Replace 48RE w/ 68RFE?

[DogramTD]

What are the hang ups with this swap? has anyone done this, is it worth it?

 

[Wingate]

Good luck. . I posted this idea a couple years ago. . I would LOVE to have a 6 speed behind my 5. 9L...

Have you been able to source the conversion parts needed for the swap? If so, I would be VERY interested of in getting a copy of the parts list.

 

[Dieselnerd]

I'd love to do it too but with all the electronics involved it might be less expensive to trade for a newer truck.

 

[HBarlow]

The new automatic transmissions are entirely computer controlled. I would think it is a nearly impossible challenge to retrofit a 68RFE into an earlier truck without the matching computer.

 

['strokeThis_'07]

Why would you replace a fair/decent (stock) trans with a weaker one anyway? Just for the extra 2 gears?





I wouldn't. Not that it matters, because you can't. Physically sure, but not electronically.

 

[DogramTD]

Well aything is possible, I am just posing the question to see if it is feasible; maybe somebody has done it. No matter which transmission I were to go with, either one would have a small build factor prior to install to ensure it would hold up to the rigors of what I put it through, so weak is relative. IMO, all chrysler trannies are weak (except for maybe the old TF 727) And yes, just for those 2 extra gears; in many cases the same reason people use the allison.



Maybe, Cerb our resident transmission guy, has some input???



I already have the basic upgrade done to my trans but i want those extra gears... I do still need a TC though... . any suggestions?

 

[cerberusiam]

The big problem is the computer to control the the trans as it is all electronically shifted and controlled. Physically its quite doable with some modifications as the dimensions are close. Getting the computer right and having a source to tune the operation is iffy.



Suncoast is supposed to be working on this with a stand alone controller but you can bet early adopters will help fund the R&D.



Is the 68RFE weak, or, weaker than the 48RE? Thats the question that needs answered and a what level is too expensive to consider. It sounds like the aftermarket is delivering the pieces for upgrades and there is enough knowledge to make things work right.



The option is getting closer but cost will be a factor.

 

[rscurtis]

DogramTD, in case you were'nt aware of it, the 48RE is a 727 with some beefed up internals and an overdrive compounder hung on the back of it. Both the gear ratios and the pan are the same parts. How many other auto's used today have almost a 50 year heritage?

 

[JJPage]

I would think the swap would be best fitted to an 03/04 truck, since the pcm is already separate from the ecm.....

 

[cerberusiam]

I would think the swap would be best fitted to an 03/04 truck, since the pcm is already separate from the ecm.....

IIRC the 03's are the only ones with a PCM. Pretty sure the 04's have the PCM functions integrated to the ECU.



Theoretically, neither would be a problem as the needed computer would not only have to control the trans but supply readings to the ECU\PCM in the range it expects, even it did nothing with the outputs. A constant CEL from readings being off with the potential for limp mode in the engine is not acceptable. Big part of the issues of retro-fitting is how to seamlessly handle the existing inputs and outputs.



The problem is not the 727/47RE/48RE transmission, the problem is a high TQ medium duty engine mated to a light duty trans that was not designed for the power inputs. It was a compromise to get a functional vehicle at an aceeptable cost.

 

[opjohnny]

It probably boils down to cracking the code, which I believe Marco has done, and understanding the inputs/outputs(electrical signals) that transmission needs to be happy. Then the time to adjust the parameters to get the drive ability. Easier said then done. To small a market.

John

 

[JJPage]

IIRC the 03's are the only ones with a PCM. Pretty sure the 04's have the PCM functions integrated to the ECU.



Theoretically, neither would be a problem as the needed computer would not only have to control the trans but supply readings to the ECU\PCM in the range it expects, even it did nothing with the outputs. A constant CEL from readings being off with the potential for limp mode in the engine is not acceptable. Big part of the issues of retro-fitting is how to seamlessly handle the existing inputs and outputs.



The problem is not the 727/47RE/48RE transmission, the problem is a high TQ medium duty engine mated to a light duty trans that was not designed for the power inputs. It was a compromise to get a functional vehicle at an aceeptable cost.

I was just thinking out loud ... so to speak, most likely more trouble at this point than the advantages.



I am completely happy with my 48RE, no changes needed.

 

[Wingate]

I would love to have a 6 speed auto behind the 5. 9. . not interested in buying a new truck due to personal preferences. I posed this question about a year or so back but I was more interested in the AISIN 6 speed from the C&C trucks.

Granted, it would definitely require a standalone controller to put the AISIN in its place. Along with having a communication pathway between the trans controller, the engine ECU, and maybe a BCM (IF the 3rd gens have one???)

I think it COULD be done, but as others have stated, IS there a large enough market to make it profitable enough for some smart guy to do the R&D????

If anybody wants to take a stab at it, I would be willing to install test components (supplied by you) on my truck for field durability testing.

 

[cerberusiam]

If anybody wants to take a stab at it, I would be willing to install test components (supplied by you) on my truck for field durability testing.

Yeah, you and a thousand other yahoos. :-laf:-laf

 

[brods]

Back in 07 I was lusting for one after doing some work in the transmission plant where the 68RFE had just gone into production. Rows upon rows of these trannys stacked up like cord wood and all I wanted was just one. No such luck. It would sure be a nice upgrade if there was any way that the price could be kept reasonable.



In all seriousness, what would you guys be willing or expect to pay for the conversion?

 

[Wingate]

Yeah, you and a thousand other yahoos. :-laf:-laf

hahaha... cant blame me for trying... !!!! :-laf

 

['strokeThis_'07]

In all seriousness, what would you guys be willing or expect to pay for the conversion?

Less than a built 48... because after the conversion, if left stock, the 68 would soon die.



It's the same with the Allison that everyone seems to think would be so great; your shelling out the same dough as a built 48 costs, and still stuck with a stock trans. That's a big factor on a modded truck

 

[HBarlow]

TDR member 2Rowdy posted that the 68RFE can't be modified by transmission builders.

He drives a highly modified 6. 7 which didn't take long to shell his factory transmission. He had it rebuilt but said he learned that it cannot be modified because it is completely controlled by the ECM.

I'm posting his comments from memory and may not have 100% of the details.

 

[cerberusiam]

It's the same with the Allison that everyone seems to think would be so great; your shelling out the same dough as a built 48 costs, and still stuck with a stock trans.

Yep. Either way, its probably $10k to do it and expect much more than a stock trans which won't hold more than 500 HP, less in some cases.



About double the cost of the 48RE that will hold pretty much anything you throw at it. Towing it would be great but thats a steep price to pay for the gain. Comes down to how much one is willing to spend.

TDR member 2Rowdy posted that the 68RFE can't be modified by transmission builders.

I am sure at one time that was true as it was a brand new product that is a total departure from anything Dodge had done. Simply takes time for trial and error to develop the a build that will function correctly.



Fortunately, thats not true anymore but the knowledge is held by a few and still in development.



The Ally is a perfect example, not everybody can build it to hold up to a decent power upgrade and if they do the limitations of the design need to be re-engineered. Same with the 68RFE, what can't be fixed needs to be produced and tested.

 

[monkeyman]

I would do an Allison Swap with a stand alone computer before that swap, thats my nickel! Price went up after my two cents worth!

Rick