Replacing Transmission/Torque Converter

[Irish_Alley]

this is what they norm look like

that one you posted is different but it just might be cause its from a different maker. but if you look it covers the th400 and thats it. i think the 4l80e should be covered also or other trans like the 700r4

[Jon87V20]

Any thoughts on whether I should use sealant with this gasket, or leave it dry?


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[Irish_Alley]

i use sealant to hold it in place but only a few dabs

[VileZambonie]

Any thoughts on whether I should use sealant with this gasket, or leave it dry?


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Use one or the other. if you use a sealant then you don't need a gasket.

[82silverado]

If it were mine I would just use the anaerobic sealant.

[hatzie]

I use a little grease to hold fiber gaskets in place.

[Jon87V20]

Hey guys, ran in to another issue. I got the new TC and transmission up in the truck and bolted up to the engine. I noticed before bolting the TC up to the flexplate, it has a bit of play in it. It's able to move away from the flexplate just a little bit. I'm not sure if this is normal. Do I need to get some washers?

I found another thread on here:

http://forum.73-87chevytrucks.com/smforum/index.php?topic=31235.msg262304#msg262304

where HAULIN' IT says it's normal for the TC to move a little bit, but if it's more than an 1/8", you should add hardened washers. I haven't measured it because I haven't been down there since I read that, but I have a picture of the gap. Just wondering what you guys think about the clearance here.

[VileZambonie]

No, the nose of the converter needs to be in the back of the crankshaft. The converter spins freely? If so just carefully draw it into the flexplate.

[Jon87V20]

Ok. So when the converter pads come in contact with the flexplate, the nose of the converter should be in the cutout on the flexplate and everything is good to go? Also, yes it does spin around freely. I just wanted to be sure so it didn't start breaking things when I fire it up.

Thanks, Vile!

[Jon87V20]

Just for future reference, the gasket I bought at the link was not the right one. Don't buy that one.

[Jon87V20]

Happy to report, I finished throwing her together today and drove it around the block. Seems like everything is operating properly, no leaks etc. The only issue I ran in to is it won't go in to park. When it's in park and it's rolling slightly, I can feel a slight "clicking" through the shift handle. I'm thinking this is probably a shift linkage issue (I hope!). Thanks to everyone for all the help! I wouldn't have been able to get this done with out the forum for sure.

[bd]

...The only issue I ran in to is it won't go in to park. When it's in park and it's rolling slightly, I can feel a slight "clicking" through the shift handle. I'm thinking this is probably a shift linkage issue (I hope!)....

Adjusting the linkage should remedy that, but don't put it off.  If Park doesn't detent correctly, neither will the other gears, which could result in slippage and overheating or other problems.

[Jon87V20]

So I went out and made sure that the linkage was correct and even took the linkage off and moved the shift mechanism with my hand and it is snapping in to the park position. However, the truck is still moving. I've noticed that if I push the truck backwards, it makes no attempt to hold it still. I hear the light clicking but there's no resistance. If I pull the truck forward though, there's a little bit of resistance and I can see the engine move a bit. It will stop the truck from moving if it's BARELY moving, but I can pull a bit more with my arms and it will move a few inches until the next catch point.

I'm not familiar with how the park mechanism works inside the transmission. Is it some kind of pin that drops in to place somewhere in there, or does it engage two gears at once or something? This is a big disappointment as I don't have anymore money for this now. Everything else seems to be working okay though. I'm thinking since the parking brake works quite well on this truck, I'll avoid parking on any significant grades and keep a wheel chalk with me for now.

I may just eventually bring it to AAMCO or another transmission repair place and tell them it won't hold still in park.

Anything else I should try before I give up on getting it to hold still?

Thanks!

[Jon87V20]

After doing some more reading I'm feeling a lot more optimistic about this now. It seems as though you can access the parking pawl mechanism from the bottom after removing the pan. As soon as I have money to buy more fluid  , I'll drain it and see what I find. 

[bd]

It's beginning to sound like a fractured or dislodged parking pawl.  See Figure 31, page 400-15 of the 1987 Unit Repair Manual.  As you've already discovered, the pawl is easily serviceable after removing the pan.  IMSM, the pawl engages the outer teeth of the output carrier assembly (item #675 in Figure 22, page 400-10 of the same repair manual).  If the pawl is damaged, you maybe able to swap in the old one from the original THM 400 with the cracked bell housing.