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Discussion Starter · #1 ·
All,

I'm planning on moving from 32" tires to 35" tires on my 2013 JK Sport auto transmission. I'm putting together a build list of what I need to purchase. Have I missed anything?
- Lift kit (Installed. AEV 2.5")
- Wheels (17" wheels with a backspace between 5.2" and 4.5").
- Tires (probably Goodyear Duratracs)
- Differential re-gear (4.56) Currently geared to 3.73
- Spare tire carrier (TeraFlex JK HD Hinged Carrier and Adjustable Spare Tire Mounting Kit)
- Front axle strengthening (RCV Ultimate Dana 30 CV Axle Set and Synergy Suspension Jeep JK Front D30 Inner C Gusset Kit)***
- AEV ProCal Module

Other stuff I'm doing along with the upgrade.
- Rear locker (Eaton eLocker to match what I have on the front end already)
- Rear bumper (GenRight aluminum)

*** I realize that I can probably get by with doing nothing for my front axle and that there is a school of thought that says wait until it breaks before you upgrade but I'd rather pay for the peace of mind of knowing that my axle is rock solid and won't fail me in the middle of nowhere and far from home.
 

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Excellent, excellent list there. Looks like you did your homework. glad you are including a re-gear!

Two things I would not reccomend.

1. the D44 Eaton E-Locker. It is notoriously weaker than the D30 E-Locker, using only a 2 pin mechanism. For selectable out back I would suggest a Yukon Zip Locker. It is air just like the ARB but with out the ARB price and a better warranty. If you do not want budget for OBA then I would suggest a Trutrac LSD. Anything over the D44 Eaton. With the Trutrac rear and locked front, you rig will be HIGHLY capable.

2. I would keep the axle shafts in the D30 stock and carry spares. The D30 R&P set is much smaller than the D44 and putting beefed axles in the D30 moves the weak point to the gear set. IMO, you want the weak point to be the axle shafts.

But like I said great list.

-Dan
 

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Excellent, excellent list there. Looks like you did your homework. glad you are including a re-gear!

Two things I would not reccomend.

1. the D44 Eaton E-Locker. It is notoriously weaker than the D30 E-Locker, using only a 2 pin mechanism. For selectable out back I would suggest a Yukon Zip Locker. It is air just like the ARB but with out the ARB price and a better warranty. If you do not want budget for OBA then I would suggest a Trutrac LSD. Anything over the D44 Eaton. With the Trutrac rear and locked front, you rig will be HIGHLY capable.

2. I would keep the axle shafts in the D30 stock and carry spares. The D30 R&P set is much smaller than the D44 and putting beefed axles in the D30 moves the weak point to the gear set. IMO, you want the weak point to be the axle shafts.

But like I said great list.

-Dan
I might also suggest an Auburn Gear ECTED in the rear. It's a limited slip that will lock when you flip the switch. I've got one in mine since it's 90% daily driver and 10% (or less) weekend wheeler.
 

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I have heard of locking/unlocking problems in the ECTED. I considered it as well.

OP, key is to weight how YOU will use your rig. There are no doubt that people run each of these traction devices successfully, with no problems and there are the few cases of failure, even in an ARB. I know, blasphemy! Just read up on each and select one for you.

--Dan
 

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- Spare tire carrier (TeraFlex JK HD Hinged Carrier and Adjustable Spare Tire Mounting Kit)
Hi there. My list, which will hopefully be completed soon, is very similar to yours. My one question, since I've seen differing answers, is... Is the adjustable spare tire mounting kit necessary? I've read (can't remember where, maybe here?) that it isn't a necessary part of the HD carrier if you're going with 35s. It's when you go up to 37 that you need it... Am I mistaken?
 

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If your going to 35" make sure you have or get a HD track bar. There is a TeraFlex video that shows the stock track bar flexing with 35's.
 

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Looks good other then rcv shafts. That's total overkill for a d30 with 35s. I'd run a chromolly axle shaft.

I'm going to 37s and Im not running one there either.
 

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Looks good but aftermarket wheel backspacing should be 4.5" or less. I'd suggest ARB or a Truetrac for the rear axle.
 

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Looks good but aftermarket wheel backspacing should be 4.5" or less. I'd suggest ARB or a Truetrac for the rear axle.


I wouldn't waste money in a true trac. I almost did but when you really really.need it. (1 wheel of the ground crawling) its useless. Also 4.5" backspacing isn't needed for 35s. I don't have 4.5 and I run 35s. The double beadlocks I will be running are also not 4.5. I'm not saying it isn't welcome but its definitely not needed.
 

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With 17 inch wheels i assume you're going with 315/70/17 dt's which are closer to 34 than 35. The 3.73 might be plenty to turn 34s. I would try it before i spent a grand regearing...
 

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Discussion Starter · #12 ·
Excellent, excellent list there. Looks like you did your homework. glad you are including a re-gear!

Two things I would not reccomend.

1. the D44 Eaton E-Locker. It is notoriously weaker than the D30 E-Locker, using only a 2 pin mechanism. For selectable out back I would suggest a Yukon Zip Locker. It is air just like the ARB but with out the ARB price and a better warranty. If you do not want budget for OBA then I would suggest a Trutrac LSD. Anything over the D44 Eaton. With the Trutrac rear and locked front, you rig will be HIGHLY capable.

2. I would keep the axle shafts in the D30 stock and carry spares. The D30 R&P set is much smaller than the D44 and putting beefed axles in the D30 moves the weak point to the gear set. IMO, you want the weak point to be the axle shafts.

But like I said great list.

-Dan
Thanks Dan.

I appreciate the warning about the 2 pin eLocker for the D44.

In regards to the rear differential, my JK Sport has an OEM LSD (ordered as an option) and it's performed ok, I guess. Rear end swapping has been an issue in snow and ice conditions but I don't know it that's attributable to the rear LSD or not.

Awhile back I spoke to an Eaton engineer about going with one of their Detroit Truetrac limited slip differentials in the rear. He said that the Detroit LSD would be head and shoulders above my OEM rear LSD but suggested that I wait until I regeared or broke the OEM diff. Since I'm regearing now's the time. Do you feel that having a locker on the front and a limited slip on the rear is the way to go versus having lockers on both ends? The budget will allow me to go with an ARB or Zip air locker on the back if that's what it takes to make it a more capable trail rig. Snow wheeling on forest roads is my passion so I'm interested in the whatever works best in snow/ice conditions.

About #2
You ain't kidding about the D30 ring and pinion being smaller than the D44. Here's a pic: http://project-jk.com/gallery2/main...oadItem&g2_itemId=79449&g2_serialNumber=2.jpg
What are your thoughts about cryogenic treatment for the ring & pinions? It's only a $100 for the front and rear R&P.
I don't mind carrying a spare axle but how long does it take to swap out an axle on the trail?


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Derf, my 14 year old WV Passat is my daily driver. Thanks for bringing the ECTED to my attention. I got the JK mostly for wheeling and playing in the snow. The Auburn Gear ECTED in the rear is an option but I haven't seen it used widely on trail rigs in my neck of the woods.
 

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Discussion Starter · #13 ·
Looks good but aftermarket wheel backspacing should be 4.5" or less...
As I understand it, the lower the backspace number the further out the wheel will sit from the Jeep body and that the general consensus is that the “magic number” for backspacing for the JK is 4.5” or less although AEV's wheels have a backspacing of aprox 5.2". I'm assuming this is because AEV tends to be conservative. I mention AEV wheels because they are an option.

A key requirement in wheel selection, which I did not mention earlier, is to be able to run at least Class S tire chains but preferably full size off road chains.
 

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Discussion Starter · #14 ·
With 17 inch wheels i assume you're going with 315/70/17 dt's which are closer to 34 than 35. The 3.73 might be plenty to turn 34s. I would try it before i spent a grand regearing...

This whole thing about actual tire sizes being smaller than advertised sizes is irksome. The main reason I'm going to 35's is so that I can stop dragging my armor across the rocks. Big bucks just to get an inch and a half of additional ground clearance. Makes me want to jump to 37s.
 

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This whole thing about actual tire sizes being smaller than advertised sizes is irksome. The main reason I'm going to 35's is so that I can stop dragging my armor across the rocks. Big bucks just to get an inch and a half of additional ground clearance. Makes me want to jump to 37s.
Yeah don't let anyone BS you. Actual measurement of my 315/70/17 (35") duratracs installed and properly inflated was 33.5". Max realistic measurement I have seen is 33.75". I am planning and saving for 37s next year... maybe. Right now the 315s are getting me by since I haven't got to wheel as much as I would like anyway... who thought my wife getting pregnant would require so much of MY time.... :whistling:
 

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You don't measure the tire with the weight of the Jeep on it. That's like saying Jeep claims you have a 285hp motor but you're only getting about 210 to the wheels. Measurements are taken on the item (tire or engine, in this discussion) itself, not the item after it's been fully engaged into its intended function.

I stand at 6' 3" tall, but if you put a 5,000# Jeep on my shoulders I'll probably squat down AT LEAST 1.5" just like your tires did. :beer:

Just giving you guys a hard time!

The list does look good, despite a few questions.

Personally, I come from the school of locking the front differential first. We're running an Aussie up front with stock shafts and Spicer 760x joints with the factory limited slip out back.

If you plan to wheel routinely, you may want to consider looking for a more rugged suspension system, but I don't say that to start a big war.

If you'd like some input from someone who upgrades Jeeps on a daily basis and wheels a 2012 JKU like his wife stayed at home, shoot me a PM and I'd be happy to share any insight I can.
 

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You don't measure the tire with the weight of the Jeep on it. That's like saying Jeep claims you have a 285hp motor but you're only getting about 210 to the wheels. Measurements are taken on the item (tire or engine, in this discussion) itself, not the item after it's been fully engaged into its intended function.

I stand at 6' 3" tall, but if you put a 5,000# Jeep on my shoulders I'll probably squat down AT LEAST 1.5" just like your tires did. :beer:

Just giving you guys a hard time!

The list does look good, despite a few questions.

Personally, I come from the school of locking the front differential first. We're running an Aussie up front with stock shafts and Spicer 760x joints with the factory limited slip out back.

If you plan to wheel routinely, you may want to consider looking for a more rugged suspension system, but I don't say that to start a big war.

If you'd like some input from someone who upgrades Jeeps on a daily basis and wheels a 2012 JKU like his wife stayed at home, shoot me a PM and I'd be happy to share any insight I can.
Well. I prefer actual measurements vs optimal unrealistic situations. Unfortunately my tires only get used with a 5,000 lb jeep sitting on top of it. Plus the 42#s that the tire shop put in them might get me closer to 35s but... that isn't how she can be driven. In my defense, I like HP measured from the wheels too... Drivetrain loss is a bitch, especially on 4wds, but it is what it is...

That being said, I like to think I know more than I do, and I will default to the dude with more real life experience! :thumb:
 

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Well. I prefer actual measurements vs optimal unrealistic situations. Unfortunately my tires only get used with a 5,000 lb jeep sitting on top of it. Plus the 42#s that the tire shop put in them might get me closer to 35s but... that isn't how she can be driven. In my defense, I like HP measured from the wheels too... Drivetrain loss is a bitch, especially on 4wds, but it is what it is...

That being said, I like to think I know more than I do, and I will default to the dude with more real life experience! :thumb:
Well... it's not real life experience that I'll squat at least 1.5" with a 5,000# Jeep on my shoulders... that's simply web wheeling!

There are tires that are measuring a good bit less than the advertised size. The 35x12.50-15 KM2s on the Forged JKU are running at roughly 34.25" and my understanding is they're on the taller end compared to some others with KM2s.

At the end of the day, the tires are being measured unloaded. Wheel width, vehicle weight, tire pressure, etc will all cause different measurements, so just get the tire that serves you best and wheel the crap out of it!

:thumb:
 

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There are tires that are measuring a good bit less than the advertised size. The 35x12.50-15 KM2s on the Forged JKU are running at roughly 34.25" and my understanding is they're on the taller end compared to some others with KM2s.

At the end of the day, the tires are being measured unloaded. Wheel width, vehicle weight, tire pressure, etc will all cause different measurements, so just get the tire that serves you best and wheel the crap out of it!

:thumb:
I think we are making the same point? The KM2 properly inflated, possibly due to stiffer sidewalls (?) is a "35" measuring 34.25". My duratracs, common for us on road more than offroaders measures 33.5". They are both technically 35" tires, but real life factors rather than manufacturers' listings are the difference. But those tires were a good starting point for me as I needed them to make it through a winter or two on road, so I was willing to give up the extra 3/4s of an inch that you gained....
 
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