R+P Swap -- Install Kits

[ramv]

If I am thinking about this right, with the AAM axles and the built in adjusters, the only new bearings required should be on the pinion for a PW ring and Pinion upgrade? Carrier bearings should stay on the lockers, obviously no shims on an AAM axle,.

[Colibri]

If you're low mileage I would agree. What ratio are you thinking?

[ramv]

Yeah, 15.5k miles currently. Thinking when I do tires would be a good time.

Looking at options. 4.88s seem to be the deepest AAM for the 9.25"; Nitro can do 5.13s f/r, can mix and match to get 5.38s.

With the double OD, I would think all would be good, I seldom use 6th at legal speeds currently with stock tires, so would prefer something in the 5 series. I did 5.13s in my second gen and they were great with 37"s (single OD) but much smaller, lighter truck and always empty compared to my PW. Plus the Hemi likes revs a lot more than the old 5.9. I had 30" tires, 4.10s with a 0.75 OD and 8.1 BB in my Chevy stock, and it was decent, would like to get back to that (which 5.13s and 34.5" should be close, other than the smaller/higher revving engine in the Ram.)

[adeluca73]

Yukon front R&P 4.88
OEM rear R&P 4.88
Requires a shim, but comes in kit if you buy from Randy's
Reduced overall GR to 4.35 w/ 37's.
Raises RPM at speed x 20-300 vs. stock

[ramv]

Yukon front R&P 4.88
OEM rear R&P 4.88
Requires a shim, but comes in kit if you buy from Randy's
Reduced overall GR to 4.35 w/ 37's.
Raises RPM at speed x 20-300 vs. stock

Figure I need a bit more than that here since 6th is worthless other than downhill, cruise is always bouncing to 3rd, 4th and 5th unless I just hit tow/haul and lock out sixth, then it tends to hold fourth most of the time. . Probably need at least 600 rpm (25%+). The 6.4 is so much better than my 2011 5.7, but still a dog on the highway. I think some gearing would wake it up; it does well above 4000 rpm.

3% power loss per 1,000' of elevation gain, and I never see anything under 6,000' so these naturally aspirated rigs are a challenge. ( For example: my Ducati 1200 was a complete joke here, but was awesome when I got to ride once in California.)

[TwinStick]

That is the problem with all truck auto transmissions these days. Geared for mpg instead of HD work (yet they fail on both accounts). It seems we are now into the "lets see how many gears we can put into an auto trans" wars. Regardless of how many, the proper ratios are KEY. IMHO, if you have 6 or 8 or even 10 gears, there is no reason for more than 1 overdrive gear---ever. And the gear right before the overdrive should be 1 : 1. And there should be at least 2 gears lower than the pathetic 3:1 that was in the 545RFE. The axle gear ratios do not matter as much because if the auto trans gear ratios are all wrong & you can't hold it in each gear until YOU want it to shift, then you are simply at the mercy of the computer & it's programming .

I simply can't believe the engineers are so incompetent that they don't know this. They have to be being told to design it that way &/or forced to, because of the strict Gov't CAFE requirements, if not, then the human race is failing miserably.

[ramv]

Agreed they are geared too tall. Can be overcome at the trans or the axle. Advantages/disadvantages to both ways. Obviously the main advantage at the axle is the cost on an existing platform. I really don't think the engineers are incompetent. I would imagine they are working within several parameters and have to compromise to best suit all requirements. Space, cost, mileage, usability across multiple platforms, etc.

Regardless, any thoughts on the extent of the install kit needed to regear low mileage AAM axles? When I did the Dana 60/70 in my second gen I needed a lot of bearings.

[TwinStick]

I guess it would come down to a cost and peace of mind issue. A Master rear diff overhaul kit for my truck is $353.85. https://www.ringpinion.com/b2c/ProductD ... howAA=true If you want total peace of mind, thats the way to go. If not, you will prob be fine with those low miles.

What year ?
what axles ?

[Reloaderguy]

That is the problem with all truck auto transmissions these days. Geared for mpg instead of HD work (yet they fail on both accounts). It seems we are now into the "lets see how many gears we can put into an auto trans" wars. Regardless of how many, the proper ratios are KEY. IMHO, if you have 6 or 8 or even 10 gears, there is no reason for more than 1 overdrive gear---ever. And the gear right before the overdrive should be 1 : 1. And there should be at least 2 gears lower than the pathetic 3:1 that was in the 545RFE. The axle gear ratios do not matter as much because if the auto trans gear ratios are all wrong & you can't hold it in each gear until YOU want it to shift, then you are simply at the mercy of the computer & it's programming .

I simply can't believe the engineers are so incompetent that they don't know this. They have to be being told to design it that way &/or forced to, because of the strict Gov't CAFE requirements, if not, then the human race is failing miserably.

This post makes no sense, the 8HP70 has a 4.71:1 first gear with up to 3.92 R/P, that's what makes it great. Lower the final drive ratios and the 66RFE is going to work great too.

[olyelr]

The half ton 8 speed trans ratios: 4.71:1, 3.14:1, 2.10:1, 1.67:1, 1.29:1, 1.00:1, .67:1, R 3.30:1. Other than not quite so low of a first gear, it pretty much has the G56 covered... and you dont have to shift it

If the overdrive is too much for your particular cruising speed, then push the button and shift out of it It is no different then down shifting a manual, just a bit easier

Dont get me wrong, I love a manual trans. Gives me added joy to driving. But I see why engineers are taking the auto trans where they are. I personally think they just have the programming a bit screwed on the new PW trans.

The 8 speed trans in my wife's '16 denali xl drives amazingly well. Actually, that motor is amazing too. Almost wish I had that package in my PW

[usmc369]

Yukon front R&P 4.88
OEM rear R&P 4.88
Requires a shim, but comes in kit if you buy from Randy's
Reduced overall GR to 4.35 w/ 37's.
Raises RPM at speed x 20-300 vs. stock

Are you sure it requires a shim? I asked my installer and they said it wasnt necessary in front or back.

[TwinStick]

Sorry guys, 4.7 is NOT 6.3:1. So, they are putting the 8-speed auto in the Power Wagons now ?

If it was up to me, I would make 2nd, 3rd & 4th in the G-56 lower than it is. All you have to do is hook up & pull 10,500 lbs, pull some long steep hills & you will see what i mean.

[DamageWagon]

TwinStick you probably have the only gas truck out there that makes the Cummins guys cry at night


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[TwinStick]

I don't think so. But you sure do learn quick what works and what don't when pulling a 10,500 lb toy hauler with a 5.7L Hemi, whether pulling long steep hills on the highway or pulling it 1800' up the side of a mountain on a very loose gravel road with 4 washouts a foot deep, in 4 Lo & actually have to stack rocks so you don't rip the plumbing off camper.

[RustyPW]

TwinStick you probably have the only gas truck out there that makes the Cummins guys cry at night


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[olyelr]

So, they are putting the 8-speed auto in the Power Wagons now ?

No 8 speed in the PW (smartass!). We were just throwing that out there, showing you that the gearing in the newer autos isnt like the old 3 speed days. Aside from the lack of the real low first gear, they basically cover all the gears in your G56.

[DamageWagon]

Auto transmissions normally have a much higher 1st gear than manuals because the torque converter makes up for it. It does this in two ways.

1. The TC actually provides an increase in gear ratio itself. I'm not entirely familiar with how it does this and I have tried to figure out the method. So far I can only think that it is basically a trade between input/output speed and some kind of Venturi valve effect. Look around and you will find agreement on this, specifically Novak-Adapt has good info on it. Most TC's provide a 2:1 torque increase, so a 4.71:1 first gear actually becomes roughly a 9.42:1 ratio.

2. The TC lets the engine rev higher than the output speed, which lets the engine get closer to its peak torque rpm. A manual trans does something similar by revving higher and slowing the engine with the clutch, but an auto does this better.

I know the Mercedes Gelandewagen (AMG Rapper-mobile) has some insane torque converter they developed specifically for off-road that gives something closer to a 5:1 torque output JUST with the torque converter. Those blinged out mall crawlers are actually pretty serious

I love manuals and would love a cummins-G56 combo, but having used both extensively off-road I love an automatic. As long as you have enough trans cooling (I think the power wagon needs more) I think they are superior to manuals off road. For towing they both have advantages.


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[adeluca73]

Yep, positive on the shim. I bought the complete install & read several gear swap forums and all pointed to an additional part, pretty sure it was a bearing race shim for the PW rear 11.5 AAM, I sent the shop the email, they reviewed & concured, & had it on hand ready for me, trivial cost compared to the gear and install kits.

[adeluca73]

Auto transmissions normally have a much higher 1st gear than manuals because the torque converter makes up for it. It does this in two ways.

1. The TC actually provides an increase in gear ratio itself. I'm not entirely familiar with how it does this and I have tried to figure out the method. So far I can only think that it is basically a trade between input/output speed and some kind of Venturi valve effect. Look around and you will find agreement on this, specifically Novak-Adapt has good info on it. Most TC's provide a 2:1 torque increase, so a 4.71:1 first gear actually becomes roughly a 9.42:1 ratio.

2. The TC lets the engine rev higher than the output speed, which lets the engine get closer to its peak torque rpm. A manual trans does something similar by revving higher and slowing the engine with the clutch, but an auto does this better.

I know the Mercedes Gelandewagen (AMG Rapper-mobile) has some insane torque converter they developed specifically for off-road that gives something closer to a 5:1 torque output JUST with the torque converter. Those blinged out mall crawlers are actually pretty serious

I love manuals and would love a cummins-G56 combo, but having used both extensively off-road I love an automatic. As long as you have enough trans cooling (I think the power wagon needs more) I think they are superior to manuals off road. For towing they both have advantages.


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You're close...I've posted a few lengthy engineering explainations previously on the magic of the TC. It's a viscous clutch that disengaged above a certain engine speed, which is tantamount to a piggy back 1st gear

[DamageWagon]

ADeluca do you know what the exact process is that increases output torque in exchange for RPM? A simple viscous clutch system only exchanges RPM for heat, not torque, so there is something else going on in there, correct? By the way I love your explanations, it's nice to hear things from an Engineer. I'm studying for Mechanical Engineering.


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[bstefanic]

So had my Nitro kit show up today, the rear pinion had a noticeable chip out of one of the teeth. Is this normal or should I send it back for a new one?

[ramv]

I guess it would come down to a cost and peace of mind issue. A Master rear diff overhaul kit for my truck is $353.85. https://www.ringpinion.com/b2c/ProductD ... howAA=true If you want total peace of mind, thats the way to go. If not, you will prob be fine with those low miles.

What year ?
what axles ?

2016 15k miles.
I don't understand the piece of mind? I have to press off an oem bearing with virtually no miles on the carrier I am going to reuse and then press on a new bearing? I would have more piece of mind to not remove and replace parts for the sake of it.

I have only ever had one carrier bearing issue and that was when I had both Dana 70 shafts literally grenade. I pulled the shafts out in chucks and with a magnet. Even then, it still just took a chunk out of a race and I am still running the bearings. Do carrier bearings fail more commonly in the AAM? I had 200k miles on my AAM axles in my Chevy with no bearing or seal issues, and those were much harder than I expect the PW will ever see since I sold my 14k lb trailer. (Which I towed with an auto btw, although the 8.1 kind of makes the 5.7 look )

[MSCH2112]

The 8 speed trans in my wife's '16 denali xl drives amazingly well. Actually, that motor is amazing too. Almost wish I had that package in my PW

no kidding! i love my wife's 2016 denali xl too. that 420hp is alot of fun. just need to swap in a good muffler and really hear it roar.

mike

[Reloaderguy]

The 8 speed trans in my wife's '16 denali xl drives amazingly well. Actually, that motor is amazing too. Almost wish I had that package in my PW

The gearing is my only gripe anymore. The transmission in my truck has really settled in and the programming feels pretty good. Eventually I'll regear but it feels ok for the time being. I'd probably feel differently if I towed heavy but then again I'd have bought a different truck if that were the case.

[adeluca73]

ADeluca do you know what the exact process is that increases output torque in exchange for RPM? A simple viscous clutch system only exchanges RPM for heat, not torque, so there is something else going on in there, correct? By the way I love your explanations, it's nice to hear things from an Engineer. I'm studying for Mechanical Engineering.

No not exactly. The TC is not a heat exchanger (HE). A HE is used to draw thermal waste in the form of heat and deposit it in sump--think 2nd law of thermodynamics where entropy of the sys increases, or remains deficit neutral in the presence of a reversible process. This is done through convection, conduction, or radiation. Large masses of lead are used for a simplified conduction sump, or a passive fan is used to convect waste heat to either the free boundary of the system, or to a material equipped to pass off heat via a radiative heat transfer through to a lower ambient temperature. HE are used to reduce thermal cycling and component heat induced wear.

If I recall all the parts correctly, a TC is similar to a mini-jet engine, minus the raw fuel dumped into the exhaust. It is comprised of a turbine, a stator section in the middle, and an impeller. The stator is a torque multiplying device which accelerates the fluid from the impeller output (shaft work from the engine) to the splined turbine (connected to the transmission input shaft) which exponentially increases net engine torque, not crankshaft output torque. This increase in output torque from a truck specifically designed low stall TC gives the perception of a lower overall 1st gear ratio than the actual gear. I do not know what the torque multiplication factor (MF) on the PW TC is, but say conservatively it's 2x:1, and the TC stall speed is 2500 RPM, then an engine making 410ft-lb peak torque at the TC stall speed of 2500rpm, is sending over 800ft-lb torque to the transmission. The TC MF is maximized at the greatest delta between turbine and impeller rotational speed, which occurs at or near rest--for the PW, we're looking at slow (1-5mph) crawl speeds or when foot is on brakes, where the TC acts like a granny or reduction gear--and once a certain speed is reached, the TC is supposedly "locked", and the impeller and turbine are spinning at the same speed, which is effectively the locked or coupled condition, yielding an effective MF of nearly 1:1, but since it's a fluid coupling, the TC doesn't actually lock or bind, and thus there's a small >5% slippage inefficiency in the flexplate link between the motor output shaft and transmission input shaft.

Anyway, that's the quick and dirty. Hope it helps.