G56 tans problems, need help

[Mhannink]

a little back ground, we have an 06 dodge std cab 3500 dually 4x4 with the g56 trans, a few weeks ago i noticed a really bad vibration at idle, felt like an injector miss. after a little research i determined it was the dmf and clutch. well we replaced the clutch with a south bend dual disc and smf. now the truck feels pretty good. no vibration idleing, and runs nice and smooth up to about 2000 rpm (i didnt go any higher). on the test drive i noticed a really bad gear grind/whine noise during accel. rpm didnt matter too much but it was worse around 1500 rpm and only during acceleration. since the dmf issue ive been poking around for more info on these trannies in general. what i found, and most of this from some literature that came with the sb clutch(i trust south bend very much they have always been good to me) was the damage the dmf can do when its failing. they also included a phamplet about the stiffener girdle. well when i got home i crawled underneath the truck and checked the driveline, everything feels tight and in good shape. my questions are as follows.



one, did the 06's with the single piece steel drive shaft have any vibration issues (all the problems i have read about have been the two piece)?



two, did the third gens have a driveline damper like the second gens(the one right at the tcase on 4x4's)?



three, does this grind/vibration noise sound like a trans problem that was refered to in the literature (should comment i noticed the same noise when i shut the engine off after idleing in nuetral for about a minute)?



lastly, who has put the girdle on, what do you think of it, and what problems have you(with or without girdle) had with the g56 trans. this truck tows 90% of the time, empty trailer is around 6k, fully loaded it can be as much a 25k gcw.

 

[Mhannink]

just had another question, im getting ready to change the oil in this trans and i am wondering what to use. im sold on full synthetic, however i dont like atf in manual trans, i just cant buy it. reading about these problems with the g56 im wondering is a heavy oil would be better. i have been reading a lot of no's about anything other than atf, but i really do wonder about some peoples so called "knowledge" on various matters. since tdr has often and almost invariably been a solid and reliable source i turn to you fellow members for advice.



what oils has anyone been running? anyone yet risk anything else other than atf? if so what was it?



like i said im just not convinced that atf is propper for the trans, i am concerned about other heavier lubes having additives that eat yellow metals, i havent yet encountered a problem like that in other applications, and in those i was not running the propper oil as per spec, anyone have more information? im currently leaning towards putting in 80w-90 gl-5 the same that has been in my nv4500 for 45k miles now. my nv4500 shifts better than any other i have driven and its got 236k miles on it, from what i can tell im not supposed to run that oil cause it will wear out the transmission too fast. think it will work in the g56?

 

[ENafziger]

No issues with vibrating rear one piece drive shafts. The front shafts sometimes give a vibration problem around 72 mph.

The 3rd gens do NOT have the driveline damper.

How many miles are on the transmission? Does the noise only happen in a certain gear or gears?

I started getting a slight whine/vibration in 6th. Then it started in 4th. Then I drained the fluid, and out came several teeth

I am in the process of getting my G56 rebuilt, and have a girdle ready to go on.

As per oils... I will NEVER put an ATF in mine again. I had been running Amsoil full synthetic ATF in mine, and changed it every 30,000 miles. Not again.

I've researched this extensively, and I think the best fluid to use is the GL-6 spec Gorilla Juice that Mike at Lazarsmith sells. Second best, Mobil One 50W synthetic, followed by Pensoil Syncromesh.

--Eric

 

[ENafziger]

Here's an interesting read if you haven't seen it:
MB G56-6 Mercedes Benz Factory Fill - NOT ATF+4!! - Page 6 - Dodge Cummins Diesel Forum

--Eric

 

[steved]

Some 3rd gens do have a driveline damper... my 04. 5 has one.

 

[ENafziger]

Some 3rd gens do have a driveline damper... my 04. 5 has one. <!-- google_ad_section_end -->

Is your truck a quad cab short bed? I would assume you have the NV5600, right?

I've not seen a G56 truck that had the damper... but I've not seen them all either!

--Eric

 

[Mhannink]

No issues with vibrating rear one piece drive shafts. The front shafts sometimes give a vibration problem around 72 mph.



The 3rd gens do NOT have the driveline damper.



How many miles are on the transmission? Does the noise only happen in a certain gear or gears?



I started getting a slight whine/vibration in 6th. Then it started in 4th. Then I drained the fluid, and out came several teeth



I am in the process of getting my G56 rebuilt, and have a girdle ready to go on.



As per oils... I will NEVER put an ATF in mine again. I had been running Amsoil full synthetic ATF in mine, and changed it every 30,000 miles. Not again.



I've researched this extensively, and I think the best fluid to use is the GL-6 spec Gorilla Juice that Mike at Lazarsmith sells. Second best, Mobil One 50W synthetic, followed by Pensoil Syncromesh.



--Eric

there are 93k miles on the trans, the noise is in all gears under light acceleration, i imagine it would be worse under high load but i have not tried it. the trans seems pretty quiet when cruising.



as for the oil, gl 6 is obsolete, my understanding is that gl-5 should be able to do everything gl-6 does. my main concern with changing to a gear lube is the compatibility with yellow metals. i was also given the implication by a mechanic (i think he's decent but maybe not entierly knowledgeable) that aluminum case gear box, i. e. trans, tcase, and anything else with an aluminum case often take atf. that has been his experience but that doesnt seem too sound to me. aluminum i do think has any problems with gear oil. its more brass, bronze, copper, etc. that has issues. i do know it really boils down to additive packages.

Here's an interesting read if you haven't seen it:

MB G56-6 Mercedes Benz Factory Fill - NOT ATF+4!! - Page 6 - Dodge Cummins Diesel Forum



--Eric

i also found this while poking around last night, my reasoning right now is, the trans is damaged to the point that it will fail sooner or later. im going to put the girdle on and try the gear lube i really like in other transmissions and see what happens. if it lasts a long time then maybe its ok. so we will see. i still want inputs though on the fluids people have used and how they seem to work.



thanks for the info, it was really appreciated.

 

[blacksheepdiesel]

Is your truck a quad cab short bed? I would assume you have the NV5600, right?



I've not seen a G56 truck that had the damper... but I've not seen them all either!



--Eric

My 04. 5 dually quadcab 2wd NV5600 has the dampener.



Godspeed,

Trent

 

[ENafziger]

as for the oil, gl 6 is obsolete, my understanding is that gl-5 should be able to do everything gl-6 does. my main concern with changing to a gear lube is the compatibility with yellow metals.

That is generally true. The GL-6 offered the most extreme additive package, and was mostly a military oriented fluid.

You may already know this, but I found it to be a good concise summary:

API ratings
Gear oils are classified by the American Petroleum Institute using GL ratings. For example, most modern gearboxes require a GL-4 oil, and separate differentials (where fitted) require a GL-5 oil. It is important that purchasers check the oil against the vehicle manufacturer's specification to ensure it does not contain any aggressive chemicals that may attack yellow metal gear components, such as phosphor bronze.
API viscosity ratings for gear oils are not directly comparable with those for motor oil, and they are thinner than the figures suggest. For example, many modern gearboxes use a 75W90 gear oil, which is actually of equivalent viscosity to a 10W40 motor oil. Multigrade gear oils are becoming more common; while gear oil does not reach the temperatures of motor oil, it does warm up appreciably as the car is driven, due mostly to shear friction (with a small amount of heat conduction through the bellhousing from the engine block).
Fully synthetic gear oils are also used in many vehicles, and have a greater resistance to shear breakdown than mineral oils.
API classification subdivides all transmission oils into 6 classes:

• API GL-1. Oils for light conditions. They consist of base oils without additives. Sometimes they contain small amounts of antioxidizing additives, corrosion inhibitors, depresants and antifoam additives. API GL-1 oils are designed for spiral-bevel, worm gears and manual transmissions without synchronizers in trucks and farming machines.
• API GL-2. Oils for moderate conditions. They contain antiwear additives and are designed for worm gears. Recommended for proper lubrication of tractor and farming machine transmissions.
• API GL-3. Oils for moderate conditions. Contain up to 2. 7% antiwear additives. Designed for lubricating bevel and other gears of truck transmissions. Not recommended for hypoid gears.
• API GL-4. Oils for various conditions - light to heavy. They contain up to 4. 0% effective antiscuffing additives. Designed for bevel and hypoid gears which have small displacement of axes, the gearboxes of trucks, and axle units. Recommended for non-synchronized gearboxes of US trucks, tractors and buses and for main and other gears of all vehicles. These oils are basic for synchronized gearboxes, especially in Europe.
• API GL-5. Oils for severe conditions. They contain up to 6. 5% effective antiscuffing additives. The general application of oils in this class are for hypoid gears having significant displacement of axes. They are recommended as universal oils to all other units of mechanical transmission (except gearboxes). Oils in this class, which have special approval of vehicle manufacturers, can be used in synchronized manual gearboxes only. API GL-5 oils can be used in limited slip differentials if they correspond to the requirements of specification MIL-L-2105D or ZF TE-ML-05. In this case the designation of class will be another, for example API GL-5+ or API GL-5 LS.
• API GL-6 is not applied any more as it is considered that class API GL-5 well enough meets the most severe requirements. When API GL-6 was still in use, it denoted oils for very heavy conditions (high speeds of sliding and significant shock loadings). They contained up to 10% high performance antiscuffing additives. They were designed for hypoid gears with significant displacement of axes. However in 2011 at least one company offers new polyol ester based API GL-6 oil, mostly for racing applications<SUP id=cite_ref-0 class=reference>[1]</SUP>. Such API GL-6 oil can replace higher viscosity GL-4 gear oil, thus increasing the efficiency of the car transmission where it is used. The application is limited to certain types of manual transmissions, but improvements in BSFC of about 5% in standard weather and driving conditions and up to 15-20% in cold extremes (arctic weather conditions) can be expected<SUP id=cite_ref-1 class=reference>[2]</SUP>.

From what I understand, Torco, Richmond, Redline, and Motivegear all still sell a GL-6 spec lube. However, the Gorilla Juice marketed by Mike is a GL-6 lower viscosity formula that has been already proven with great success in the G-56 application. Not only that, but it's alot cheaper than the other manufacturer's as well.

If your noise is in all gears, you likely have a damaged input shaft bearing. If so, continued use may render your transmission case un-usable for a rebuild.

--Eric

 

[ENafziger]

Have you read this?

This is one place indicating it's a good idea NOT to drive the transmission any more if it's making noise...

http://www.southbendclutch.com/g56-2.pdf

--Eric

 

[Mhannink]

hey eric thanks for the info, it is good info to know. here is our problem though, we have three trucks that for some reason all decided to have serious problems all at once. the 06 with the dmf and a turbo problem, our 99 ford 450 needed new batteries, changed to road draft breather tube due to amount of oil in intake, im hoping we dont have other problems, had to change a coolant reservoir and coolant, also replaced a wheel abs sensor, and its had an injector stick and then clear up before i could diag the problem, i put fuel additive in hoping it wont come back for a while, also had to replace the lower intake hose since it was cracked and sucking dust. on my 97 i had to replace the fan clutch cause it was failing, also replaced the belt, and i found an external coolant leak that i think is the head gasket. for the moment i would love to install a new trans before it has any major problems but buisness is not great and we have had a lot of repairs going on all at once. not to mention i am also spending a lot of money building up the propper supplies for our shop so that when i go away for school my folks can maintain the equipment properly.



the way i see it, the transmission is toast, no saving it, it is only a matter of time before it fails. so what i did was change the oil to my personal favorite, it is gl-5 rated 80w-90, it has worked very very well for me in other units that are not supposed to take this oil. my figuring is that it will either prolong the the transmissions' life or it will shorten it. by next week i hope to have the torque shield girdle installed as well to help it out some. took the truck on a moderate test drive and felt a big difference in the trans. it shifts better, noise is completely gone through 3rd gear, 4th has a tiny bit of noise still but not to bad, 5th does not seem to have changed much at all maybe a little less, and 6th i think is quiet though im not completely sure. this is a big difference from the grinding i heard in all the gears before. so overall it has improved, for how long i dont know. as i mentioned above i would love to put a new trans in, good gear oil, and the girdle all so i can forget about the damned thing, however we do not have either the time nor funds for it right now, so i am going to eek out what i can get and when it gernades then i will put a reman in from standard or bluementhals, with proper fluids and such.

 

[ENafziger]

however we do not have either the time nor funds for it right now, so i am going to eek out what i can get and when it gernades then i will put a reman in from standard or bluementhals, with proper fluids and such. <!-- google_ad_section_end --> <!-- / message --><!-- sig -->

Hey, I definitely understand where you're coming from, and I wish you the best! Sometimes you have to do what you have to do. It'll be interesting to see how long this holds together for you! Keep us updated if you think about it...

--Eric

 

[Mhannink]

Will do, the truck doesn't go to many miles a year, so it'll be a while before I start getting tangible results

 

[Joseph Donnelly]

I'd use Torco RTF (racing transmission fluid) or Pennzoil Synchromesh fluid in a G56.

 

[AH64ID]

When I put a SBC clutch in my truck this spring it made a god aweful noise (vibrated really bad) at low load, rpms for about 500 miles. It was the clutch breaking in, and I assume the dual disc is going to be the same way.

In order to get it to break in I had to do some WOT runs and tow about 200 miles. Light driving didn't do it, you have to put some power thru the springs in the discs to get them to soften up.

Looking at the MB specs a 75w-90 GL-4 is what it calls for, and probably what will go in my dads G56 when it gets changed next time.

All NV5600 trucks have driveline dampeners, I don't believe any G56 trucks do. . may not be a bad idea to add one if you ditch the DMF.

 

[TAllsop]

Eric Where did you get your transmission rebuilt. Mine is coming apart.
Dewey