Lost drive to front wheels

[Petros]

you would have to pull the trans to replace the coupling. you have to separate the diff/bell housing from the front of the trans, and it exposes the damage input shaft coupling. No further dis-assembly is required. it is well worth doing if you can find the replacement part, it is no worse than replacing a clutch on a manual trans car.

too bad, it seems these couplings in the auto trans cars are vulnerable to eventual failure. I do not know if the manual trans coupling is the same (I do not think it is because I do not think I have heard of these failing in a manual trans car). If it is the same, I have a spare front diff assembly from a manual trans tercel, if you can use the parts you are welcome to it.

[Mark]

You should be able to remove the front diff cover to inspect the insides of the diff without removing anything else. I have an '84 auto and it was no problem. The cross member wasn't in the way. It's probably worth having a look inside just to rule out anything obvious in the differential. I still suspect that it's the governor valve body "coupling" though. If you do remove the front diff cover, try to have a replacement gasket ready since the old one often comes off in pieces.
As Petros said, to get at the governor valve body, you have to drop the transmission and separate the trans from the differential "bell housing". If you have access to a lift, it wouldn't be such a painful job.

[tercle]

By the way, you should be able to drive it around in RWD if you want. I did that for about a month before I bought a 2wd hatchback as a replacement while I fixed the 4wd wagon. I'm surprised you have noise when driving in RWD. On mine, the torque all went to the rear differential and there was no noise from the trans. When I took it out of 4WD, there was a nasty grinding noise.

I got it back together and drove around the block with the 4WD button depressed.
There is a scraping or metallic rubbing noise from the right front.
Not real loud like the worse FWD noises.
I can get used to it, like road and other noises before it.

[Mark]

That noise almost makes me think that it is a problem in the diff. When you had the drive axles out did you have a look in the holes in the diff and see if the splines were ok? Especially the right one? Maybe it's stripped.

[tercle]

Not really.
I felt around with my finger and could see some of the splines.

[tercle]

you would have to pull the trans to replace the coupling. you have to separate the diff/bell housing from the front of the trans, and it exposes the damage input shaft coupling. No further dis-assembly is required. it is well worth doing if you can find the replacement part, it is no worse than replacing a clutch on a manual trans car.

too bad, it seems these couplings in the auto trans cars are vulnerable to eventual failure. I do not know if the manual trans coupling is the same (I do not think it is because I do not think I have heard of these failing in a manual trans car). If it is the same, I have a spare front diff assembly from a manual trans tercel, if you can use the parts you are welcome to it.

Thanks.
I wonder how hard it is to just replace the differential.
I wonder if the manual and automatic differentials are the same.
I wonder if a 2wd automatic diff and 4wd automatic diff are the same.
They use different speedometer gears.

Without knowing how extensive the damage is, it seems like swapping in another differential would be the fool-proof repair.
But the gear ratios of the front and rear differentials have to match (I think) and the 21-tooth speedometer gear indicates that it has ratio specific to automatic 4x4s.

[rer233]

Wow-sux to be you. you could swap in the 2WD trans and have a fwd wagon or i know someone who has an auto 4wd transaxle... Damn shame you're on the other side of the country!

Rich.

[tercle]

Wow-sux to be you. you could swap in the 2WD trans and have a fwd wagon or i know someone who has an auto 4wd transaxle... Damn shame you're on the other side of the country!

Rich.

Actually, it sux even worse.
I had 3 wagons parked on the street a couple months ago, but got rid of the other two to make neighbors happy.
Few weeks ago, I pulled the good motor out of the standard trans 2WD (that just needed a new transmission) and was planning to plug it into my automatic 4WD.
Had the 2WD towed away by wrecker last weekend.

Just got a new windshield (free, because someone broke it) - so this is the first Tercel Wagon with a perfect windshield I've ever had.

[Mark]

Thanks.
I wonder how hard it is to just replace the differential.
I wonder if the manual and automatic differentials are the same.
I wonder if a 2wd automatic diff and 4wd automatic diff are the same.
They use different speedometer gears.

Without knowing how extensive the damage is, it seems like swapping in another differential would be the fool-proof repair.
But the gear ratios of the front and rear differentials have to match (I think) and the 21-tooth speedometer gear indicates that it has ratio specific to automatic 4x4s.

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.

[Mark]

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.

[tercle]

That governor valve body is common to just automatic transmission (like the one I recently gave away? arghhh!) Tercels?
Or is it the same on standard transmission 2wd and 4wd vehicles?

I was thinking of renting a cherry picker and swapping in a better engine.
I could pull the engine and transmission as a unit instead.

Oh, wait.
You're saying the governor valve body is probably OK?

[tercel4wdrules]

But the gear ratios of the front and rear differentials have to match (I think) and the 21-tooth speedometer gear indicates that it has ratio specific to automatic 4x4s.

For 1985 and later they came with 3.909 final drive.

[Mark]

That governor valve body is common to just automatic transmission (like the one I recently gave away? arghhh!) Tercels?
Or is it the same on standard transmission 2wd and 4wd vehicles?



Oh, wait.
You're saying the governor valve body is probably OK?

The governor is only in automatics. The governor valve body is like a sleeve with internal input and output splines. The input splines from the transmission are probably fine and the governor valve body is spinning with the transmission like it should. The governor valve body's output splines (where it connects to the differential) are probably stripped. So yes the centrifugal valve in the governor is fine, but the output splines in the valve body are likely stripped so the whole governor valve body is now no good and has to be replaced.

[Petros]

based on the pictures that Mark posted, there is nothing equivalent to that in the manual trans cars. first thing is to get the trans out and the front bellhousing/diff assembly removed and have a look at it. You will have to find another one if that is the issue.

[tercle]

You should be able to remove the front diff cover to inspect the insides of the diff without removing anything else. I have an '84 auto and it was no problem. The cross member wasn't in the way. It's probably worth having a look inside just to rule out anything obvious in the differential. I still suspect that it's the governor valve body "coupling" though. If you do remove the front diff cover, try to have a replacement gasket ready since the old one often comes off in pieces.
As Petros said, to get at the governor valve body, you have to drop the transmission and separate the trans from the differential "bell housing". If you have access to a lift, it wouldn't be such a painful job.

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.