4l80e rebuild on a suburban

Joined
Feb 26, 2018
Messages
68
Location
AZ
I have a 1995 suburban 4wd with a 4l80e and 454 engine.
Long story short I bought it cheap and decided to rebuild the engine and tranny. Engine had broken vales.
Engine is rebuilt but since I pulled the engine/tranny/tcase , I decided to rebuild the tranny too.

On the transmission I decided to keep it cheap and do a stock rebuild with transgo SK 4l80e shift kit (not the HD2) – this after doing much reading.
Well I put the whole assembly together (without the valve body) and continued to keep reading the forum subjects.

And now the dilemma:

After even more reading, I think all I should do now is just rollerize the output ( I already have new frictions, steels and bushings all pressed in) and call it a day.

Unfortunately during the rebuild days I did the following (all of which I wish now that I did not do)

Had the 3 pump modifications done
1) Under "X" drill a 3/64 (.042 - .055) hole thru side of wall in direction of arrow
2) enlarge the seal drain back hole in the pump cover with a .250” drill
3) used the new boost valve & spring supplied

I also drilled one of 2 holes in the valve body
1) Transgo pressure relief valve – drilled
2) Drill the hole in the valve body between the torque signal and "void" passages, it is a side wall – not drilled yet


So the question is can I leave the pump mods as is and get a valve body that Is not messed up ? Or do the pump mods have to go with the valve body mods?

I would prefer to go with the dual feed direct clutches after having gone in this deep, but then again I read a quote from Clinebarger that
“Dual Feeding the directs is a fantastic modification.......On rigs making north of 450 horsepower!! I rarely do this mod on a heavy duty unit, It is just not warranted.”
The suburban is only 230hp!

Any ideas how I can seal that valve body hole? (the one drilled for the pressure relief)

Thanks
 
Drilling the "Lube to Line" bypass in the pump cover is a GOOD modification, As is drilling the Drain hole in the pump body!

If you only drilled one of the holes for the pressure relief.....You don't need to plug anything, The "Void" doesn't lead anywhere 'til you drill through the partition. Runaway line pressure is caused by Boost Valve Sleeve wear, The Trans Go SK-4L80E boost valve assembly is OK.....Though I like the Sonnax 4L80E-LB1 better.
There are some other contributing factors to runaway pressure like Pressure Solenoid issues & PCM issues (Especially the PROM PCM's like yours).
Always replace the EPC, If the EPC harness connector is discolored where the terminals are.....That means the terminals have been hot, Replace the harness!

I highly recommend rollerizing the Output! Measure the "Rear Unit Endplay" before disassembly.

Dual Feeding the Direct Clutch slows down reverse apply & release, Apply can be sped up by opening up the Direct Clutch reverse apply orifice. The release (Even with high rate springs) will always be slower than before because your blocking one of the exits for the ATF.
It is a MUST to run higher rate return springs for the Direct Clutch, Aids in knocking the Directs "Off" faster, Cleaner 3-2 downshifts, Helps prevent centrifugal/residual apply of the Direct Clutch.

Dual Feeding alters the 3rd "Clutch Fill Volume" by 200%, Add in the High Rate springs......3rd gear apply can be hundreds of RPM later than they were at WOT! If you have a way to tune shift points in the PROM, This is a moot point.

IF your willing to spend the money to do it right (Aluminum TH400 Direct Piston, Retainer & High Rate return springs) And also live with the Reverse apply/release issues (Wait for the Directs to fully come "ON" & "Off")......Go ahead & dual feed!

How do the Direct Frictions look anyway?
Does this unit still have the Aluminum Pistons in it?
 
Last edited:
Originally Posted By: skyactiv
I'd have to look at it, but maybe you can use JB Weld.
I don't know anything about a transmission. But JB Weld sticks great to aluminum. Let it cure 24 hrs and you can drill it or grind the excess off to a smooth surface. Whatever you do please post a follow up.
 
I have used JB weld before and I think it will work. But I hate the thought of that nugget just chipping off one day. All the place I use is where I can see the fix. This would be inside and I would never know.
I am trying to post pictures, not sure how. Do I just drag them into the post?
 
zuxPa


hopefully the images I added does not blow up
 
It is only about 0.13 inch thick, was not too sure how many threads I can get on it.
 
The frictions looked ok to me. This is my first time on this so I do not really know. They are not cracked or appear thinner than the new ones except for that scarring on one of them in the picture.


"If you only drilled one of the holes for the pressure relief.....You don't need to plug anything, The "Void" doesn't lead anywhere 'til you drill through the partition." - Are you sure? See the picture I sent.

The harness just tore apart when I took it apart - so i am using a new one.

One I can get some pictures through it would be easier to communicate.
 
Why don't you just give their tech support number a call? One of their guys Larry lives in AZ. I have found them very easy to deal with and will set you in the right direction.
 
who's tech support - Transgo?
I don't really want to. I am sure many can testify to their kits. For all I know , I could be trouble free just proceeding with their mods. But after reading more on the forums, I just decided against the mods on the valve body.
 
Yes the unit has aluminum pistons.

Is this the "Aluminum TH400 Direct Piston, Retainer & High Rate return springs"? It is $80, I am ok with that
http://www.ckperformance.com/View/4L80E-...SPRING-ASSEMBLY

No other springs to change for the dual feed mod?

The dual feed mod from what I read is
1) Take the sealing ring at the second from the top of the center support and leave it off
2) Disassemble the direct drum take sealing out from inside of drum (not piston)
3) 3/8" cup plug and plug the hole to the right of the center support bolt as seen from case valve body
4) take a 0.030" drill bit and drill a bleed hole on the edge of the drum.


What do you mean by "live with the Reverse apply/release issues (Wait
for the Directs to fully come "ON" & "Off")"
I am trying to imagine this.
 
Originally Posted By: kawan

Is this the "Aluminum TH400 Direct Piston, Retainer & High Rate return springs"? It is $80, I am ok with that
http://www.ckperformance.com/View/4L80E-...SPRING-ASSEMBLY
YES

No other springs to change for the dual feed mod?
NO

The dual feed mod from what I read is
1) Take the sealing ring at the second from the top of the center support and leave it off
2) Disassemble the direct drum take sealing out from inside of drum (not piston)
3) 3/8" cup plug and plug the hole to the right of the center support bolt as seen from case valve body
4) take a 0.030" drill bit and drill a bleed hole on the edge of the drum.
You got it!


What do you mean by "live with the Reverse apply/release issues (Wait
for the Directs to fully come "ON" & "Off")"
I am trying to imagine this.


When shifting to reverse.....Wait for it to FULLY latch-up, It doesn't take forever...Just longer than stock.
When shift from reverse to drive....Wait for the directs to fully come off, Again it's not long (@ 1 second).

If your not patient, The direct frictions will become distressed & eventually burn up! Folks that tow a lot/back trailers, Get the vehicle stuck, Or plow rarely have patience.
 
Last edited:
Originally Posted By: Fred_Garvin
Why don't you just give their tech support number a call? One of their guys Larry lives in AZ. I have found them very easy to deal with and will set you in the right direction.


The pressure relief valve is known to leak Torque Signal pressure causing burnt frictions.
 
Originally Posted By: kawan
Yes the unit has aluminum pistons.


The early aluminum 4L80E piston can fracture, I would replace the forward piston with a Steel/Bonded '97 & up version, The CK kit will take care of the direct piston.
 
Ok. Thanks! I think I can be patient for reverse apply & release .

What about the hole I drilled in the valve body as pictured? Leave it as is or plug it?
 
You only drilled one of the holes, Correct?....If so, You don't have to plug it. The passage you drilled into is a "void".

Here is the Direct Clutch Reverse feed orifice, Drill it out to .093".....This will quicken the reverse apply without making it overly harsh by removing the checkball like most builders do.

cl8W83Q.jpg
 
Yes only one hole is drilled - the one shown (2 pictures showing the same hole)

Thanks for the separator plate picture. I will post when I get to that stage.

"forward piston with a Steel/Bonded '97" - Are the 97 year forward piston come in all steel/bonded only or do they come in aluminum as well? I tried searching for them but they do not mention if it aluminum or steel. I assume they will fit for the 95 4l80e.

Should I get a new center support bolt? I had one new one but I torqued it to specs when I fitted all the assemblies into the case. That is when I read about rollerizing and took it all apart again.
Should I also avoid the new transgo 4th clutch housing bolt and just use a new stock one?

Thanks!
 
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