Heavy-Duty 4L80E Torque Converter

[rustyk]

I think my torque converter clutches have crapped out; the TC was replaced 2 years ago when the tranny was rebuilt. Shoving an 8T motorhome around is tough.

Any suggestions on an aftermarket replacement?

[john8662]

Give Art Carr a call, they build TC's in house.

www.artcarr.com

Tell em John from Lubbock sent ya if you talk to Alan.

J

[rustyk]

Thanks - I've bookmarked it (currently on the road) along with TransGo.

[Robyn]

The good aftermarket converters can be purchased with a heavier lockup clutch.

One of the biggest killers of the lockup clutch is the "Pulse width Modulation" programing used to engage the clutch.

The ECM basically bumps the pressure on and off until the speed of the converter pump and turbine are the same then finally fully applies the thing.

This method of locking the clutch is a real stupid mistake as it wears the clutch out fairly quick with all the extra slippage.

Transgo shift kits can be set to apply the clutch real firm and all at once.

The Heath Power chips also do this, only in a different way.

When the truck hits 43 MPH CaWhooomp the clutch is on, right now and its fairly abrupt.

GM has always errored on the side of soft mushy shifts to try and please the whiners that complain.

If you get a fresh converter, be sure that the programing is also changed to get that thing hooked up solid and right now.

The best converter clutches are the new KEVLAR material.

I am not sure if a Multiple disc clutch is available for the 4L but you should ask.

Get a heavy duty stator if its available.

Be sure that the pump and turbine blades are welded too.


This area is one place that needs attention. The blading in stock converters are not welded and they wiggle and over time can break loose. This wiggling also creates a lot of extra metal junk that contaminates the fluid.

If you can get the builder to install a drain plug in the converter, this is a good thing.
Then you can actually do a full fluid change on the thing.

Back in the old days, we could do a fluid change in under an hour and actually drain the whole tranny. Wow what a concept.

With a failed converter clutch comes the need to yank the tranny out. I personally would take this time to have the box pulled apart and freshened up.

The failed clutch will literally fill the thing with chewed up clutch lining and then metal shavings from the clutch plates chewing on each other.

Flush the cooler real well and install a return line spin on filter.

The cooler will never be totally free of crap even after a flush, so the filter will handle any junk that comes out later.




Good luck, keep us posted on whatcha get.


Missy

[ronniejoe]

I installed a Suncoast converter in my transmission. It has a machined front cover and increased capacity clutch. They were/are working on a multiple disk clutch. Don't know if it is done yet though.

[Robyn]

Ron

Is that the "Billet" front cover ??? I have heard good things about those.

The ability to have multiple disc clutches depends on the amount of room that is available inside the converter itself.



Robyn

[rustyk]

Also been looking at TCI (also here).

My problem may be imaginary, as I got the radiator pretty well crudded up in the rain in IN and KY - engine and tranny temps were higher than usual - and a brisk tailwind worsened the issue.

Nevertheless, I don't like the tepid lockup on the current one; the Peninsular engine has plenty of torque, but the TC unlocks at the slightest chance.

[ronniejoe]

Yes. "Billet" is just a cool word for "machined from solid".

Rusty, you might consider a BD Torqloc...

[rustyk]

Thnks, RJ - I'm thinking a true HD TC and more control over lockup will be the solution.

[ronniejoe]

I also installed a Suncoast kit in the transmission using Alto friction plates and Koleen steels. This kit has increased numbers of disks for increased clutch capacity. I also installed a TransGo reprogramming kit. It's a pretty stout 4L80E now.

[Robyn]

Yesssssssss the ever popular, highly overused term "Billet"

More frictions and steels is always a good thing.

Transgo has been around since the 70's and probably before that.

I bought my first transgo shift kit in 71 to install in a little Ford Fairlane with a C4 tranny.

The folks at Transgo, literally beat on this stuff until they get the issues figured out and fixed.

Overall the 4L is a good box, basically a TH400 with the OD added.

Along with the addition of the electronics came a fair selection of specific problems that have/can plague this unit.

Transgo has addressed each and every one of these problems.


Sounds like your heading in the right direction for sure.

Having some extra control on the lockup, especially in a Motorhome application is a great idea.

You should definately get a remote filter installed on the cooler return line.

The nice part with these is that during a normal engine oil service, you
can take a second and spin on a fresh filter for the tranny and really help keep that oil clean.

Contamination is a killer on the 4L80 as the VB is aluminum and will wear a lot when exposed to a lot of crap.

The VB on the TH400 was cast iron and held up real well, not so with the 4L

The electric shift solenoids, even though they have filter screens, dont do well with crap either


Missy

[rustyk]

Contamination is a killer on the 4L80 as the VB is aluminum and will wear a lot when exposed to a lot of crap.

Shifts are normal. Fuel economy runs ~10.7 mpg, not bad for the weight and frontal area. The rebuild used HD Borg-Warner parts. I don't use the cruise control because it made the tranny too busy.

I'd still like more persistent lockup.

I appreciate everyone's advice; I know engines and most of the other systems on motorhomes, but auto-trannies are based on witchcraft...

[ronniejoe]

...but auto-trannies are based on witchcraft...

Not really. They're pretty straight forward once you get into them and study them for a while. The GM service manuals are extremely helpful in this regard. You have to understand planetary gear sets and how they work, but it is just application of mechanical principles.

[rustyk]

I have degrees in ME, EE, and MarineE. I can make a steam turbine or reciip system work when others can't. Don't tell me ATs don't employ Eye of Newt and Chicken Gizzards!

[phantom309]

I have degrees in ME, EE, and MarineE. I can make a steam turbine or reciip system work when others can't. Don't tell me ATs don't employ Eye of Newt and Chicken Gizzards!

you,re right they do have all kinds of magic gizmo's in them,.
you can hook up a manual lockup switch,.it,s what i like to use under certain circumstances,. with the cruise on, it is nasty, jumping when coasting down a hill,so i never manually lock it up when its on cruise.
With the chip and mods i have in my dually,i like to lock the tranny 1/2 way thru 2nd gear when i,m "in a hurry" it lets you use the torque better.
If you go this route,. with the heavy outfit you have, you should definitely consider an egt guage,.Me personally if i were to be using a 6.5 for heavy work i,d drop the compression a couple of points, and seriously look at a better turbo to keep the heat out of it,.
jm2c.

Nick

Nick

[a5150nut]

Nick,

You might want to read his signature. AMG 18:1 and other mods.

[rustyk]

with the heavy outfit you have, you should definitely consider an egt guage,.Me personally if i were to be using a 6.5 for heavy work i,d drop the compression a couple of points, and seriously look at a better turbo to keep the heat out of it,.
jm2c.

Nick

Nick

I have an EGT gage, and non-wastegated turbo. On the floor, I get 17 psig boost and EGT settles in at around 1050°F. CR is 18:1.

[rustyk]

Quasi-Epilogue: Because the transmission is operating normally, I replaced the thermostats (5-hour job because obstructions necessitated the removal of the entire housing to get at the 'stats).

New 'stats were installed, and after 370 miles, the temps are still "what I'm not used to". But testing the old (OEM) 'stats revealed one was sticky, and in testing neither 180° stat cracked until over 195°.

Coolant temp on straight-and-level runs around 190° with the new 'stats. Tranny temp is nailed around 180°. This is what I would expect in theory.

I suspect that one of the OEM 'stats was stuck open, and only recently closed normally; prior "normal" temps were coolant <160°, tranny ~150°. These are cooler than I would have expected. Apparently, the stuck-open 'stat corrected itself, and in operating normally, increased the temps.

Anyway, The tranny is due for change of fluid, which I'll do when I get home. I expect no difference in operating temps after. But at least I'll be able to collect any TC lockup residue for the Missy Good Wench Museum and Leftover Parts Emporium.

Bottom line: I think the system is now working normally after not for a long period.

Any comments?

[rustyk]

Quasi-Epilogue: Because the transmission is operating normally, I replaced the thermostats (5-hour job because obstructions necessitated the removal of the entire housing to get at the 'stats).

New 'stats were installed, and after 370 miles, the temps are still "what I'm not used to". But testing the old (OEM) 'stats revealed one was sticky, and in testing neither 180° stats cracked until over 195°.

Coolant temp on straight-and-level runs around 190° with the new 'stats. Tranny temp is nailed around 180°. This is what I would expect in theory.

I suspect that one of the OEM 'stats was stuck open, and only recently closed normally; Prior "normal" temps were coolant <160°, tranny ~150°. These are cooler than I would have expected. Apparently, the stuck-open 'stat corrected itself, and in operating normally, increased the temps.

Anyway, The tranny is due for change of fluid, which I'll do when I get home. I expect no difference in operating temps after.

Bottom line: I think the system is now working normally after not for a long period.

Any comments?

[rustyk]

I've moved the current questions to this thread, now that in addition to a new TC, I may opt for a Real HD tranny.