[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [New Search]

Auto tranny drivers, learn from my mistakes.


Hey all,

Well, Betty's back on the road and her new motor (my first build!) is breaking in nicely.  Y'all might recall a recent dismal post of mine in which I mentioned that I got everything back together, but my otherwise fine working auto tranny had no drive in any gear.
I figured out the problem, i.e. I broke it.  Let me describe what happened, if any of you are in a similar situation perhaps you can avoid a bonehead mistake.
As you may or may not know there is a long skinny shaft to drive the ATF pump deep inside the front of the transmission.  This shaft is splined on both ends, one end fits in a drive socket in the pump, and the other end fits in a socket in the torque converter.  If you've ever pulled the motor on an automatic, the tourque converter will try to come off with the engine, unless you work to keep them separate.  Mine had come off about halfway as the motor pulled off.  It's done it in the past, and all I did before was re-fit the TC per the Bentley and it was fine, so I thought nothing about it.  This time the ATF pump shaft pulled out with it.  The Bentley sez it's removeable, so I re-inserted it to where I *thought* it was ok.  My problem was that the pump-end of the shaft wasn't inserted correctly, but was actually resting on the lip of the socket.  Even with the shaft seated uncorrectly, the torque converter installed and seated on the drive shafts in a way that appeared normal.  I forgot all about it while I spent the next few weeks cleaning and painting.
Later, in a neglectful anticipitory rush, I installed the new motor and got it running.  I didn't check that the tranny was driving at first.  I was more concerned with dialing in the carbs and timing on my new motor, so it was run at various RPMs (2000 or less) for about 20 minutes before I tried putting the tranny in drive to check it.
What happened was when the motor mated to the tranny, the ATF shaft was pressed against the lip of it's socket, and broke it.  OUCH!  I pulled it all back apart and looked down the shaft with a strong light in time to see it fall off.  Fortunately, I have a spare tranny.
Here's what I learned from all this.  To avoid the torque converter coming off with the motor I used to pry between it and the flex plate with a screwdriver.  I discovered that if you place a socket, like a 17 or 19mm on top of the TC so it rests between the external cooling vanes and the bellhousing it will hold the TC while the engine comes out.  Most of the time I do my work alone, and this is way easier than trying to pry and pull at the same time.  If it does all come apart on you, don't panic, but keep everything you exposed remorslessy clean till you put it all back together.
To tell if your ATF pump drive shaft is installed correctly, install it to where you think it's correct and check it two ways:  Turn it.  It should turn smoothly with some resistance.  Some wobble is normal, but it shouldn't spin too freely, roughly, or bind at all.  Measure it, the visible end of the shaft should only protrude about half of it's splined surface or less from it's hole.  If it passes the turning test but looks too far out to you, tap it gently but firmly with a soft wood block.  My second shaft was like this, a gentle tap got it in all the way.  Re-seat the torque converter by turning it back and forth slightly so it seats up.  It'll clunk and seat, but keep turning and it'll clunk and seat again as the ATF shaft mates with it's socket.  It should turn freely.  Watch everything when putting the motor in.  The motor should not press on the TC as it goes in, but rather just meet it when it's fully mated against the bell-housing.  If they meet up any sooner STOP, pull the motor back out and recheck everything.  Take your time and triple check as you go.  When it's all back together and running, check that the tranny has drive asap.  If you have no drive, stop immediately, pull the motor and inspect everything.  It might not be too late.  If you've r&r'd the tranny, check that the shift cable is installed on it's clamp correctly first.
Despite my experiences, I still love the auto type 3 tranny.  It's simple, durable and efficient, and great to drive in an urban battleground.  VW got it right when they built these babies. 

Best to all, 
Curt
70  SB, auto and proud of it
66, 75, and 77 busses


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [New Search]