408W eating auto trans'

[1970Custom]

So I'm having issues with my 408W, it's gone through two autos (one was behind my 302 for four years prior). Had both looked at and something caused the input shaft to be stuffed into the pump and destroyed it along with scorching the TC where it meets the crank.

There's no unusual noise coming from the engine when it runs, the converter(s) was seated properly, flexplate was not distorted and was correct for the engine, nothing in the crank (i.e. pilot bearing etc), engine does seem to have a bit more vibration at an idle than what I'd expect.

I was told to check for crank walk or the thrust bearings, I have a new set of bearings for it but have never put them in, could it help fix my problem?

 

[5.0Flareside]

which tranny is it?

 

[1970Custom]

AOD's but I want to put it in front of the C4 currently in my '71

 

[5.0Flareside]

Aod's arent the strongest. is the C4 a 300,302,351W bellhousing? if it is i'd most definatly put the C4 behind it. much stronger. it will hurt you on gas with not having the overdrive but if i was you if i had a 408W i wouldnt care bout gas.

 

[1970Custom]

It ate them on start up, fired it up put it in reverse and it made it about 10ft...

 

[flareside_thunder]

The C4 has a removable bellhousing Chris but yes it is the smallblock bellhousing.

 

[Bricks]

I was told to check for crank walk or the thrust bearings, I have a new set of bearings for it but have never put them in, could it help fix my problem?

A definite possibility, imo.

 

[1970Custom]

Talked to a couple of drag racing gurus and they said that's is a clearance problem, either the TC isn't right or the flex plate is backwards (Never done it before, but at the time I was in a hurry and could've not payed attention to what i was doing...).

 

[Moto Mel]

That's exactly what happens when the T/C isn't properly installed on the input shaft of the trans. When you pull the trans up to the block you force the T/C too deep into the front pump, destroying it. No front pump = no go.
When installing the T/C onto the input shaft you should start it on the splines and then spin it while pushing it further back into the trans., you should feel it slide back about 1/4 inch ans hear a clunk indicating that it is fully seated in the pump.
Sorry for the late input to your problem but , this info may help someone else.

 

[conanski]

So I'm having issues with my 408W, it's gone through two autos (one was behind my 302 for four years prior). Had both looked at and something caused the input shaft to be stuffed into the pump and destroyed it along with scorching the TC where it meets the crank.

There's no unusual noise coming from the engine when it runs, the converter(s) was seated properly, flexplate was not distorted and was correct for the engine,

Yeah.. seen this problem first hand.. I did exactly what you have done.. used the wrong flexplate. It has to be an AOD flexplate.. the offset is shallower that those for the C6 and E4OD, and it must be the right balance for your motor. 351's were 28oz but some stroker kits are internally balanced and need a 0oz flexplate, while the 5.0 uses a 50oz balance. All these are available for the AOD since the trans was used with the 4.9, 5.0 and 5.8.

An AOD flexplate will have AOD stamped into one of the flat areas.. look for that. This trans will need a complete overhaul to handle a 408 anyway so you're really not out much. It'll need improved clutches and bands and a hardend input shaft or possibly a conversion to non lockup TC which eliminates the input shaft completely if this is goin to be raced. See here... http://www.ford-aod.com/
P.S. The TV cable must also be connected to the throttle linkage and adjusted properly. This is not a kickdown cable and the trans cannot be used without it, it controls line pressure inside the trans so everything just slips if it's disconnected.

 

[cipsmithers]

Maybe this is a dumb question, but what is a 408w?

 

[LEB Ben]

Maybe this is a dumb question, but what is a 408w?

A stroked 351W

 

[cipsmithers]

A stroked 351W

Thats what i was thinking