2006 G56 transmission Noise

[RussellSullivan]

I bought a 2006 with a G56 a few years ago. 85,000 miles on it.
After experiencing some odd clutch noise I took out the DMF and replaced it with a SMF with organic disc.
It made a little more transmission noise with the clutch released.
After 20,000 mostly highway miles the release bearing failed and contaminated the disc.
Thinking I may tow some heavy trailers in the future I decided on Kevlar for the new disc and replaced the release bearing and pilot bearing also. I did not replace the flywheel or pressure plate as they still looked
like new.
Its all together now. Filled with 7 quarts Penzoil Synchro oil. With the clutch in the transmission is quiet. With the clutch out it is four to five times as noisy with the new Kevlar than it was with the organic disc. It's really loud. kind of a coarse BURRRING noise.
I'm stumped. And hoping someone has has seen this problem before and can enlighten me.
Thanks,
Russell

 

[GCroyle]

Short comments.

1. Are you sure that the synchromesh is correct fluid for G56? I use it in my NV5600 but that’s not a G56.

2. Trans noise. Engine running at idle, trans warmed up, clutch pedal up (clutch engaged) trans in N. The type of friction material in this condition has no input to trans noise.

3. Repeat above scenario with a G56 OE system vs HD disc and the damper will not filter out the Cummins pulsations that create gear noise or rattle like the OE did.

Pic of clutch you installed?

Gary

 

[Darkbloodmon]

I'm stumped. And hoping someone has has seen this problem before and can enlighten me.

Oh let me tell you about my on going issue with my NV5600. What your describing is similar to several symptoms I have described at length in that on going thread.

I've installed a Kevlar single disk, a South Bend Dual Disk organic, a South Bend Single disk organic, going on my second South Bend Single disk organic some time soon.

My current SBC HD Single Disk Organic is chattering and rattling like a dual disk, clunking, excessive noise on engagement, squeals from the bell housing, etc....... I'm also using a Fluid Damper Harmonic Balancer.

Of the things you can do before removing the transmission to inspect components in the bell housing. You can check your fluid level, fluid type, mess with your hydraulics, break in the Kevlar clutch if it's not already been. But ultimately the trans will have to come out.

Changing different fluid types can quite down the operational noise of the transmission but it won't solve the issue if the noise is being generated by components inside the bell housing, components that shouldn't be making as much noise as they are....

Here is a clip of my Kevlar clutch noise

Here is a clip of my Single Disk Organic Clutch noise.

Here is a driving clip of my Single Disk Organic Clutch noise.

Any of these sound similar?

 

[RussellSullivan]

Short comments.

1. Are you sure that the synchromesh is correct fluid for G56? I use it in my NV5600 but that’s not a G56.

2. Trans noise. Engine running at idle, trans warmed up, clutch pedal up (clutch engaged) trans in N. The type of friction material in this condition has no input to trans noise.

3. Repeat above scenario with a G56 OE system vs HD disc and the damper will not filter out the Cummins pulsations that create gear noise or rattle like the OE did.

Pic of clutch you installed?

Gary

Thanks for your prompt reply. I use the Penzoil Synchro in my 2001 NV5600 and had read the it is a superior replacement for ATF+4. Since posting this I drained the Penzoil and added ATF+4. and ran the truck. Still very noisy, so I don't think it's the fluid. I don't have any photos of the clutch but it is part # 05-124CK from Phoenix Friction coupled with their Kevlar disc.
Is it possible that this will quiet down when the new disc gets broken in after 1000 miles?
R

 

[RussellSullivan]

Oh let me tell you about my on going issue with my NV5600. What your describing is similar to several symptoms I have described at length in that on going thread.

I've installed a Kevlar single disk, a South Bend Dual Disk organic, a South Bend Single disk organic, going on my second South Bend Single disk organic some time soon.

My current SBC HD Single Disk Organic is chattering and rattling like a dual disk, clunking, excessive noise on engagement, squeals from the bell housing, etc....... I'm also using a Fluid Damper Harmonic Balancer.

Of the things you can do before removing the transmission to inspect components in the bell housing. You can check your fluid level, fluid type, mess with your hydraulics, break in the Kevlar clutch if it's not already been. But ultimately the trans will have to come out.

Changing different fluid types can quite down the operational noise of the transmission but it won't solve the issue if the noise is being generated by components inside the bell housing, components that shouldn't be making as much noise as they are....

Here is a clip of my Kevlar clutch noise

Here is a clip of my Single Disk Organic Clutch noise.

Here is a driving clip of my Single Disk Organic Clutch noise.

Any of these sound similar?

The noises you sent are very similar to the loud noise I am hearing in my G56.
Maybe it is the new kevlar disc with only 20 miles on it. Not nearly broken in yet! Or maybe I need to
replace the flywheel and pressure plate. But it is interesting that it was much quieter with the organic disc using the same flywheel and pressure plate. Will drive it for a while and see if it gets quieter with some mileage.
Thanks for you input.
R

 

[AH64ID]

Are you hearing gear rollover noise or something different?

Try a GL-4 75w-90 fluid as that’s OE spec from Mercedes.

 

[Darkbloodmon]

Thanks for your prompt reply. I use the Penzoil Synchro in my 2001 NV5600 and had read the it is a superior replacement for ATF+4. Since posting this I drained the Penzoil and added ATF+4. and ran the truck. Still very noisy, so I don't think it's the fluid. I don't have any photos of the clutch but it is part # 05-124CK from Phoenix Friction coupled with their Kevlar disc.
Is it possible that this will quiet down when the new disc gets broken in after 1000 miles?
R

Hey what a coincidence, my Kevlar clutch was from Phoenix Friction as well. Verify with Phoenix Friction the warranty on bad parts out the box first before you put 1K miles on it and they tell you it's not returnable.

The Kevlar clutch as described is supposed to be a "better" organic material, longer lasting, smooth engagement, little to no noise comparable to the OE organic clutch.

I doubt it's going to get better with any additional miles, I parked my truck and removed the clutch shortly after. It's a noise that it shouldn't be making.

My SBC single disc organic is making noise still thousands of miles after the break in and daily driving.

But hey try everything I didn't already you might stumble upon something I overlooked. Keep us posted, I'm very interested to see if you find the cause of your issues, it might help me with mine.

For what its worth the factory spec ATF 4 for the G56 is pretty noisy, I use Amsoil Manual Synchro Mesh in my NV56. I know everyone has their "Go team!, Grandpa always said..., family tradition, special sauce" oil brand but most opt out of the ATF 4 and are happy with the results.

I don't think oil is your problem, though take it with a grain of salt.

 

[BigPapa]

The issues with using the wrong fluid are the viscosity differences and the chemical reaction that the wrong oil has on the synchro’s. For example, GL5 fluids will disintegrate the clutch material in the NV4500’s in a short period of time.

 

[NIsaacs]

Russell, What was your first replacement clutch? Was it a stock type SMF like this (first pic)? Note the mushy torque springs in the disk hub, they cushion the torque pulse of the Cummins to keep the transmission gears quiet. The second picture is probably what you have now. Note the HD springs, hub and solid disk, they are noisy but don't hurt anything. Just drive it.

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[GCroyle]

Why not consult with Phoenix Friction and get their .02$

The G56 had a belt and suspenders approach to gear noise, the DMF and a torsion dampened disc. Now you are solid and if the damper is like second pic that Nick posted those are strong but simple and do not have the same dampening ability as the one above it or the OE setup.

A solid flywheel and its pressure plate are bystanders in a discussion about gear noise.

 

[CVR222NV]

Standard Transmission and Gear requires 7 quarts of Manual Transmission Fluid Synchromesh 30 weight for their warranty and recommends and sells Amsoil for the G56.

I have a South Bend Clutch dual disk organic clutch and have no noise at idle with the clutch out in neutral.

When I depress the clutch at idle I get a noise that seems to be the engaged throw out bearing.

I get no noise when the clutch in engaged while driving unless my shift point is at too low of rpm and then I will get the roll over noise.

 

[RussellSullivan]

Are you hearing gear rollover noise or something different?

Try a GL-4 75w-90 fluid as that’s OE spec from Mercedes.

I would imagine it's gear rollover noise. Neither old '91 five speed or my '01 NV5600 ever made any noise so
this is new to me. I will try seven quarts of the Mercedes GL-4.
Thanks
R

 

[RussellSullivan]

The issues with using the wrong fluid are the viscosity differences and the chemical reaction that the wrong oil has on the synchro’s. For example, GL5 fluids will disintegrate the clutch material in the NV4500’s in a short period of time.

I will keep that in mind.
Thanks
R

 

[RussellSullivan]

Russell, What was your first replacement clutch? Was it a stock type SMF like this (first pic)? Note the mushy torque springs in the disk hub, they cushion the torque pulse of the Cummins to keep the transmission gears quiet. The second picture is probably what you have now. Note the HD springs, hub and solid disk, they are noisy but don't hurt anything. Just drive it.

You are correct. Picture #1 shows the unit I removed. Picture #2 is the unit I installed. Much heavier springs. It's warm here in Arizona so I'll try 7 quarts of the Mercedes GL-4.
Will reply with results.
Thanks
R

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[AH64ID]

I would imagine it's gear rollover noise. Neither old '91 five speed or my '01 NV5600 ever made any noise so
this is new to me. I will try seven quarts of the Mercedes GL-4.
Thanks
R

My NV5600 had some gear rollover but not as loud as a G56 since the G56 has an aluminum housing.

These FAQ's have some good info on G56 noises.

https://www.southbendclutch.com/resources/faq/

 

[RussellSullivan]

Finally, after holidays and a bout with the covid I found time to get this done.
I made a new PTO cover with a high fill port and added seven qts Amzoil MTG 75-90.
The amount of gear noise is now dramatically less than when using ATF+4.. Amazing!
I also installed a Fluidamper up front and that made things a little quieter yet.
Thanks to all of you for your input.
Russell