Lost drive to front wheels

[tercle]

I am amazed it still can get from Point A to Point B after a catastrophic failure like I experienced Friday.
I feel like I am OK if I just run it into the ground/an explosion.
But it would be incredible if I could fix it and keep the Poor Man's 4x4 driving.

I am guessing the gasket for the front diff cover is a Dealer-only item?

[Petros]

you can probably use Permeate Form-a-gasket without issues (I have done it lots of times). I would be surprised if the dealer can get any parts for the trans on a car this old. when I check for the manual trans they told me the only parts they show for the manual transmission in the whole country was the second gear sycro.

[Mark]

Hmmm. Seems like it's sort-of in the way.
Do you remember what tools you used to get the cover bolts off?
If I could get the cover off and maybe one axle out and inspect it next weekend, maybe I could figure if I can do it.
It's my only daily driver now.
I put 185 miles on it today.
So far, so good.

I think I just used a 10 or 12mm socket. Maybe a 14mm? I can't remember. I assume you don't have some kind of aftermarket differential cover.
I drove mine in RWD for about a month or so. I read somewhere on this forum about someone who drove it for years in RWD. My issue was that I was paranoid with 100% of the torque going through the rear output shaft to the rear differential. Usually it only has about 50% of the torque. I wasn't sure if it could handle the same torque as the front output shaft and differential over the long term. There was probably no reason to think this way. I was just paranoid about driving the car in a configuration that it wasn't designed for.

[Mark]

I am amazed it still can get from Point A to Point B after a catastrophic failure like I experienced Friday.
I feel like I am OK if I just run it into the ground/an explosion.
But it would be incredible if I could fix it and keep the Poor Man's 4x4 driving.

I am guessing the gasket for the front diff cover is a Dealer-only item?

I ended up having to order the differential cover gasket online and wait for it to show up. Like many gaskets (water pump, thermostat, etc.), It really isn't much more than paper. The Toyota dealer up here won't have anything to do with cars this old. They just have generic parts like drain plug gaskets. You could always get a sheet of gasket material at an auto parts store and cut your own gasket using the diff cover as a template. You could just use scissors and cut it like the paper that it is. You'd need a hole punch to do the bolt holes neatly.

[tercle]

I think I will make a paper gasket so that I will be able to take it apart again.
If a decent pickup with a shell or other vehicle shows up, I might just bail.
But I would hate to abandon my parts and vast accumulated knowledge about Tercels.

[dlb]

you could always just use a liquid gasket or sealant. i usually prefer that to paper gaskets.

[tercle]

Another by the way... If you can drive fine in RWD, the transmission itself (up until the output shaft (and governor valve body) going into the front differential) is probably fine. If it's shifting ok then the governor valve body is spinning with the transmission as it should (the governor valve uses the centrifugal force of the "spinning" to open or close the valve which controls fluid pressure I think). This means that the stripped splines are on the OUTPUT side of the governor valve body. This is preventing the torque from the transmission from going to the front differential. Of course it could be the splines on the input shaft to the front differential. I couldn't find a decent picture so I drew one up to show what I'm talking about. The Governor Valve Body is a pretty small part. It fits in the palm of your hand with room to spare.

So, what is the procedure for removing it?
Does it have a seal that needs replacing too?

[tercle]

The differential is part of the bell housing and it can't be removed from the transmission unless the whole assembly, including the transmission is first removed from the car. If you've gone that far and removed the differential from the transmission, it would be easier to just replace the governor valve body (which is easily accessible), than worry about replacing the whole differential and worrying about gear ratios. Of course this is assuming that the problem is the governor valve body. Finding a replacement governor valve body isn't as easy at it sounds either. They're not available through Toyota anymore (they told me that when it was available it was about $400). I ended up buying an old 2WD transmission from a local transmission repair shop for $75 and using the governor from that.

I think I see this on page AT-76 of the 85 service manual.
But it looks like removing that differential cover does not allow me to inspect it.
The triangle on the left points to where the governor valve body is and the other triangle points where the differential cover is.
What do you call that shaft that goes through the splines of the Governor Body Support?
Can that thing be withdrawn from the differential cover side, so that both ends can be inspected?

[Mark]

From what I remember there is no seal on the governor valve body itself. I think it's easier to remove if you pull it off the shaft along with the governor pressure adapter which is held on with 2 or 3 bolts. The adapter is sealed with a flat gasket.

governor.jpg

That's the easy part. First you have to remove the transmission and differential assembly from the car. The factory service manual on this site has step-by-step instructions on how to do this. Removing all the linkages, brackets and exhaust components was more difficult than removing the trans itself I found. Once the transmission is out you have to separate the transmission from the differential bell housing. These are sealed together by a flat gasket.

trans.jpg

Once this is done, the governor valve body is visible and easy to remove and replace (assuming that's the problem). It's too bad I didn't take any pictures when I did it, but my hands were filthy and I assumed no one else would have the same problem especially since most people have standards.

[Mark]

Why I suggested removing the differential cover was not to inspect the governor valve body (which as you said isn't visible from that end), but to have a look at the gearing in the differential to rule out any visible problems in there before going to the trouble of removing the entire transmission. The shaft that goes through the splines in the governor valve body is officially called the differential "drive pinion", but I call it the differential input shaft. You can't pull it out through the differential cover unless you remove most of the other internal differential components first. If you did this they would be a nightmare to put back in properly and adjust the backlash and clearances, etc.
If you do decide to remove and disassemble the transmission it would be a good idea to have a gasket kit ready in case you end up wrecking any seals or gaskets. I bought mine off E-bay for about $60. Here's a site that has some listed, but I don't know if they're actually available:http://cobratransmission.com/index.php? ... _1286_1287

[tercle]

thanks.
Really excellent information.

[tercle]

The ring gear teeth are very chewed up - chewed up by fragments of the pinion gear.

I can see that the pinion shaft is not turning when the ring gear turns.
So some of the teeth are broken off the pinion.

http://tinypic.com/view.php?pic=6z3nr7&s=5

[Petros]

looks like the ring and pinion gear set got trashed. I have seen it, but not that common. looks like you will be in the market for a new front diff assembly. If you can find the whole front diff/bell housing assembly that would be the best bet, you just swap them out. The Mark may have one that might work for you (not sure if the 2wd auto and the 4wd auto trans is the same diff ratio), presuming what failed in his trans is still good in yours.

[tercle]

It seemed to me that the rpm at freeway speeds is higher on the 4WD automatic than the 2WD automatic.
Hopefully, I am wrong.

[tercle]

The tool needed to get the top diff cover bolt off is a 12mm offset box wrench.
I don't have one...
All the others are accessed easily with a regular 12mm box wrench and/or socket.

I tried everything else.
Removed the passenger-side stiffener plate.
I ended up using a 12mm 1/4 drive socket - to universal joint at almost a 90 degree angle - and ratchet to move it a little.
Once I broke it free, I finished with my fingers.

A 12mm offset across the cover from below would have saved me a lot of time, and wouldn't have required removing the stiffener plate.