Automatic Transmissions ?'s

[Steven242]

Alright, if any of you read my last post about the strange vibrations coming from the car right around the first/second gear at low rpm/light throttle... I have a theory to throw at ya'll.

I've been reading up on automatic transmissions and their workings. Seems there is a lot to them, but they are pretty straight forward when it comes to why they shift, pressure from the ATF routed thru the valve body.

Well, I'm thinking I burnt up the clutch material in my lock up torque converter, or fried my stator to a point at light throttle it is having a hard time locking the torque converter.

Reason I'm leaning towards the TC is if it was the clutch packs or steel rings inside the trans that change gears, it would slip, not shake, because those spin different ways depending on how they are locking/unlocking. The TC spins one way, and one way only, the direction of the engine. And it has developed a new symptom too. When accelerating there seems to be a slight shudder/shimmy/shake (what ever you want to call it) at the engine speed and forward speed that the Torque Converter should be locking up.

If any of you think I may be on to something with this theory of me frying my TC, please let me know if you agree or disagree, and where I can find just the torque converter. I've found several sites that do Rebuild trans w/torque converter, but non that offer the converter seperate...

Here is a Link to a site that has a write up of how to diagnose AT problems. http://www.babcox.com/editorial/bf/bf90222.htm
At the end you will notice them using the term lock up shudder. This site along with many other's I've searched is what I'm basing my issues on.

Thanks for your time,
Steven

[billofdurham]

In my reply to your earlier post I did say:

It may, and I stress may as I am not certain, have a lock up torque converter which does give the impression that another gear has been selected. The lock up torque converter was used in Borg & Warner boxes in the 1950s but went out of fashion and only re-appeared in the late 1970s. I'm not sure when they appeared on the 240s but I do know they are on the AW70 and AW71.

Have you confirmed that the BW/AW55 boxes do have a lock up torque converter? I have a comprehensive list of all boxes fitted to the 240 from its launch and none of the BW35, BW55 nor AW55 are shown as having a lock up. As stated earlier the AW70 and AW71 are listed as having that unit fitted.

You can also experience shudder and shake if the engine or transmission mountings are bad.

Bill.

[Steven242]

I've been to three trans shops, and all of them say it isn't the original trans, and it has a lock up in it. How they are finding this out, is beyond me. What I'm reading online is making me lean towards the tc is having issues. The motor and trans mounts are good. So I dunno what is going on...

[billofdurham]

How they are finding this out, is beyond me.

There is a plate on the side of the transmission which gives the mechanic a good idea of what he is working on.

Did any of them tell you which box it is?

Bill.

[Steven242]

they gave me a number, but I can't recall it... but they said there is an overdrive solenoid and someone bypassed it to make the trans switch into fourth on its own without wiring. So I'm guessing it is the transmission that goes in the eighties model with the overdrive switch.

Doesn't have the lock up though... just feels that way cause of the torque converter that someone had installed... has a lower stall rating.

All this came from the AAMCO an hour away from me.

[billofdurham]

The most likely replacements would be the AW70 or AW71, both of which were fitted to the later 240s, with 3 speed with 4th on overdrive. The overdrive invariably went wrong and the solenoid was by-passed. The labels on the boxes would be 03-70L or 03-71L.

They both had the lock up torque converter although I now see you are saying that it does not have the lock up.

Bill.

[Steven242]

that's it, the stamp on the side was the 03-70l