Axle gearing: 4.56, 4.88, or 5.13?

[GoldenGorilla]

While I agree with this to a point then why doesn't the AX15/NV3550 have the same vibrations when regeared to 5.13 or 5.38?

I have an NV3550 Rubicon with 4.56s and 32.6"s. I have had balance related vibrations on 3 different front driveshafts at ~72 mph and higher since the gears. Our interstates are largely 75mph, so I'm often in it. Before with 4.10s this vibration was up in the mid-80s with the factory shaft and was rarely encountered. Varied a bit with the different shafts with the second TW being the worst. It's spinning a bit over 3600rpm at this speed, which is our local shop's balancer's max rpm and Tom Woods who made shafts 2 and 3. Minus the front shaft it runs smooth at any speed.

There is also some sort of harmonic factor in 4th which amplifies the vibrations.

 

[Woodrow]

You are not wrong and there is wisdom here. I think it's just ego and also the crazy thinking that if I ever sell it that a clean LS swap with Dana 44/Dana 60 would give me a better chance of moving it or the dream of passing it down to my kids and maybe they wheel it. You should have heard me try to convince my wife to let me katzkin the seats with cooling/heating today, she shares your sentiment of making no sense on spending too much money on the old mall crawler!

If you were me, and front axle gearing didn't matter (pretend I disconnect driveshaft), with the rear would you go 4.56, 4.88 or 5.13?

You never get the money you put into a vehicle back when you sell it, so don't put an expensive axle you don't need purely for the next guy

@lBasket is spot on. Resale value is absolutely not a reason to buy expensive axles. Don’t forget, there are also some downsides to Currie axles in your situation besides money. The Dana 60 is longer and so will shorten your already short rear driveline. And they are HEAVY and that won’t help your acceleration. A TJ or LJ Dana 44 and your Dana 30 make the most sense to me. If you are going to change your gears, 5:13 would likely be my choice. The difference between 4.56 and 4.88 isn’t enough to make it worth the work or expense. I just went from 4.11 to 5.13 (stroker, AX-15 and 35s). I wheel and daily drive mine. The gear change definitely helps on the trail but the improvement in performance driving on the road is the best thing I’ve noticed. I don’t have any vibes to over 80mph but rarely exceed 65-70mph where I drive it.

 

[Longhorn84]

The 489 uses the JK larger R&P so you're gaining that added strength which was why I'd brought it up for a rear axle. The TruTrac is just a gear driven limited slip so you aren't wearing out the clutch pack like in a normal limited slip. So on the road you won't notice it but when it's wet out it'll help with the traction. It's just a thought.

I'd do a big brake kit on the front & maybe cromo shafts but other than that since you're not wheeling it hard/hardly I'd leave it open.

I like this idea if I go new, I did just look and I like that the 489 from ECGS allows me to run disc brakes. That axle comes out to $4,785 after all the selections. Currie keeps drums on the rear Dana 44 ($5,145). Any concern with the 5.13s, TruTrac, and my v8 in terms of breaking r&p once some friction is added? Meaning, should I just go open and save $625?

@lBasket is spot on. Resale value is absolutely not a reason to buy expensive axles. Don’t forget, there are also some downsides to Currie axles in your situation besides money. The Dana 60 is longer and so will shorten your already short rear driveline. And they are HEAVY and that won’t help your acceleration. A TJ or LJ Dana 44 and your Dana 30 make the most sense to me. If you are going to change your gears, 5:13 would likely be my choice. The difference between 4.56 and 4.88 isn’t enough to make it worth the work or expense. I just went from 4.11 to 5.13 (stroker, AX-15 and 35s). I wheel and daily drive mine. The gear change definitely helps on the trail but the improvement in performance driving on the road is the best thing I’ve noticed. I don’t have any vibes to over 80mph but rarely exceed 65-70mph where I drive it.

I appreciate this perspective a lot. So you would do something like this, regear it to 5.13, and keep the TJ LSD style locker? I'm not comfortable regearing it myself so I'd have to factor in that cost and then there is the fear of the unknown with buying any used axle as well as the smaller R&P vs Currie or ECGS (or would a re-gear bump up to larger R&P or is the actual housing larger to accommodate on aftermarket?). It probably comes down to $1-2k and that's where I wonder if I'll want new/warranty.

 

[Woodrow]

I like this idea if I go new, I did just look and I like that the 489 from ECGS allows me to run disc brakes. That axle comes out to $4,785 after all the selections. Currie keeps drums on the rear Dana 44 ($5,145). Any concern with the 5.13s, TruTrac, and my v8 in terms of breaking r&p once some friction is added? Meaning, should I just go open and save $625?



I appreciate this perspective a lot. So you would do something like this, regear it to 5.13, and keep the TJ LSD style locker? I'm not comfortable regearing it myself so I'd have to factor in that cost and then there is the fear of the unknown with buying any used axle as well as the smaller R&P vs Currie or ECGS (or would a re-gear bump up to larger R&P or is the actual housing larger to accommodate on aftermarket?). It probably comes down to $1-2k and that's where I wonder if I'll want new/warranty.

That ebay Dana 44 is what like what I’m suggesting. The price is in the middle to high range and doesn’t include shipping which will be hundreds of dollars. You can do better, but not much and you’ll have to be patient. You can break anything, of course. But I’m not aware of the 8.5” ring gear in a TJ Dana 44 being a common failure point even with a mild V8 and 35s (or the tiny 7.25” diameter ring gear in the Dana 30 for that matter). Lots of folks tend to prefer things to be overbuilt or “bullet proof”. I get the perspective but I prefer a more elegant build where everything is well matched. The Currie TJ front Dana 44 is a good example of overbuilt. It has lots of extra metal in the housing and tubes for strength (even though the stock housing and tubes are proven to stand up well) but still uses stock ball joints which fail a lot with big tires. In a build like yours, I would use CroMo axle shafts. The differentials could be anything. True Tracs are strong and simple and may be a good choice for your primarily street driven rig. Open would be reasonable too. I’m not a fan of clutch style LSDs because the clutches wear out and engagement is not as smooth as helical LSDs like the true trac. Because I wheel and because I prefer open differentials on the road, especially in a short wheelbase rig, I run selectable lockers. Another option is to find JK axles. They are wider (JK WMS to WMS is 65.5” vs 60.5” in a TJ, IIRC) which is helpful for turning clearance in front with larger tires and they have bigger ring gears, if that’s a big concern (JK Dana 44 is 8.9”). But for a street driven rig, tire coverage becomes an issue. I’ll stop there. It is an interesting topic and I could go on all day…

 

[Wildman]

I have an NV3550 Rubicon with 4.56s and 32.6"s. I have had balance related vibrations on 3 different front driveshafts at ~72 mph and higher since the gears. Our interstates are largely 75mph, so I'm often in it. Before with 4.10s this vibration was up in the mid-80s with the factory shaft and was rarely encountered. Varied a bit with the different shafts with the second TW being the worst. It's spinning a bit over 3600rpm at this speed, which is our local shop's balancer's max rpm and Tom Woods who made shafts 2 and 3. Minus the front shaft it runs smooth at any speed.

There is also some sort of harmonic factor in 4th which amplifies the vibrations.

I haven't read every vibration thread but I'll say this is the first time I've read about one with a manual having vibrations. So I guess I should say isn't the vibration/harmonic issue more common with the 42RLE than other transmission? And I guess I was lucky with mine since I had 4.88 gears & then 5.13 with a AX-5 & then a 46RE & now a 545RFE and I don't feel any vibrations.

I like this idea if I go new, I did just look and I like that the 489 from ECGS allows me to run disc brakes. That axle comes out to $4,785 after all the selections. Currie keeps drums on the rear Dana 44 ($5,145). Any concern with the 5.13s, TruTrac, and my v8 in terms of breaking r&p once some friction is added? Meaning, should I just go open and save $625?

When you start seriously looking write it down or do a spread sheet or whatever is how you do these things...

Price out buying the used axle and then adding gears and TruTrac plus seals and brakes and everything else to make it "new".
Then compare that to the ECGS axle...

As far as disc brakes go even if you got a Dana 44 that had drum brakes you could do a disc brake conversion on it.

I appreciate this perspective a lot. So you would do something like this, regear it to 5.13, and keep the TJ LSD style locker? I'm not comfortable regearing it myself so I'd have to factor in that cost and then there is the fear of the unknown with buying any used axle as well as the smaller R&P vs Currie or ECGS (or would a re-gear bump up to larger R&P or is the actual housing larger to accommodate on aftermarket?). It probably comes down to $1-2k and that's where I wonder if I'll want new/warranty.

I don't think you'd have any issues in your usage breaking gears with the 5.13's.

Jantz Engineering makes a kit to use the JK R&P called a Jana K4 in a TJ type Dana 44 housing. https://www.jantz4x4.com/jantz.php?p=detail&pro=jana_k4
So if you went with a used axle you could have the shop install the JK R&P instead of stock Dana 44 R&P.

 

[Longhorn84]

That ebay Dana 44 is what like what I’m suggesting. The price is in the middle to high range and doesn’t include shipping which will be hundreds of dollars. You can do better, but not much and you’ll have to be patient. You can break anything, of course. But I’m not aware of the 8.5” ring gear in a TJ Dana 44 being a common failure point even with a mild V8 and 35s (or the tiny 7.25” diameter ring gear in the Dana 30 for that matter). Lots of folks tend to prefer things to be overbuilt or “bullet proof”. I get the perspective but I prefer a more elegant build where everything is well matched. The Currie TJ front Dana 44 is a good example of overbuilt. It has lots of extra metal in the housing and tubes for strength (even though the stock housing and tubes are proven to stand up well) but still uses stock ball joints which fail a lot with big tires. In a build like yours, I would use CroMo axle shafts. The differentials could be anything. True Tracs are strong and simple and may be a good choice for your primarily street driven rig. Open would be reasonable too. I’m not a fan of clutch style LSDs because the clutches wear out and engagement is not as smooth as helical LSDs like the true trac. Because I wheel and because I prefer open differentials on the road, especially in a short wheelbase rig, I run selectable lockers. Another option is to find JK axles. They are wider (JK WMS to WMS is 65.5” vs 60.5” in a TJ, IIRC) which is helpful for turning clearance in front with larger tires and they have bigger ring gears, if that’s a big concern (JK Dana 44 is 8.9”). But for a street driven rig, tire coverage becomes an issue. I’ll stop there. It is an interesting topic and I could go on all day…

I appreciate the insight and agree its an interesting topic! I actually just went out for a ride and floored it at a stop sign and got a bit of a chirp from the rear wheels, that got me thinking that 5.13s and a higher stall might actually spin the tires from a stop which is not what I want. If that's the case and I were to go to 4.88, I think upgrading the rear without a current "issue" with the rear doesn't make sense. I still think a higher stall would make it a bit easier to drive, it wants to go at a stop sign which I also think the big brakes would help.

So, I think I'm going to put in a 2400 stall since I have to fix a rear main leak anyway, have it tuned, big brake the front axle and probably do ball joints while I'm in there and call it a day until the rear breaks. If it does blow, I think I'd look for a great used TJ Dana 44 or if I can't find anything compelling go ECGS 489 with discs and maybe 4.88 again for fear of spinning the tires.

 

[Abendage]

I appreciate the insight and agree it’s an interesting topic! I actually just went out for a ride and floored it at a stop sign and got a bit of a chirp from the rear wheels, that got me thinking that 5.13s and a higher stall might actually spin the tires from a stop which is not what I want. If that's the case and I were to go to 4.88, I think upgrading the rear without a current "issue" with the rear doesn't make sense. I still think a higher stall would make it a bit easier to drive, it wants to go at a stop sign which I also think the big brakes would help.

So, I think I'm going to put in a 2400 stall since I have to fix a rear main leak anyway, have it tuned, big brake the front axle and probably do ball joints while I'm in there and call it a day until the rear breaks. If it does blow, I think I'd look for a great used TJ Dana 44 or if I can't find anything compelling go ECGS 489 with discs and maybe 4.88 again for fear of spinning the tires.

I think that’s a sensible approach for what your goals are with the Jeep.

 

[Apparition]

I appreciate the insight and agree its an interesting topic! I actually just went out for a ride and floored it at a stop sign and got a bit of a chirp from the rear wheels, that got me thinking that 5.13s and a higher stall might actually spin the tires from a stop which is not what I want. If that's the case and I were to go to 4.88, I think upgrading the rear without a current "issue" with the rear doesn't make sense. I still think a higher stall would make it a bit easier to drive, it wants to go at a stop sign which I also think the big brakes would help.

So, I think I'm going to put in a 2400 stall since I have to fix a rear main leak anyway, have it tuned, big brake the front axle and probably do ball joints while I'm in there and call it a day until the rear breaks. If it does blow, I think I'd look for a great used TJ Dana 44 or if I can't find anything compelling go ECGS 489 with discs and maybe 4.88 again for fear of spinning the tires.

If you did the 5.13’s and spinning tires when flooring it was a problem, you could just not floor it so much.

 

[Rickyd]

I appreciate the insight and agree its an interesting topic! I actually just went out for a ride and floored it at a stop sign and got a bit of a chirp from the rear wheels, that got me thinking that 5.13s and a higher stall might actually spin the tires from a stop which is not what I want. If that's the case and I were to go to 4.88, I think upgrading the rear without a current "issue" with the rear doesn't make sense. I still think a higher stall would make it a bit easier to drive, it wants to go at a stop sign which I also think the big brakes would help.

So, I think I'm going to put in a 2400 stall since I have to fix a rear main leak anyway, have it tuned, big brake the front axle and probably do ball joints while I'm in there and call it a day until the rear breaks. If it does blow, I think I'd look for a great used TJ Dana 44 or if I can't find anything compelling go ECGS 489 with discs and maybe 4.88 again for fear of spinning the tires.

Its ok to have cruise rpm be 1500-2000rpm with larger motors. Not everyone needs 3000rpm like the anemic stock engines

 

[Longhorn84]

If you did the 5.13’s and spinning tires when flooring it was a problem, you could just not floor it so much.

This is true and it might be cool to have the option when I wanted to spin out, you know, to show everyone how cool I am!

Its ok to have cruise rpm be 1500-2000rpm with larger motors. Not everyone needs 3000rpm like the anemic stock engines

This is what I asked Currie when they recommended 4.56 or 4.88 and mentioned highway RPM as the reason for no 5.13s. The calculator I used showed 5.13 gears with 35's at 2500 RPM would be going 73 MPH with my .7 overdrive gear, that doesn't seem crazy annoying to me.

 

[Apparition]

This is true and it might be cool to have the option when I wanted to spin out, you know, to show everyone how cool I am!

For your reference I ran the gearing calculator on my in process LS build. It’s using 6.2, 6L80 and 40’s.

Says 70mph will be a little over 2100 rpm.

Toximus is building with the same engine and trans as mine but 37’s would be just under 2300 rpm.

 

[Wildman]

I appreciate the insight and agree its an interesting topic! I actually just went out for a ride and floored it at a stop sign and got a bit of a chirp from the rear wheels, that got me thinking that 5.13s and a higher stall might actually spin the tires from a stop which is not what I want. If that's the case and I were to go to 4.88, I think upgrading the rear without a current "issue" with the rear doesn't make sense. I still think a higher stall would make it a bit easier to drive, it wants to go at a stop sign which I also think the big brakes would help.

So, I think I'm going to put in a 2400 stall since I have to fix a rear main leak anyway, have it tuned, big brake the front axle and probably do ball joints while I'm in there and call it a day until the rear breaks. If it does blow, I think I'd look for a great used TJ Dana 44 or if I can't find anything compelling go ECGS 489 with discs and maybe 4.88 again for fear of spinning the tires.

I like this idea... I think you might be OK with 4.56 gears with a different stall converter. Adding a limited slip in your rear axle will help with excess spinning of your tires also... Think back to the 70's when a posi-traction was a BIG thing... A limited slip does basically the same things.

For your reference I ran the gearing calculator on my in process LS build. It’s using 6.2, 6L80 and 40’s.

Says 70mph will be a little over 2100 rpm.

Toximus is building with the same engine and trans as mine but 37’s would be just under 2300 rpm.

The GrimmJeeper chart I posted yesterday shows 2346 RPM's @ 70 MPH with 4.88 & 2466 RPM's with 5.13 gears. That was guessing his 35" tires were 34.25" tall.

 

[Abendage]

For your reference I ran the gearing calculator on my in process LS build. It’s using 6.2, 6L80 and 40’s.

Says 70mph will be a little over 2100 rpm.

Toximus is building with the same engine and trans as mine but 37’s would be just under 2300 rpm.

For more reference, mine cruises down the highway at 70 at around 2,100, 35’s, 4.10’s and a 4l80. Over the winter I’m swapping in JK axles with 4.88’s and switching to 37’s and should be around 2,300-2,400 at 70. My current setup is completely acceptable on the highway and I’m sure the new one will be too.

 

[Rickyd]

This is true and it might be cool to have the option when I wanted to spin out, you know, to show everyone how cool I am!



This is what I asked Currie when they recommended 4.56 or 4.88 and mentioned highway RPM as the reason for no 5.13s. The calculator I used showed 5.13 gears with 35's at 2500 RPM would be going 73 MPH with my .7 overdrive gear, that doesn't seem crazy annoying to me.

The 4l60e/700r4 has a lower first gear than jeep autos. I think with a lock up converter with a higher stall you can make it get out of hand off the line.

Lord knows your kids will be able to when they get their licenses regardless!

 

[Longhorn84]

I like this idea... I think you might be OK with 4.56 gears with a different stall converter. Adding a limited slip in your rear axle will help with excess spinning of your tires also... Think back to the 70's when a posi-traction was a BIG thing... A limited slip does basically the same things.





The GrimmJeeper chart I posted yesterday shows 2346 RPM's @ 70 MPH with 4.88 & 2466 RPM's with 5.13 gears. That was guessing his 35" tires were 34.25" tall.

Plot thickens as I just measured my tires, 33”!!! The 35” Mickey Thompsons I just noticed were manufactured in 2013, no idea when PO put on. Should I change these out??

 

[Wildman]

Plot thickens as I just measured my tires, 33”!!! The 35” Mickey Thompsons I just noticed were manufactured in 2013, no idea when PO put on. Should I change these out??

Did you measure from the ground to the center of your wheel/hub? And of course at your standard street tire pressure.

I can recalculate stuff on GrimmJeeper if you want.

12 year old tires???? Yes they are due for replacement... But I'd get your other work done and while doing that start researching what new tire you want to get. Since you're mostly street I'm going to guess either a A/T or R/T type tire over a M/T? And because you're looking for performance you'll want a tire with the least weight...

 

[Longhorn84]

Did you measure from the ground to the center of your wheel/hub? And of course at your standard street tire pressure.

I can recalculate stuff on GrimmJeeper if you want.

12 year old tires???? Yes they are due for replacement... But I'd get your other work done and while doing that start researching what new tire you want to get. Since you're mostly street I'm going to guess either a A/T or R/T type tire over a M/T? And because you're looking for performance you'll want a tire with the least weight...

It was just a quick measuring tape from ground to the top of the tire and a visual look across the tape. I have thought about just going bfg all terrains but I’d be lying if I said I like the look, I think bfg mud terrains look better but agree it’s not ideal for my use. Last I looked tires were around $400 a pop so just another few thousand dollars my wife won’t understand be spending!

Are there tires that tend to have mass support on here for look and pavement performance?

 

[Wildman]

It was just a quick measuring tape from ground to the top of the tire and a visual look across the tape. I have thought about just going bfg all terrains but I’d be lying if I said I like the look, I think bfg mud terrains look better but agree it’s not ideal for my use. Last I looked tires were around $400 a pop so just another few thousand dollars my wife won’t understand be spending!

Are there tires that tend to have mass support on here for look and pavement performance?

Some of the newer A/T & R/T tires have a more aggressive looking sidewall design so you might find something that suits you. You'd have to go back and read through some of the tire threads.

I've got super aggressive tires so I'm the wrong guy to ask. And I like Super Swampers too so my choice of tires isn't the norm.

 

[Abendage]

It was just a quick measuring tape from ground to the top of the tire and a visual look across the tape. I have thought about just going bfg all terrains but I’d be lying if I said I like the look, I think bfg mud terrains look better but agree it’s not ideal for my use. Last I looked tires were around $400 a pop so just another few thousand dollars my wife won’t understand be spending!

Are there tires that tend to have mass support on here for look and pavement performance?

I’ve been running the Goodyear Territory MT for the exact reasons Wildman mentioned. They are super light, load range C, and their traction is excellent. Super soft compound and air down beautifully. They aren’t the best in mud, but I wheel in Colorado and Moab so they’ve been perfect for what I do. Best part, they’re like $215 a tire. The bad part, they only make them in a couple sizes and for a 35 equivalent you have to go to 17” rims. I wanted to keep the Rubicon “Moab” look on my Jeep anyways, so wasn’t a big deal for me to switch to the 17” JK Moab wheels and run adapters, when I swap to JK axles they’ll bolt right up. I have about 7,000 miles on them so far, just rotated for the first time today, and they’re wearing great so far. If I was staying with 35’s I’d run them again for sure. Not the most aggressive looking tire but they’ve performed great.

 

[NashvilleTJ]

... you could just not floor it so much.

Are you insane????