Gear Whine AAM 11.5

[Big MAK]

First of all -- this is the THIRD Ram 3500 I've owned with an AAM 11.5. (tenth Cummins Ram overall)

This particular vehicle has a very annoying differential gear whine. When we first asked for it to be looked at they replaced the ring and pinion, then the seals, then reset the preloads. Now they say they can do no more.

I test drove a couple others and they made noise - but to varying degree. One was quite tolerable (explained not having an issue with them previously) and the other was almost (but not quite) as bad as mine. It causes headaches on road trips and my wife is a migraine sufferer so that makes it worse.

This is at 70mph+, it's louder the faster you go, and only happens under load. When warm/hot it gets progressively worse.

If I get backed into a corner and have to fix this myself - how? All I can think of is replacing the axle to get all new internals. My opinion is it's potentially a heat and lack of lubrication problem - i.e. insufficient lube on the pinion gear at speed.

The AAM 12" is whisper quiet -- I wonder if they're swappable.

 

[grabinov]

I have two starter ideas: 1. Find out what differential gear lube the dealer is using and switch to something else. I know there are two lube specs for the rear axle, a lighter and a heavier viscosity. Maybe the heavier one will do the trick. I know lots of guys on here switch lube types and/or specs when they do the first change.

2. Try an aftermarket diff cover. If you look at the Gayle Banks videos on rear diff covers, you'll see that they can be very different one to the next. Many are worse than the factory cover in terms of lubrication so choose carefully. I am not a huge Banks follower or believer or anything, but that set of videos is REALLY good. It may be that added lube oil quantity, cooler lube oil and different lube oil will solve the problem, and we're talking a few hundred bucks for parts and lube that, even if they don't solve the noise problem, are worthwhile anyway??? And all that is way less expensive than getting into the diff or the axle...

Greg

 

[AH64ID]

I have two starter ideas: 1. Find out what differential gear lube the dealer is using and switch to something else. I know there are two lube specs for the rear axle, a lighter and a heavier viscosity. Maybe the heavier one will do the trick. I know lots of guys on here switch lube types and/or specs when they do the first change.

Greg

Only 1 OE spec for the AAM axles, 75w-90. There hasn't been a light/heavy spec since 2002.

I agree on changing fluid thou.

Did they replace the LSD? Or any bearings?

 

[Cummins12V98]

Towing heavy AMZ/OIL recommends 75/110. I would give that a try.

The OE lube is SH!TE.

 

[Alan Reagan]

Mine did the same thing. The gear lash was not set correctly from the factory. Whine started at 65 and got worse, especially climbing hills.

The dealer installed new gears, bearings, etc. and set the lash to spec and the problem disappeared. You could probably just set the lash but would really need to flush the rear end because of the metal particles.

 

[R.Taylor]

My brand new 2018 2500 has diff whine also.... It was doing it with only 124 miles on the odometer.... Now at 4350 miles it's louder. I'm just going to beat it into the ground till it fails. 2 days after I bought this truck.... I had an appointment with the service department. I took it there for 2 issues.

#1 - Sunroof does not sit flush when closed, It sticks up in the rear and barely makes sealing contract (the sheet metal is pushed down on the back of the cab like Jose stood on it at the factory).

#2 - Rear diff whine at freeway speed, Loud clunking from diff when feathering on and off the pedal in 15mph traffic (ring and pinion not set up right)

Now seeing I've been going to this same dealership since 2005 and had/have the same service advisor... Here's what they said.

#1 - "Well, We looked at other vehicles with sunroofs and they pretty much all look the same when closed."

#2 - "Well, Our tech could not reproduce the clunking or whine but he suspects your hearing the turbo whine and not the differential."

I looked at her and scoffed. FU FCA.... Shoulda kept my 06.

Not to be off the subject but most car manufactures offer a loaner if you come in for service when your vehicle is under it's original new car warranty. Well for some reason Dodge/RAM does not.... Only if you have a MaxCare extended warranty. When I dropped off my 2 day old 2018 2500 I asked for a loaner and only to be told MaxCare warranty holders get loaner vehicles.... I then looked at her and said "Why did you not ever offer me a loaner with my 2006 all those times I brought it in for warranty service as I had MaxCare on that truck, All you offered was a shuttle ride back to where I came from?" She said "Customers usually ask for a loaner."

Long story short... I'm not going to rent a car while I wait for some unskilled mechanic to try setting up a ring/pinion gear for perhaps the first time. I'd Lemon this truck if I could get 29 more days in service. California has no nonsense lemon laws.... 30 accumulated days in service and its a lemon. FCA has no choice but to repurchase it.

In the mean time, I ordered a 2019 3500 Megacab Laramie built to suit, It should be here mid August.... With no sunroof.

I've owned 3 CTD Rams.... When did quality control go downhill??

 

[jhenderson]

Why would you order another if you’re so dissatisfied with the the build quality and service on this truck?

 

[R.Taylor]

Why would you order another if you’re so dissatisfied with the the build quality and service on this truck?

When I was truck shopping... All of the trucks had sunroofs and I was adamant about not getting a sunroof, I had no choice unless I ordered one. I'll be going to a different dealership from now on for service needs, the new dealership ordered the 2019 from. There will always be a bad apple in the bunch when it comes to vehicles.... I'm not leaving RAM for some V8 diesel BS. Honestly, Coming from an 06 2500 with a leaf spring rear and going to 2018 with a 5 link coil rear... I don't like how the rear feels. The 3500's still have leafs. I'm satisfied with everything else in the truck, it's beautiful inside and comfortable, fuel economy is good. The only thing I don't like is the location of the exhaust brake and tow/haul buttons.... They should have put them on the stick or wheel.

 

[jhenderson]

Good enough

 

[RVTRKN]

Big MAK, the 2014 CTD I drove for a short period completely scrambled the rear diff, to the point the entire diff was ordered in pieces and repaired at local dealer. The diff tubes were not true causing the ring and pinion to wear incorrectly taking out the assembly, at around 14K miles.

 

[KATOOM]

If you look at the Gayle Banks videos on rear diff covers, you'll see that they can be very different one to the next. Many are worse than the factory cover in terms of lubrication so choose carefully. I am not a huge Banks follower or believer or anything, but that set of videos is REALLY good.

I agree that a differential lube change may quiet up the OP noise.
But.....I'm sorry, as those Gale Banks video's are HORRIBLE. Gale has become the epitome of smooth talking salesman who was clearly doing everything in those videos to pitch his up and coming products, nothing else. For almost an hour on YouTube he proved nothing, he showed nothing, and he never offered any real data other than his opinions based on other opinions which are completely irrelevant. He might as well said, "buy mine because I think it will be better than these other ones".
In short...all his differential cover videos were embarrassing to the Gale Banks name I remember growing up.....but they sure stirred up a rats nest of opinions and panic as people tossed their aftermarket diff covers on the classified section anxiously awaiting Gales new bling.

 

[RVTRKN]

I've never been sold on Banks systems, I'm sure there is some good products that they have, but I just have always felt the snake oil sales pitch. KATOOM, can you link the video you mentioned?

 

[CAROLINA CUMMINS]

- This is Part 1

- Clear Stock Cover

Not a fan of Banks, but the videos are interesting.

 

[Big MAK]

Thanks for the replies. At this point the dealer(s) refuse to work on it. Went into lemon law proceedings, accepted a buy back offer they made 2 days before the hearing, FCA refused to honor their offer after they took all the cash from me they could and had tricked us into cancelling the hearing (we were honoring the offer and lowering the loan principal), FCA told me to hire an attorney, I hired an attorney, new lemon law hearing scheduled.

I know I can fix it myself by replacing the internals but at this point it's about FCA doing everything they can to screw me over. I'd be 100% ok with fixing it myself if FCA paid for the parts and didn't void the rest of the vehicle's warranty when I fixed it. Which was the objective of my original post. Well... I WAS ok with it. Now it's time to fight.

The truck hasn't been driven for over a month because FCA is charging me 67 cents a mile to drive it on top of loan payments, etc. I.e. on the buyback they claim I have to pay 67 cents per mile for usage.

So we bought another car because I didn't want them to have me over the barrel with no vehicle to drive - and the use penalty just driving it to work is $25 per day. Paying "rental fees" on a vehicle you are making payments on blows my mind.

Meanwhile, we have no truck to tow our RV with - which we were prepping for a long trip in 2020 (Alaska). Now plans are canceled, we're older and not sure if we will be healthy enough for a trip like that in a few years, everything is f'd. It's also the reason the excessive gear whine is a problem - we bought the truck specifically to have a dependable vehicle to take into far northern back country. If I can't rely on it, I can't take it into the back country. If the gearset is grinding away on smooth city highways there's no way it'd survive thousands of miles on tore up dirt roads.

This has been a massively expensive fiasco that is making me ill.

I'm still a huge fan of Cummins. And of Jeep/Wrangler. Sorely disappointed in FCA.

 

[Big MAK]

As for the 'root cause' of the problem - I am very suspicious that there is insufficient lubrication at speed. Which could possibly be fixed with lubrication as pointed out here. Either different lube or better routing of the lube forward to the pinion at speed. I'm leaning towards both - better lube and a diff cover that 'throws' the lube at the pinion gear at speed.

If I was able to be adequately reimbursed and not void the warranty I was going to replace the gears and install a diff locker in the AAM 11.5 - basically replacing all internals.

One of the discoveries of this whole mess was that ALL AAM 11.5 have this problem just to varying degree vehicle to vehicle. This particular truck happens to be at the extreme end of the spectrum. I'm curious which year it started - because if my previous 2 AAM 11.5 had the problem it was not loud enough to be an issue.

 

[KATOOM]

Sorry for all that...
Keep the thread posted.

 

[kthaxton]

The diff tubes were not true causing the ring and pinion to wear incorrectly taking out the assembly, at around 14K miles.

All these years you've been blaming it on the 3.42 ratio....

 

[RVTRKN]

I was suspicious of that, however according to the dealer the axle tubes were not true and caused the misalignment. I still don't like the 3:42 rear diff, and I'm not the only one apparently, they have been replaced with the 3:73 for MY 2019. If they were so successful, they would have not gone back to the 3:73's.

 

[nukegm]

I was suspicious of that, however according to the dealer the axle tubes were not true and caused the misalignment. I still don't like the 3:42 rear diff, and I'm not the only one apparently, they have been replaced with the 3:73 for MY 2019. If they were so successful, they would have not gone back to the 3:73's.

hey comrade rv - just curious how the dealer determined the tubes were bent or not aligned? i had that problem on a ford 9 inch on a 71 bronco i drove in college. went through 4 center sections in a year. even one built be the famous mark williams....i finally found a differential shop in aurora colorado, and the guy used a long solid tube ( of known straightness ) which he inserted through the entire diff. and determined the housing was tweaked. i still have the bronco 30 years later. diff still good. just a giant pain for a broke college kid at the time. cheers comrade!

 

[RVTRKN]

I wasn't there in the actual inspection, but the tech showed me the wear pattern on the ring and pinion which indicated incorrect alignment. I'm sure he checked for FCA, because of the cost of the repair. I'm surprized FCA just didn't send a complete assembly. Instead they sent the assembly in pieces, which the tech had to rebuild. The diff was never opened due to only 14K miles on it.