Ring and pinion patterns Nitro 4.56

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Clark Kent

Clark Kent

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Is your pinion preload at spec?

OH CRAP, I used new bearings and I set them to the spec of used bearings. That was about 9 lb in vs 25-35 listed in the install sheet.

I'm guessing that's the whine under load?

EDIT: Finding online that should have caused the opposite with a whine on decel.
 
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pacofortacos

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It is possible to still have caused your whine depending on your pinion depth.

Did you also get the carrier bearings preload and torque settings correctly set?

You might have to open the backlash up a bit to the high side with that steep of a gear ratio.

Do you have a infrared thermometer to check the temp after a cruise - it's amazing how hot new gears can get. I like to check it after a short run and then again at a decent sustained higher speed run.
They are nice to just bend over and shoot the beam at the rear cover and get a good idea of the temp of the gear lube. You could also check pinion bearing temps to a degree by shooting in different spots on the pinion area.
 
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pacofortacos

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Is your gear set listed as a street gear or performance gear - street gears will be quieter but are a little weaker vs. a performance gear.
 

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OH CRAP, I used new bearings and I set them to the spec of used bearings. That was about 9 lb in vs 25-35 listed in the install sheet.

I'm guessing that's the whine under load?

EDIT: Finding online that should have caused the opposite with a whine on decel.


You might be able to just tighten it and be ok, check the pinion bearing preload at several positions.
If it seems off, you might have to replace the crush sleeve - if the AAM has one.

I find the carrier bearings harder to get right than I do the pinion - just much more time consuming.
 
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Clark Kent

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It is possible to still have caused your whine depending on your pinion depth.

Did you also get the carrier bearings preload and torque settings correctly set?

You might have to open the backlash up a bit to the high side with that steep of a gear ratio.

Do you have a infrared thermometer to check the temp after a cruise - it's amazing how hot new gears can get. I like to check it after a short run and then again at a decent sustained higher speed run.
They are nice to just bend over and shoot the beam at the rear cover and get a good idea of the temp of the gear lube. You could also check pinion bearing temps to a degree by shooting in different spots on the pinion area.

Nitro doesn't specify street or performance gear from what I could see.

Carrier preload was correct and backlash per Nitro's spec is 5-7 thous. I had it at 6 thous at final assembly.

I immediately checked the temp after the first run, which was hottest up near the pinion flange at 120ish F. Everything else was just barely over 100. The second run, this drop to 108 F. Both were short, easy runs at speeds no greater than 50mph.
 

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East Coast Gear will not warranty any other gear install but Nitro......said this aftermarket gear made the least noise.
 

pacofortacos

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That's pretty cool, so you know you aren't tight.

My Yukon 4.10's after a long 70+ mph tow was reading right around 250 F if I remember correctly - was definitely over 200F.
 

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What was the Original shim thickness ?? usually the thickness of the factory Pinion shim is the correct one to locate the pinion center to ring gear center for that particular case !!
 
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Clark Kent

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New crush sleeve and seal arrived so I put this back together with 4 thous more shim to drive the pinion deeper.

I emailed these images to Nitro, who also liked the 54 thous pattern. That's the factory shim size, 54 thousands. However I took a gamble and went deeper based on how loud it was at 54 thous. It's still not perfect...

At 54 thous I could hear the cruise, accel hum with the windows down. Sounded like I was on meaty mud tires. With the windows up it was very obvious and annoying. Now at 58 thous, I can't hear anything with the windows down. With them up and the radio off, Accel and light throttle input are completely quiet, very very slight hum noise coasting. It's hard to pick out the coast hum. There is a very audible hum right at that transition of barely any throttle input to completely letting off and coasting. That noise seem to improve towards the end of my 10-12 miles test drive.

Pinion temp was 129F when I got home.
 
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I'm getting real good at breaking down this rearend....

After another 10 mile test drive, I could hear a slight hum coasting. I didn't catch on the first test drive. A cruise hum was present at 40-50mph as well. I'm looking for perfection so I decided to break it down again, check pattern, and see if I could improve it. The pattern at 58thous changed and looked like a nike swoosh. Similar to the images I attached where the pattern starts to distort as depth is too high.

Again, the 54 factory shim pattern was the best compromise between too shallow and too deep. It was a perfect pattern, but the same almondish shape. I went with 54, which was also Nitro's suggestion. Another crush sleeve and preload at the higher end of nitro's instructions 35 in lbs, I put her back together. Backlash varied from 6-8 thousands at multiple points of the ring gear. Ring was etched at 0.007, so I'm assuming that's the backlash they used during lapping. Final pattern check in multiple spots was unchanged from the setup bearing pattern.

She still has a coast hum at certain conditions and it's driving me nuts. I'm looking for perfection and based on what I'm seeing with the pattern when I vary the pinion depth, I don't think I'll get a perfectly quiet gear from this set. I do a lot of 12 hour or so road trips per year and I'd rather go back to the factory 3.73's then listen to 12 hours of gear whine. I've given up and ordered a AAM set of 4.56's, crush sleeve, bearings, etc....

I've set up a handful of 8.8's and never had a problem getting them to be quiet. This set is frustrating the hell out of me.

Hopefully the front Nitro 4.56's are quiet when I get those installed.
 

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I'm getting real good at breaking down this rearend....

After another 10 mile test drive, I could hear a slight hum coasting. I didn't catch on the first test drive. A cruise hum was present at 40-50mph as well. I'm looking for perfection so I decided to break it down again, check pattern, and see if I could improve it. The pattern at 58thous changed and looked like a nike swoosh. Similar to the images I attached where the pattern starts to distort as depth is too high.

Again, the 54 factory shim pattern was the best compromise between too shallow and too deep. It was a perfect pattern, but the same almondish shape. I went with 54, which was also Nitro's suggestion. Another crush sleeve and preload at the higher end of nitro's instructions 35 in lbs, I put her back together. Backlash varied from 6-8 thousands at multiple points of the ring gear. Ring was etched at 0.007, so I'm assuming that's the backlash they used during lapping. Final pattern check in multiple spots was unchanged from the setup bearing pattern.

She still has a coast hum at certain conditions and it's driving me nuts. I'm looking for perfection and based on what I'm seeing with the pattern when I vary the pinion depth, I don't think I'll get a perfectly quiet gear from this set. I do a lot of 12 hour or so road trips per year and I'd rather go back to the factory 3.73's then listen to 12 hours of gear whine. I've given up and ordered a AAM set of 4.56's, crush sleeve, bearings, etc....

I've set up a handful of 8.8's and never had a problem getting them to be quiet. This set is frustrating the hell out of me.

Hopefully the front Nitro 4.56's are quiet when I get those installed.

You need a louder muffler,lol.Just kidding keep us updated on how you make out as this is a very interesting thread you have going here
 

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I'm getting real good at breaking down this rearend....

After another 10 mile test drive, I could hear a slight hum coasting. I didn't catch on the first test drive. A cruise hum was present at 40-50mph as well. I'm looking for perfection so I decided to break it down again, check pattern, and see if I could improve it. The pattern at 58thous changed and looked like a nike swoosh. Similar to the images I attached where the pattern starts to distort as depth is too high.

Again, the 54 factory shim pattern was the best compromise between too shallow and too deep. It was a perfect pattern, but the same almondish shape. I went with 54, which was also Nitro's suggestion. Another crush sleeve and preload at the higher end of nitro's instructions 35 in lbs, I put her back together. Backlash varied from 6-8 thousands at multiple points of the ring gear. Ring was etched at 0.007, so I'm assuming that's the backlash they used during lapping. Final pattern check in multiple spots was unchanged from the setup bearing pattern.

She still has a coast hum at certain conditions and it's driving me nuts. I'm looking for perfection and based on what I'm seeing with the pattern when I vary the pinion depth, I don't think I'll get a perfectly quiet gear from this set. I do a lot of 12 hour or so road trips per year and I'd rather go back to the factory 3.73's then listen to 12 hours of gear whine. I've given up and ordered a AAM set of 4.56's, crush sleeve, bearings, etc....

I've set up a handful of 8.8's and never had a problem getting them to be quiet. This set is frustrating the hell out of me.

Hopefully the front Nitro 4.56's are quiet when I get those installed.

Damn man I'm seriously pondering if you could hear a mouse fart the gear whine :D

But my curiosity has me. How loud is this whine you have going on? Anyway to video it? I have a Yukon 4.56 in mine and I can't hear a thing. A guy with 25 years exp did the install. Me = lol
 
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Clark Kent

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Damn man I'm seriously pondering if you could hear a mouse fart the gear whine :D

But my curiosity has me. How loud is this whine you have going on? Anyway to video it? I have a Yukon 4.56 in mine and I can't hear a thing. A guy with 25 years exp did the install. Me = lol

I'm doubtful it would be heard over video. At reasonable radio volume levels, I can pick it out. The family cannot. With the radio off and windows up, the family can hear it. Perfectly livable since it's only audible at the right cruising conditions. I'm finicky and it will drive me nuts if I continue with this setup.

My AAM gearset will be here at the end of the week, which from what I can tell requires the same conversion bearings and crush sleeve as the Nitro gears did (late model AAM with larger pinion bearing OD). Hopefully that assumption doesn't bite me in the butt because I just ordered all new Timken bearings.
 

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@Clark Kent could you give me your opinion on a gear set, 2019 Ram 2500 6.7L, 12" Kelderman air lift, 43" M/T Pro XS tires....I'm debating on 4.56 or 4.88 gears. I used this calculator and I think I will be ok with 4.56 gears. All the parts are sitting in my garage. I'm in Kabul right now but I'm getting all the pieces together for when I get home. I know you have the 6.4L so it's a little different. I'm not really going to tow anything or beat on it real bad. I have the EFI live tune, EGR, DPF delete all that sitting there as well. I'm just trying not to burn up the 68RFE trans right away even though it might be inevitable sooner or later. Just trying to get some half way decent cruising gears with a little power on tap if needed. Thanks for any opinions. Here is the link I used for my guesses...lol..

https://www.dieselhub.com/tech/ratio-tool.html
 
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Clark Kent

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@Clark Kent could you give me your opinion on a gear set, 2019 Ram 2500 6.7L, 12" Kelderman air lift, 43" M/T Pro XS tires....I'm debating on 4.56 or 4.88 gears. I used this calculator and I think I will be ok with 4.56 gears. All the parts are sitting in my garage. I'm in Kabul right now but I'm getting all the pieces together for when I get home. I know you have the 6.4L so it's a little different. I'm not really going to tow anything or beat on it real bad. I have the EFI live tune, EGR, DPF delete all that sitting there as well. I'm just trying not to burn up the 68RFE trans right away even though it might be inevitable sooner or later. Just trying to get some half way decent cruising gears with a little power on tap if needed. Thanks for any opinions. Here is the link I used for my guesses...lol..

https://www.dieselhub.com/tech/ratio-tool.html

We're in two different worlds. You're tire size is massive and you're running a diesel that doesn't like to rev as much as the hemi. If it was me, first thought would be shooting for close to stock revs or maybe slightly higher in 6th gear. With my 35's and 4.56's I'm revving around 2k RPMs at 70k, which for me is perfectly acceptable on a hemi.

I like this calculator personally: http://www.grimmjeeper.com/gears.html

I believe you're year started using 3.73's over the previous gen's max of 3.21? If so, then 4.88's puts you right back into stock RPMs at 70mph. That would be my choice.


I believe the 68RFE's weak point is the overdrive clutches and excessive loading. Probably a safe bet that those 43's would be excessive loading. Even if you're not towing. I have no first hand experience, but I've read posts of guys wearing out the overdrive quicker than expected on 37's and having elevated power levels (i.e. deleted trucks). I have no feel for how often that happens, just regurgitating forum posts.

There's a youtube channel, Beast Project or something like that. He had a 6.7 on 37's and went with 4.56's. He said something along the lines of regretting going that low in gears due to drop in highway mileage. He also recommended regearing asap if you go larger tires as he experienced trans issues. Look him up, search beast and 4.56's and you should find his channel.
 

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Looking for opinions on these patterns. Setting up a 11.5 AAM with Nitro gears. Backlash was 5-7 thous for each pattern below.

I went with the 54 thousands pattern and took her down the road, but I was getting whine under load or acceleration only. Decel was dead quiet. I'm thinking that means pinion depth is too shallow so I started increasing depth but I'm not getting a clean pattern off these gears. I took a major jump from 63 to 75 just as a sanity check, which shows too deep.

I'm leaning towards the 60 thous.

View attachment 209002

Edit:
Added coast sides
View attachment 209019

Just for comparison's sake I found a photo of the markings on my install. I didn't get the details on the specs but it's lived in the carrier for 2 years now.

IMG951583.jpg

IMG951582.jpg
 
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Clark Kent

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I'm no expert, but the pattern suggests the pinion depth is too deep? Especially on the coast side. You're drive side although deep doesn't break up like mine does as I drive deeper on the pinion. But are they two cut gears, that would make more sense with that pattern? It's hard to tell from the pictures, but it looks like tooth depth is the same from heel to tow. That and the slight slant on the drive side looks like what you expect with 2 cut gears.

The AAM set I order are 2 cut, which will pattern different from these Nitros I have.

Does it make any noise?
 

Felt

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We're in two different worlds. You're tire size is massive and you're running a diesel that doesn't like to rev as much as the hemi. If it was me, first thought would be shooting for close to stock revs or maybe slightly higher in 6th gear. With my 35's and 4.56's I'm revving around 2k RPMs at 70k, which for me is perfectly acceptable on a hemi.

I like this calculator personally: http://www.grimmjeeper.com/gears.html

I believe you're year started using 3.73's over the previous gen's max of 3.21? If so, then 4.88's puts you right back into stock RPMs at 70mph. That would be my choice.


I believe the 68RFE's weak point is the overdrive clutches and excessive loading. Probably a safe bet that those 43's would be excessive loading. Even if you're not towing. I have no first hand experience, but I've read posts of guys wearing out the overdrive quicker than expected on 37's and having elevated power levels (i.e. deleted trucks). I have no feel for how often that happens, just regurgitating forum posts.

There's a youtube channel, Beast Project or something like that. He had a 6.7 on 37's and went with 4.56's. He said something along the lines of regretting going that low in gears due to drop in highway mileage. He also recommended regearing asap if you go larger tires as he experienced trans issues. Look him up, search beast and 4.56's and you should find his channel.

Thanks! I agree with what you're saying and appreciate the info!!
 

RedSRT4Me

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I'm no expert, but the pattern suggests the pinion depth is too deep? Especially on the coast side. You're drive side although deep doesn't break up like mine does as I drive deeper on the pinion. But are they two cut gears, that would make more sense with that pattern? It's hard to tell from the pictures, but it looks like tooth depth is the same from heel to tow. That and the slight slant on the drive side looks like what you expect with 2 cut gears.

The AAM set I order are 2 cut, which will pattern different from these Nitros I have.

Does it make any noise?

I don't hear any noise from the diff at any speed.
 

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