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JL Dana 30 & Dana 35 - how strong are they?

Digger 5

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I didn't read every post of the 5 pages but the first couple of pages had some very questionable info provided.
While the M186 (D30) in the JL uses a unique diff cover, the gears are the same as a JK. Check any Spicer guide and you'll see the part numbers for JK and JL are the same. The stock 3.45 gear is unique in that it is a thin gear. The usual carrier break on a D30 is 3.54 down, 3.73 up. This 3.45 ring gear is factory fitted to a 3.73 up carrier so no new carrier is needed to go to lower (like 4.88) gears. 35" tires have usually been the limit for the D30 ring gear. The weight of these trucks can be very heavy and that must be considered when trying to determine what will survive. Drive style, tire design and weight also matter. As usual, your experience may vary. Some guys can make a weak assembly last forever while some guys can break a steel ball in a rubber room. Due to gear tooth contact area, a 3.45 gear will be much stronger than a low gear such as a 4.88 or 5.13.

The rear M200 is called a 35 but really isn't the same. The gear is different, it is not a c-clip design and has 29 spline shafts. It's certainly stronger than the old POS D35 but not as strong and as JK 44.

JL Sport M220 rear axles are pretty readily available so they would be your best option to build instead of the M200.

FWIW, the new JT has 2 different axle track widths, MAX Tow/Rubicon and standard (?). All JT trucks are supplied with the M210 (D44) front axle regardless of package. I would consider looking for a standard width JT M210 front axle for replacement on any sport JL with the M186 front.
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yotajeeper

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I didn't read every post of the 5 pages but the first couple of pages had some very questionable info provided.
While the M186 (D30) in the JL uses a unique diff cover, the gears are the same as a JK. Check any Spicer guide and you'll see the part numbers for JK and JL are the same. The stock 3.45 gear is unique in that it is a thin gear. The usual carrier break on a D30 is 3.54 down, 3.73 up. This 3.45 ring gear is factory fitted to a 3.73 up carrier so no new carrier is needed to go to lower (like 4.88) gears. 35" tires have usually been the limit for the D30 ring gear. The weight of these trucks can be very heavy and that must be considered when trying to determine what will survive. Drive style, tire design and weight also matter. As usual, your experience may vary. Some guys can make a weak assembly last forever while some guys can break a steel ball in a rubber room. Due to gear tooth contact area, a 3.45 gear will be much stronger than a low gear such as a 4.88 or 5.13.

The rear M200 is called a 35 but really isn't the same. The gear is different, it is not a c-clip design and has 29 spline shafts. It's certainly stronger than the old POS D35 but not as strong and as JK 44.

JL Sport M220 rear axles are pretty readily available so they would be your best option to build instead of the M200.

FWIW, the new JT has 2 different axle track widths, MAX Tow/Rubicon and standard (?). All JT trucks are supplied with the M210 (D44) front axle regardless of package. I would consider looking for a standard width JT M210 front axle for replacement on any sport JL with the M186 front.
From what I've read it seems the M200 is a decent axle for running 35s. Question is do you know how much wider the JT M210 is?
 

mgroeger

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From what I've read it seems the M200 is a decent axle for running 35s. Question is do you know how much wider the JT M210 is?
They are a decent axle for Mall crawling 35s. Dana/Spycer has already commented that if you are doing anything other than light off roading you are running a risk on those axles with 35s and up.
 

Digger 5

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The standard Sport JT has the same track width as a JL Sport. The Max Tow JT and Rubicon JL/JT versions all have the same wide track.
 

yotajeeper

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They are a decent axle for Mall crawling 35s. Dana/Spycer has already commented that if you are doing anything other than light off roading you are running a risk on those axles with 35s and up.
I’m surprised because it’s 29 spline. My yota 8 inch rear is 30 spline and guys run 35s day and night
 

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I’m surprised because it’s 29 spline. My yota 8 inch rear is 30 spline and guys run 35s day and night
On my JK I ran 35's with 5.13 gears 44/30 setup for a long time and never had any issues. I ran Metal Masher, Poison Spider, Kane Creek, etc. like trails several times. Never broke anything. *knock on wood*

On my JL I ran 35's with 4.56 gears 35/30 setup for awhile before upgrading to the Rubicon axles I found for sale. Again ran Moab with no issues. I also towed my trailer quite a bit with this setup. Side by Side the JL housing is WAY beefier than the JK. Thick tubes, c's, etc. The JL "35" is also a 29 spline as you pointed out and I would put it up against a JK 44 any day. I don't know whey they called this a 35 when in fact it really isn't anything like the older 35's.

On another note the rear axle shafts on the JT are thicker than the JL even though they are both 32 spline. (on the 44)

My observation over the years is as follows, and I am guilty of this as well. People read about something and build up in their head they need more than they really do. If you are running hard core rock bouncing type trails all the time with a heavy foot then get bigger axles like a 60 or 80, but most do not need them. I have always been a firm believer the 2 most important things for your rig are the tires and the driver, but that is just me. I have seen guys out there that say they would run 37's without 60's and I have seen guys who have run 37's on 44's for many many years. I have even seen 37's on a front 30 on several occasions.
 

yotajeeper

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On my JK I ran 35's with 5.13 gears 44/30 setup for a long time and never had any issues. I ran Metal Masher, Poison Spider, Kane Creek, etc. like trails several times. Never broke anything. *knock on wood*

On my JL I ran 35's with 4.56 gears 35/30 setup for awhile before upgrading to the Rubicon axles I found for sale. Again ran Moab with no issues. I also towed my trailer quite a bit with this setup. Side by Side the JL housing is WAY beefier than the JK. Thick tubes, c's, etc. The JL "35" is also a 29 spline as you pointed out and I would put it up against a JK 44 any day. I don't know whey they called this a 35 when in fact it really isn't anything like the older 35's.

On another note the rear axle shafts on the JT are thicker than the JL even though they are both 32 spline. (on the 44)

My observation over the years is as follows, and I am guilty of this as well. People read about something and build up in their head they need more than they really do. If you are running hard core rock bouncing type trails all the time with a heavy foot then get bigger axles like a 60 or 80, but most do not need them. I have always been a firm believer the 2 most important things for your rig are the tires and the driver, but that is just me. I have seen guys out there that say they would run 37's without 60's and I have seen guys who have run 37's on 44's for many many years. I have even seen 37's on a front 30 on several occasions.
My group ran dishpan springs trail a few weeks ago in SoCal. There where 3 JKs on non rubi 44s running 35s. Same group ran John Bull no issues. Here’s a video. And yes I’m the guy that broke the cv couldn’t clear the obstacle kept getting hung up on rear diff and cross member

 

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On here I am reading some Sports have the 35 rear and some have the 44. I just purchased a 2021 Jeep and I was under the impression that my rear would be the 44. I plan on installing the PR44 front from Dynatrack with RCV and keep the factory rear with new chromoly axle shafts. Gear ration would be 5.13, I plan on running 38 maybe go up to 40 seeing how well they handle the 38s. I appreciate y'alls input.
 

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you only get the Dana 44 if you have the LSD rear if you don't have it you got a dana 35. its that way on the Sports and Saharas.
 

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On here I am reading some Sports have the 35 rear and some have the 44. I just purchased a 2021 Jeep and I was under the impression that my rear would be the 44. I plan on installing the PR44 front from Dynatrack with RCV and keep the factory rear with new chromoly axle shafts. Gear ration would be 5.13, I plan on running 38 maybe go up to 40 seeing how well they handle the 38s. I appreciate y'alls input.
Second what the other guy said and also the D44 on the Sport and Sahara is known as the narrow 44 where the ones on the Rubi are wider.
Your game plan sounds solid assuming you have the narrow D44 rear. I'd mention that you have the narrow one to PR when you are purchasing the front PR44 in case it would matter in some way.
 

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breakerbaker

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Second what the other guy said and also the D44 on the Sport and Sahara is known as the narrow 44 where the ones on the Rubi are wider.
Your game plan sounds solid assuming you have the narrow D44 rear. I'd mention that you have the narrow one to PR when you are purchasing the front PR44 in case it would matter in some way.
Thank you both for the helpful information! I did purchase the LSD Rear so I would have the 44. When I do purchase the PR44 I will get the sport diameter to have the same width. Then install the ARB lockers front and rear of course.
 

SmoothJeepOperator

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I didn't read every post of the 5 pages but the first couple of pages had some very questionable info provided.
While the M186 (D30) in the JL uses a unique diff cover, the gears are the same as a JK. Check any Spicer guide and you'll see the part numbers for JK and JL are the same. The stock 3.45 gear is unique in that it is a thin gear. The usual carrier break on a D30 is 3.54 down, 3.73 up. This 3.45 ring gear is factory fitted to a 3.73 up carrier so no new carrier is needed to go to lower (like 4.88) gears. 35" tires have usually been the limit for the D30 ring gear. The weight of these trucks can be very heavy and that must be considered when trying to determine what will survive. Drive style, tire design and weight also matter. As usual, your experience may vary. Some guys can make a weak assembly last forever while some guys can break a steel ball in a rubber room. Due to gear tooth contact area, a 3.45 gear will be much stronger than a low gear such as a 4.88 or 5.13.

The rear M200 is called a 35 but really isn't the same. The gear is different, it is not a c-clip design and has 29 spline shafts. It's certainly stronger than the old POS D35 but not as strong and as JK 44.

JL Sport M220 rear axles are pretty readily available so they would be your best option to build instead of the M200.

FWIW, the new JT has 2 different axle track widths, MAX Tow/Rubicon and standard (?). All JT trucks are supplied with the M210 (D44) front axle regardless of package. I would consider looking for a standard width JT M210 front axle for replacement on any sport JL with the M186 front.
Has anyone done this? Sounds like it would be pretty straight forward, perfect pick up for a sport or sahara that wants to run 35s+ and add lockers. I would think this would be one of the cheaper options too.

Edit: Looks like the willys has that same front axle? nice to know there are options there.
 

Jmonroe

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For what it's worth, I regeared my last JK Sahara with 4.10s and Eaton electric lockers. I hated the stock gearing, had been used to a Rubi with the 4.10s. Figured as long as we're in there, throw in the lockers.

I stayed with the stock 31" tires, never had a problem. Mostly "light" wheelin with a bit of rock climbing.
 

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you will not need a new carrier. I run 4.56 gears, originally had 3.45’s.
Have you been able to find a limited-slip diff for the front Dana 30 I'm trying to find one just because I don't want to run a locker, limited slip would be easier for me in my weather and my driving and my style of Wheeling but I can't find one
 

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Have you been able to find a limited-slip diff for the front Dana 30 I'm trying to find one just because I don't want to run a locker, limited slip would be easier for me in my weather and my driving and my style of Wheeling but I can't find one
I saw someone on here with a eaton trutrac in the front dana 30.

arb uses the same front diff Locker for the JK as the JL- RD100

so assuming the eaton trutrac would fit as well. Id like to throw in a limited also
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