Author Topic: 391 FE + Iron Tailhousing C6 on FB  (Read 513 times)

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drdano

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391 FE + Iron Tailhousing C6 on FB
« on: September 17, 2026, 10:31:42 AM »

galaxiex

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Re: 391 FE + Iron Tailhousing C6 on FB
« Reply #1 on: September 17, 2026, 07:10:31 PM »
Just a caution to get more pics if you are interested in the C6 with the iron tail housing.
It looks like short cast iron bolt on yoke truck extension housing, it's not the same as a CJ slip yoke iron housing.
Every 20 minute job is 1 broken bolt away from becoming a 3 day ordeal.

pbf777

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Re: 391 FE + Iron Tailhousing C6 on FB
« Reply #2 on: September 18, 2026, 11:10:43 AM »
     But, it should still have the "4-pinion" planet and the "4/5-plate" clutch drum.   :)

     Scott.

galaxiex

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Re: 391 FE + Iron Tailhousing C6 on FB
« Reply #3 on: September 18, 2026, 07:18:55 PM »
     But, it should still have the "4-pinion" planet and the "4/5-plate" clutch drum.   :)

     Scott.

True that Scott, "most" FE truck units have the 4 pin rear planet.
Some only got the 3 pin. 1/2 tons mostly.

I've never seen one with the 5 plate drum. Not saying they don't exist. Probably only in the FT units.
Not the "regular" FE light trucks.
Most have the 4 plate drum and some were built with the 3 plate.

Heck I once built a 66 T-Bird C6 that had never been touched before, and it had a 2 plate direct drum.
Up to that point I didn't know there was such a thing.
That was in the 80's and I was shocked that such a heavy car would have that.
It was "only" a 390 car... but still... a 2 plate direct drum??? what was Ford thinking.

Never seen another since...
Every 20 minute job is 1 broken bolt away from becoming a 3 day ordeal.

pbf777

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Re: 391 FE + Iron Tailhousing C6 on FB
« Reply #4 on: September 21, 2026, 12:08:10 PM »
I've never seen one with the 5 plate drum.


     What I meant by the: "4/5-plate" was that it's a "4-plate" that you swap-in the bevel plate and convert to a "5-plate".   :)

     Scott.

galaxiex

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Re: 391 FE + Iron Tailhousing C6 on FB
« Reply #5 on: September 21, 2026, 12:41:26 PM »
I've never seen one with the 5 plate drum.


     What I meant by the: "4/5-plate" was that it's a "4-plate" that you swap-in the bevel plate and convert to a "5-plate".   :)

     Scott.

OIC, I actually never liked that mod, tho I have to admit, it does work.
Cheap and easy, doesn't mean it's bad, it works.

These days there are arguably "better" solutions.

ALTO makes a "PowerPack" for the direct drum where you can get as many as 7 or 8 friction plates in a 4 plate drum.

I have also cut a new snap ring groove in a 4 plate drum, to get 5 plates using normal factory type frictions, steels and (thick) pressure plate.

The ALTO PowerPack uses very thin steels, frictions, and pressure plate to get more in the drum.

To really step up the game you can get a Billet drum $$$$ that holds more too.

I've built some 1000 HP pulling truck and mud bogger 460 based C6's using the billet parts.
Forward drum, direct drum, input shaft.
Nice stuff if you can afford it.

Sorry for the OT ramble...
Every 20 minute job is 1 broken bolt away from becoming a 3 day ordeal.

pbf777

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Re: 391 FE + Iron Tailhousing C6 on FB
« Reply #6 on: September 21, 2026, 04:09:55 PM »
Cheap and easy, . . . . . . . , it works.

     Yep, it is, and it does!  ;D    Though, I've noticed that the "bevel" plate will cup more so than the "thick" plate (probably why Ford didn't do it!).  :(

Quote
I have also cut a new snap ring groove in a 4 plate drum, to get 5 plates using normal factory type frictions, steels and (thick) pressure plate.

     But it's just that placement isn't really optional so you have to consider the stacking and the placement movement with wear, as it 'is' possible to have a steel catch on the old grove!    :o

Quote
ALTO makes a "PowerPack" for the direct drum where you can get as many as 7 or 8 friction plates in a 4 plate drum. The ALTO PowerPack uses very thin steels, frictions, and pressure plate to get more in the drum.

     I like this "idea", except where/when slippage exists, because the thin steels can't absorb as much heat as the thicker examples, so they'll likely suffer blueing and warp sooner!  Also, I've had instances where even thicker plates are split/broken so . . . . . .   And the frictions (steel carrier) can't be any thinner as I've had the inner-splines just roll-formed outward and disengaged from the hub.   :o

Quote
To really step up the game you can get a Billet drum $$$$ that holds more too.  Nice stuff if you can afford it.

     Yes, this 'is' the correct process, . . . . . . "if you can afford it"!    ;)

     But my experience is from a long time ago, before all this new-fangled stuff was available;  heck, we used to weld reinforcement strapping to the O.E.M. drum to try and keep it from expanding!  Of course later we started stripping the "low/rev." plates out of the aluminum case!   

     You just can't win!   ::)

     Scott.
« Last Edit: September 21, 2026, 04:12:01 PM by pbf777 »

galaxiex

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Re: 391 FE + Iron Tailhousing C6 on FB
« Reply #7 on: September 21, 2026, 08:54:56 PM »

Quote
I have also cut a new snap ring groove in a 4 plate drum, to get 5 plates using normal factory type frictions, steels and (thick) pressure plate.

     But it's just that placement isn't really optional so you have to consider the stacking and the placement movement with wear, as it 'is' possible to have a steel catch on the old grove!    :o


That can happen if you are not "careful" where you cut the snap ring groove.
On a 4 plate drum, you have just enough room to cut the groove for 5 plates, BUT...
You MUST use a factory thick top pressure plate.
That plate "covers" the lower 4 plate groove and there is no danger of having a steel plate get caught in the groove.

The general "rule of thumb" is...

You can cut a 4 plate drum to get 5 factory type plates in with a factory thick top pressure plate.

You can cut a 3 plate drum to get 4 factory type plates in also with a factory thick top pressure plate.

You CANNOT get 5 plates in a 3 plate drum with factory type plates. Or any type plate for that matter...

If you try to cut a 3 plate drum to get 5 plates...

You WILL have a problem with one of the steel plates getting caught in the original 3 plate snap ring groove.


Also beware there are some factory drums that have 2 grooves already cut.
The lower groove for 3 plates and the top groove fits 4 plates.
If you have one of those, you're stuck, you cannot get 5 plates in it.
That lower 3 plate groove limits you to 4 factory plates max.


Quote
ALTO makes a "PowerPack" for the direct drum where you can get as many as 7 or 8 friction plates in a 4 plate drum. The ALTO PowerPack uses very thin steels, frictions, and pressure plate to get more in the drum.

     I like this "idea", except where/when slippage exists, because the thin steels can't absorb as much heat as the thicker examples, so they'll likely suffer blueing and warp sooner!  Also, I've had instances where even thicker plates are split/broken so . . . . . .   And the frictions (steel carrier) can't be any thinner as I've had the inner-splines just roll-formed outward and disengaged from the hub.   :o


Good point about the thin plates, they "can" overheat and warp. However...

I build 4R100 diesel units that have a factory 5 plate drum. (no you cannot swap that drum into a C6, I've tried)

When a customer requests a "HD" 4R100 build cuz they are gonna be towing heavy, and/or boosted the power on the 7.3L IDI... then...

I use the ALTO PowerPack and get 8 plates in the direct drum.

In 7 years of building these HD 4R100's I've never had one fail from having the thin frictions and steels.
The ALTO plates are hardened, both friction core internal splined steel and outer splined steel.

They will pound "notches" into the clutch hubs before the splines fail.

As far as warpage... they just don't.
If the clutch pack slips enough to cause heat warpage of the thin plates,
you have other problems that are causing the slippage in the first place.

That all said... the first time I saw those thin ALTO plates I thought..

"Oh boy, here we go... thin plates are gonna warp" but time has proven them to be very reliable.

And that said... there "are" other thin plates out there for other units, and they "do" have a warping problem.

Not the ALTO ones for the C6 and 4R100.
The increased friction surface area seems to be able to take the heat and provides more/better holding power.


YMMV
« Last Edit: September 21, 2026, 09:01:34 PM by galaxiex »
Every 20 minute job is 1 broken bolt away from becoming a 3 day ordeal.