Having issues getting a TH400 torque converter to seat onto the input shaft.

Seems to be a tapered bulge on the input shaft to allow a press fit of sorts :?: never seen this before.

The TC will slide onto the shaft but will only be flush with the bellhousing and not recessed to allow the flex plate to sit inside the housing.
I did have the notched key-way lined up with the key.

I tried to torque it down on the engine to see if it will pop in but it sits way too tight and I am afraid I might crack the bell housing.
I've never ran into this issue with TH350's or TH2004R's...

The trans is a PR TH400 from a '76 Grand Prix SJ going onto a '73 Olds 455 from a Custom Cruiser all into a '72 Cutlass Supreme.
The trans does have a single wire coming out of it, is this for a switch pitch converter?

Are TH350 TC's interchangeable with TH400's?

I am wondering if I was given the wrong TC but I am almost positive this is the right one since my dad pulled it just recently.
It has a number 4 stamped around the perimeter if that matters...
TIA

 

The single wire is for kickdown on a TH400
Two wires can be for that plus SP or that plus Trans Controlled Spark Bullshed [TCSB]

Sounds to me like all your parts should be compatible. measure and verify that the keyway things are sized to mate properly. Turn a lot. Yes, the 350 & 400 TC's are interfittable.

Maybe make sure you do not have part switch pitch and part not.... google for the Buick "how to tell" page?

 

you have too spin it, sometimes quite a few times to seat it, if its like other ones ive done

 

I spend about an hour messing with it by spinning it, pulling it out slightly, lining up the keyway etc...
I guess I will keep at it.
Going to ask my pops if he grabbed the wrong TC by accident, it's possible the keyway is mismatched.

 

The first time I ever installed a converter into a TH400, it took me about an hour. The last fifteen minutes involved sitting on the suspension crossmember and cussing at the trans. That apparently did the trick.

Also, note that you often need to pick up on the converter as you push inward and spin it to get the splines and pump drive tangs to all engage simultaneously.

 

Noted, thanks.

I am going to hang the trans vertically with the engine hoist and work at it.

I've never experienced this with any other trans (TH350 and Th2004R) and I've swapped quite a few...

 

Evidently, it's your turn to agonize now...

 

a 4 stamped into the convertor? like this?



^^^^ that's a switch pitch convertor, it aint gonna fit a non-switch pitch thm400.


bill

 

Yes it has a 4 stamped on it like that but they are all facing the same direction and not alternating like that.
I am going to check to see if I was given the wrong converter.

 

There are difference you can easily learn to spot
Just find that Buick info page, with photos.

 

Couldn't find it and I am pretty good at searching for things on the internet...
Perhaps a link?

 

http://www.buickperformanceclub.com/switchpitch.htm

http://www.442.com/oldsfaq/oftsp.htm

 

Thanks for the links!

Wound up being a switch pitch converter.
5 out of the 6 I had were all switch pitch converters, would you believe that!

 

"Wound up being a switch pitch converter.
5 out of the 6 I had were all switch pitch converters, would you believe that!"

Hold onto them!

 

This is one of the reasons I'm afraid to put my 455 in my CS . I never messed with a TC before , and I personally know someone who put there TC on wrong and ended up with a big broken mess as a result of it .