Impressions from a 5.13 gears install on a JL Wrangler Unlimited Rubicon (JLUR)

[chevymitchell]

@chevymitchell do you have pics showing the two? I thought it was you who posted a pic long ago showing the smaller pinion.

I replied to him with a video. Smh...

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[conFUcius]

I replied to him with a video. Smh...

Over-achiever, haha.

 

[AnnDee4444]

I think it's worth noting that the pinion tooth count is the same for a 4:88 & 5.13 gearset. I'm not sure if this means the pinion diameter is the same though, but I could see the number of pinion teeth dictating its diameter with just the gear pitch being steeper.

Somewhat related: https://www.currieenterprises.com/gear-matters

 

[chevymitchell]

I think it's worth noting that the pinion tooth count is the same for a 4:88 & 5.13 gearset. I'm not sure if this means the pinion diameter is the same though, but I could see the number of pinion teeth dictating its diameter with just the gear pitch being steeper.

Somewhat related: https://www.currieenterprises.com/gear-matters

Thank you for posting this. It's good for everyone to see the tooth count comparison to understand this.

The 4.88 and 5.13 use the same tooth count. The ring being thicker for the 5.13, pushed the cut of the pinion teeth down to where the engagement point of the ring and pinion teeth are right at the same thickness of the pinion shaft. This extra depth in the pinion is the reason for the extra 2 teeth in the ring gear.

I'm working on getting a good picture for everyone right now. I have 3 sets of 4.88 here, but no 5.13's.

You can use the following two pics and compare the best you can, but I'm working on getting a 4.88 and 5.13 pic.

The first pic is 4.10 and 4.88. The second is 4.10 and 5.13.

 

[word302]

The pinion's are absolutely different size. How do you think they change the ratio? The ring gear doesn't change it's diameter, it only gets thicker. A thicker ring means a smaller pinion gear must be used. I've never heard such a thing.

Go to 6:15:

I think his point is the shafts are about the same size. Smaller head on the lower gear but the same robust shaft. The pinions on the Advantek axles are significantly more stout than earlier iterations.

 

[chevymitchell]

I think his point is the shafts are about the same size. Smaller head on the lower gear but the same robust shaft. The pinions on the Advantek axles are significantly more stout than earlier iterations.

I don’t think that was his point. I didn’t speculate. I read something that was untrue and needed to fix that. Too many people here that need accurate info and honest opinions. Either way, I welcome a great conversation with different perspectives; I mean, I’ll nerd out on all of this with people. I just feel the need to correct bad gouge.

 

[JAY1941]

I made it 14 pages in before I placed an order at my local shop for 5.13s

 

[JWAustinVTX]

I made it 14 pages in before I placed an order at my local shop for 5.13s

You're going to love them

 

[JAY1941]

You're going to love them

I think So, I went with you Yukon ultimate kit and somehow rear chromoly 35 spline and RCVs with FAD in the front made it into the order as well. I def did some damage today

 

[CarbonSteel]

Thank you for posting this. It's good for everyone to see the tooth count comparison to understand this.

The 4.88 and 5.13 use the same tooth count. The ring being thicker for the 5.13, pushed the cut of the pinion teeth down to where the engagement point of the ring and pinion teeth are right at the same thickness of the pinion shaft. This extra depth in the pinion is the reason for the extra 2 teeth in the ring gear.

I'm working on getting a good picture for everyone right now. I have 3 sets of 4.88 here, but no 5.13's.

You can use the following two pics and compare the best you can, but I'm working on getting a 4.88 and 5.13 pic.

The first pic is 4.10 and 4.88. The second is 4.10 and 5.13.

@chevymitchell - same number of teeth but smaller diameter. Does that equate to a weaker pinion/ring gear interface as you go lower in gearing (higher numerically)? It would seem so simply because there is less metal on the pinion of 5.13/5.38 gears versus 4.10/4.88 for the same or even higher loads.

Especially since re-gearing typically means increasing the unspung weight considerably from what it was originally by adding larger tires, and/or increasing vehicle weight by adding skid plates, winches, etc. It may not mean anything other than the lower numerically gear ratios have a much higher capacity for load than the higher numerically gear ratios.

Thoughts?

 

[chevymitchell]

@chevymitchell - same number of teeth but smaller diameter. Does that equate to a weaker pinion/ring gear interface as you go lower in gearing (higher numerically)? It would seem so simply because there is less metal on the pinion of 5.13/5.38 gears versus 4.10/4.88 for the same or even higher loads.

Especially since re-gearing typically means increasing the unspung weight considerably from what it was originally by adding larger tires, and/or increasing vehicle weight by adding skid plates, winches, etc. It may not mean anything other than the lower numerically gear ratios have a much higher capacity for load than the higher numerically gear ratios.

Thoughts?

This can be such a long response. I'll try to keep it short.
There are a ton of cool, nerdy tangents one could go down.

It doesn't weaken the interface. It just means the torque (linear from engine to tire) to move the vehicle has less material to work with torsionally and that torsional force is concentrated into a smaller diameter.

Smaller diameter means more heat. More heat means more the elasticity of the material comes into play. Once the material has been fatigued under shock loads enough (almost always driver error, bouncing, for example), it will sheer the teeth off or break at the shaft. This happens a lot with axle shafts, but axle shafts are designed to bow and bend before breaking. The ring and pinion are not. The shock load is eaten up by the oil between the teeth. This is why race trucks use a 250w oil and why I run 140w in every rear diff regardless of towing or not.

The "weak" conversation between gear ratios is usually summed up into "less material" in most conversations, but there are about 15 factors that come into play to justify that conclusion. All of which are able to be proven mathematically.

For retail vehicles like what we drive, the JL, there isn't much to worry about. Almost all of these are daily driven rigs with a marginally higher NET weight gain from lifts and tires and whatnot. The choice will come down to the butt dyno for most people. Breaking pinions and axle shafts are 95% driver error and the remaining 5% would be installation error or material defect. (Arbitrary figures, of course).

It's a probability scale. Higher the ratio, the smaller your "insurance" is, and the higher your probability of breaking it is. Will it break, probably not. It's just a risk/reward kind of decision. I personally choose to let the math makes my decisions for me and I run a 4.88 gear with a 37. If and when I run a 39, I'll go to a 5.13 regardless of the housing I'm running.

Told you there's a TON of tangents...Lol. Last comment:

In this new axle, they have changed the placement of the pinion shims for the Dana 35 and 44.

The 44 now has the shims under the head bearing race. This puts the head bearing that shim thickness closer to the pinion head. This makes the pinion itself stronger. Every little bit helps. The Dana 30 in the new axles are still set up with the pinion shim under the head bearing, just FYI.

As time goes on, I bet we'll see more rings missing teeth than we will pinions breaking or sheering their teeth off. Either way, they would get replaced as a set, so it doesn't really matter.

 

[CarbonSteel]

This can be such a long response. I'll try to keep it short.
There are a ton of cool, nerdy tangents one could go down.

It doesn't weaken the interface. It just means the torque (linear from engine to tire) to move the vehicle has less material to work with torsionally and that torsional force is concentrated into a smaller diameter.

Smaller diameter means more heat. More heat means more the elasticity of the material comes into play. Once the material has been fatigued under shock loads enough (almost always driver error, bouncing, for example), it will sheer the teeth off or break at the shaft. This happens a lot with axle shafts, but axle shafts are designed to bow and bend before breaking. The ring and pinion are not. The shock load is eaten up by the oil between the teeth. This is why race trucks use a 250w oil and why I run 140w in every rear diff regardless of towing or not.

The "weak" conversation between gear ratios is usually summed up into "less material" in most conversations, but there are about 15 factors that come into play to justify that conclusion. All of which are able to be proven mathematically.

For retail vehicles like what we drive, the JL, there isn't much to worry about. Almost all of these are daily driven rigs with a marginally higher NET weight gain from lifts and tires and whatnot. The choice will come down to the butt dyno for most people. Breaking pinions and axle shafts are 95% driver error and the remaining 5% would be installation error or material defect. (Arbitrary figures, of course).

It's a probability scale. Higher the ratio, the smaller your "insurance" is, and the higher your probability of breaking it is. Will it break, probably not. It's just a risk/reward kind of decision. I personally choose to let the math makes my decisions for me and I run a 4.88 gear with a 37. If and when I run a 39, I'll go to a 5.13 regardless of the housing I'm running.

Told you there's a TON of tangents...Lol. Last comment:

In this new axle, they have changed the placement of the pinion shims for the Dana 35 and 44.

The 44 now has the shims under the head bearing race. This puts the head bearing that shim thickness closer to the pinion head. This makes the pinion itself stronger. Every little bit helps. The Dana 30 in the new axles are still set up with the pinion shim under the head bearing, just FYI.

As time goes on, I bet we'll see more rings missing teeth than we will pinions breaking or sheering their teeth off. Either way, they would get replaced as a set, so it doesn't really matter.

Totally good stuff being a bit of an axle nerd myself! The part I bolded above is what I have embraced/come to acknowledge for the most part--the 5.38 gears in a D44 are "strong enough" for the vast majority of what the axle will be used for and is exposed to and every lesser gear ratio beneath it is just that much stronger. This also goes to the heart of why past a certain load/operating condition and despite any axle shaft constraints, one has to consider D60 or similar since the ring gear is larger in diameter and by proxy the pinion gear will be as well.

I too chose 4.88 for my ideal ratio and 37" tires are the largest I would ever go so I am gearing for that from the onset even though I am currently running 35's. Thanks for the information!

 

[No IFS]

Now that 488 gear ratio is available with a 31 inch tire. Where are all the 488 guys telling us they’re perfect for 37 inch tire. so if your vehicle came with a 31 inch tire and a 488 gear ratio what would the gear ratio be with a 35 or 37 inch tire?. Reread the threads all the expert said 456 or 488 no reason to go any lower. lol

 

[OBJLU]

Now that 488 gear ratio is available with a 31 inch tire. Where are all the 488 guys telling us they’re perfect for 37 inch tire. so if your vehicle came with a 31 inch tire and a 488 gear ratio what would the gear ratio be with a 35 or 37 inch tire?. Reread the threads all the expert said 456 or 488 no reason to go any lower. lol

Run out of jokes to tell? Lol

 

[word302]

Now that 488 gear ratio is available with a 31 inch tire. Where are all the 488 guys telling us they’re perfect for 37 inch tire. so if your vehicle came with a 31 inch tire and a 488 gear ratio what would the gear ratio be with a 35 or 37 inch tire?. Reread the threads all the expert said 456 or 488 no reason to go any lower. lol

I’ve always said using the factory gear ratios to deduce anything is a fool’s errand.

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