G56 laid down on me at 100,800 miles

[JBlackwell]

Ran a search and found lots of threads about them not being bulletproof, but not a lot of guys who at personal experiences with them laying down on them.



Mine happened yesterday. Started having a bad tick/rattle in low, 2nd, 3rd, rev, and could have been in other gears, but road noise after 3rd would have drouned out the trans. noise. Definetly loud enough I knew something wasn't right.



Anyways yanking it out and letting Standard rebuild it. Hopefully it didn't completely grenade internally. Sure thought it would have lasted longer then it did.



I wanted to give details about the history of the truck/transmission so others can maybe learn from this if I screwed it up myself and maybe they can help prevent theirs from happening.



Owned the truck since 2 miles, serviced at 25k, 50k, 75k, & a couple weeks ago at 100k. Used ATF+4. Have about 10k worth of towing miles and all of those miles and 1,500 of those miles were at 26,000# to 30,000# gross weight. All of those heavy heavy loads were all in 5th except 6th gear for about 100 miles back and forth and never under 1,600rpms. The other 8,500 miles were small stuff under 12k gross.



Also it has had a Southbend OFE in it since around 27k miles and it has never had any issues. Slipped stock clutch bad with Quadzilla at the time and after that it was never the same, so I upgraded.



I have run a programmer on it since about 25k miles, swapped to Smarty around 45k. TQ managment has never been on high, but ran it at #9 several times. Ran it on #7 several times towing.



Anywho, maybe this thread will help prevent from someone tearing up their G56. I can't say I am disappointed too much since I put a lot of power through the transmission, but I never have power shifted it or hotrodded through the gears. I have always slipped it out of 6th gear coming to a red light or stop and never grind it and pulling into the house I always let it idle and slip it into 3rd gear when slowing down and also same in 2nd gear. If you don't count that has shifting without the clutch then It has never been done.



Not sure if anything I said I have done is abusing it, but if you think I did then I did. Not really griping about it not lasting any longer then it did if you think I abused it. I am willing to fess up and pay out of my pocket, but I sure thought it would have lasted longer though.



I guess we will see what the rest of the story tells when Standard opens it up. I will post when I do.



Well what do you guys think?

Justin

 

[Regcabguy]

Per Standard's recommendations,I switched to Pennsoil Synchromesh and overfilled it by a quart. I've serviced it three times in 35K. I wonder if some fast cooler/filters installed while they've got it would help next time?



You definitely pushed it past it's parameters. Standard should fix it better than new though. I believe they'll reinforce the shifter base while they've got it also.



My 47re on the '98. 5 cost me $4500 to beef up when I upped the hp by 100.

I trust I'll make out better on this one.

 

[HBarlow]

I don't think anything you've done was "abuse" but the added power probably added to the stress and shortened the life some.

I don't think the G-56 is anywhere near as strong as the old cast iron case NV-5600 but it is the choice Daimler made and manual transmission owners are stuck with it.

Please let us know what you learn from Standard. When they rebuilt my NV-5600 at 302k miles they "hospital" cleaned the case and all the internals then invited me back to the bench to show me the parts, pointed out the wear, and explained what had to be replaced.

 

[CKelley1]

we run several g56's the overfilling of one quart is a must we tow way heavier than you and most of the time, one of our 06's came from the factory about a quart low the dmf went out at 35,000 miles and when we checked the fluid it was burnt, nearly lost it. we got the trans-cool's from genosgarage.com

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we also wrap the pipe by the transmission and add a temp gauge

 

[ENafziger]

I'm in the exact same situation as you. The G56 in my '06 went out in February at 103,000 miles. In my case, I lost teeth off of 4th and 6th gear. I've done a lot of research since then, and this is what I've found.

• I had presumed the death of my G56 at 100k was due to running higher power than designed. This is not the case. It turns out that a large percentage of G56 trucks are having failures not far past the 100k mark. Failures seem to be 3rd, 4th, and 6th gears, the front mainshaft bearing, and case cracking at the bellhousing. These failures seem to be consistant across all trucks, and thus far have not been tied to anything. Failures are happening in stock trucks with primarily highway miles that have never towed anything.
• One problem with the G56... it was never "designed" for the Cummins application. It was pulled from an existing European platform, namely a medium duty 30k pound vehicle. As such, the heat treating of the gears is not optimal/correct for the torsional spikes/vibrations/low torque of our trucks. The heat treat on the gears offer GREAT wear resistance and hardness, but at the expense of toughness and being too brittle.
• Another problem... The aluminum case does not work well to resist the torque of our engines. Flexing of the case causes the mainshaft and countershaft to separate from each other; this moves the line contact on the helical gears to the edge of the teeth resulting in poor gear mesh and high tooth loading. The stock dual-mass flywheels are known to fail prematurely; the fix is to take it out and replace with a solid flywheel. The stock clutches, being of organic material, slip slightly under load; alot of us have replaced the stock clutch with a SB/Valair/etc that doesn't slip like the stocker. Some of us have added traction bars, modified suspension, etc that allow more power to be put to the ground by eliminating undesired movement in the drivetrain. Having done all this, the transmission case now becomes the flexible element. In fact, a torsional moment of 50 ft-lbs induced to the case separates the mainshaft and countershaft by 0. 001". Or, in other words, 1000 ft-lbs causes the shafts to move apart 0. 020" or more... and line contact loading on the helical gear mesh moves toward infinity as the case flexes.
• Another problem... the chemistry of ATF is completely different than a gear lube, in that there is no "cushion" effect of the fluid. Gear-to-gear drives need the cushioning of a well designed gear lube with a high EPL additive package. GL-6 spec gear lube is second to none, and offers many benefits over ANY ATF, synthetic or not.

Obviously, abusing a truck will place undue and premature wear on many components. Obviously, drivers' habits and styles play a part in the longevity of mechanical components. However, as the '06 + trucks are beginning to accumulate some miles, repeated failures across a wide demograph of people/places/usages/power levels/tire sizes/modifications/etc, indicate that the 100k mile mark is an uncomfortable place to be.

If weak points in the drivetrain have been minimized, the flexing of the case, torsional spikes of the engine, non-cushioning ability of ATF, tooth separation and high loading at non-optimal mesh, brittle gears, etc, all add up to disaster.

--Eric

 

[ENafziger]

Wow... is there not many people with G56 transmissions on here? Have not many people reached the 100k mile mark yet? Are most people well past the 150k mile mark with no transmission problems?

I thought this would be a thread with a lot of interest...

--Eric

 

[HBarlow]

Eric,

Your explanation above is outstanding. I believe you have researched the issue thoroughly and written a very clear and understandable article.

I would like to see Robert Patton pick it up and publish it in TDR magazine. It should be read by all who own or are considering owning a truck with the DMF/G-56 combination. I'm sure that drivetrain is satisfactory for those who want a manual transmission but you have explained the shortcomings very well.

I knew none of the things you wrote above but back in late '05 when I was planning to order a new truck I learned a few basics and test drove one. I didn't like the gear ratios and Bill Stockard told me the history of the DMF when used in Furd applications. It was reasonable to assume that at least part of the reason Dodge drivetrain engineers selected the DMF was to protect the aluminum cased G-56. I think your and the OP's experiences and reports of others are proving that to be the case, at least with some owners.

 

[JBlackwell]

Standard called me and told me what all was wrong. He said something about a main cluster come apart and a tooth was broke off 3rd, 4th, & 6th gears and then of course a new bearing kit. I think he said he had some used parts he started saving for these trannys and thought he could keep it under $2,500 if no other surprises arise. I guess I will have to live with that.



Putting coolers back on it when it goes in and I went ahead and bought a new clutch disk from Southbend. The OFE I have now has around 73k miles and Peter said anything under . 290 on the clutch needs to be replaced. I measured . 303 on mine and after thinking if it would last another 100k I went ahead and got a new one. I sure am glad Peter sold only what I needed. For the money it was a no brainer.

 

[Grizzly]

Eric, thanks for your excellent write-up on the G56 manual.



First of all I'm sure glad my early 05 came with the NV5600.



I was talking with my Dodge dealer (Meloy Dodge) in Albuquerque about the short life performance of the G56 with the infamous DMF about 3 weeks ago. He said that Chrysler will eliminate all manual transmission on heavy duty Dodge trucks in 1 1/2 to 2 years. He also said that Dodge currently is the only truck offered with a manual transmission, as we all know.



I have never had a truck, Dodge or Furd, with an automatic before, but the next truck I buy will be a Dodge with an auto. It may well be a CC with the Asian 6 speed. The time has come for us die hard standard shift, old timers to switch to an auto transmission because they are now better.

 

[Regcabguy]

Upgrading to a 285-75-17 looks more proportionate to the body size and enables much more humane gearing with the G-56. Regardless of which transmission you have,it's a lot of shifting.



I drove a built 48re today and have to admit,I sure enjoyed it!

 

[HBarlow]

I had a built 48RE using all the high $$ DTT parts in an '06. The new six speed automatics are better in my opinion.

 

[Regcabguy]

Yeah,I had a DTT in my 98. 5. Six speeds would be better yet!



I still couldn't handle a slushbox though. I like the firmer shifts of a built auto.

 

[HBarlow]

Yeah, my DTT definitely shifted firmly. It would spin four rear tires on full throttle shifts from 1st to 2nd.

But the hunting back and forth between 1st and 2nd at around 20mph was annoying and the hard shifts even under light throttle got old after a while.

 

[ENafziger]

I was talking with my Dodge dealer (Meloy Dodge) in Albuquerque about the short life performance of the G56 with the infamous DMF about 3 weeks ago. He said that Chrysler will eliminate all manual transmission on heavy duty Dodge trucks in 1 1/2 to 2 years. He also said that Dodge currently is the only truck offered with a manual transmission, as we all know.

Wow... that's interesting. I know automatics have progressed remarkabley in the last decade; notwithstanding, I'm not sure I like NOT having a choice. I tend to be over-anxious about things anyway... but I'm not sure I would've been comfortable heading to Alaska last summer on a 10,000 mile trip, often without reception and hundreds of miles from anywhere, knowing my automatic transmission had 100k on it and could go out at any time. I know that's somewhat silly, as my manual transmission lost teeth on 2 gears within 4k miles of returning from Alaska, but somehow I still like it better.

Your explanation above is outstanding. I believe you have researched the issue thoroughly and written a very clear and understandable article.

Eric, thanks for your excellent write-up on the G56 manual.

Thanks guys... that means alot coming from two of the long-standing members I respect the most here! I have to credit Mike from Lazarsmith with alot of the info however. I've got a donor transmission to replace my broken hardparts, and hopefully within a month or two, I should be sending both transmissions to Mike for repair. It looks like I can get the gears redone with proper heat-treating, normalizing, and cryogenic treatment to avoid problems in the future. He also sells a steel exoskeleton of sorts to help elimate case flex.

--Eric

 

[Regcabguy]

The DTT shift controller killed that and enabled me use a Pacbrake. More money. :{



Initially my shifts were really firm. A return trip to Fred Swanson cured that with some internal magic he did.



I'm scheduled to win the Super Lotto soon,and will take some of the winnings to order a 2012. I'll report back on my impressions. Yeah,right!

 

[Grizzly]

Eric, About shelving the manual transmission on the HD Dodge, it is just one opinion from one dealer, who's honesty and integrity is undisputable in my book. I'd like to hear what other TDR members have heard on the subject.



When are you making another trip to Alaska. My wife and I are considering another trip soon. When she retires that is.

 

[Regcabguy]

I think it was Dodge's being controlled by Mercedes that led to the G-56 decision.



I wonder if Fiat's got something out there to replace the G-56? Hopefully not.

 

[HBarlow]

Several events led to that decision by Daimler when Daimler owned a controlling interest in Dodge. GM stopped using the NV-5600 about the same time. The New Venture Gear plant that built them shut down.

I don't know which came first. Perhaps NV closed for other reasons, or perhaps Daimler made the decision because they wanted to sell the G-56 for use in Ram trucks and that caused NV to close.

The G-56 is a German Daimler design, built in Brazil, for use in large box trucks in Europe behind engines probably with lower hp and torque ratings than our Cummins. The European trucks probably don't run at the gross combined weights that many of our Rams do.

 

[Regcabguy]

It's unfortunate they closed their doors with all the NV5600's out there with the inevitable replacement parts as they age. It would seem that just the manufacturing of those parts could have keep lots of guys working.



I've read where some replacement parts are now coming out of China.

 

[HBarlow]

Yeah, I agree. IMO the NV-5600 was a better transmission than the G-56 and thousands of them are probably still in service in Gen II Rams. Some of them will remain in service for another 20 or 30 or more years. There will be a need for replacement parts for them. It would be my choice for Americans to be building them but . . .

I wouldn't be surprised if some company in China doesn't begin manufacturing them, perhaps that is already happening.