As I said you can just change the shaft although I would drain it and pull the pan then remove the transfer case and check the pump. You need to disassemble the pump anyway and and look for scoring inside. I generally don't just reassemble the without I installing new clutches and bands while I'm in there.

 

They are an easy transmission to work on, similar to a Ford C4 reversed. I think Rockauto still has most of the parts for them.

Oh, yes, I don't want to try to run it without finding all those pieces of spline that have to be somewhere.  There was nothing in the pan except clean ATF.  I also figure, if I'm opening it up, I should check stuff like bands, clutches, seals.  No point doing all the work and having some other stupid small thing kill it again.

I picked up a used 3AT. Pulled the pump drive shaft out. The splines are worn a bit on the shaft. I have to try to see what the splines on the pump look like. I have another pump drive shaft from another 3AT that shows no wear. This also makes me want to know what / how these wear. It's a spline in oil, there shouldn't be any sliding to wear them.

Interesting.  If you were in Oz I've got a 3spd auto that's flogged the front diff that you could have for parts - it's just taking up space in Dad's driveway.

My sister tells me that having the front diff lock up at 80km/h isn't fun, can't imagine why!

Glad you've got a grip on these gearboxes, we swapped ours out for a manual.  Getting way better fuel economy now!

Cheers

Bennie

I have found that with a well maintained trans in my Brat I get 29-30 mpg highway and 25 in town. It didn't change when I changed engines to an 1.8 ea82 SPFI but I tend to stay on top of tuneups.

Yeah, getting the parts would be cool.  I'm afraid the shipping would be unreal!

 

Interesting.  If you were in Oz I've got a 3spd auto that's flogged the front diff that you could have for parts - it's just taking up space in Dad's driveway.

a T1 LED on long solid wires

 

 

 

Looking at the pump splines.

 

 

I can't get a good picture.  I looked into 3 of them.  The stripped one, the one with no noticeable wear, and the intermediate one.  Going by the wear on the splines on the pump drive shaft.  I can't see clearly enough to tell if the splines on the pump are any different.

Right now, I am leaning toward installing the intermediately worn one so I can take the time to disassemble the others and do a good rebuild.

 

I also have a 3AT with no reverse that won't go into 3rd, a 2WD only, and one with a dead differential, but the rest of it is good.

While I  remove the no reverse no 3rd from the car, I'll think about the options...  Any thoughts from here considered also.

If it was me I'd put the diff off of the no reverse trans on the one with the bad diff with the shaft that has intermediate wear. I've pulled the trans changed it over and reinstalled in the car in a little over 4 hours. Hardest thing is saving the gasket between the trans and the diff.

I realize the gaskets for the governor housing arent stocked at autozone but I would pull the governor and check the drive gears for signs of excess wear as well.

As long as you have it out and easy to reach be sure and adjust the 2-3 band. It's easier to get to on the bench but not terribly hard in the car.

I managed to get to the storage trailer and check another 2 3ATs. Both have worn pump drive splines. Seems to be a common weak point. It really makes me wonder what is going on in there. Splines shouldn't wear.

I would assume that with the length of the shaft and the amount of fore and aft slop built into it, it is because of movement. I would imagine that there is some flex as well, which would actually shorten the shaft minutely each time it is used as well as lengthening when it is shut off.

It is odd though - only the pump end gets the wear. The torque converter end is like new. There is nothing mechanical that holds the shaft toward one end or the other. I suppose oil pressure might.

Dave something has occured to me. Ive been working on an engine with a slight ammount of thrust play. I guess you couldnt check easily for this now, but say your mains were worn in this way and causing the crank and thus the converter to move fore and aft and slam the shaft into the pump? Also ill have to check the parts break down but there is some sort of bushings or bearings for the shafts. They are so long there has to be. Inpust shaft play could mess this all up.

From what I can see so far, the pump shaft just goes into the pump spline.  The only thing other than the splines at each end is a seal [Could be a seal, or maybe just a spacer to make it possible to slip the torque converter on. ] near the torque converter end. 

 

I've looked at the pump shafts in 5 3ATs at this point.  Mileage range from a bit under 100,000 to a bit over 200,000.  Only my 86 has no significant wear.  It has a different gear ratio on the final drive and diff.  I doubt that is related.  It's not that different, just different enough to make a car feel logy and slow compared to the other ones.  That one, I'll keep everything together, and investigate changing the final drive and diff to make it compatible with my others.

Started dis-assembly of the 1990 3AT.   So far, the only thing that looks wrong is the stripped spline on the pump drive shaft.  Even the spline on the pump looks good.  This thing has over 200,000 miles on it, I've driven it since it had 15,000 miles. 

Have you actually disassembled the pump and checked for scoring on the faces?

There is a little wear in that you can tell it has been turning, but not what I think of as scoring. I'll see if I can get a decent picture.

I found out why the 1993 transmission lost reverse and 3rd.  The release servo tube fell out, and was sitting in the pan.  Checked the flow diagrams in the FSM, yep, that would do it.  I could have fixed that on the car, BUT I would not have found the pump shaft spline wear.

 

Seems to me there should be a little clamp / clip to hold those tubes in place.  There's a bolt right near each of them anyway...

Per fsm these tubes are NOT reusable. Unfortunately they arent readily available

Edited April 20, 201510 yr by ihscout54

Here is a picture of the pump from the 1990 3AT

I have now removed the transfer section and oil pump from 2 of my 3ATs.  Removed most of the gears and clutches from a 3rd.  Except for the stupid oil pump drive shaft input splines, so far, nothing else looks bad.  Hard to believe all of these have 150,000 to over 200,000 miles on them.

3AT parts from a dealer.  I just ordered 3 pump drive shafts.  There are still a handfull available.  Also, I ordered a seal kit, there are still some of those available also.  Also, some gaskets.  They are getting low too.  When they do a stock search, it searches the US.  

What did the shafts run?

They were about $89.