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TH-400 Fluid change. Lots of Material - Rebuild needed ?


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I ended up pulling the trans and dropping it off. There at a 7 to 10 week turnaround time. I knew that before dropping it off. Thinking about pulling the flywheel possible replacement since I had starter issues previously and wore the teeth down a little. She still starts fine but wonder if I should since I am in there. 

  Only thing is its a 454 and flywheel is externally balanced. Can I get a new one and have the balance mirrored onto the new one?  

Trans Tunnel 1.jpg

Trans Tunnel 2.jpg

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The flexplate is already balanced. It has the weights on it. That sux on the turnaround time. Too bad you weren’t closer my got rebuilt in 4 days including cutting open converter and changing, adding bearings. He normally charges about a grand but did mine for 850 and that included all parts 

Edited by Dtret
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It was, and I believe it does. I dropped it off to get done again.  I pulled the flexplate and doesn't seem as bad as I thought it was. Teeth seem ok. What do you guys think? If I did replace it Im not sure how I would since its externally balanced. That was done when motor was built.   Here are the pictures. 

 

 

Flexplate 6 .jpg

 Flexplate 5.jpg

Flexplate 3.jpg

Flexplate 2.jpg

Flexplate .jpg

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Hard to tell, but some of those teeth look a little worn and rounded. Did you check the starter to flexplate clearance when you installed it initially? Sometimes they need to be shimmed for proper clearance.

As far as 'externally balanced', the 454 requires a different flexplate because of the way it is balanced (same with 400 small block). The flex plate for the 454 is usable right out of the box, as is, unless your engine builder specifically added weight to the flex plate when he built your engine. On your last picture, the welded on external weight is on the left side and looks to be original and un-modified. If you want to replace it, should be a simple bolt on deal, maybe with new bolts too. 

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I agree. Because the trans needs to be at least backed off the engine a few inches to do a flex plate change, do it now. Whatever brand and part number it is, get the same.

 

Some nice ARP crank and torque converter bolts cleans it up nice and you'll sleep better too.

 

How's the crank rear main seal?

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Thanks guys, I ordered what appears to be the same flywheel. I will verify once it comes in . Ive had an oil drip for some time. Not horrible but annoying. The engine builder  in my opinion did a shoddy job of gaskets, I also asked him to use brass - freeze plugs and they didn't. . The pan was sealed with a silver sealant from the builder. There is oil that drips by the bottom of the rear main seal metal on the pan. I can't confirm if its actually the rear main though. The corners were gooped with that siver stuff. Some was hanging loose. So I cleaned the silver gasket sealer off and there you see the pan Gasket. I cleaned everything up with alcohol and sealed it with RTV Black. I painted up the freeze plugs  plugs , painted flaked off didn't want rust to pop them ... Only time will tell. 

rear main .jpg

rear main  1.jpg

rear main  2.jpg

IMG_9695.jpg

rear main  final.jpg

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So I ordered the Same Brand Flexplate that is on the car. Pioneer inc. They appear to be practically the same. Original one  "November - 2012 made in USA"  New one December 2020 "Made in Mexico.  Only difference I really see is 4 Holes drilled on new flywheel bottom to the right of weight. Being external balance anyone know if this is just bolt on or should I contact builder? But its been so long out they have records of it...

flywheel 1.jpg

Flywheel 2.jpg

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It should bolt right on. It didn't appear that the original one was modified as far as balance adjustments by the engine builder judging from the pictures you provided of both sides earlier. He DID need the flexplate when he balanced the engine initially, but he would have made the adjustments to the internal rotating assembly parts. That would be the correct way to do it, so there is no drama in the very situation you are currently in as far as the flexplate, and also a harmonic balancer if you ever needed to replace that. If it eases your mind, call him though. See if he typically modifies the flexplate when he balances (but again, your original appears untouched).

You can bolt it on and don't look back. You may want to check the starter engagement clearance though, to minimize the gear tooth wear. Instructions for that procedure are easy to find.

EDIT: Tom beat me to it, as I was typing, lol

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Thanks guys. I installed the new flywheel. checking the starter clearance. I thought it was supposed to be about the distance of a large paperclip. Is this too much clearance? 

 

Thanks again for all your advice.

 

starter gear 1.jpg

starter gear 2.jpg

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Looks a little big. That's why your other ring gear was probably worn the same way, too close to the tip of the teeth. You may need to shim up the starter mounting to tighten that gap. To tighten up that gap, add half a shim at a time (as needed) to the outer bolt mount. Meaning, cut a shim in half and slip it on the outer bolt hole. That'll rotate the starter drive towards the ring gear. Look at the instructions below for tips, they're pretty good.

https://static.summitracing.com/global/images/instructions/summit gm starter-shimming instructions.pdf

https://f01.justanswer.com/heavy_chevy_396/33f1127d-7c8f-4039-8cb7-4a8ec3ac019d_how+to+shim+a+starter.pdf

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