TAC Tech => Mechanical => Topic started by: kev 190164 on March 16, 2025, 10:38:46 AM

Title: putting a t56 in my 1974 455
Post by: kev 190164 on March 16, 2025, 10:38:46 AM
hello can someone tell me which flywheel i need to put on my 1974 455 trans am . converting to manual and using a t56 magnum . is  the engine internally or externally balanced   
Title: Re: putting a t56 in my 1974 455
Post by: nUcLeArEnVoY on March 16, 2025, 01:58:26 PM
For what I've researched on the fly in response to this question, a lot of people are just using a stock-style flywheel.
Title: Re: putting a t56 in my 1974 455
Post by: 5th T/A on March 16, 2025, 02:02:03 PM
I don't have an answer for you. Likely someone who sells Tremec upgrade kits could answer your question. A quick search turned up Modern Driveline. There are likely lots of options.
Title: Re: putting a t56 in my 1974 455
Post by: 70_71_78 on March 16, 2025, 05:57:46 PM
As assembled from the factory they are balanced externally at the flywheel. However, they are not so far off as to require a severely off balance harmonic damper like a chevy small block 400. When I had my '70 455 built I had the option to select internal balance, requiring a neutral balanced flywheel. A factory flywheel was neutral balanced, but I am not sure I would use a factory cast iron flywheel and aluminum bell housing again for safety reasons. 
Title: Re: putting a t56 in my 1974 455
Post by: 71455formula on March 26, 2025, 07:08:39 PM
With my t56 swap. I used a Pontiac flywheel and clutch kit. My rotating assembly was internally balanced when i had it built, so I'm using a neutral balance flywheel. When you pull your trans out; you can look at the flywheel or flex plate to see if you need a neutral balance or external balance for your engine. Here's a link that has info on how to tell the difference.

https://butlerperformance.com/n-13498-internal-neutral-vs-external-stock-balance.html



Title: Re: putting a t56 in my 1974 455
Post by: kev 190164 on March 30, 2025, 02:33:46 PM
the 455 is all standard just want to fit the t56 . its an auto at the moment just want to know for sure if external or internal balanced . i have a duel clutch and a steel bellhousing