Clearance with dry vs wet clutches

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I've been wrong before (just ask wife), the only way to creep forward when in park or neutral is from the forward clutch pack due to its driven by the input shaft. possible due to the 5th plate you added is binding on inner spline hub?
 
FIVE?!?!? Okay...it's like this....time to buy some pla-doh and check drum and clutch to drum clearance. I prefer the green, but that's only cuz I'm a transmission magician.. THe front ring gear hub might be pressing on the forward clutch; engaging it. JUST LIKE moparlvr166 says. Four forward red eagles is PLENTY. They're (5) needed in the front drum. .061's
 
moparlvr166 said:
I've been wrong before (just ask wife), the only way to creep forward when in park or neutral is from the forward clutch pack due to its driven by the input shaft. possible due to the 5th plate you added is binding on inner spline hub?
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CudaFactHackJob said:
FIVE?!?!? Okay...it's like this....time to buy some pla-doh and check drum and clutch to drum clearance. I prefer the green, but that's only cuz I'm a transmission magician.. THe front ring gear hub might be pressing on the forward clutch; engaging it. JUST LIKE moparlvr166 says. Four forward red eagles is PLENTY. They're (5) needed in the front drum. .061's
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There are five clutches in my front drum, four in the rear drum. I know it's confusing because the rear drum is the forward drum. I try to stick with "front" and "rear" for the clutches/drums but I might have slipped up somewhere in this thread. The clutch configuration is OK though.

CudaFactHackJob said:
Is the belleville spring putting pressure on the piston? Or does the direct engagement hub just sort of flop around?
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The clunking I mentioned is caused by 0.020 play between the clutch retainer and the piston retainer. They slide on the splines as intended. There is no play between the belleville spring and the piston.
 
The belleville spring retains the piston; the retainer spacer ring and a waved retainer ring retain the belleville spring in the drum; against the piston. How can you have .020 slop if the belleville spring is against the piston? What is a clutch retainer? What is a piston retainer?
 
CudaFactHackJob said:
The belleville spring retains the piston; the retainer spacer ring and a waved retainer ring retain the belleville spring in the drum; against the piston. How can you have .020 slop if the belleville spring is against the piston? What is a clutch retainer? What is a piston retainer?
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Terminology from the FSM

1671279381611.png

The drum slides on the teeth. The belleville spring is as it should be, pressing on the piston.
 
I bet mine has the early belleville spring and it's original to this 1970 transmission. Probably inverting under pressure.

I am hopeful.
 
That's some good information. But your added assumption that the drum slides on the splines is where you get into trouble. It FITS on the splines but isn't supposed SLIDE.
 
That video is WRONG. You can't go switching around springs. He even admits that he isn't familiar with other thickness stock pistons. I have to stock both early and late springs to replace the ones that a previous guy installed. PLUS; if your spring INVERTS, that's just proof that the clutch clearance was WAAAY to loose to begin with; or that oem parts were mismatched. The only take away from the video is that loosness is bad and you have to go with aftermarket pistons...but he doesn't tell you that if somebody switched springs; that that will cause looseness. The spring has to match the piston...early with early and late with late.
 
CudaFactHackJob said:
That video is WRONG. You can't go switching around springs. He even admits that he isn't familiar with other thickness stock pistons. I have to stock both early and late springs to replace the ones that a previous guy installed. PLUS; if your spring INVERTS, that's just proof that the clutch clearance was WAAAY to loose to begin with; or that oem parts were mismatched. The only take away from the video is that loosness is bad and you have to go with aftermarket pistons...but he doesn't tell you that if somebody switched springs; that that will cause looseness. The spring has to match the piston...early with early and late with late.
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What causes the slop when the correct parts are used? I had 0.025" of slop with an early spring and piston and 0.048" with later piston and spring. Is it because the spring flattens out over time with use??
 
I have a few of each spring and I'll measure them to compare. When I get my new mill up and running, I'm going to try early/late piston/spring combinations and then mill each piston for perfect clearance. then the spring won't be too preloaded; and the piston won't be coming out too far. If that's not feasible, then I'll tig up the pistons. Or find a thrust washer with inner tangs to lock into the piston to take up the clearance. But, all things considered, I would rather put a spacer under the piston like some do on the th350 intermediate and run the proper clutch clearance, than have that extra slop in there; which contributes to a delayed forward clutch engagement. That might cause extra wear. I don't see how ordering a new piston without having exact clearance knowledge beforehand..wouldn't accidentally preload the spring so much so that it can more easily reverse itself. As it stands now, placing a spacer under the piston of the exact thickness seems to be the best quickest solution. I would prefer .025 on the early over .048 on the late. Thing is, the early springs seem to have a rep for breaking more easily. But if I do find a lot of variation in the spring heights, I'm going with the deeper ones. It's a shame that the extra piston/spring clearance doesn't contribute to extra clutch clearance.
 
CudaFactHackJob said:
I have a few of each spring and I'll measure them to compare. When I get my new mill up and running, I'm going to try early/late piston/spring combinations and then mill each piston for perfect clearance. then the spring won't be too preloaded; and the piston won't be coming out too far. If that's not feasible, then I'll tig up the pistons. Or find a thrust washer with inner tangs to lock into the piston to take up the clearance. But, all things considered, I would rather put a spacer under the piston like some do on the th350 intermediate and run the proper clutch clearance, than have that extra slop in there; which contributes to a delayed forward clutch engagement. That might cause extra wear. I don't see how ordering a new piston without having exact clearance knowledge beforehand..wouldn't accidentally preload the spring so much so that it can more easily reverse itself. As it stands now, placing a spacer under the piston of the exact thickness seems to be the best quickest solution. I would prefer .025 on the early over .048 on the late. Thing is, the early springs seem to have a rep for breaking more easily. But if I do find a lot of variation in the spring heights, I'm going with the deeper ones. It's a shame that the extra piston/spring clearance doesn't contribute to extra clutch clearance.
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Looks like A&A sells them in different thicknesses as does CRT.

1671389145277.png



I ended up measuring the slop in mine with a new later-style belleville spring using a dial indicator. I picked up a 0.850" thick piston from CRT for like $90. That eliminated the slop completely and only amounted in minimal preload.

Seems like using the deeper earlier spring and later thicker piston, then milling it accordingly would be a slick way to do it. Only thing then is you're stuck with the weaker design of the early spring. Not sure how common this is:

Busted%20Bellevilles.jpg


Here's a video by John Cope addressing this topic as well. Looks like he sells a spring kit for use with the earlier thinner piston that removes all of the slop as well.

 
Duster346 said:
For building these since 1980 you sure don't know jack ****, do ya?


Why not?
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CudaFactHackJob said:
I rebuilt a C4 for a guy one time. He called and said it didn't work; wouldn't even move. He said he revved it and nothing. Had a new torque converter he bought off a buddy... So he brings the trans back along with the converter. I said where's the converter? He picks it up out of his trunk with one hand; like an 8" donut...5k stall...His old worn out 302 two barrel couldn't even rev high enough to hit stall.



:rofl:


CudaFactHackJob said:
What rpm do you think a 5k stall should engage
 
As for the original topic of this thread, it sounds like a hydraulic problem, and I would be looking closely for cross leaks in the forward clutch circuit. This will include the valve body (also verify manual valve position), and the stator support that is bolted to the pump.

As for my video that was posted above addressing the inherent play in the input assembly on all 727, 518, 618, 46, 47 and 48RE until model year 2007.5, the general rule of thumb with the later 1/2 moon style Belleville spring, is an .875" tall piston for the 727, 518, 618, 46 and 47 forward clutch drum, and the .850" tall piston for the 48RE (hemi style) forward clutch drum retainer. The best way to do it, and for a perfect fit, is to start with a .900" tall forward apply piston and cut it to your desired height in a lathe.

On the Belleville spring, they went back to the early spring in the overdrive units, and I have an updated video that talks about that as well. You'll want to use a new Chrysler spring or a used Chrysler spring in good condition. The aftermarket Bellveille springs I've used in the past have all flattened.

Thanks for reading,

Chris Andrews
Andrews Racing Transmissions
720-939-0183
andrewsracingtrans.com
facebook.com/andrewsracingtrans
 
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Duster346 said:
On the Belleville spring, they went back to the early spring in the overdrive units, and I have an updated video that talks about that as well. You'll want to use a new Chrysler spring or a used Chrysler spring in good condition. The aftermarket Bellville springs I've used in the past have all flattened.
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What are the symptoms of a flattened belleville spring? I used what in all likelihood is an aftermarket one in my 727 and I'm hoping I don't have any issues down the road.
 
Despite the enormous amount of misinformation that is posted in this forum section by a certain individual, the excessive play has nothing at all to do with forward clutch pack clearance and everything to do with spring to piston clearance. And also, everything to do with total unit end play.

You likely won't notice the problem until it gets bad enough and the apply piston comes out of the bore, and then your forward clutches will be applied at all times. Again, with the piston popping out of the bore and inverting the spring, this is most common with high pressure valve body (up to 215 psi) racing transmissions.

In a stock application, with 70-80 psi line pressure in forward gear, you aren't even going to notice anything from the inherent excessive play. This is something that needs to be addressed in all racing and performance high pressure valve body combinations. It is also addressed in all of the diesel transmissions that we build.
 
Duster346 said:
Despite the enormous amount of misinformation that is posted in this forum section by a certain individual, the excessive play has nothing at all to do with forward clutch pack clearance and everything to do with spring to piston clearance. And also, everything to do with total unit end play.

You likely won't notice the problem until it gets bad enough and the apply piston comes out of the bore, and then your forward clutches will be applied at all times. Again, with the piston popping out of the bore and inverting the spring, this is most common with high pressure valve body (up to 215 psi) racing transmissions.

In a stock application, with 70-80 psi line pressure in forward gear, you aren't even going to notice anything from the inherent excessive play. This is something that needs to be addressed in all racing and performance high pressure valve body combinations. It is also addressed in all of the diesel transmissions that we build.
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Thank you for the detailed response. I'm using a RMVB CRT valve body, which I believe is around 170? psi. Hopefully this belleville spring holds up. If not, it looks like there's plenty of fixes, so it's not the end of the world.
 
I don't like words like "minimal". Mopowers, what was the actual measured preload? I ask because any amount of preload is that much closer to inversion. I think I'd rather have play than preload. I can't spend $100 extra on rebuilds then mill every piston as well. As long as the clutch pack isn't overly loose, then spacing under the piston won't result in the piston coming up out of the bore. I just don't like the idea of that clutch retainer ( l learned new words) flopping around.
 
OK, I watched both videos, and wondered if the piston/belleville would cause my car to creep in neutral without having popped the piston seal out? It was totally normal other than the play in that assembly.
 
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