C6 drums
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Cargo Master
Joined: Sep 2007
Posts: 2,470
Likes: 535
From: Chandler, AZ
C6 drums
I have a C6 with 351m/400 bell out of a 78/79 bronco with np205 adapter that I plan to use for my 425 hp 460 build.
My trans guy has disassembled and verified that it has what he calls 'small drums', and says I should use 'big drums' for my 460 application.
I have a FE/390 C6 in the truck now I would rather sell in functional condition with the 390 as a package. He thinks the FE C6 would have the large drums and could be used in the 351m/400 case I have.
Looking at diagrams I see there is a 'forward drum' and an 'direct drum' each with there own clutch packs. It appears that the 'direct drum' that can hold 5 clutches is available from a few places for about $80. Wondering if this is an option, or do I still need the larger forward drum as well...
He said the difference is in the location of the retainer clip that allow more or thicker clutches. So maybe small and big aren't really the right descriptive words.
Builder also states that the 351m/400 case has a smaller reverse clutch that can cause chatter in reverse with big tires (40s). Anyone have an experience to share?
Trying to educated myself so I can make the right decisions, thanks.
My trans guy has disassembled and verified that it has what he calls 'small drums', and says I should use 'big drums' for my 460 application.
I have a FE/390 C6 in the truck now I would rather sell in functional condition with the 390 as a package. He thinks the FE C6 would have the large drums and could be used in the 351m/400 case I have.
Looking at diagrams I see there is a 'forward drum' and an 'direct drum' each with there own clutch packs. It appears that the 'direct drum' that can hold 5 clutches is available from a few places for about $80. Wondering if this is an option, or do I still need the larger forward drum as well...
He said the difference is in the location of the retainer clip that allow more or thicker clutches. So maybe small and big aren't really the right descriptive words.
Builder also states that the 351m/400 case has a smaller reverse clutch that can cause chatter in reverse with big tires (40s). Anyone have an experience to share?
Trying to educated myself so I can make the right decisions, thanks.
Transmission Rebuilder
Joined: Jul 2008
Posts: 1,570
Likes: 63
From: North Georgia
More clutches in the drums increases surface area of the clutch pack and that will increases the load capability of the entire clutch.
What he means in a larger drum is the amount of clutches the drum can hold, larger drum will hold more clutches. The drum is the exact same size between the large and small just the snap ring groove is moved up to allow another clutch.
I would change the drums if it was my truck.
The low reverse clutch has a pressure plate that comes in two sizes, the thinner one will give you a extra clutch, so maybe that's what he is meaning with the size of the reverse clutch.
Make sure he updates and or replaces the low reverse sprag assembly too, use the one with the plastic cage for the E40D/4R100.
What he means in a larger drum is the amount of clutches the drum can hold, larger drum will hold more clutches. The drum is the exact same size between the large and small just the snap ring groove is moved up to allow another clutch.
I would change the drums if it was my truck.
The low reverse clutch has a pressure plate that comes in two sizes, the thinner one will give you a extra clutch, so maybe that's what he is meaning with the size of the reverse clutch.
Make sure he updates and or replaces the low reverse sprag assembly too, use the one with the plastic cage for the E40D/4R100.
Laughing Gas
Joined: Sep 2013
Posts: 1,116
Likes: 103
From: North Idaho
You can get "stepped" pressure plates for any of the clutch packs, I got mine from Broader Performance. You will likely need a different thickness snap ring to correct clearances once you start changing things, but you won't know for sure until assembly.
FTE Emeritus
Joined: Jan 2006
Posts: 2,288
Likes: 200
From: springfield Missouri area
From what I was told, 20 years ago or so. The early c-6 had the bigger drums. If I remember right it was pre 73 c-6's. I used to get them out of my derby cars of the 70-71 vintage with the 429's.
disclaimer, old memories could be incorrect.
disclaimer, old memories could be incorrect.
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