4L80E build

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With 90 psi of clean shop air applied to the center support bolt port it takes an 11 count for the air to bleed off and the piston to reach its fully relaxed position after air supply is stopped.

Sound ok?
 
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I used the CLinbarger method of plugging the center support. The closest ball I could get at the bearing house was 9/32 so I bored in .125" @ .281 and then necked the bore down to H. I red'd it in and did 3 internal punch marks. Nice interference fit.
FYI I cleaned up the top of the original bore and used gauge pins to figure out exactly what bore GM did and it's .251". I sourced some cup plugs that will work perfectly for this but they are hard to locate any stock.
I found 15, when I get them I'll send you some to try. They are a dorman part # 555-122
 
I need to run one by you here too.
I decided rather than use my hss drills I went to the machinist supply house and got all of these different sizes required in screw machine length cobalt to maximize strength and forgiveness . Well I more than likely miscommunicated the .055" and ended up drilling the direct drum centrifugal vent with a #55 (.052")
Ok?? Skeered to run a #54 in there because that is a good set up for breaking S.
 
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I set up the mill and gave it all I had to set up, measure and aim exactly for the transition corner @ 45 degree. The exit wound is about 5 thou high.... shame shame
 
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CLine .... so by reading into this the best seal is obtained with the lathe cut's and not the scarf cut's??
 
11 seconds sounds OK for air testing....You don't have a constant supply of ATF to lube the lip seals & the lip seals are new.
DO make sure the bleed orificed cup-plug on the back of the center support is open & free of debris!!.....Interesting fact, Early TH400's didn't have a intermediate clutch bleed orifice causing the first 1-2 shift of the day to be super soft.

I usually just straighten the Intermediate Piston return springs out with a pocket screwdriver after installing the retainer. But......I like the chamfer!!!!
ALL TH400's used the flat retainer with no spring guides. The 4L80E retainer is a flimsy POS & I've seen many warp enough to rub against the direct drum in service.
The springs won't coil bind in service as the Intermediate Clutch itself will limit the pistons travel.

.251" sounds right
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......A standard .250" checkball will have a slight interference fit right at the top of the bore & fall straight to bottom! Ask me how I know
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.052" will be fine for the Direct Clutch centrifugal bleed orifice! I definitely agree that trying to open it up .003" will result in a broken bit!!!!
*While we're on this subject....Another tech tip from the trans bench.....

I've ran across many Direct Drums that have to big a bleed hole drilled, Some being expensive aftermarket Aluminum.
TransGo SK-4L60E shift kits come with 2 .125" OD orificed cup-plugs for the Reverse Input Piston, That are only needed on 1993 models. They work great for fixing a hacked-up TH400/4L80E direct drum bleed holes.
Drill out the hole to .120" from the inside of the drum.....Leaving some material for the cup-plug to seat against.....Then drill out the cup-plug to the desired diameter after driving it in.
 
Originally Posted by P10crew
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CLine .... so by reading into this the best seal is obtained with the lathe cut's and not the scarf cut's??


They want you to use the Viton D-rings supplied in the kit, They supply the best seal over the widest temperature range.

TH400/4L80E units have used a wide range of materials over the years for Accumulator seals......Step-cut Cast Iron, Step-cut Aluminum, Scarf-cut Teflon, Solid Teflon, Polyacrylate rubber.....And Viton D-ring starting around 2006.
 
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Right at 50 thou. Ck piston in direct.

Yes bleed holes are open and clean in both drums and orrifaced cup plug is in place. Thanks for bringing that kind of stuff up! I can see that the need for attention to detail is going to increase exponentially as this progresses. One good thing is that at least now I can pick up any component of the rear half and know the name of the Part. Sheesh
Well I got the band in the case and all the rear seals in. I'm going to final assemble up to the center support snap ring, check rear unit end play one last time, clean this joint up, have some beers and put this to bed for the week.
Noticed that the belt is loose on my home made vibratory tumbler so gotta get that cherried out too.
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Couple more questions
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I looked in the parts books and can't locate this case to center support seal. Is this gm only?
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Which of these should I use?
 
That Case to Support seal is a TransGo part.

In real world usage.....The Plastic step-cut Center Support sealing rings work very well & maintain pressure against the Direct Drum longer than any of the designs.

When installed & sized correctly.....The one piece Teflon sealing rings give the best bench/air test results & give the best initial sealing when in service.

I'm running the Plastic one's in my personal 4L80E......
 
Ok thanks I think I'll run the plastic as well.

Did some searching and that case to center support seal is a 48270 used in the 200r4 and several others.
That was from ck. Well see if they are correct when I get them.
 
The 200-4R, TH200, TH325-4L have a floating Center Support necessitating a press-in seal, The TH400/4L80E with it's bolted design doesn't really necessitate a press-in seal.

Not that it will harm anything & can only help further seal the 3rd clutch apply circuit. I don't run them because I've always been able to trace a direct clutch failure to something else.

One could argue....Why do I plug the reverse passage in the Center Support if I'm not concerned about the 3rd clutch feed to center support interface leakage??

*The Center Support flexes/loads CCW.....Which will cause the Reverse feed interface to open up & 3rd clutch feed (If anything) seal better.
 
CLinebarger I pressed a cup plug into a junk center support. The interference is good but the plugs are not tall enough. They can easily can't in the bore. Fail!
For future reference can you tell be if the balls you are useing are 7mm.
 
Back on task
I am stacked up to the center support snapring.
Next step is to determine front end play correct?
If so can I empty stack all the way up?
 
Originally Posted by P10crew
CLinebarger I pressed a cup plug into a junk center support. The interference is good but the plugs are not tall enough. They can easily can't in the bore. Fail!
For future reference can you tell be if the balls you are useing are 7mm.


I'll get a measurement of a 700R4 TV Exhaust checkball tomorrow, I never bothered to measure them as they just "Work".

Originally Posted by P10crew
Back on task
I am stacked up to the center support snapring.
Next step is to determine front end play correct?
If so can I empty stack all the way up?


It's really up to you......As the Front Unit End-Play is controlled by the Thrust under the Pump.

You can go ahead final assemble the unit up to the Forward Drum......Omitting the 4th Clutch Housing during the check & adjust process.
*Leave the Outer Pump Housing O-ring off.
*It's advisable to leave the Turbine Shaft Sealing Rings off as well.....'til the end-play is checked & adjusted.
*Make sure the Paper Case to Pump Gasket is in place!
*Lightly snug the pump bolts & VERIFY you have some kind of end-play BEFORE you torque them to 18 ft lbs!!!!!
*Check end-play & readjust as needed.



TECH TIP........
The Turbine Shaft floats in the OD Carrier.
To make checking end-play easier....Shim the the space between the Turbine Shaft Snap Ring & the OD Carrier....To prevent the Turbine Shaft from moving vertically in the OD Carrier.
Make sure to remove the shim upon final assembly!
**I had to machine a shim as I couldn't find a suitable one laying around.

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Pretty sure they sent me the wrong part
No wave or dish 34127A is supposed to be .068 this one is .070 as well
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And I can make the stock wave stick under the broach.
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Bummer
 
Another snag that I failed to see prior.
In the msrk instruction it says to use 3 oem th 400 intermediate plates to reduce shock loading of the intermediate sprag.
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Is this the part he is referencing?
In my steel kit there is (4) .078 steels or is he instructing to use (3) th 400 frictions. Totally lost as to what I'm supposed to use and how many because if it's the frictions there is steels for 4. Please give me some direction as to the intermediate stack up. Thanks
 
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