flexplate C6
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From: Meridian
flexplate C6
I have a 1971 F250 with original 85,000 miles. The engine and transmission were completely gone through sparing no expense. The original 390 had an internal crack and was replaced with a 352 block and bored out to 390. In the process, (the engine was removed 3 times)the flex plate was broken each time. The transmission was completely gone through including new torque converter. The transmission guy says it is aligned and nothing wrong with it. The engine guy says there is nothing wrong with the engine. Each time this occured within a few thousand miles. Anyone with suggestions/recommendations they would be greatly appreciated. Micheal
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From: All over Texas
flexplate C6
Let's see. You've broken three flexplates within the last couple thousand miles. Is this what you are saying? If so, I cannot imagine what would be causing this unless your truck vibrates and shakes like crazy. Where are they breaking? In half? Teeth? Cracking? Details are important when trying to diagnose a problem.
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From: Meridian
flexplate C6
The flexplates are cracking around the bolt holes. The truck drives like a new truck. Including new engine mounts etc. The original transmission was completely rebuilt with new parts. New torque converter etc. Each time the flex plate was purchased new, the last time was from the Ford dealer. I have alot of people looking into this and trying to figure it out. The engine is completely remanufactured except for the original crankshaft. This truck is a 8-9 on a 10 scale except for breaking flex plates. About $7,000 invested in the total restoration and 85,000 original miles. Never been wrecked.
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From: Creedmoor, North Carolina
flexplate C6
Mike, I am betting the dowel pins were left out of the rear of the block. A pilot bushing could still be in crank also. 
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From: Meridian
flexplate C6
John the dowel pins are there. The bushing I will have to look into. Since all the work is being done by certified and expensive mechanics one would assume things like this would not be overlooked.
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From: Sun River St. George
flexplate C6
Is it possible that the spacer(I know that is not the correct name), that goes between the flexplate and the flexplate retaining bolts is missing? Is the big spacer between the engine and transmission installed? Are the flexplate retaining bolts torqued properly? I know this is basic but you never know!
William in Atlanta
William in Atlanta
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From: Meridian
flexplate C6
William That spacer thing its called a flywheel reinforcement plate
I researched this this morning. No one has even suggested that such a thing exist. I am thinking it doesn't exist and maybe the cause of all the cracking flexplates. Now locating one is another thing the Ford dealer parts guy said it shows they are still avilable 3 to a pack at $30.00 bucks apiece. The transmission parts house I deal with doesn't carry them, but, the guy I talked to there just happened to have a 66' ford truck and had to take his tranny out for something. He said there is definitely one there. He told me it goes between the flexplate and converter. As for thightening the bolts down I haven't gotten any specifics on this yet. Thanks for the tip william.
I am still wondering where the pilot bushing goes on an automatic trans. I thought that was for the manual trans. I had to think about that for awhile even asked the parts guy at the dealership.
I researched this this morning. No one has even suggested that such a thing exist. I am thinking it doesn't exist and maybe the cause of all the cracking flexplates. Now locating one is another thing the Ford dealer parts guy said it shows they are still avilable 3 to a pack at $30.00 bucks apiece. The transmission parts house I deal with doesn't carry them, but, the guy I talked to there just happened to have a 66' ford truck and had to take his tranny out for something. He said there is definitely one there. He told me it goes between the flexplate and converter. As for thightening the bolts down I haven't gotten any specifics on this yet. Thanks for the tip william.
I am still wondering where the pilot bushing goes on an automatic trans. I thought that was for the manual trans. I had to think about that for awhile even asked the parts guy at the dealership.
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From: Brea CA
flexplate C6
This subject was discussed on another board:
http://fomoco.com/forumfe/reply.asp?ID=11454&Reply=11454
I don’t think we were ever able to determine what they were for or what all engine/trans combos needed them.
Here’s a scan from the MPC:
https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=7954&.jpg
It says 1 or 3 are used:
https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=7956&.jpg
Barry
http://fomoco.com/forumfe/reply.asp?ID=11454&Reply=11454
I don’t think we were ever able to determine what they were for or what all engine/trans combos needed them.
Here’s a scan from the MPC:
https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=7954&.jpg
It says 1 or 3 are used:
https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=7956&.jpg
Barry
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From: Meridian
flexplate C6
is that me melting down or is that me melting down this ford truck
That certainly confirms it. There was a plate known as a reinforcement plate.
I talked to the dealer parts guy he said there was such a thing
I talked to the transmission parts wharehouse local he said there was one on his 1966 ford truck but didn't carry them instock
I talked to the local parts house he said he had never heard of such a thing or ever seen it listed he couldn't find it
I talked to the local tansmission shop he had no clue what I was talking about said he had never seen one he said I had an alignment problem and needed to find a new block (this one was just re-man with all new parts)
I talked to a large transmission parts supplier I found on the internet. He said this was a common problem on these old engines. He said there was no reinforcement plate on the 390 flywheel. either the rear main thrust was excessive or the dowel pins were missing
No one else has suggested excessive thrust although the engine is being looked at as a possible cause in fact the transmission guys say there is nothing in the engine that would cause this breakage
So as it stands this much I know I am sooooo confused
But still searching for the cure Thanks
That certainly confirms it. There was a plate known as a reinforcement plate.
I talked to the dealer parts guy he said there was such a thing
I talked to the transmission parts wharehouse local he said there was one on his 1966 ford truck but didn't carry them instock
I talked to the local parts house he said he had never heard of such a thing or ever seen it listed he couldn't find it
I talked to the local tansmission shop he had no clue what I was talking about said he had never seen one he said I had an alignment problem and needed to find a new block (this one was just re-man with all new parts)
I talked to a large transmission parts supplier I found on the internet. He said this was a common problem on these old engines. He said there was no reinforcement plate on the 390 flywheel. either the rear main thrust was excessive or the dowel pins were missing
No one else has suggested excessive thrust although the engine is being looked at as a possible cause in fact the transmission guys say there is nothing in the engine that would cause this breakage
So as it stands this much I know I am sooooo confused
But still searching for the cure Thanks
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From: Brea CA
flexplate C6
Mike, I feel your pain! Looking at the MPC closer, it says that 3 plates are used on the 352 and only 1 for the 360 and 390. Also, are you running a motor plate between the engine and trans?
Seems like it would take a lot of crank end play to do that, besides, isn’t your motor freshly rebuilt? Maybe they didn’t set the thrust bearing correctly. You can push and pull on your crank snout to get an idea on the slop.
Do you have to buy all three plates from the dealer? Can’t buy just one?
Sorry, just taking shots in the dark. Next time my tranny is out I’m gonna check and see if there is a plate.
Barry
Seems like it would take a lot of crank end play to do that, besides, isn’t your motor freshly rebuilt? Maybe they didn’t set the thrust bearing correctly. You can push and pull on your crank snout to get an idea on the slop.
Do you have to buy all three plates from the dealer? Can’t buy just one?
Sorry, just taking shots in the dark. Next time my tranny is out I’m gonna check and see if there is a plate.
Barry
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From: Meridian
flexplate C6
Thanks Barry for your input and your empathy. Trying to troubleshoot something like this is most frustrating. Especially when you get different and varying responses from the "professionals" I am just amazed at how many transmission specialits I have talked to that say the reinforcement plates do not even exist. I am thinking of trying all three as the MPC suggested for the 352. I am not sure what year the block is, just know its part of the fe family and everthing went right in. Atleast in the process of doing this I have found a multitude of sources for the flexplate itself. Prices from $25.00 to over $100.00. I looked for heavyduty plates, but, thats not a ford thing. The other guys have them though. Thanks once again
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