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Discussion Starter · #1 ·
my flex plate holes on my L31 are about 1/2" to far from center to line up with my 700r4 torque converter. i had not expected any problems as the l31 is usually mated to a 4l60 (700r4) or 4l60E. i tried my dremel, but the grinding stones i have barely do anything. is there a grinding stone out there that can take care of this?

and before anyone ask, NONE of the bolt hole patterns line up. already marked it and rotated it 360 twice. and at this point i have no interest in pulling the anything out to replace it. I know the holes can be elongated, just dont know what to use.
 

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I use diamond / carbide bits when I am working on engine blocks or cylinder heads. I imagine you'd have good luck on about anything with them. They're pricey though.

However, and I know this isn't what you 'want' to hear, but I suggest you drop the transmission, and either get a different flex plate or torque converter.
 

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Discussion Starter · #3 ·
thanks. going to Lows'
 

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Drop the tranny and change to correct flexplate or change the convertor. No good will come from trying to elongate the hole. You would need to mark the holes remove the flexplate and use an end mill to drill the holes straight.
 

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my flex plate holes on my L31 are about 1/2" to far from center to line up with my 700r4 torque converter. i had not expected any problems as the l31 is usually mated to a 4l60 (700r4) or 4l60E. i tried my dremel, but the grinding stones i have barely do anything. is there a grinding stone out there that can take care of this?

and before anyone ask, NONE of the bolt hole patterns line up. already marked it and rotated it 360 twice. and at this point i have no interest in pulling the anything out to replace it. I know the holes can be elongated, just dont know what to use.
....never heard of this before, are you going to use elongated
bolts too....:laughing: ....sorry not trying to be an ass....:D

....are you not worried about the flex plate staying secure...:huh:
 

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Get the correct parts... You will save money in the long run.
 

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A carbide burr would be the best tool for enlongating the holes. They make them in the shape of a long skinny Christmas tree.

Now, I've been drilling, welding, grinding, adapting, scratching and clawing parts onto cars for almost 50 years. I'm certain that I wouldn't have the "testicular fortitude" (ballz) to try to enlongate the flex plate holes to make it fit. The bolts are a precise fit in the holes and that makes for ideal alignment and centering.

What are your plans to precisely enlongate each hole to make sure that it's perfectly centered. Possibly you will get lucky and hit it head on but I'd bet that you are going to pick up a really cool vibration that will vibrate the body off the chassis.

If you look closely at your flex plate bolts you will see that they even have a small shoulder on them near the head that make sure that they are a snug fit into the holes in the flexplate. That's to insure that they are centered. Enlongating those holes will defeat that and throw your torque converter ever so slightly off center. That's all it will take to get a really neat vibration.

If you try this and are successful......make sure to rush out while on your test drive and purchase a lottery ticket. If you're car doesn't get a royal case of the shakes you should hit the lottery that night. Take a small portion of your lottery winnings and buy the correct part. I've never seen a torque converter vibrate loose. Let us know what all it destroys when it comes off spinning at 5000 RPM. I'll bet that's a really great noise and be sure to carry a roll of toilet paper. I predict you'll need it. Good luck
 

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I've never seen a torque converter vibrate loose. Let us know what all it destroys when it comes off spinning at 5000 RPM. I'll bet that's a really great noise and be sure to carry a roll of toilet paper. I predict you'll need it. Good luck

I have. :laughing: It was on a Chevy truck a friend was modifying. He invited me over for the startup. Typically he's a well put together guy.

I seem to remember him telling me afterwords that he used the wrong bolts to mate the SBC's flex plate to the TH350 torque converter.

During startup, while he was setting the timing, we heard a funny 'tink' followed by a 'thunk' and then a bolt came flying out from under the truck, and bounced past our feet where we were standing watching. (No dust cover.)

There was no exhaust on the truck at the time, just open headers, so it was very loud. Jeff couldn't hear us, as my buddy Matt and I, yelled for him to kill it. I moved in to grab his attention, but...

...basically, as the other bolts came loose, the truck started shaking badly. Jeff realized something was wrong and reached in to turn off the ignition.

The vibrations stopped just before he shut it down, probably because the last bolts came loose, the flex plate was no longer connected to the torque converter, and they separated and the torque converter stopped spinning.

Nothing catastrophic but I believe the transmission input shaft was damaged and the front seal blew apart.

Long story short, use the right parts, no matter if it's bolts, flex plate, or torque converter. Use a thread locking product of some kind too.
 

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I personaly would find a new flex plate. But if you are trying to stay on the cheap, don't elongate the holes, rotate the hole pattern 45 degrees and re-drill the correct hole pattern :lookinup:
 

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the only "right tool" involves a mill, indicator, and the skills to do a proper layout to blow new holes in it.

You are playing with fire trying to grind the holes bigger, go buy the proper flexplate, take this as good advice as no good can come from grinding the holes to fit. your either going to experience vibrations from throwing it out of balance, or worse yet cause it to break

Unless you have access to a Bridgeport or cnc mill and the years of experience to do the setup/layout do yourself a favor and buy the new flexplate
 
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