.

I removed the extension housing and measured about .042" of clearance in the bushing. I also noted excessive wiggle in the output shaft.

I decided to bite the bullet and pull the tranny. I have a very nice large place to work. Unfortunately, it was colder than a walk in refrigerator. Temps have been in the single digits at night and the garage never really warms up since it's on the north face of a hill.

Anyway, it looked something like this:

With the tranny off, I set out to find out if the 3 oil sealing rings were the culprit. Unfortunately, the transmission has to be completely disassembled to get to those rings. After getting to them, I found a worn bushing for the output shaft (about .008" clearance). But the bore that the oil rings sit in was in good condition and I found that the rearmost ring was JUST starting to polish into the case. There was only about .001" of wear there.

The rings were still in very good condition.

These rings spring outward and are supposed to hold themselves stationary inside the bore of that tranny. There is a hole for fluid going in and for fluid going out(which gets directed through the shaft to and from the governor, which controls shifting!)

So now that it's apart, it's getting new bushings, seals, clutches, o-rings, and oil sealing rings.

I think the culprit could be the fact that the fluid is getting so hot in this application that it can no longer effectively lubricate the bushings.

To make a long story short, I was lucky I caught this before it ruined the tranny case. I'm REALLY lucky that I addressed it now instead of finding out the hard way this spring.

You may not avoid the extension housing bushing failure and the trouble it bring, but you can fix it without removing the transmission IF you catch it before it wears the case bushing.

I've been hearing good things about synthetic ATF and I can't help but wonder if it would have provided better lubrication under the high temperatures involved. Also, I believe a larger tranny cooler is in order. I'm going to weld a fitting on transmission pan to install a temperature sensor. Per Toyota, ATF will last 100,000 miles if it never gets hotter than 175 degrees Fahrenheit. Every 20 degrees above that cuts its lifespan another half. I have no doubt some of these rigs are seeing 300 degrees.

BTW, huge thanks goes out to spungo for his help and his original post.