Trying to "remotely" help a young guy get his truck going. It has a 4L80E transmission.
He just replaced the trans with a fresh remanufactured one, and new converter from same trans builder, who said it was correct for the truck. It came with an extension/ adapter on the T.C. snout that he was told to remove, (apparently LS engines require a longer snout, this is a 8.1L / 496).
The Torque Converter was installed into the trans properly, engaging all shaft splines and the pump. But when he moves the T.C. forward to bolt it to the flexplate, there is still a gap of 3/16" between the lugs on the T.C. and the mating pads on the flexplate. The only possible obstruction I can think of would be the converter snout is bottoming in the crankshaft pilot hole. Checked the converter snout and crank pilot hub, they are free of any burrs or dings, and did engage. Converter rotates freely, it is not binding up. Everything I have been able to find on the web appears to show that there should be a gap of 1/8 to 3/16 inch between the flexplate and converter, which would mean this is ready to bolt together. But this does not make sense to me, it seems like it would cause the plate to crack. My understanding and experience over decades has always been that the converter and flexplate mating points should be touching before the bolts are installed. I will admit to having no previous experience with installing a 4L80E. Dozens of TH400's, TH350's 700R4's, 4L60E's, and Powerglides. All of them the T.C. and plate were mated without flexing the plate.

I could be wrong, and maybe this is normal for these, but I figured I would ask, since some of you guys would probably know. (I do know there are spacer shims made for solving this issue, if it is not correct).

Any and all advice and info will be appreciated.

This message has been edited. Last edited by: FootbrakeJim,

No you should have a gap between the TC and the Flexplate. Normally around 1/8" to 3/16". Just make sure the pilot on the converter is going into the back of the crank.

This gap is need or you will damage the trans pump, flexplate andor thrust bearing.

https://hughesperformance.com/...ion-instructions.pdf

1Leg, thank you for your reply.
My guess is that instruction sheet would apply to most of the common racing transmissions that we all use. I believe the 1/8" to 3/16" clearance is measured with the converter fully seated into the transmission pump, before sliding it forward to meet the flexplate.
If you look at the Hughes instruction sheet you linked to, at the top of Page 2, it says:
"...Verify that the flexplate bolts do not interfere with the torque converter. Verify that the torque converter mounting pads sit flush against the flexplate" Which is what I have always done.
And down on Page 3, it says "You should observe 1/8” (.125”) to 3/16” (.187”) of air gap between the torque converter mounting pads and flexplate before sliding the converter forward to attach it to the flexplate.

But I am still wondering if maybe the 4L80E is different with regard to this.

But that part in the instructions that says "Verify that the flexplate bolts do not interfere with the torque converter" caught my attention, I had not thought of that, it just might be what is going on with the truck my friend is working on.
So again, thank you, that might have been exactly what I needed to see. I appreciate it you, Sir.
I will have him check on that.

I guess when I first read your post I did not do a very good job. Sorry.

If the converter is orginally for a LS engine it would have a longer pilot by about .400". I suspect maybe the pilot is bottoming out in the crank. I have a 8.1 in my truck but never had the trans out(yet)

https://www.facebook.com/groups/1046094835740412

This has been a good 4L80 group if you have FB.