Torque Converter doesn't properly mate to flexplate

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specter539

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So I bought a used 1997 K2500 RCLB with a 5.7L and a 4L80E that the owner reported was slipping in 1st and 2nd. It was originally equipped as a plow truck so I thought that wasn't unusual. I got under the truck to inspect everything and noticed there were only 3 bolts holding the torque converter to the flex plate. (There should be 6) They were also two different sizes. After pulling the bolts I found that I could push the torque converter back into the transmission like it wasn't properly seated before. There is a half inch gap now between the torque converter and flex plate. The previous owner had the engine go on him over the winter and he had a shop do an engine swap. He said they used a 98 5.7L. Out of what I have no idea. The swap was the worst quality I've ever seen, but I won't get into it. So a month later he says the trans is slipping. I'm guessing the 5.7 was out of a 1500 and that is the reason for the gap? Although the flex plate and torque converter are both 6 bolt. Where a 4L60E torque converter and flex plate would have been a 3 bolt if my information is correct.

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Am I correct in thinking this gap shouldn't be there? I did an engine swap In my Jeep before and the torque converter and flex plate mated with no room to move the torque converter around.
 

RDF1

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The limit of the gap should be no more than 3/16". If it is, shim it.
On the LS stuff you would need a 0.4" spacer with the correct flexplate. I bet they dont have the correct flexplate on the engine.
3 torque converter Bolts is plenty for that setup tho. Ive ran 3 in all my 4L80E swaps.
 

evilunclegrimace

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So I bought a used 1997 K2500 RCLB with a 5.7L and a 4L80E that the owner reported was slipping in 1st and 2nd. It was originally equipped as a plow truck so I thought that wasn't unusual. I got under the truck to inspect everything and noticed there were only 3 bolts holding the torque converter to the flex plate. (There should be 6) They were also two different sizes. After pulling the bolts I found that I could push the torque converter back into the transmission like it wasn't properly seated before. There is a half inch gap now between the torque converter and flex plate. The previous owner had the engine go on him over the winter and he had a shop do an engine swap. He said they used a 98 5.7L. Out of what I have no idea. The swap was the worst quality I've ever seen, but I won't get into it. So a month later he says the trans is slipping. I'm guessing the 5.7 was out of a 1500 and that is the reason for the gap? Although the flex plate and torque converter are both 6 bolt. Where a 4L60E torque converter and flex plate would have been a 3 bolt if my information is correct.

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Am I correct in thinking this gap shouldn't be there? I did an engine swap In my Jeep before and the torque converter and flex plate mated with no room to move the torque converter around.


The gap is normal. It does not make a difference if the engine is out of a 1500-2500 or,3500 the block dimensions are the same.
 

specter539

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I think RDF1 is right about the flexplate. Last night I put the torque converter bolts back in and only 3 of the 6 holes line up correctly. I also did a little research.

The part number for a 2500/4L80E flexplate is 12554824. The flex plate has 6 bolt holes and the torque converter has 6 bolt holes.

The part number for a 1500/4L60E flexplate is 10128414. The flexplate has 6 bolt holes, but the torque converter has 3 bolt holes.

Seeing as the part numbers for the flexplates are different I think what happened was a 5.7 out of a 1500 was used and that flexplate was used, so my flex plate is incorrect and that's why the torque converter and flex plate don't mate up nicely.
 

evilunclegrimace

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I think RDF1 is right about the flexplate. Last night I put the torque converter bolts back in and only 3 of the 6 holes line up correctly. I also did a little research.

The part number for a 2500/4L80E flexplate is 12554824. The flex plate has 6 bolt holes and the torque converter has 6 bolt holes.

The part number for a 1500/4L60E flexplate is 10128414. The flexplate has 6 bolt holes, but the torque converter has 3 bolt holes.

Seeing as the part numbers for the flexplates are different I think what happened was a 5.7 out of a 1500 was used and that flexplate was used, so my flex plate is incorrect and that's why the torque converter and flex plate don't mate up nicely.


The only difference in the two flex plates is one is a dual pattern 3 bolt flex plate and the other is a single pattern 6 bolt flex plate. 700R4's and 4l60's had a dual pattern flex plate and 4L80's had a single pattern flex plate. They both will work. There is no difference in how far the ring gear teeth are from the end of the crank shaft. It is normal for the TC to be able to move forward to be bolted to the flex plate.
 
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