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Discussion Starter · #1 ·
Hello all!

I believe that I have a cracked flexplate on my 2005 Silverado 2500HD. There is an ungodly grinding/clacking noise coming from the bellhousing. Yesterday morning it was just a bit of a knock only when I was in gear but not moving. By the afternoon it was a very loud and fast grinding clatter even when the vehicle is in park (much much worse when I put it in gear).

I talked to a local transmission mechanic and he said it was most likely a cracked flexplate. Unfortunately every mechanic in my very small town is at least 3-6 weeks out on work, and this truck is my daily and work truck.

So, 1 does this sound like a cracked flexplate? And 2, is this something that I should be able to do on my own? I am relatively comfortable working on vehicles, I have just never taken on something of this magnitude before. Also through work I have access to a full shop, only thing missing would be a vehicle lift.

Any help or advice is much appreciated!

Cheers!
 

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Cracked flexplate sounds legit.

I wouldn't want it on a lift to pull the transmission. If you do it on a lift you'll need a high rise transmission jack. A regular transmission jack will be easier to come up with. I think some rental stores carry them. You can do it with a regular floor jack but it's sure nice to have help if you do. I've done it and it's not much fun, especially with something as big and heavy as an Allison. You'll need the front end of the truck up on stands to make room to roll the transmission back.

The flexplate bolts are kind of a rip. The transmission mounting bolts really aren't that bad. I'd try to make sure the torque converter stays engaged in the pump. If you pull it out you might learn a few new words trying to get it stabbed back in. Toughest TC to stab that I've ever messed with.
 

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Discussion Starter · #3 ·
Thanks for the advice! My shop at work has a regular transmission jack, so I already have that available to me. And I think I can get our mechanic to give me a hand with some of it, so I won't have to do it completely alone.

Do you have any experience with billet flex plates? It seems like it might be a decent idea to put one in, and a local mechanic friend of mine has one he's willing to sell me for $300. It does need to be balanced and it's for a later model Duramax, so I'm not sure if it would work on mine.
 

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I'm guessing the billet flex plates are for high performance apps like pulling or the like.

I wouldn't be afraid to go back with a stock flex plate. To my knowledge, a broken plate is not a very common failure.

Good deal on the jack and the help.
 

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Might want to confirm that a bolt in the torque converter isn't coming loose, if it comes loose will cause major damage, Just something to look at if you plan on continuing to drive it.
 

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Discussion Starter · #6 ·
Thanks everyone for the replies! I've got a new flexplate and flywheel coming in this weekend, and a mechanic at a local dealership is going to slip it in on the weekend.

I decided to just go with stock, from everyone I've talked to, it's not a common problem and even if I have to change it in another 250000 miles, I'm okay with that 🤪

I am going to have the mechanic take a look at everything else while he's in there to make sure it's all good to go, and nothing else wrong besides the flexplate.
 
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