727 Rebuild. Front clutch hub piston question

[DWinTX]

Hi guys,

I rebuilding my first transmission, an early (65) 727. I am to the point of putting the front clutch hub together and I'm having some trouble getting the piston in with the new seals. I'm using Carl Munroe's book and he suggests using a product called Door Ease to lube the outer seal, but I can't find that locally. There are a series of YouTube videos on rebuilding the 727 and he recommends putting the piston in the freezer for 15 minutes. I'm trying that, but I was wondering if anyone has any tricks that helped them do this.

When I pulled the hub apart, the outer seal was twisted in the groove. Don't want to repeat that.

 

[mopar 3 B]

I use the same transmission fluid it will operate on for assembly. Try working the outer seal in with a thin fellers guage.

 

[miller]

Or hunt down a local tranny shop. A decent trans shop will have a 'trans assembly lube', that will make getting things together a lot easier. Have even used a wipe of vasoline, in a pinch. Want something that will mix with the fluid okay.

 

[dvw]

I use a large zip tie around the seal then put it in the fridge foe 15 minutes. Lay the piston in and start the inner seal around the center. Then get a 4x4 block of wood. Holding the piston with your thumbs and the drum in both hands tap the drum down against the 4x4. The force of the impact will slide the piston in. After you get the hang of it it works well. I've tried all types of lubricants, none are any better than the other.
Doug

 

[moper]

Use assembly lube, or vaseline on the seal. I don't freze them. Just take a sharp seal pick or dental pick and carefully walk the outer seal in while gently rocking the piston. Once the whole outer seal has made it onto the bevel in the housing, it will go in easy. The inner seal goes over the hub no problem.

 

[DWinTX]

Doug, thanks for the tip on the zip tie. That did the trick.

 

[dvw]

Use assembly lube, or vaseline on the seal. I don't freze them. Just take a sharp seal pick or dental pick and carefully walk the outer seal in while gently rocking the piston. Once the whole outer seal has made it onto the bevel in the housing, it will go in easy. The inner seal goes over the hub no problem.

Would you like to explain how you walk the seal in in a 727 high clutch piston when it's buried under the top of the piston? They do not all go in "easy".
Doug

 

[spenceryoung]

Need help I have a 72 charger se with a 727 transmission and the front clutch isnt coming apart easily is there something I'm doing wrong

 

[747mopar]

I've used thin slick cardboard or plastic lubed up to form a funnel that compresses the seal as it's pushed in. This was on a Chevy, don't recall having any issues on the 727? Glad to hear you got it.

 

[moper]

Would you like to explain how you walk the seal in in a 727 high clutch piston when it's buried under the top of the piston? They do not all go in "easy".
Doug

When did the OP ask about the high gear piston?

On those the trick is I keep the actual seal in my pants pocket while I'm doing other stuff. Then when it's body temp, I install it, use a good amount of lube on the seal and the drum, and install the piston in the clutch drum. By gently pushing down while rocking alternately on opposing sides and twisting slightly back and forth they go in really easy. Every time. I've only done around 30 over the years so your results may vary. But I've never had a problem with one, and the "pocket heat" deal was taught to me by my tech school instructor.

 

[dvw]

When did the OP ask about the high gear piston?

On those the trick is I keep the actual seal in my pants pocket while I'm doing other stuff. Then when it's body temp, I install it, use a good amount of lube on the seal and the drum, and install the piston in the clutch drum. By gently pushing down while rocking alternately on opposing sides and twisting slightly back and forth they go in really easy. Every time. I've only done around 30 over the years so your results may vary. But I've never had a problem with one, and the "pocket heat" deal was taught to me by my tech school instructor.

You can not use any kind of tool mentioned earlier as the seal is buried under a 1/2" lip of the piston. Also it doesn't rotate more than .060" due to the lugs on the piston. I've done way more than 30. They can be a pain.
Doug

 

[AR67GTX]

This sort of sounds like trying to seat the disc brake piston seals on my 66 Corvette. After a recommendation I used a .020 flat feeler gage and it eased the lip of the seals into the bores without issue. The .020 is just thick enough to avoid sharp edges that might damage to seal.

 

[magvan]

I wrap it tight with electrical tape and throw it in the freezer for 15 or 20 min. Peel the tape, wipe it with green goo and put it together.

 

[moper]

You can not use any kind of tool mentioned earlier as the seal is buried under a 1/2" lip of the piston. Also it doesn't rotate more than .060" due to the lugs on the piston. I've done way more than 30. They can be a pain.
Doug

Yeah, I had my "Front" and "Forward" mixed up. My bad. That's why I mentioned the tools initially.
That being said, I've never had to use a freezer or tie wraps or wood blocks to install that piston. Get the seal pliable, get the bevel greased up, wiggle the piston within the confines of the luggs, and they always go right in. Myabe I'm just not in as much of a hurry.

 

[727]

To add to what Magvan said. I wrap mine with Teflon tape then wrap the Teflon tape with electrical tape and put it in the freezer. The Teflon reduces the need for clean up.
"If you give the hardest job to the laziest guy, you'll find the easiest way to do it"