Turbo 400 / 4L80E

[bkahler]

Originally Posted by ElCamino Man

Its far from a bolt on upgrade. Youll need a big block bell housing to start with, and a different tranny crossmember, shorter driveshaft, AND a stand-alone controller.

I just measured the bell housing on the 4L80E and the dimensions match up with the 454 block. So at least that is one thing I won't have to worry about. Now to figure out where to get a cross member.

Brad

[ElCamino Man]

Thats good news! Iv been working on Fords recently so Iv forgotten some of my Chevy stuff lol.

As for the other things I pointed out: the 4L80Es tranny mount is about an inch further back than the TH400. You could probably fab up your own corssmember like im doin to fix this issue. Same goes for the driveshaft. Inch further back, inch needs cut off. You could also cut the driveshaft yourself and weld it back up and hope like hell its still balanced lol. Iv seen it done! Your biggest expense is gonna be either reprogramming your current chip or buying a stand-alone system to make it shift. I did lots of research on the standalone and its about $400 for the cheap one. And, if I remember correctly, you have to have a switch of somesort to lock-up the torque converter and unlock it when slowing down yourself. Kinda a hassle but worth the reward!

[bkahler]

Originally Posted by ElCamino Man

As for the other things I pointed out: the 4L80Es tranny mount is about an inch further back than the TH400. You could probably fab up your own corssmember like im doin to fix this issue.

I'm going to have to get under the motorhome and take a peak at the rear mount and then compare it to the 4L80E mount. I prefer the simple approach whenever possible

Same goes for the driveshaft. Inch further back, inch needs cut off. You could also cut the driveshaft yourself and weld it back up and hope like hell its still balanced lol. Iv seen it done!

I think I'll leave the drive shaft to the professionals. It's amazing what an out of balance drive shaft can feel and sound like

Your biggest expense is gonna be either reprogramming your current chip or buying a stand-alone system to make it shift. I did lots of research on the standalone and its about $400 for the cheap one. And, if I remember correctly, you have to have a switch of somesort to lock-up the torque converter and unlock it when slowing down yourself. Kinda a hassle but worth the reward!

That does sound like a cheap approach. I'd be willing to spend a couple hundred more to have an automatic lockup. The older I get the more forgetful I get so I'd likely leave it locked up all the time!

Brad

[ElCamino Man]

Youd have to have the switch either way Im pretty sure. You CAN get all fancy with it and hook it into your brake pedal and run a vacuum line so when you hit the brakes/slow down it automatically kicks the torque converter off. You can get some info off the internet... its been awhile since Iv done mine lol.

[bkahler]

Originally Posted by ElCamino Man

Youd have to have the switch either way Im pretty sure. You CAN get all fancy with it and hook it into your brake pedal and run a vacuum line so when you hit the brakes/slow down it automatically kicks the torque converter off. You can get some info off the internet... its been awhile since Iv done mine lol.

I researched some of this about five years ago but I've slept since then so I'm pretty much starting all over again

I think it's time to start googling again.

Thanks!

Brad

[ElCamino Man]

Just a little more info: if you start ookin around and see someone swapping in a 200-4R, its essentially the same thing. Only difference is the 200-4R doesnt need the driveshaft shortened. I think they even use the same tranny controller but dont quote me. And also, in case ya didnt know, the 4L60E and 4L80E are identical (pretty sure) except the 80 is more heavy duty!

[ElCamino Man]

If you know a thing or two about cars, here is an essentially free way to get your lock-up:

200-4R Simple Lock-Up Installation! - El Camino Central Forum : Chevrolet El Camino Forums

If you dont know a whole lot about cars, that thread will make you scream lol. Been there done that...

[Keyair]

I was interested in the 200-4R after I read an article on how they can be made really strong in Car Craft Magazine June 2009.
The idea of a mechanical based 4 speed trans was interesting.

However, I called and spoke to Art Carr, and his advice was its not strong enough even with the mods for such a heavy vehicle.
He advised to find a used, low mile 4L80E from a 2007/8 truck as the best conversion.
He told me he had done this conversion on a motorhome, and he had put over 50k miles on it, and had no problems. He said with the 4th gear, and lock-up converter, his mpg went from 6 to 9.
You would need a stand-alone electronic controller for the 4L80E's control.

Read here about the 200-4R.
How to Build a TH200-4R for 1,000 Horsepower - Car Craft Magazine

[ElCamino Man]

^^^ I 2nd what Art said. If I remember correctly, the 200-4R is cheaper in stock form. Theyre not as desireable as the 4L60E. But when you talk about upgrading to handle big block power PLUS weight, the 4L60E/4L80E is the cheaper option in the long run. Im not even sure if youd HAVE to upgrade the 4L80E

[LimeyRich]

Hi bkahler, guys, camper friends all.
Do the swap!
Forget all about 200R4s, 700Rs, 6L70s, ad nauseum, etc. They were never designed to take the load of anything as heavy as an Airstream/Argosy! No rancor or dislike of those units, they just were never intended for this use.
Half way through my own conversion to a 4L80. Ordered a trans support crossmember for a mid '90s P30 from Colaws rv salvage, [but, they sent me the same crossmember that was in my '88 345 :-( ], hopefully I can get that straightened out this week. Otherwise, the shortened drive shaft should be done midweek, new trans mount on the way, then shift linkage fabrication time. Then hook up the Optishift (now US shift) . Most awkward and difficult part? hooking up the new style park brake so that it works like the old type, what a bear!
Conversion worth doing? Well, only since I burned up my TH475 going over Jellicoe mountain in Tennessee, and I was ready for an overdrive gear anyway. Plus I was going to take the old girl out of service this year to install my Banks exhaust system .
So might as well be hung for a sheep instead of a lamb.
By the way, with the [damaged] TH475, 9.5 mpg when religiously setting cruise on 55mph for a 670 mile trip, flattish terrain, [Asheville was the steepest bit], no toad.
Hoping for 12+- mpg going to Florida in December, fingers crossed!

[Keyair]

Originally Posted by LimeyRich

Hi bkahler, guys, camper friends all.
Do the swap!
Forget all about 200R4s, 700Rs, 6L70s, ad nauseum, etc. They were never designed to take the load of anything as heavy as an Airstream/Argosy! No rancor or dislike of those units, they just were never intended for this use.
Half way through my own conversion to a 4L80. Ordered a trans support crossmember for a mid '90s P30 from Colaws rv salvage, [but, they sent me the same crossmember that was in my '88 345 :-( ], hopefully I can get that straightened out this week. Otherwise, the shortened drive shaft should be done midweek, new trans mount on the way, then shift linkage fabrication time. Then hook up the Optishift (now US shift) . Most awkward and difficult part? hooking up the new style park brake so that it works like the old type, what a bear!
Conversion worth doing? Well, only since I burned up my TH475 going over Jellicoe mountain in Tennessee, and I was ready for an overdrive gear anyway. Plus I was going to take the old girl out of service this year to install my Banks exhaust system .
So might as well be hung for a sheep instead of a lamb.
By the way, with the [damaged] TH475, 9.5 mpg when religiously setting cruise on 55mph for a 670 mile trip, flattish terrain, [Asheville was the steepest bit], no toad.
Hoping for 12+- mpg going to Florida in December, fingers crossed!

Pics and more info PLEASE!

[ElCamino Man]

What do you need more info on? Heres what youll need:

Either a built 4L60E, 200-4R, 700-4R, or a stock 4L80E
Crossmember
Shorter driveshaft
Standalone tranny shift module

Install it all and youve got an overdrive! Just be ready to fork out some cash

[Keyair]

I get that it fits and works with the stand alone controller, and the driveshaft needs mods.

Some of the details that interest me are:

1/ How different is the X member?
2/ What mods were needed on the shift linkage?
3/ How did you get the transmission parking brake to fit?

I would like an idea of costs and how that compares with say adding a Gear Venders unit behind the TH475.

[ElCamino Man]

The standalone tranny controller is gonna be at least $400.
X-Member (or similar) about $150-$180
Tranny will cost prolly $300 for a used one. New one will be through the roof. Not 100% sure on that though

Only thing I see different on aftermarket crossmembers is they have two "humps" to allow for dual exhaust
My 200-4R didnt need different linkage, so not sure why a 4L80E would
Not sure what a trans park brake is

[bkahler]

Originally Posted by ElCamino Man

The standalone tranny controller is gonna be at least $400.
X-Member (or similar) about $150-$180
Tranny will cost prolly $300 for a used one. New one will be through the roof. Not 100% sure on that though

Only thing I see different on aftermarket crossmembers is they have two "humps" to allow for dual exhaust
My 200-4R didnt need different linkage, so not sure why a 4L80E would
Not sure what a trans park brake is

I'm curious about the x-member also since I will be needing to buy or make one for my Argosy, assuming of course there is any difference. I wonder why a cross member would be so expensive?

The odd thing I found on the 345 is I can't physically remove the crossmember from the vehicle. I can unbolt it and slide it around but you can't actually get it out of the frame. I plan on saving it which means I will need to cut the frame around it to get it out. No big deal since the rest of the frame is going to the scrap yard.

I'm also curious what will need to be done to the shift linkage to make a 4L80E work in a 74 Argosy.

The transmission parking brake is a big drum brake mounted on the back of the transmission. I have a 1951 Dodge pickup with the same arrangement on the back of the transmission. I'm not sure if it was cheaper to install a drum brake on the motorhomes or if it is actually a better arrangement.

Brad

[ElCamino Man]

Iv never heard or seen that type of parking brake lol. Sounds like a cheap way to do it though!

As for your crossmember, if you can slide it back and forth, then it can come out. You may need a large hammer but they were ment to be removed. You just have to rotate it one way or the other. Its probably a tight fit but a couple whacks with a dead-blow ought to get er out. If the new crossmember is that tight, then shave some metal off the ends. Thatll save some headache later on down the road.
DO NOT CUT YOUR FRAME
It is THE structure for your motorhome. Cutting it will make it weak

As for the x-member. Its just a fancy crossmember. You have to move the tranny mount back an inch and this crossmember does that with some tabs (not sure if theyre included). Id custom fab your stocker or make your own like im doin if youve got the know-how

[bkahler]

Originally Posted by ElCamino Man

As for your crossmember, if you can slide it back and forth, then it can come out. You may need a large hammer but they were ment to be removed. You just have to rotate it one way or the other. Its probably a tight fit but a couple whacks with a dead-blow ought to get er out. If the new crossmember is that tight, then shave some metal off the ends. Thatll save some headache later on down the road.

I layed under the motorhome for over an hour when I was removing the transmission and no matter what I tried that crossmember would not move in such away that I could get it out. I'll try again this weekend and take pictures if I can't get it out.

DO NOT CUT YOUR FRAME
It is THE structure for your motorhome. Cutting it will make it weak

I was referring to cutting the frame on the 345 motorhome in which I am dismantling and scrapping the frame

As for the x-member. Its just a fancy crossmember. You have to move the tranny mount back an inch and this crossmember does that with some tabs (not sure if theyre included). Id custom fab your stocker or make your own like im doin if youve got the know-how

I'll either get the 345 crossmember to work or modify it to work on my Argosy rather than buy anything.

Thanks!

Brad

[vswingfield]

Originally Posted by ElCamino Man

Iv never heard or seen that type of parking brake lol. Sounds like a cheap way to do it though!

That parking brake design is part of the frames truck heritage. I've driven P30 based trucks with Allison automatics that did not have a "P or Park" position at all, just a "N or Neutral."

There were a couple of reasons behind this. A park paul, such as used in a car might not be up to securing the load of a parked truck. Also, they were intended for truck drivers, not the typical car driver.

It's a truck (pickups don't count here) thing. And, as you noted, it is a good, cheap way to address the issue.

[LimeyRich]

Hey again.
Ok Crossmember first. The crossmember/trans support for a 4L80 is deeper by about 3 inches than the corresponding crossmember in a 345, the tailshaft housing on bigger trucks and motorhome 4l80s is completely different than a car tranny. The original xmember will come out of the motorhome BUT you probably have some small bolts in the way which prevent much movement. They are fiddly and time consuming to remove. Once there is nothing physically blocking, tap one side of the mount rearwards, the other forwards. Use at least a 2 pound machinists hammer. El Camino is right, Grind about 1/8' of metal off each end of the x member and it will go in much easier.
If you are able to use a car type 4L80 rear trans housing and slip yoke you will be miles ahead. It will fit closer to your original TH400 xmember, and no Ebrake!
Do you have all wheel disc brakes? If you have rear drums you are lucky, your regular emergency brake will work just fine. You can just throw away the brake shoes from the transmission mounted drum, and fit your shortened driveshaft.
If you have a Ebrake 4L80 to install, your old TH 400/475 drum Ebrake probably will not fit it, the bolt pattern is wrong ( at least on mine). GM/Workhorse changed from a normal emergency brake to a brake that is ON unless pressure unlocks it. Hence the large number of people stuck in strange places with a locked E brake! This ebrake system is a brilliant piece of engineering, cough,cough.
Fiddling with the linkage. (If your hair is not grey or white before you start this project, it will be when your done!) My TH475 rod linkage is tantalizingly close to the shift mechanism on the 4L80 but I just cannot fab' it up to fit . So it looks like cable linkage from Ididit or Lokar, with a longer cable than they offer.
Your TH475 dipstick and tube will fit the 4L80 nicely , the full mark even lined up in the right place for mine.
Sorry about pics, but wife borrowed my camera and now it will not focus.
I will get into speedometer and loss of cruise control etc' a little later when i am not so tired and pressed for time.
I work exceedingly slowly four weeks into this now.
Very busy week starting for me and the 345 will just have to wait until next Monday or Tuesday.
All the best! Stay safe.

[Keyair]

P30 Parking brake for 1984..