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Discussion Starter · #1 ·
So, I'm getting ready to go to 37s on my Willy's. Currently:
D30 front axle
3.6, auto, 3.73 gears, ARB front locker (yeah, sorta regretting that investment)
2.5" AEV lift with antirock swaybar, currectlink sterring, jks trackbar front

In the spring/summer/fall I try to wheel 2-3 times a month. Would like to go more too!

I was advised that the r&p in the 30 were the weak points thus replacing D30 should be in the build. Question 1: is this accurate?

So then I researched D44 options and first started deciding between Dynatrack's ProRock44 or TeraFlex 44. Then see both offer setups for stock suspension or 3+ lifted suspensions. I'm thinking get my caster and pinion angles right at the axle so go for the unlimited/high pinion. Question 2: do y'all agree?. Question 3: which would y'all recommend?

Then I need to think of lift. I'm currently torn between:
a) MC gamechanger 3.5" lift with OME shocks
b) RK JK 3.5 X Factor - Stage 1
Question 4: which would y'all recommend?

Gears... I do a lot of highway at 70mph so don't wanna run my RPM's too high but at the same time don't wann invest in gears to be disappointed. Question 5: what do y'all think, 4.88 or 5.13?

Lastly, wheels and tires. I'm thinking maybe 37s on 15" wheels might make a very nice setup both on and off-road. But have read they feel squish at highways speeds sometimes. Question 6: 15" or 17"?

For tires I'd like something more aggressive than DuraTracs (which I do like) but not all the way to full on MT's (too loud and I do too much highway driving). I'm leaning towards Nitto Trail Grappler and MT Baja ATZ P3 but still deciding since this will be my last purchase.

BIG questions: am I thinking about this properly? Am I missing any components?

I know this is a lot in a single post and appreciate any help that can be given. I'm looking for folks experienced down this path who can help me get to where I want to be effectively!

Very grateful.
 

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In regards to gearing choices. Look at the gearing charts for the JK:


Jeep Wrangler JK Gearing Charts - Resources - Articles - Articles - Tennessee Jeeps

Notice that for the 3.6 auto trans JK, the only gear ratio that puts you in the "green" for 37" tires is 4.56:1. I'm running 4.56 gears and 37" tires on my JK, and I think it works just fine. The speed limit around here is 80 mph though, and most people drive 90 mph, so that makes a difference. For more off road use, or for areas where you wont be driving over 70 to 75 mph, 4.88s may be better.

There is a big difference in transmission gearing between pre-2012 auto trans JKs and 2012+ auto trans JKs. A pre-2012 JK with auto trans needs 5.38 gears to be turning close to the same engine RPM at 70 mph as a 2012+ JK with auto trans is turning with 4.56 gears, if both Jeeps have the same tire size.
 

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Discussion Starter · #3 ·
THANK YOU! I pulled the wrong chart from google. So I really need to decide 4.56 for the daily commute or 4.88 for the trails. Appreciate!

Your sig shows a great build! Anything you'd do differently?
 

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Thanks for the kind words. I don't think I would do anything different at this point. Everything seems to be working very well.
 

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Wred,

On your build questions here are my thoughts.
1. Going to 37's and either of the lifts you're looking at I would suggest the D44. Currie is another that might warrant some consideration but either of your choices are good axles. You will probably want to go ahead a look at new drive shafts as well since you are planning to wheel it more and are looking at going to the 3.5 lifts.
2. Not 100% sure on that I would ask Dynatrac what they would suggest for the way your specific build is looking to go.
3. I would call them and see what they suggest. Both companies are great to deal with and will provide great input.
4. Either of the kits will be great additions to your build. I like the Rock Krawler kits since they seem to handle added weight better, but I know the MetalCloak kits are really well built so either would be solid. You shocks is where I would make sure you're set on. Many shocks are steel bodies and up north, where the roads get salted, sometimes a steel body shock can get damaged and start to rust. Rock Krawler and Fox are aluminum body shocks so those are good for consideration. You could also look at the 6 pack shock from Metal Cloak if you want to go that direction.
5. Gears will depend on terrain and driving specific to your location. I am running 35's and heading to Alaska soon so I went with the 5.13 for better response on hilly terrain.
You could also look at MTR from Goodyear since the kevlar wall absorbs sound. The Trail Grapplers are a nice tire as well.

Overall it appears that you are on the right path. Some other considerations would be possibly a pro tie rod kit, or ultimate steering package from RK. The Currie Antirock is a definite to keep, those are really nice. Like I said driveshafts are going to be a plus.
Wheels you might want to consider 16" or 17" since some of the 15" wheels will require grinding the caliper down to make them fit. I would also get an AVE procal or Flashcal for readjusting the tire size.

Jeremy
 

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Discussion Starter · #7 ·
Hi Jeremy! Thank you very much for jumping in! Yup, already have the AEV so covered there. Love the Antirock and with the Currie currectlync I've already got HD tie rod and drag link and JKS track bar up front so hoping that trio covers me there!

Driveshafts. I knew I was missing something! THANKS!

I'll definitely hop on the phone with TF, Dyna & now Currie (thanks for advising about them. I'm a big fan of their products as you can see didn't know they did axles too!).

Good call on shock material. I'm just outside of Chicago and yes, the salt trucks are out in force trying to eat up my JK. Would be nice to have some aluminum where I can!
 

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Dynatrac unlimited all the way. No real experience, but I read horrible CS With CURRIE. DT's CS is 2nd to none. I'm partial to RK because I have experience with them. I agree with KOR tho, either kit will work out great.
Another thing to remember. The RK shocks are cheap to rebuild and revalve if needed.

If keeping your stock rear 44, look into a set of Chrome-moly axles.

Good luck ...!!!!
 

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Hi
I have a 2013 auto also. I just went to the 37's with 4.56's and love them. I also have the MTRK's and they are pretty quiet so far. Much quieter than my KM2's were. I also have the X Factor 3.5 lift with King Shocks. But when I had the RK shocks on there they worked just fine. I have a built factory 44 in there. So far it's working fine and I do wheel it hard. Looks like your on track for a monster.
 

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It seems like you are on the right track to build it right.

4.88's seem to be the overwhelming choice for 37's and the 3.6/5spd auto.

Flat fenders would also be something to look into(provided you dont already have them). They REALLY help get all the flex possible out of your suspension. Both of your suspension choices are solid IMO.

Stick with a 17" wheel. On 15's your choices are limited on the JK due to brake size. If you decide to do something like the BR6 upgrade down the road no way they will fit under 15's. Also the side wall on a 37" 15 gets REALLY tall and your on road handling can start to suffer. I also believe it can make it easier to pop a bead off road with such a tall sidewall.
 

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So, I'm getting ready to go to 37s on my Willy's. Currently:
D30 front axle
3.6, auto, 3.73 gears, ARB front locker (yeah, sorta regretting that investment)
2.5" AEV lift with antirock swaybar, currectlink sterring, jks trackbar front

In the spring/summer/fall I try to wheel 2-3 times a month. Would like to go more too!

I was advised that the r&p in the 30 were the weak points thus replacing D30 should be in the build. Question 1: is this accurate?

So then I researched D44 options and first started deciding between Dynatrack's ProRock44 or TeraFlex 44. Then see both offer setups for stock suspension or 3+ lifted suspensions. I'm thinking get my caster and pinion angles right at the axle so go for the unlimited/high pinion. Question 2: do y'all agree?. Question 3: which would y'all recommend?

Then I need to think of lift. I'm currently torn between:
a) MC gamechanger 3.5" lift with OME shocks
b) RK JK 3.5 X Factor - Stage 1
Question 4: which would y'all recommend?

Gears... I do a lot of highway at 70mph so don't wanna run my RPM's too high but at the same time don't wann invest in gears to be disappointed. Question 5: what do y'all think, 4.88 or 5.13?

Lastly, wheels and tires. I'm thinking maybe 37s on 15" wheels might make a very nice setup both on and off-road. But have read they feel squish at highways speeds sometimes. Question 6: 15" or 17"?

For tires I'd like something more aggressive than DuraTracs (which I do like) but not all the way to full on MT's (too loud and I do too much highway driving). I'm leaning towards Nitto Trail Grappler and MT Baja ATZ P3 but still deciding since this will be my last purchase.

BIG questions: am I thinking about this properly? Am I missing any components?

I know this is a lot in a single post and appreciate any help that can be given. I'm looking for folks experienced down this path who can help me get to where I want to be effectively!

Very grateful.
Okay...I'm gonna likely be against the common grain on some of these things here. I'm working on my transition from stock Sport to 37's. Rather than tell you what I was going to do (when I was contemplating keeping the D30 front axle...I'm not now because I ran across a pair of 1tons used for almost nothing).

Question 1: D30 R&P weakness. Yes...you are correct. The R&P is considerably smaller than that of the D44. This is the one MAJOR difference between the D44 and D30. Tubes are same, C's, etc...essentially this is the sole critical factor to overcome if you plan on keeping your D30.

Still answering Question 1...you can do a few things to that D30. Primarily, if trying to keep it, I would regear. At the time of regear, when I received the gears themselves, I would have them cryogenically treated. This will significantly increase the strength of the gears. Most sources I've run across say it's 100-150% increase in strength. I prefer to err on the side of caution, so I'd bank on 50% increase...which still is significant.

Aside from having the R&P cryo'd, all other things remain essentially the same between the D30 and D44. So you would ideally want to truss ($400ish, plus whatever cost is involved welding them in. I do my own welding). DEFINITELY want to gusset the C's ($100ish). Sleeves will strengthen the axle tubes, but will not strengthen where the tube enters the housing (truss will), so personally I wouldn't bother with the sleeves...just my preference. If you're changing your locker, go to 30-spline locker and shafts. At this point, you've done all you can probably do to strengthen that D30. So long as you don't abuse it, it'll likely hold up long term, even with 37's. Many here will disagree, however many here don't see them "grenade" like they would make you believe.

Alternatively...Question 2 & 3If you swap the axle, you can inexpensively get a NEW non-rubicon D44 front axle for not a lot of money. So you'd be out about the same moolah for R&P, locker, shafts as you would be to strengthen the D30, but just add about another $700-$1100 (prices I've seen recently on new housings). Probably less if you're patient and more diligent in your search. Mind you...it would still be wise to truss and gusset the C's. But your R&P issue is gone. Especially if you pay the $30 + shipping and handling to have those gears cryo'd :D

Question 4:Either of the lifts you named are great lifts. You will not be going wrong if you choose one of those.

Question 5:Personally I wouldn't go higher (numerically) than 5:13...and if you're keeping your D30, 4:88 (so you'll have more ring-gear material). Gearing ratios are pretty subjective, so you'll likely get the gammut of recommendations here. But I still wouldn't go higher than 4:88 on a D30 CRYO'D.

Tire choice is also very subjective. Hard to go wrong with Nittos, but they are heavy. Also...if you're going 37's, the general rule of thumb is wheel sizes of no less than 17".

Looking forward to seeing the build...definitely post your progress, please.:punk:
 

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Discussion Starter · #12 ·
MOPWR2U - you're welcome! It's true!

Blue Baby Sound - 60s cost more about $500 more and most have less clearance at the pumkin. As 37 is my max (garage, investment, trail restrictions, jeep jamboree limits) I'm ok with 60.

kjeeper10 - good to know about shock rebuilds and revalve & their CS! I'll check out their site for the kits! Good call to reinforce rear 44!

Gunner - thanks! how's your mpg on highways around 65mph? why did you switch to King shocks?

Rjacobs - I do have flat fenders so covered there! Thanks for the thinking on wheel sizes! I'll stick with 17"!!
 

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If you're considering 60s, be aware that your JKS track bar will limit up travel with a Pro Rock 60. The Rock Jock 60 and Tera 60 don't have that problem because the top of the differential is rotated backwards.

Here is where the PR 60 hits a JKS trackbar. I tried to use a JKS front track bar on my JK, and found the problem. Changing to a Teraflex track bar allowed for another 1 1/2" of up travel compared to the JKS track bar.

 

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If you plan to really wheel 37s and switch out axles- selectable lock both front and rear and go hydro assist steering.

I love my Nitro Trail Grapplers.

For a lot of on road speed driving, I would stay 4.56 or 4.88. You don't have the 4:1 transfercase to get enough benefit out of 5.13 on the trail to outweigh the low gearing at a lot of road driving in my opinion.
 

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Discussion Starter · #15 ·
dvn4life1972 - thanks for all the thoughts!! That's interesting.... Let's think keeping the D30 since I've already got my ARB locker in it...So would even a 4.56 be stronger? I'm happy with 35s and 3.73 gears so I'm sure I'd even be okay with 4.1. LOL! This link was interesting: http://www.fourwheeler.com/how-to/t.../129-1103-making-stock-dana-30-axles-survive/. Here it is $50 plus shipping. CRYO SCIENCE

This is something that I hadn't taken off the table and exciting to consider! Truss & gusset is a lot cheaper than a new axle and ARB. If I had a failure could I still limp off a trail? Assuming I had a 36mm socket of course and pull the axles.

Good call on 17" reco!

And yes, I'll be keeping everyone posted!
 

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Discussion Starter · #16 ·
MOPWR2U - I mistyped above. I'm okay with 44s. No need for 60s for me at this point!

mommymallcrawler - thanks for more advice! This whole thing is mindblowing :)
 

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dvn4life1972 - thanks for all the thoughts!! That's interesting.... Let's think keeping the D30 since I've already got my ARB locker in it...So would even a 4.56 be stronger? I'm happy with 35s and 3.73 gears so I'm sure I'd even be okay with 4.1. LOL! This link was interesting: Making Stock Dana 30 Axles Survive. Here it is $50 plus shipping. CRYO SCIENCE

This is something that I hadn't taken off the table and exciting to consider! Truss & gusset is a lot cheaper than a new axle and ARB. If I had a failure could I still limp off a trail? Assuming I had a 36mm socket of course and pull the axles.

Good call on 17" reco!

And yes, I'll be keeping everyone posted!
I'm pretty confident that, with the wheeling you plan on doing, this would work well long-term keeping in mind that you'd have to be conservative on the skinny pedal off-road.

And yes...the 4.56 would be stronger than 4.88 by a bit. Basically there's more beef there, which means a bit more strength...coupled with cryo treatment I think you'll be golden.

You could limp off the trail, yes.

Also....if you have a bit of time between now and when you plan to begin all this, keep an eye out for a really good deal on a D44 housing. Every now and again you can come by them super cheap. Doesn't hurt to have the eyes peeled.
 

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MOPWR2U - I mistyped above. I'm okay with 44s. No need for 60s for me at this point!

mommymallcrawler - thanks for more advice! This whole thing is mindblowing :)
It is a lot to consider. The positive is you are doing the considering FIRST rather than just throwing money at it and wondering why things don't work or break.

I was tempted by 60s, but I have some perfectly good trussed 44s. If I can grenade those, then I need an upgrade lol and will do it then.
 

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My last trip I got 17 mpg at 65 to 70 cruise. I have double checked the dash at the pump and it comes out within 1/10 all the time so I gave up checking it. I switched to the kings because I had bought an older used kit. When the RK shocks started to leak I just wanted something adjustable. Up till then they were working just fine.
 

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Discussion Starter · #20 ·
Ok! Thanks again both y'all!
 
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