I'm trying to bolt a TH125 to a 2.8L, and I get to the last 1/4"to 3/8" and the gap starts closing more on the top, even though I am tightening the two side bolts.
When it gets to that point, I can no longer turn the front pulley bolt to rotate the crank, so I know it is binding up, and the splines must not be meshing.

Is there a trick to rotating the trans. input shaft to try to mesh with the engine side splines?

Thanks for the help.

You can rotate the engine with a socket on the main pulley

Just rotate it the right direction so as to NOT loosen the nut on the balancer pully.

It seems I spent half the afternoon rotating the crank pulley trying to get the spines to mesh, but it doesn't seem to be working by the time I get down to the last 3/8" gap between trans and block.

If the trans is a TH125 then that would make it an automatic. I had a similar problem once. Try rotating the torque converter so the pads on the flex plate are away from the torque converter bolt holes. Otherwise, it will bind and lock up everything.

Ventura, thank you for the idea.
Is that if the torque converter is newly installed on the flex plate?
I am just swapping transmissions. I did not remove the torque converter from the flex plate when I removed the old transmission I am replacing.
Otherwise, I may not be understanding your suggestion completely.

the torque converter must be installed in the transmission first and then bolted to the flex plate after the engine and trans are bolted together. the other way around won't work. There are 2 notches on the converter that fit into the transmission front pump, you need to slide the converter onto the splined shaft and rotate it around until it engages the pump gear and then it will slide in all the way. If you do not do this correctly, you will destroy the front pump and ruin the transmission. Properly installed, there should be a small gap between the flexplate and converter when the engine and trans are bolted together. This lets you know the converter is in all the way. The converter will slide up to meet the flexplate and then can be bolted to the flexplate.

[This message has been edited by seajai (edited 11-11-2013).]

seajai,
Got it. Thanks.
It's been I while since I have worked on an auto. trans. car. Just trying to get this one together to sell, and get back to my 5-speeds.
Now that you mention it, I think that's what I did in the past with RWD auto. cars in the past when I was a kid.
Thanks again.

Please, Please, Please make sure the converter is in the trans right. If not, when you start it up it will wipe out the front pump in the transmission.
When you install the converter in the trans you should "feel" 3 bumps. Look in the converter, you will see splines for the input shaft. You will also notice square notches on the end of the converter shaft. If you look in the trans you will see 2 "fingers" that line up with those notches.
The first bump will be the converter passing the seal and seating in the from bushing. The second will be the input shaft splines lining up. You don't have to turn/spin the converter for those. The third(VERY IMPORTANT) turn the converter till you feel it line up the square cut notches. This will allow it to drop in another 3/8". If you don't feel that last bump, pull it out and do it again. You have to turn it to get it to line up. You''ll know when it happens. If not the converter will sit on the fingers of the front pump. You will be able to bolt the trans up, but the converter will force the front pump into the face of the housing, destroying it. When you bolt up the transmission you should still be able to turn the converter freely until you install the converter bolts.
This goes for all GM and most automatics.

[This message has been edited by cmechmann (edited 11-11-2013).]

I always use my hands to spin the tc on the splined shaft FIRST before I mate it to the engine.

and then I go underneath and bolt the tc to the flywheel.

check your pilot bearing in the tc snout to see if its damaged. you will end up paying for that later when the bearing finally burns up.

Check your front pump seal on the trans as well - with the TC "off center" you could have torn up the front seal. When the TC is fully installed, you will not be able to get your fingers between the TC and front pump.

quote Originally posted by cmechmann: If you look in the trans you will see 2 "fingers" that line up with those notches.

Today I am trying to install the torque converter onto the trans. I am not really seeing the 2 fingers, as mentioned, when I look into the trans.

I can get the torque converter on to what seems to be all the way, but when I rotate the converter, I feel it bumping up and down like it is passing over splines that it is not meshed with.

[This message has been edited by hdryder (edited 11-16-2013).]