Anyone here done the 68RFE conversion on their trucks?

[Motorhead]

I'm sure I'll get a few "Boo's" but I am very seriously looking into changing out my AE ratio, G-56 for a light modified 68RFE. I have the link to the guy that has done it and supplies the controller. I only have 107,000 on my truck but with the South bend Stock replacement clutch and a bad left knee, an automatic sounds good. The nice thing about the 68rfe is that it has a .82 towing OD. My G-56, being the same one as the 6.7 used has a .74 OD. It tows well and I love the truck on the highway, towing and empty. It's just the extra "Rowing" I need to do around town. I Installed a set of the adjustable pedals and it made the clutch easier
I have my eye on a 2017 68rfe with low miles on it. Aside from the controller and I am sure other things, what would I need to do for a steering column or shifter? My instrument cluster has the PRD21 led's. I have done several stick to automatic conversions on earlier Ford vans but what made it very handy was that I had the DONOR Vehicle for any and all little incidental parts. I would sell my COMPLETE G-56 setup so it will off set the cost to convert.
So, Anyone done this and what glitches if any did you run into?

 

[AH64ID]

Subscribing!

First thing that come to mind is the dash display for the ERS. I wonder if you could get a 07.5 dash to work in your 07???

Everything else should bolt up, or have mounts available.

The 5th towing OD is very handy! The .82 will work better on a 5.9 than the .77 in the AS69RC.

 

[Motorhead]

John... I thought you might have some insight, like possibly a START to FINISHED and dialed in full instructions with diagrams and pictures! . STILL enjoying that turbo! Wonderful mod for the 5.9!

 

[AH64ID]

Wouldn’t that take all the fun out of it thou .

Yeah that’s a great turbo mod, will be killer with that .82 OD.

 

[cerberusiam]

It will work, it won 't be perfect, not for a truck that has multiple drivers. Biggest problem will be getting electronics to work correctly. Not sure on the PRNDL display as that is coming from the TCM via the range sensor, I think PRND will be fine if you turn it on in the ECM but not sure there is a way to display what actual gear without some external electronics display. The biggest downside I see if the 68RFE itself stand alone scenario, under clutched and over managed means it will need some had part upgrades and good programming to address the lack of management. I don't think the PCS controller allows that tight of an integration. For a light usage DD it is probably an excellent choice like the Ally, just a lot of work and relatively expensive to do.

 

[Motorhead]

Only Me as 95% driver. My wife will drive the G-56, even towing the 5th wheel. She does well with it.
I am experimenting with the stock clutch hydraulics. We all know that the stock hydraulics were non adjustable at the master cylinder. The stock hydraulics use a smaller bore master cylinder and slave so it would be less foot pressure. I took the clutch master, non adjustable, pushrod out and installed a modified adjustable pushrod from a HD setup that was supplied with a South Bend clutch. Haven't put it in yet. If I can get a softer pedal then the G-56 might stay.

 

[JR]

Are you referring to this guy?

http://transmissiontuner.com/68RFE-Swap.html

When I had my gen 2 I seriously considered it as well, and had a few conversations with him. In the end the lack of a true crew cab was the deciding factor for me and the sole reason I sold the 98. The 68 is also one of the drivers of why I skipped the gen 3 and went to the gen 4. In factory calibration and tuning they are an under rated unit.

Please keep this thread updated.

 

[Motorhead]

JR, That's the guy. What do you mean by the 68RFE is an under rated unit?

 

[AH64ID]

What about a 6.7 wire harness and ECM?

Get a “deleted” tune for it.

 

[JR]

JR, That's the guy. What do you mean by the 68RFE is an under rated unit?

What I mean is, so many people are too quick to compare it to the short comings of the 47/48RE. In reality it is both a completely different unit and a very capable one at that. In stock form approaching 800+lb ft torque I've seen first hand transmissions that have gone 7k+ hrs of farm use.


To compare the 68rfe to a 47/48 is irrelevant.

 

[cerberusiam]

In stock form approaching 800+lb ft torque I've seen first hand transmissions that have gone 7k+ hrs of farm use.

That isn't enough miles to start judging it. In a stock application the point it EVER sees 800 fl\lbs it will be slipping the TCC and a very narrow range. The transmission in stock form even with the updates won't take excessive TQ thru it like one gets with a stand alone controller. there ar efixes fro it and better tuning but you don't just retrofit a stock unit and expect too much, cost is going to be considerably more to address the issues that a 47\48 ever was.

What about a 6.7 wire harness and ECM?

Transmission control for the 68RFE was in separate controller until 2016 or so when it was added back tot he ECM. Adapting a newer platform ECM to an older 5.9 platform is not a simple thing though it could be done with a fair amount of fiddling.

 

[JR]

Cerb, I never said anything about miles, I'm talking engine hours.

Actual miles are rather low compared to the clock.

Low speed use in hot weather towing heavy loads. IE hay wagons, gravity wagons, sprayers, etc. in and out of fields. That's about the worst service I can think of for an automatic transmission, but I am by no means profiecient in this area. Just stating what I see.

cost is going to be considerably more to address the issues that a 47\48 ever was.

But you still have a deficit of two gears...don't matter how much you pump into a 4 speed it's still a 4 speed at the end of the day.

This was the biggest crutch on my 98. And I had a 47 that was built by the most proficient performance diesel trans builder within a days drive of here.

 

[Motorhead]

The 4 speed 47/48re was the reason I bought the 6 speed stick in my 2007. I had an '01.5 with a DTT built trans, 50hp injectors and an edge ez. Not towing, the truck was a blast to drive. Towing a heavy load, say 8-10,000 pounds was a different story. You were either in 3rd lock up which was direct, 1 to 1 winding the engine or in 4th lock up lugging which is .69 to 1. I did some research with an online calculator that asks tire diameter, rear dif gear ratio and transmission ratio for what ever gear you are inquiring about. It gives road speed and engine RPM. The .82 to 1 would be ideal with my 285/75-17 oversized tires. Now, when I tow, I put my stock wheels and tires back on. It tows okay, especially out of Commiefornia and their darned 55 mph.
The 47/48 RE would be good with a Gear Vendors .78 OD. Only bad part about the Gear Vendors is that you can't use an exhaust brake while the GV, OD is engaged. Something about that the unit isn't built for deceleration load.? The GV is too close to my .74 to warrant the cost of the unit other than gear splitting which would give me essentially a 12 speed, in 2wd only.

 

[cerberusiam]

The problem with a stock trans is you only get one more usable gear for towing in most cases, 5th. 6th is under clutched and over managed so with heavy loads it doesn't get used much or it just breaks. The trans will actually last longer in slow speed usage and heavy weights than the the 47\48 because it spends more time in lockup in lower gears which the other units never did. There are things about the 68RFE that were good and other things that were not so good, more or less pick you poison type of deal.

In the 7k hours just how much was idle time and time under 1600 rpms which is as good as idle time? Good bet it is significant portion as is usual in those scenarios.

There is no debate 6 gears are better than 4, IF you can use them effectively. The MB transmission is a perfect example, 6th gear with a set of gears for towing heavy weights and it was way short of gearing. Add final ratio and it just moved the cost point elsewhere. Upsize the tires and the economy suffered with a 5.9, lower final drive ration and the clutch and trans suffered.

It is all a series of trade-offs in what you are trying to do and the results you want, there is more to it than just a parts swap.

 

[Motorhead]

When I wear out the 285/75-17's I plan to go to a smaller but not stock tire. I doubt if I would EVER tow in 6th. It would be good empty.

 

[bigceltic]

When I wear out the 285/75-17's I plan to go to a smaller but not stock tire. I doubt if I would EVER tow in 6th. It would be good empty.

I have checked out this swap as well, using the same guy you found, and the only thing stopping me is really the inability to use cruise control - I tend to use cruise a lot when out on my camping trips. Other than that, it looked like a great upgrade.

 

[Motorhead]

I'll check on that when I call him as to whether he has conquered that hurdle or not. Darn ELECTRONICS....Love them and HATE them.
I would think that the cruise control would be tied into the wheel speed sensor. He might be staying away from the cruise control due to liability reasons. When I have done transmission conversions or any conversions, I want everything working as it did when it left the factory.

 

[bigceltic]

I'll check on that when I call him as to whether he has conquered that hurdle or not. Darn ELECTRONICS....Love them and HATE them.
I would think that the cruise control would be tied into the wheel speed sensor. He might be staying away from the cruise control due to liability reasons. When I have done transmission conversions or any conversions, I want everything working as it did when it left the factory.

Let me know what you find out. Here is what it says: "For the 06-07 models, it is possible to fool the auto ECM to think there is still a 48RE in the truck and one advantage to this method is that it allows you to keep your digital gear display in your dash. It is also possible to flash the ECM to a manual trans calibration and solve some of those issues, but it creates other issues of it's own. Another challenge is cruise control. It will still work, without any modification, but it will ruin your transmission, since the aftermarket trans controller will not be seeing the correct throttle position with the cruise on. I have dealt with these issues before and can assist you with sorting through those options"

The "ruin your transmission" statement gave me pause!

 

[cerberusiam]

I would think that the cruise control would be tied into the wheel speed sensor.

Not with an auto trans, recipe for disaster since the trans shifting is electronic not hydraulic. If it cannot see throttle position to know when to downshift it will happily wood the throttle in high gear and lug it down to where it starts bucking against the TCC. Have to have wheel speed and throttle position to keep from destroying the equipment. The PIDS for transmission control are not mapped very well, literally have to convert hexadecimal and add the positions to most tuners to compensate for the missing controls of TTVA, transducer, and gov solenoid. Probably the best way to approach those is resistors to keep the CEL off if possible.


Speed control will work but you have to manually shift the trans or shut it off on grades, the gear indicator is harder because it is part of the TCM and you have to selectively mess wit things that are not well mapped in the public domain.

 

[Motorhead]

bigceltic, My truck is a standard transmission, G-56. Due to wear and tear on ME with knee issues, I am considering this mod.
I CLEARLY realize that this won't be like putting an automatic in a pre electronics vehicle. That's why I am asking if anyone here has done it. Lots more issues to consider and to solve to get a well shifting automatic. It just may not be feasible. Might have to sell and find the one or two year, pre smog Duramax that has the Allison with all 6 speeds enabled. A friend of mine has one and said I could drive it anytime. Sure would hate to have to go that way.