Cracked Flex Plate

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oldkimmer said:
Has the tranny builder even rebuilt a 727 b 4? Do u know anyone else that had a 727 done by him and was he recommended by someone? If he is a trusted builder let him change the pump and install the converter. Did he measure the hub on the converter to make sure it isn’t too small? I bet a sealing ring is broken on the stator or on the input shaft. Kim
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Kim, I don't believe the issue is with the builder. It appears that the information I got out of Munroe's book on 727s was just plain wrong. He wrote that the converter should not be pulled anymore than 1/8 of an inch forward toward the converter after being fully seated. If it does, he wrote you have to use spacers between the flex plate and the converter so the pull out does not exceed 1/8. Well, the problem with that is it appears by only pulling it out 1/8 did not allow the snout on the converter to fully seat in the crank register, which caused the converter to not be fully supported and centered, which then cracked my flex plate and then also probably messed up my front pump. It is a balance, the converter must be pulled forward enough to allow the snout to seat in the crank register, but not so far that you pull the converter hub out of the pump.

Also, I added 1/2 liter last night (about 1 pint here in US), and no difference. It still is slow to engage.
 
I just thought I would post up and close the loop on this. It turned out to be a thrashed front pump. The stator rings were fine. It seems that by using the spacers, as that book's author suggested, the converter snout was not fully engaged in the crank and allowed slop and over time cracked the flex plate. After I pulled the tranny, I pulled the front pump apart, I replaced the pump gears, which were galled, pump body and cleaned the stator. I measured the snout and the crank and made sure they were both 1.81. Everything is fine now. No delayed engagement. Thanks for the advice guys.
 
I've spaced plenty of converters back. The big caveat that nobody mentioned is that first you have to check crank end play and make sure the crank is all the way rearward; otherwise when the crank walks rearward it can push the center pump gear into the housing. And of course you have to make sure the snout doesn't drop out of the crank. I did a vega converter in an Oldsmobile once and I had to flip the center pump gear to get it to catch (GM tangs aren't centered); otherwise the converter dropped out of the crank when I set it back far enough to run the pump. In the other extreme, if you don't space the converter back, it can actually pull out of the pump tangs on a motor with worn mains; and of course, wrecking the pump once it walks back.
 
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