Transmission advice

[xjtony]

My wife and her sister bought a little motorhome a few years ago for their annual road trip. It's based off of a 79 Frod van and has a 351W that runs great. The only real issue they have it that with the 3 speed auto it only runs about 65 down the highway. I want to overdrive it so it runs a bit better on the highway, but am looking for some hopefully real world advice on options.
1. Older Ford AOD- most folks say this trans wont hold up in anything other than a car or light truck. They are also fairly hard to find

2. Gear Venders- while probably the best option it's really pricey. Honestly it would cost about what we have into the whole camper.

4. E4OD- this is the coice I originally wanted to go with, but finding a 2wd, Windsor pattern E4OD is akin to finding chicken teeth. I would also need a controller which runs sabout $600.

5. Convert to a chevy trans and run a 700r4- here is where I need some input. For about $550 I can convert to run this trans, and they are a dime a dozen. My issue is that looking through the ol' interwebs I see everything from "I've towed thousands of pounds for years with no problem" to basically "if you put in in drive in a motorhome itll explode". Does anyone have any experience with this trans. Can one be built with TC lockup and survive the few thousand miles a year that it will see?

 

[mbryson]

A 700r4 can be built to put behind a healthy big block. I think that'd probably work behind a motorhome? You'll just need a TV cable and probably a driveline (I'm sure you knew that?)

What about a 2 speed rear diff? You'd likely get a different bolt pattern axle which could be problematic? I'd imagine that's kind of available in that vintage of medium duty but I'm aware of a "light duty" truck 2 speed rear?

 

[I Lean]

Seems like a 4L80E would be a better choice than a 700?

 

[Greg]

Seems like a 4L80E would be a better choice than a 700?

That's a great option for this vehicle, just need an adapter, standalone controller and new DS.

Quick 4 Stand-Alone Transmission Control

The Quick 4 controller makes your 4L60E, 4L80E, 4R70W, E4OD, or 4R100 transmission work in a wide variety of vehicles, including ones not originally equipped with electronic control. It also allows customization of the transmission's behavior with user-friendly software.

www.usshift.com

 

[skippy]

Is the vehicle capable of holding freeway speeds in an overdrive gear

 

[Mouse]

I've heard stories of 700r4's holding up to big power, but never seen one with my own eyes. On the other side, I've seen/experienced many failures. My scrambler currently runs a 700r4, and I can't wait to get rid of it (poor shifting).

 

[haulinshine]

an AOD behind a 351 in a small motor home like that would hold up just fine, the AOD doesn't have a high GCVWR so when people bought f250 and f350s with it then hooked up a 10k trailer the trans just couldn't do it for long. that motor home is probably only 10k tops and as long as they don't try to race it an AOD will do just fine.

 

[The_Lobbster]

6.0 and 4L80E,

 

[Greg]

Is the vehicle capable of holding freeway speeds in an overdrive gear

The 351W is built for torque vs HP, but the late 70's weren't kind to engine performance. I'd say it all depends on the OD ratio, axle ratio and final RPM at 65-70 mph.

 

[xjtony]

I'll try to reply all at once here.
1. I had given some thought to a 2 speed rear, but they will mostly be cruising without much assistance so I'd prefer to set them up so they dont really have to actively do anything (more like a modern vehicle)

2. I know very little about Chevy stuff. I like the idea of the 4l80e, they are fairly easy to come by for a decent price, and plenty strong but here is my question for the Chebby guys. The AA adapter kit I found says it's for the th350/th400/700r4 family of trans. Can I make that work with the 4l80e? I also really like the standalone controller. When I was looking at E4ODs i spoke with a few companies and they can even help set the controller up for my specific needs so it performs as needed.

@skippy The vehicle itself is very sound and the engine runs surprisingly well (only like 70k miles) it just doesn't have the gear to move any faster than about 65 without the RPMs being higher than I'd like.

I really looked at AODs at first but I've heard horror stories about not setting them up properly and burning clutch disks. I've been a mechanic most of my life, but auto transmissions are not my expertise. I have a decent overall understanding, but as far as I can tell there are magic fairies in there that do all the fancy stuff lol. I worry about my ability to set it up properly

 

[Mouse]

I think a big part of why the 4L80E is so appealing is that the electronic controls are almost fool-proof vs. the AOD. I have no experience with either, but I sure see a lot of offroaders who swap to the chevy transmissions and not an AOD.

 

[xjtony]

The 351W is built for torque vs HP, but the late 70's weren't kind to engine performance. I'd say it all depends on the OD ratio, axle ratio and final RPM at 65-70 mph.

The gears are fairly steep, but I cant read the tag to see what they are. This winter when I service the diff I will confirm. I want to recall that at 65-70 the RPM were somewhere around 3200-3500. I'd really like to see it more around 2500ish

 

[lhracing]

A 700r4 can be built to put behind a healthy big block. I think that'd probably work behind a motorhome? You'll just need a TV cable and probably a driveline (I'm sure you knew that?)

What about a 2 speed rear diff? You'd likely get a different bolt pattern axle which could be problematic? I'd imagine that's kind of available in that vintage of medium duty but I'm aware of a "light duty" truck 2 speed rear?

A 700R4 can be built to take some power when done with the correct parts, modifications and by the right person. I have ran one in a 650hp BBC, 4000lb car on slicks at the drag strip with good success. Are there stronger transmissions, for sure.

 

[mbryson]

....
2. I know very little about Chevy stuff. I like the idea of the 4l80e, they are fairly easy to come by for a decent price, and plenty strong but here is my question for the Chebby guys. The AA adapter kit I found says it's for the th350/th400/700r4 family of trans. Can I make that work with the 4l80e? I also really like the standalone controller. When I was looking at E4ODs i spoke with a few companies and they can even help set the controller up for my specific needs so it performs as needed.
....

I'm 90% sure (I'd be really surprised) if the 4L80 family isn't the same bellhousing bolt pattern as the other GM trans. That's just against the GM philosophy (which can be changed obviously)

 

[Greg]

I'm 90% sure (I'd be really surprised) if the 4L80 family isn't the same bellhousing bolt pattern as the other GM trans. That's just against the GM philosophy (which can be changed obviously)

It is!

 

[Rot Box]

Another option might be to re-gear the axle or add larger tires IF it doesn’t feel too underpowered as is.

Something I learned from the 2F Landcruiser guys years ago is to download a bunch of Grateful Dead and enjoy life in the slow lane 😁

 

[xjtony]

Another option might be to re-gear the axle or add larger tires IF it doesn’t feel too underpowered as is.

Something I learned from the 2F Landcruiser guys years ago is to download a bunch of Grateful Dead and enjoy life in the slow lane 😁

Honestly they stop like every 20 minutes to see something along the way lol. I had thought about a set of longer gears, but driving around town it is actually quite responsive for what it is. I guess my overall goal is to give them something that will perform more like a modern car, but with the style and fun of a vintage rig. The next step after I figure out the trans is a fi tech efi system.
I appreciate all the input. It seems that running a 4L80e with the adapter and controller might get me the results I need

 

[RustEoldtrux]

Quickest and easiest is to install taller tires. You can experiment with different sizes to get the best results. Having spare sets will allow changing to shorter tires for mountain travel versus taller tires for flatland travel.

 

[SnwMnkys]

What about a 4R70W? The 4R70W still requires a stand alone controller but one out of a V8 Explorer would bolt right up to the 351w. Not sure about the 4.6/5.4 transmissions. Supposedly they handle good hp in stock form.

 

[xjtony]

What about a 4R70W? The 4R70W still requires a stand alone controller but one out of a V8 Explorer would bolt right up to the 351w. Not sure about the 4.6/5.4 transmissions. Supposedly they handle good hp in stock form.

I've been looking at those as well as the E4OD, but they are fairly rare in the Windsor pattern.