Notices
Modified JK Tech Tech related bulletin board forum regarding subjects such as suspension, tires & wheels, steering, bumpers, skid plates, drive train, cages, on-board air and other useful modifications that will help improve the performance and protection of your Jeep JK Wrangler (Rubicon, Sahara, Unlimited and X) on the trail.

PLEASE DO NOT START SHOW & TELL TYPE THREADS IN THIS FORUM
Sponsored by:
Sponsored by:

37's on a 3.8L JK? what are your thoughts

Old 06-01-2016, 09:48 AM
  #1  
JK Enthusiast
Thread Starter
 
jeepjkgrrl's Avatar
 
Join Date: Nov 2011
Location: Jersey Shore
Posts: 282
Likes: 0
Received 0 Likes on 0 Posts
Default 37's on a 3.8L JK? what are your thoughts

I have a 2011 JK Automatic with the 3.8l . I have 5.13 gears adj. Front and rear track bar. Adjustable front lower control arms. A new upgraded front drive shaft. And grease able ujoints in the front.....
So the question is what else do I need?
Old 06-01-2016, 09:57 AM
  #2  
JK Super Freak
 
webejeepin's Avatar
 
Join Date: Mar 2010
Location: Ontario Canada
Posts: 1,182
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by jeepjkgrrl
I have a 2011 JK Automatic with the 3.8l . I have 5.13 gears adj. Front and rear track bar. Adjustable front lower control arms. A new upgraded front drive shaft. And grease able ujoints in the front.....
So the question is what else do I need?
I'm sure others who have this set up will chime in, I dont, but from what I understand.....

Sounds like you have gearing taken care of. Would assume you have a programmer already to adjust for the gears, you will need it for new tires size too.

With 37s I would think bare minimum on the front stock D30 or 44 C gussets ....and axle sleeves

Assume you have a tall enough lift, fender flares ect you allow full wheel stuff

Good luck with the buikd! I myself have a 3.8l and auto....33s and stock 3:73s.....for now
Old 06-01-2016, 10:10 AM
  #3  
JK Jedi Master
FJOTM Winner
 
nthinuf's Avatar
 
Join Date: Jan 2008
Location: Austin <--> Colorado Springs
Posts: 11,465
Likes: 0
Received 162 Likes on 154 Posts
Default

The 3.8 is underpowered, you will wish that you had 5.38's. And a supercharger. And a v-8. (it's not as bad as all that, but I do wish I had more power...)

Start looking for threads talking about strengthening the front housing (gussets, sleeves, truss, etc) to see what fits your budget and needs. There are a bunch of different opinions on it, so read as much as you can. For any other components, like shafts and hubs and whatever, leave it alone until there is a reason to replace. (my opinion, anyway)

Other than that, 37's are just about clearance. You want more backspace to move the tires out and enough trimming and/or lift to keep them off the body. Hard to say what you will want/need to do, since all builds can be different.
Old 06-01-2016, 10:27 AM
  #4  
JK Enthusiast
Thread Starter
 
jeepjkgrrl's Avatar
 
Join Date: Nov 2011
Location: Jersey Shore
Posts: 282
Likes: 0
Received 0 Likes on 0 Posts
Default

This is my jk. I had to replace the front drive shaft because stock sucked and that boot ripped off and the shaft seized . So I upgraded. Also I don't do highway driving really. Maybe 60 mile drive to my parents and trails. I have a charger hemi for daily. Also my front is a d30. Which I'm looking for a d44 from a junk yard

Is there upgraded steering? Like pump? Or pitman arm?

Click image for larger version

Name:	ForumRunner_20160601_142341.png
Views:	395
Size:	682.3 KB
ID:	648544



Click image for larger version

Name:	ForumRunner_20160601_142311.png
Views:	385
Size:	529.8 KB
ID:	648543
Old 06-01-2016, 10:28 AM
  #5  
JK Enthusiast
Thread Starter
 
jeepjkgrrl's Avatar
 
Join Date: Nov 2011
Location: Jersey Shore
Posts: 282
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by webejeepin

I'm sure others who have this set up will chime in, I dont, but from what I understand.....

Sounds like you have gearing taken care of. Would assume you have a programmer already to adjust for the gears, you will need it for new tires size too.

With 37s I would think bare minimum on the front stock D30 or 44 C gussets ....and axle sleeves

Assume you have a tall enough lift, fender flares ect you allow full wheel stuff

Good luck with the buikd! I myself have a 3.8l and auto....33s and stock 3:73s.....for now
I have a programmer from superchips.
Old 06-01-2016, 11:46 AM
  #6  
JK Freak
 
JKphotoshoot's Avatar
 
Join Date: Jan 2013
Location: Cedar city, Utah
Posts: 513
Likes: 0
Received 1 Like on 1 Post
Default

It's bearable if you live where it's flat.
My 07 auto with 5:38s and 37s was terrible out here in the mtns.
Even with a extra tranny cooler with a fan on it I was on the verge of overheating it on long grades.
Add a additional tranny cooler if you haven't already.
Old 06-01-2016, 12:14 PM
  #7  
JK Jedi
 
Maertz's Avatar
 
Join Date: Apr 2011
Location: Neenah, Wisconsin
Posts: 4,482
Likes: 0
Received 2 Likes on 2 Posts
Default

im on an auto 3.8l with 41.5 and cant complain.. in hilly areas it would struggle and i may hate it a tad but as long as your not towing im not concerned. Has plenty of power for me especially in this flat area im in now. i dont even have an extra tranny cooler... I personally wouldn't get a turbo, id just do a motor swap myself, but not many will do that. id say power steering cooler also as even with hydro my box got very got...
Old 06-01-2016, 12:16 PM
  #8  
JK Freak
 
SoK66's Avatar
 
Join Date: Apr 2009
Location: Colorado
Posts: 771
Received 31 Likes on 29 Posts
Default

Originally Posted by jeepjkgrrl
I have a 2011 JK Automatic with the 3.8l . I have 5.13 gears adj. Front and rear track bar. Adjustable front lower control arms. A new upgraded front drive shaft. And grease able ujoints in the front.....
So the question is what else do I need?
I've run 37s for the last six years on my '09 JKUR with the setup in my profile, no issues whatsoever that would lead me to not recommend them. At the risk of stating the obvious, you need enough lift, bump stop, wheel well clearance and wheel offset to prevent rubbing, and deep enough gears to permit the engine to run in its power band. You can pull it off with around 3" lift, flat flares like MCEs, Bushwackers, etc., and at least 4.5" of wheel offset via wheels themselves or spacers. With 5.13s you should be ok, but you'd be better off with 5.38s. The 3.8L is a notorious dog, but mine has cheerfully taken me on long journeys, conqueed tough trails and returned me home. The only problem being a cracked exhaust manifold.
Old 06-01-2016, 12:49 PM
  #9  
JK Enthusiast
Thread Starter
 
jeepjkgrrl's Avatar
 
Join Date: Nov 2011
Location: Jersey Shore
Posts: 282
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by SoK66

I've run 37s for the last six years on my '09 JKUR with the setup in my profile, no issues whatsoever that would lead me to not recommend them. At the risk of stating the obvious, you need enough lift, bump stop, wheel well clearance and wheel offset to prevent rubbing, and deep enough gears to permit the engine to run in its power band. You can pull it off with around 3" lift, flat flares like MCEs, Bushwackers, etc., and at least 4.5" of wheel offset via wheels themselves or spacers. With 5.13s you should be ok, but you'd be better off with 5.38s. The 3.8L is a notorious dog, but mine has cheerfully taken me on long journeys, conqueed tough trails and returned me home. The only problem being a cracked exhaust manifold.
I had 35s before the 37s. Had rubbing in the rear as you can see from the picture. But cut that area and seems fine. But rubs in the front on hard turns. Have 1.5in wheel spacers.


Click image for larger version

Name:	ForumRunner_20160601_164733.png
Views:	350
Size:	440.9 KB
ID:	648561
Old 06-01-2016, 02:07 PM
  #10  
JK Enthusiast
Thread Starter
 
jeepjkgrrl's Avatar
 
Join Date: Nov 2011
Location: Jersey Shore
Posts: 282
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by Maertz
im on an auto 3.8l with 41.5 and cant complain.. in hilly areas it would struggle and i may hate it a tad but as long as your not towing im not concerned. Has plenty of power for me especially in this flat area im in now. i dont even have an extra tranny cooler... I personally wouldn't get a turbo, id just do a motor swap myself, but not many will do that. id say power steering cooler also as even with hydro my box got very got...
Question then for you....steering issuses?

Quick Reply: 37's on a 3.8L JK? what are your thoughts



All times are GMT -8. The time now is 01:21 AM.