G56 vs 68RFE

[EMoroney]

Thank you to everyone who responded to my original question. I will do some more reading, as suggested, about the DMF/G56 and the issues. Sounds like the majority of you folks like the 68RFE. Thanks again.

 

[RVTRKN]

I've been following this thread, and I guess its time to respond. The 68rfe seems to have proved itself since its introduction in the 07. 5 MY, as well as the Aison. The G56 has had somewhat of a successful run, if used within Dodges GVWR/GCVWR, the obvious weak link is the Dual mass flywheel. You can expect it to make it through the warranty period, and maybe the extended warranty period. But after that, the DMF (Dual Mass Flywheel) will more than likely have to be replaced.



Pro's - You pick your gear when you want to. Less heat introduced into the radiator. Less cost of maintenance. The feel of a real Diesel truck (I know, but I just thought I would throw that in there. ) The ability of climbing long grades without hunting for the right gear. The braking with the EB and the manual combined together while descending long steep grades.



Con's - DMF. Weak Aluminum transmission case allowing it to flex, causing the gears to mesh incorrectly, (when going over GVWR/GCVWR). Not being able to comfortably drink your coffee in the morning. Better resale value, (But don't forget it costs more when purchased).



I'm sure that there are more Pro's & Con's, and welcome any addition to them. If I had to make the same decision today, I would still be on the fence about it. The new HO CTD with the higher GCVWR would probably sell me on the auto option. Both CTD's I've owned had manuals, (look at sig). The NV5600 is a very strong transmission, but when New Venture stopped making them, that is when Dodge went to a proven G56 (in other markets with weaker engines). One of the main reasons New Venture stopped making the NV5600, was the introduction of the Allison from GM which decided to eliminate the Manual option for the Duramax. I never liked the Allison, and hated the TM on the 05 D/A I had to drive for awhile, and if it were the transmission Dodge went with, I would not convert to the auto.



Good luck with whatever option you go with, at least you have a track record you can compare the options to, unlike me in late 06 with C&C I ordered.





Steve.

 

[HBarlow]

How many miles do you have on your G-56 which allows you to claim the DMF will make it through the warranty period?

Several failures have been reported in the pages of TDR with mileage around 20,000.

Domehead experienced several failures with his and was so disillusioned he traded his for a Furd.

 

[ENafziger]

To me, DMF failure is a mute point in the auto/manual transmission argument. A solid flywheel from Peter is only ~ $200. A good automatic built to take some power can be quite expensive from what I understand ($4 - 8k), and that's definately not bullet proof... there is still input shafts and output shafts that get twisted, flexplates that shear, torque convertor failures, etc, etc. The DMF is a know problem with the manuals, but it seems like it pales in comparison to potential costs of failures in an automatic.

It may seem that, strong personal preferences aside, a simplistic determination with today's transmissions may be:

1. If you stay within power and gvwr guidelines from the factory, a new automatic offers a much more pleasant driving experience, and is proven to be robust. This is probably the best choice for most people.

2. If you plan to make substantial power modifications and/or exceed other guidelines from the factory, a manual transmission seems to take more abuse at a much lower cost (basically clutch/flywheel replacement, and GL-6 lube).

3. If you plan to make extreme power modifications with the intent of fast daily driver, drag racing, etc, an automatic lends to an undisputedly quicker truck... if you're willing to pay the price of failure when it occurs. The manual handles the power but shifts slower, and is less expensive to rebuild at this level.

 

[HBarlow]

Eric,

The solid flywheel may be a moot point to some but is only a small part of the problem. A complete solid flywheel and clutch assembly costs considerably more than $200, probably closer to $1000 for parts and labor.

Replacing the DMF which is by design the weak link with a real flywheel and clutch assembly results in placing additional stress on the new weak link which is then the G-56. The G-56 aluminum case is already weak and challenged with factory tune and is further threatened by increased power levels.

When the cost of a couple of replacement G-56s is added to the complete clutch and flywheel system you are in the price range of the high dollar automatic rebuild.

Without power upgrades the factory six speed automatics are good for at least 300k miles of heavy towing according to TulsaOkie's and EB's service history.

I don't think anyone could make a similar claim for the DMF/G-56.

 

[KLauber]

Eric,



The solid flywheel may be a moot point to some but is only a small part of the problem. A complete solid flywheel and clutch assembly costs considerably more than $200, probably closer to $1000 for parts and labor.



Replacing the DMF which is by design the weak link with a real flywheel and clutch assembly results in placing additional stress on the new weak link which is then the G-56. The G-56 aluminum case is already weak and challenged with factory tune and is further threatened by increased power levels.



When the cost of a couple of replacement G-56s is added to the complete clutch and flywheel system you are in the price range of the high dollar automatic rebuild.



Without power upgrades the factory six speed automatics are good for at least 300k miles of heavy towing according to TulsaOkie's and EB's service history.



I don't think anyone could make a similar claim for the DMF/G-56.

EB and TulsaOkie (and you) are on the road at highway speed for most of their 300K (yours is about 100K). Its likely the grocery getters and power junkies that cause most of the early failures in either trans (Domehead?). Stock applications like mine (and yours) will have long lives as per the mfgs design.



PS a single mass flywheel at AutoZone was about $350 last I checked.

 

[HBarlow]

EB and TulsaOkie (and you) are on the road at highway speed for most of their 300K (yours is about 100K). Its likely the grocery getters and power junkies that cause most of the early failures in either trans (Domehead?). Stock applications like mine (and yours) will have long lives as per the mfgs design.

PS a single mass flywheel at AutoZone was about $350 last I checked.

That's inaccurate but you can defend your choice of a DMF/G-56 if you wish. There have been lots of reports of early failures among TDR members who use their trucks for a mix of towing and general use.

 

[KLauber]

That's inaccurate but you can defend your choice of a DMF/G-56 if you wish. There have been lots of reports of early failures among TDR members who use their trucks for a mix of towing and general use.

WHat is inaccurate? SO why hasn't my DMF/G56 failed like the others (at 94K now)? I bet the operator has a lot to do with this, something that can't be measured easily.



PS I picked the truck with the G56 because it was the only one at the dealer at the time. I needed the dually more than anything.



Ken

 

[HBarlow]

It is inaccurate because you don't have a clue how either of those other members uses their trucks. They certainly run lots of highway miles but EB probably drives a lot of lease roads to pick up and deliver oilfield equipment and his operating range is over a relatively small territory much of the time which means he travels lots of southeast TX secondary highways and small towns.

I don't know why your flywheel and clutch haven't failed YET but I am certain they will. Have you read the failure reports by numerous other TDR members? Have you heard the history of the DMF when used by Furd?

Did you read Joe Donnelly's article in the last TDR magazine about his rebuild experience and interviews with Standard Transmission when his G-56 was rebuilt?

And you wrongly assumed my truck was only highway driven. I quit transporting before I ever ordered this truck. It was my daily driver until last summer when I bought myself a motorcycle.

 

[EB]

I do drive on a lot of rough lease roads and secondary roads in Texas, Louisiana, and Oklahoma, but really the place I really hate to drive and is probably harder on the transmission than anything else is heavy, rush hour traffic in Houston (or any other city)with a heavy load. That probably generates more heat in the transmission than anything else. If you have a stick, it's harder on the clutch and throw out bearing. I'm not telling you anything you don't know. I do know that I have gone over 360,000 miles without doing anything to the Aisin transmission other than change the filter and fluid, and I do pull heavy. Don't know anything about the G56 transmission, but I do know a lot of people, not all, but a lot, have had trouble with the dual mass clutch. Probably a lot of it has to do with the operator. I know nothing about the 68RFE other than what I've read, but I don't believe I'd be afraid of it. It probably is more about personal preference than anything else. Neither the stick or auto is junk, they both will do the job. There aren't many people that will run a truck as many miles as I do, but that is my job and the C&C with the Aisin is working for me.

 

[RVTRKN]

How many miles do you have on your G-56 which allows you to claim the DMF will make it through the warranty period?



Several failures have been reported in the pages of TDR with mileage around 20,000.



Domehead experienced several failures with his and was so disillusioned he traded his for a Furd.

34K and it still feels like new. That is 1 year past the time limit and 2K miles to go, if miles were counted, but I do have an extended warranty still, and that will cover most of the cost. Sorry if it hasn't fit into your theory, I could of got the auto with the TCM. :-laf

WHat is inaccurate? SO why hasn't my DMF/G56 failed like the others (at 94K now)? I bet the operator has a lot to do with this, something that can't be measured easily.



PS I picked the truck with the G56 because it was the only one at the dealer at the time. I needed the dually more than anything.



Ken

I believe that has some bearing on it, but they have issue's, and its a fact. I wish they were as stout as a NV5600, but then again they had failures and scrambled if not taken care of as well. I believe you have to fill them a little over what the book says, but then again I never changed the oil or over filled my NV5600, and my brother just reported its 2K shy of 100K now and no issues. I don't know if he has changed it by now, but I'm sure he has.



I learned to raise the RPM's when starting out unlike the NV5600 which was, let the clutch out and give it throttle just after it engaged. It might have some bearing on it, my truck stalled a couple of times when starting out with the G56 as I did with the NV5600, but just learned not too. The very first test drive with another C&C truck with the G56, at the dealer, I stalled it when entering the street. I learned latter that its just the way you have to start out with G56. Because I slip it a little more than I did with the NV5600, maybe why it hasn't fit into HBarlow's theory. :-laf

 

[HBarlow]

My theory? My theory is your DMF will fail. You haven't driven it enough to learn yet but you will.

Wow! That's a great technique. Rev the engine up and slip the clutch just like a weak little gas-powered Chevy small block. That will certainly help clutch and flywheel life expectancy. Few of us who have owned manual transmission Rams would have ever thought of that (or been foolish enough to do it).

 

[RVTRKN]

Yes! Its your theory that every DMF will fail. In fact, you just can't help yourself to make sure everyone knows it. But the fact is, there are DMF's that have over 100K on them. If mine makes it through the warranty period, it was worth my decision to go with the G56, and if it doesn't, I wont have to pay, except for the deductable. Either way it goes, I got my money's worth.



WOW, how much did you pay for the Aison option on your truck? I'll bet it was more than one solid flywheel & a Quality clutch, including labor, would cost me, if I had to flip the whole bill myself, and less than what you paid for your auto option.



I wake up the neighbors every morning, when I rev up the engine up to the red line, to slip the clutch saving my DMF! :-laf You just can't help yourself, can you? I didn't design it, I just drive it, and if I have to give it a little throttle slipping the clutch so it doesn't stall, and you don't like it, then take it up with Dodge. My only foolish thing I do, is to keep arguing with someone who doesn't have a G56, and is ignorant when it comes to the driving technique of one.



BTW, I would love to have a 327 Small block Chevy with a manual trany, in a Chevy II, or Nova. :-laf

 

[HBarlow]

Yes! Its your theory that every DMF will fail. In fact, you just can't help yourself to make sure everyone knows it. But the fact is, there are DMF's that have over 100K on them. If mine makes it through the warranty period, it was worth my decision to go with the G56, and if it doesn't, I wont have to pay, except for the deductable. Either way it goes, I got my money's worth.

WOW, how much did you pay for the Aison option on your truck? I'll bet it was more than one solid flywheel & a Quality clutch, including labor, would cost me, if I had to flip the whole bill myself, and less than what you paid for your auto option.

I wake up the neighbors every morning, when I rev up the engine up to the red line, to slip the clutch saving my DMF! :-laf You just can't help yourself, can you? I didn't design it, I just drive it, and if I have to give it a little throttle slipping the clutch so it doesn't stall, and you don't like it, then take it up with Dodge. My only foolish thing I do, is to keep arguing with someone who doesn't have a G56, and is ignorant when it comes to the driving technique of one.

BTW, I would love to have a 327 Small block Chevy with a manual trany, in a Chevy II, or Nova. :-laf

That's a great post. Thanks for providing all that great wrong-headed information in your own words.

Yes, you got that right. I believe that every dual mass flywheel and clutch assembly used in every Dodge Ram will fail at an unreasonably low mileage if used to tow heavy trailers or haul around a heavy contractor bed loaded with tools and equipment. Lots of them have been reported here in the TDR forums. I believe yours will fail too if you drive it.

Just for fun I reached over to my file cabinet and pulled out the file folder for my Ram. The MSRP for the Aisin in MY08 was $1,125. I paid invoice not MSRP for my truck so my actual cost was probably $1,000 for the Aisin six speed automatic. I don't know what Southbend Clutch gets for their solid flywheel conversion and clutch assembly but I'd guess you won't get the complete assembly and change out labor for $1,000. And that doesn't begin to cover the cost of the G-56 rebuild or replacement if you ever accumulate any towing miles on the truck.

Have you read any of the recent thread reporting G-56 failures or Joe Donnelly's article in the last TDR magazine? You could probably call Blumenthal and Standard for estimates on a replacement G-56. I haven't priced one because I won't be needing one but rebuilding my NV-5600 in my '01 cost about $2200 with new clutch and labor if I remember correctly. I expect their prices are higher now with the dollar devaluation and inflation that has occurred since early 2005.

You may be the only owner of a diesel powered truck with a manual transmission who has learned the secret advantages of revving the engine and slipping the clutch at launch to lengthen service life of the flywheel or clutch assembly. Everyone else understands that one of the great strengths and advantages of a Cummins diesel is its very high torque at idle and max rated torque developed at 1500 or 1600 rpm which allows simply engaging the clutch at idle rpm then increasing engine speed once the clutch is fully engaged. There must be some goofy ECM programming on yours that reduces clutch engagement torque if you have to rev it before engaging the clutch. I could launch my old '01 with an 8,500 lb. Airstream or Avion travel trailer on the ball at idle in 2nd gear if I gently engaged the clutch. I never had a clutch failure and the NV-5600 lasted 302k miles before Standard rebuilt it.

Yes, 265 ci, 283 ci, 305 ci, 327 ci, and 350 ci small block Chevys were fun to drive in 3400 lb. passenger cars. They never were worth much as truck motors or in heavy cars because they didn't produce any torque below about 3500 rpm. Those engines, unlike Cummins diesel engines, required the driver to increase the engine rpm before engaging the clutch to avoid stalling the engine.

I owned a '57 Bel Air sport coupe with a 327 and 3 speed od in the early '90s but converted it to a modified 350 with TH-700R4. I sold that one for enough cash to buy my '01 Ram but kept a '56 sedan. It came with an original 265 and powerglide. I changed it to a 350 with TH-700R4 a few years ago.

 

[RVTRKN]

Show me a post of mine were I claim the G56 is the best or even that it has no failures.



My theory is that a solid flywheel has more mass/weight that allows starting out with out throttle applied behind CTD, until engaged, unlike the DMF. My hope is that when I change to an SBC setup that issue will disappear.



I don't need to be told how to drive a manual.

 

[HBarlow]

I remember a poll you initiated a couple years ago and got several owners of low mileage DMF/G-56 trucks to agree with you that the manual transmission trucks were great and nobody was having any problems with them.

I haven't weighed either but I can't imagine why a DMF flywheel which is I think is a two piece flywheel with friction plates sandwiched between would be lighter than a solid one. Also a few more posts where you claimed they were perfectly reliable, etc. It's good to see you now recognize their shortcomings.

I'm pleased to hear that you know how to drive a manual transmission truck. I was worried earlier. I thought maybe you were trying to learn when you wrote of revving the engine and slipping the clutch.

 

[RVTRKN]

Your correct about the poll, but it was to see how many failures of the trany as well as the DMF's had happened, because of your claims at the time, that every DMF failed early, which has been proven not to be true. Again, I never claimed that the G56 was bullet proof, and especially concerning the DMF. I knew that the DMF was an issue, and at that time, I made the decision to go with the G56. I considered that, as long as my warranty covered it, I wouldn't worry about it. And I'm still not worried about it.



Only recently with enough miles driven and lots of tear downs to examine the reasons for the one's that have failed, are in the most part due to heavy GCVW and I don't mean Dodges GCVWR, they were talking about 23-30K on a daily basis. If the trany is subjected only to Dodges GCVWR the odds are you will have a long life from the transmission, Not to include the DMF.



Again, I challenge you to show a post or thread of mine were I claim that they were bullet proof. I read Joe's write up on them, and it was determined that they can't, on a daily basis, heavy hauls. NV5600's have failed as well, so does that mean they are junk as well. You know I've owned both at the same time, the NV5600 and now I only own the G56, so I talk from experience



If it makes you feel any better, if or when my G56 fails it will be converted to an Eaton Fuller manual trans.

 

[Barry]

230,000 miles... ... ... ... .....



Clutch started slipping at 160K in the tow mode. Replaced with Perfection Clutch Pack. Will be at Perfection plant next week for clutch change... ... they have an SD prototype to field test.



Transmission fluid replaced at 105K when the trannie tail cone seal started leaking. Guess I should change it again... ... ... ... ... .

 

[RVTRKN]

Barry, how many miles did you have when you lost the DMF?

 

[Barry]

Never really "lost" the DMF. I was coming back from OKC with a new 4 horse Elite trailer. Somewhere in south Arkansas I engaged the resume on the CC, the motor accelerated and the truck did'nt. I had the Edge set on #2 Tow. So, I dialed it back to #1 Economy and eased on home... ... ... ... ... that happened around 160K... ... .