4L80e Saturday challenge.
Just rebuilt my transmission during winter and just had a testdrive.
To my big disappointment it is slipping in forward gears. Moves and shifts but acts like a rubber band. Reverse is really firm!!
1992 case, red alto and kolene steels, Transgo HD2 kit and internally dual fed, fully rollerized, steel forward hub, case saver, new solenoids, bearings, seals, EZ-TCU, 3200 stall.
Drilled pump against seal blow out, strator against convertor drag, rear strator support and overrun clutch housing for better flow and finally direct drum to prevent centrifugal apply. HD2 Separator plate drilled to 2nd: 0.11inch, 3rd: and 4th: 0.125inch
Omitted 3rd clutch and reverse checkballs.
Rear end play 0.1 mm, front 0.2 mm. All clutch pack plays within spec.
80% sure intermediate sprag is in right direction...
Pressure according to picture, when increasing pressure in TCU 3rd and 4th increases as well. Most things checked more then twice..
Any suggestions before I start splitting it again..

 

I have heard of some super knowledgeable experts in this forum. @MaroonMonsterLS1 beeing one of them. Any ideas on above?

 

So you installed the full HD2 kit with the Transgo separator plate and did the direct drum/valve body mods for internal dual feed? If so, you created a leak and is likely your problem.

 

Thanks @BigKID!
Yes, I have done both!
An experienced Swedish builder says he builds his 4L80e’s like that.
Don’t understand how he does differently, just talked to him and he still claim it should not be a problem with both... really trust the guy too.
I questioned it myself and you are the second person to highlight that. I will put the old separator plate back and test it.
Can I use a pre 94’ separator plate or are any mode needed to that plate?

Thanks for your input!!!

 

I did some research on this last year when rebuilding mine. I used parts of the HD2 but dual feed the directs internally as that is what the consensus from the builders on Tech as the better method. IIRC, the HD2 separator plate redirects fluid from the reverse circuit to dual feed the directs in forward so be sure to replace the check ***** removed for the HD2 as well when installing a stock separator plate. It was also recommended to NOT use the pressure relief from the HD2 kit as it has a tendency to leak.

 

I have also researched this for days but still missed this one.. I don’t have a checkball in either 3rd or reverse. HD2 kit instructs to remove the reverse one and jakes recommended removing the 3rd. Did you keep them all in there?
Did you go with the HD2 boost valve and still skipped the pressure relief valve? Read that many use the sonnax self adjusting one instead, same as having the relief.. I have the HD2 boost valve and I am unsure if that one requires a relief?

 

I installed all 8 check *****. I would have to look back at my notes to confirm but I believe its a HD2 boost valve and Sonnax TCC valve.

 

Ok, thanks! I’ll go for all eight then!
Just dropped the pan, what do you think about this? Too much or worth a try?

 

Put the VB back today with stock separator plate, all eight check *****.

On the test drive it started out good, manual second is nice and firm! Rubber burns instead of clutches.

Still slipping when starting in 3rd and 4th thou. Almost like it wants to slip start from 3rd gear or something.



I dared to take it up in speed for more tests.

I can’t get it into 1st, it starts in second. EZ-TCU controller says 1st but I feel no shift when moving shifter from 1st to second at higher rpm.
It shifts nice and firm when shifting manual positions, 2nd to 3rd and later to 4th and lock up.

Once in 3rd or 4th at speed it seems quite responsive as well.

Checked pressures during shifts, 170-180 psi, not drops, even when slipping.



Any ideas?

 

Took the transmission out and disassembled it today.
I can’t find anything that might cause this. Any expert that can help me figure this one out? @MaroonMonsterLS1

All clutches and steels look fine. Measured the direct and forward clutch pack clearances and they were about 0.012inches from what they were when they went in.

So, missing first in manual low, starting in second. Not staring in first gear in gear selector 3 or D as well as slipping.

Have pressure and do have air tight clutches.

Experienced some leak in the direct, my drilled hole for the centrifugal apply fix leaked, I punched that together to rule that one out. The ball valve might have been slightly leaky.



I don’t dare to believe that was is so I did some testing on the valvebody circuits.

All electronics but the harness is new and the solenoids are tested. All sprags are in right direction.

I assembled only the VB and servos to the case. I put air supply to channel 2 in the case and blocked of some other passages leading to the pump.
If I understand it correct passage 2 should be oil supply. With this I tried running thru all shifting options with the solenoids.


P/N seemed to work fine. No difference on solenoid A energized.


Reverse worked with both reverse band pin moving and direct air in the case. Solenoid A did not do any difference.



D, when both solenoids off, forward clutch air, intermediate applied.

When energizing solenoid B direct applies.

When energizing solenoid A, nothing happens.

When energizing both, same case as for solenoid B energized.

Solenoid A is just clicking and sitting the solenoid leak but nothing happens..


​Same for the other gear selections and combinations. Including manual low where front band and intermediate stay applied and rear band unapplied even if solenoid A is energized.

Is this a valid test method and what could be wrong?

1-2 valve looks ok..

Super hard to find a valvebody in Sweden, otherwise that would be nice to test to rule that out.


If it weren’t for that I already had my driveshaft shortened I would go back to my TH400 now, can’t get it figured out and it is killing me.

Appreciate support and advice!