Need Help - 40's on JK Unlimited - What Lift? - JKowners.com : Jeep Wrangler JK Forum
 12Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 30 Old 05-31-2017, 09:27 AM Thread Starter
Granite Guru
 
Texas_Jester's Avatar
 
Join Date: May 2017
Location: Texas
Age: 55
Posts: 188
Garage
Feedback: 0 reviews
Cool Need Help - 40's on JK Unlimited - What Lift?

Any help/feedback is appreciated, pulling the trigger shortly on a lift and I am definitely planning to run 40" tires on my build, so along with upgrading diffs and gears. Can you guys that have already been down this road help me with lift height/fenders, etc. for clearance. I was thinking to just go with Teraflex long arm 6" lift but I see a lot of you on here run around 4" lifts with 40" tires.

Do you have all the clearance you need on a 4" lift? No rubbing, etc. when off-road?

This won't be a daily driver for me, but more of a weekend/recreational vehicle. So go when ready and I'll try to keep up. And thanks in advance.

Oh and any pics you can post of your rig on 40's along with lifts specs, etc. are much appreciated as well.
Texas_Jester is offline  
Sponsored Links
Advertisement
 
post #2 of 30 Old 05-31-2017, 09:44 AM
Rock God
 
Dkjeep's Avatar
 
Join Date: Aug 2010
Age: 39
Posts: 1,017
Feedback: 0 reviews

D30 axle and 40's is a stretch.

Sent from my SM-G955U using Tapatalk
Texas_Jester likes this.
Dkjeep is offline  
post #3 of 30 Old 05-31-2017, 10:06 AM
JKO Addict!
 
thedirtman's Avatar
 
Join Date: Aug 2010
Location: southwest reno, nv
Age: 51
Posts: 4,343
Feedback: 0 reviews

you can do it a couple ways, go big 5"+ and lots of bump stop that results in a rather unstable off road rig that won't drive very good on the road. This is what to look for on factory axles. Or a low center of gravity build in the 3.5"-4.5" range with high steer and lots of trimming that will perform better all around.

Don't worry about re-gear as you are going to want full width full float ton axles for 40's.

You are going to want axles for one thing strength as 40's on stockers even with upgraded shafts and gussets is a bad idea. You also want the extra width so you can maintain full steering. 40's on a factory width axle needs around a 1.5" back spaced wheel or you limit steering and put a lot of stress on the outers of the axle. You will bend the rear flanges on a semi float axle as well. The third thing you want is to have a front axle that is caster corrected for your lift. The bigger you lift the more you need caster correction. The full width axle will also give you more room for the hydraulic assist cylinder which you will need for the 40's.

Most long arm kits for the JK are not really that great and with 40's I would really look into a custom set up. The location of the fuel tank is the biggest issue with a well designed rear long arm. Genright has the best set up out there but it is in the $30k range for the parts and if paying to install it is closer to $50k. That being said you can get cheap stuff from Rough County or Rubicon Express.

If you want to run a reliable jeep on 40's don't be surprised to drop $20k if you are doing all the work yourself and that includes building axles not buying them. Actually the lift kit is one of the minor expenses and brackets and arms can be built pretty easy. You can find brackets from many suppliers like ruff stuff, ballistic, genright, synergy, WFO, blue torch fab and others.

There are lots of guys that buy a jeep and think they can just throw a lift and 40's on it which is really not the case and quickly find out its going to cost way more and need more things then they initially thought. If this is you do some searching and learn what you are actually going to need.
Some things are:

1. Wheels as most go with a 8x6.5 bolt pattern for tons as that is what comes on aftermarket and the popular Ford front swap.
2. Hydraulic assist is needed to turn those big meats and not toast your steering box.
3. axles, like mentioned some year ford kingpin 60's are popular as well as 14 bolt rear axle for those building and companies like dynatrac pro rock, dana ultimate 60's, and fusion 4x4 for being axles.
4. High steer kit to reduce bump steer and have a better steering feel both on road and off.
5. Driveshafts are going to be needed because of the lift height and the after market axles.
6. Big winch, a JKU on 40's is going to be heavy so look at least a 10,000 pound winch, big recovery gear too.
7. On board air for airing up those big tires and operating lockers if you go ARB.
8. You will need stubby bumpers for tire room up front.
9. High lift jack.

Once you are done building this big heavy pig the highway performance is going to suck. The V6 is just not enough for something that is going to be pushing 6000+ pounds on the big rubber. Hills are horrible.

Some build info here:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


[COLOR="Red"]New to jeeps, check this link
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Last edited by thedirtman; 05-31-2017 at 10:16 AM.
thedirtman is offline  
Sponsored Links
Advertisement
 
post #4 of 30 Old 05-31-2017, 10:11 AM Thread Starter
Granite Guru
 
Texas_Jester's Avatar
 
Join Date: May 2017
Location: Texas
Age: 55
Posts: 188
Garage
Feedback: 0 reviews

Quote:
Originally Posted by Dkjeep View Post
D30 axle and 40's is a stretch.

Sent from my SM-G955U using Tapatalk
Thanks, I am trying to decide whether to go with a Dynatrac 44 Front and beef up the 44 rear that is in it for now, or just jump to Dana 60's......big decision obviously

Realistically I know I will spend 90-95% of my time on the highway, but I definitely don't want the 5-10% offroad time to keep me from getting home either
Texas_Jester is offline  
post #5 of 30 Old 05-31-2017, 10:16 AM Thread Starter
Granite Guru
 
Texas_Jester's Avatar
 
Join Date: May 2017
Location: Texas
Age: 55
Posts: 188
Garage
Feedback: 0 reviews

Quote:
Originally Posted by thedirtman View Post
you can do it a couple ways, go big 5"+ and lots of bump stop that results in a rather unstable off road rig that won't drive very good on the road. This is what to look for on factory axles. Or a low center of gravity build in the 3.5"-4.5" range with high steer and lots of trimming that will perform better all around.

Don't worry about re-gear as you are going to want full width full float ton axles for 40's.

You are going to want axles for one thing strength as 40's on stockers even with upgraded shafts and gussets is a bad idea. You also want the extra width so you can maintain full steering. 40's on a factory width axle needs around a 1.5" back spaced wheel or you limit steering and put a lot of stress on the outers of the axle. You will bend the rear flanges on a semi float axle as well. The third thing you want is to have a front axle that is caster corrected for your lift. The bigger you lift the more you need caster correction. The full width axle will also give you more room for the hydraulic assist cylinder which you will need for the 40's.

Most long arm kits for the JK are not really that great and with 40's I would really look into a custom set up. The location of the fuel tank is the biggest issue with a well designed rear long arm. Genright has the best set up out there but it is in the $30k range for the parts and if paying to install it is closer to $50k. That being said you can get cheap stuff from Rough County or Rubicon Express.

If you want to run a reliable jeep on 40's don't be surprised to drop $20k if you are doing all the work yourself and that includes building axles not buying them. Actually the lift kit is one of the minor expenses and brackets and arms can be built pretty easy. You can find brackets from many suppliers like ruff stuff, ballistic, genright, synergy, WFO, blue torch fab and others.

There are lots of guys that buy a jeep and think they can just throw a lift and 40's on it which is really not the case and quickly find out its going to cost way more and need more things then they initially thought. If this is you do some searching and learn what you are actually going to need.
Some things are:
Thanks for the feedback, No, that's not me, I generally know I'm in for a huge cost and lots of upgrades to get to 40's (with proper performance) on a JK, just trying to figure out the best way of going about it before I start spending money in the wrong direction and have to back track, figured plenty of help here from those that have already been down this road. The searching is what I'm trying to do now.

Excellent article at the bottom of your sig, thanks for sharing!

Last edited by Texas_Jester; 05-31-2017 at 10:22 AM.
Texas_Jester is offline  
post #6 of 30 Old 05-31-2017, 10:20 AM
JKO Addict!
 
thedirtman's Avatar
 
Join Date: Aug 2010
Location: southwest reno, nv
Age: 51
Posts: 4,343
Feedback: 0 reviews

Don't even bother with a pro rock 44 go straight to 60's or bigger. Too many people make the expensive mistake of building a front axle, then move to a pro rock 44, then get smart and go to 60's or bigger.

These builds are also hard to piece together and is best done all at once to minimize buying stuff twice and paying for labor twice. If I were to start over with a new jeep build I would limit it to 35's but mine is way too far gone to go back to 35's.
Texas_Jester likes this.

Some build info here:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


[COLOR="Red"]New to jeeps, check this link
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
thedirtman is offline  
post #7 of 30 Old 05-31-2017, 10:46 AM
TRD
Granite Guru
 
TRD's Avatar
 
Join Date: Jun 2013
Location: Hermosa Beach, Ca
Posts: 375
Feedback: 0 reviews

I'm on 40's with 4.5" lift and had to cut the grill and body mount to clear the tires. Also had to run a narrow front bumper. I expect clearance to get better once I have one tons and less back spacing.

-Ryan @
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

424-377-0808
Pre-Tuned
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
&
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Shocks

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Coilovers, IBP's, Bypasses & Adjustable Shocks In Stock
TRD is offline  
post #8 of 30 Old 05-31-2017, 11:00 AM Thread Starter
Granite Guru
 
Texas_Jester's Avatar
 
Join Date: May 2017
Location: Texas
Age: 55
Posts: 188
Garage
Feedback: 0 reviews

Quote:
Originally Posted by TRD View Post
I'm on 40's with 4.5" lift and had to cut the grill and body mount to clear the tires. Also had to run a narrow front bumper. I expect clearance to get better once I have one tons and less back spacing.
Don't suppose you have a photo of where, how much you had to cut the grille do you?
Texas_Jester is offline  
post #9 of 30 Old 05-31-2017, 11:09 AM
Rock God
 
tapcola's Avatar
 
Join Date: Jan 2013
Location: Las Vegas
Posts: 1,095
Feedback: 0 reviews

Quote:
Originally Posted by Texas_Jester View Post
Don't suppose you have a photo of where, how much you had to cut the grille do you?
If you run tons you won't have to trim the grill , theay are much wider , just one of the many reasons why you SHOULDN'T run 40s on stock axles .

Sent from my SAMSUNG-SM-G891A using Tapatalk
Texas_Jester likes this.

SYNERGY, FOX,VKS,HUTCHINSON,
tapcola is offline  
post #10 of 30 Old 05-31-2017, 11:13 AM
TRD
Granite Guru
 
TRD's Avatar
 
Join Date: Jun 2013
Location: Hermosa Beach, Ca
Posts: 375
Feedback: 0 reviews

Here's a picture from the back side.
Attached Images
 
Texas_Jester likes this.

-Ryan @
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

424-377-0808
Pre-Tuned
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
&
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Shocks

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Coilovers, IBP's, Bypasses & Adjustable Shocks In Stock
TRD is offline  
post #11 of 30 Old 06-01-2017, 07:29 PM
JKO Addict!
 
TCdawg's Avatar
 
Join Date: Jan 2011
Location: Woodstock, Ga
Age: 50
Posts: 3,720
Garage
Feedback: 2 reviews

3.5" RK suspension.

Love the height and stance. You can go higher to make things easier but with a little clearancing work and proper bumpstops, 3.5 works great

4.5 to 5.5" of lift is pretty damn high, starts to get unstable
Attached Images
 

Last edited by TCdawg; 06-03-2017 at 03:58 PM.
TCdawg is offline  
post #12 of 30 Old 06-01-2017, 08:14 PM
Granite Guru
 
Join Date: Jan 2011
Posts: 198
Feedback: 1 reviews

Quote:
Originally Posted by thedirtman View Post
you can do it a couple ways, go big 5"+ and lots of bump stop that results in a rather unstable off road rig that won't drive very good on the road. This is what to look for on factory axles. Or a low center of gravity build in the 3.5"-4.5" range with high steer and lots of trimming that will perform better all around.

Don't worry about re-gear as you are going to want full width full float ton axles for 40's.

You are going to want axles for one thing strength as 40's on stockers even with upgraded shafts and gussets is a bad idea. Once you are done building this big heavy pig the highway performance is going to suck. The V6 is just not enough for something that is going to be pushing 6000+ pounds on the big rubber. Hills are horrible.
Quote:
Originally Posted by thedirtman View Post
Don't even bother with a pro rock 44 go straight to 60's or bigger. Too many people make the expensive mistake of building a front axle, then move to a pro rock 44, then get smart and go to 60's or bigger.

These builds are also hard to piece together and is best done all at once to minimize buying stuff twice and paying for labor twice. If I were to start over with a new jeep build I would limit it to 35's but mine is way too far gone to go back to 35's.
I have to DISAGREE with Dirtman on this, because I've done it and wheel it successfully all the time. I don't even trailer it, which amazes my friends that do trailer.

Yes, I have 40s on a 4dr on "bombproof" D44s! My last break was 2 years ago on 37s and 30 spline chomoly axles.... Ever since I upgraded to ARBs with 35 spline axle shafts, I haven't worried about breaking and in some cases I was amazed I didn't..... I have a 5" long arm lift made up of MetalCloak springs, TNT front radius arms and basically a LA RK 3-link rear (except I built the lowers with DOM and MC ends); it rides like a Cadillac on and off road!

I've wheeled the piss out of 39.5" IROKs and currently on 40" ProComp mud tires....soon I'll be moving to 40" TSL SXIIs.

You have to use wheels with minimum 3.5 backspacing in order to turn and not hit the frame, but its still real close and rubs a little when major flexing offroad. My 5.13 gears have held up great for years and I can still do hwy speeds and get 13-14mpg, but who cares about that, right!

The only thing that sucks is its a V6 and not a V8, so of course I'm going to eventually do a swap and see if I break the D44s then. But, honestly I don't think the V6 has the power to break these 35 spline shafts OR maybe I just wheel smarter than others.......
Texas_Jester likes this.

Last edited by azjeepN; 06-01-2017 at 08:20 PM.
azjeepN is offline  
post #13 of 30 Old 06-01-2017, 08:50 PM
Rock God
 
Join Date: May 2016
Location: Woodinville, WA
Posts: 913
Feedback: 0 reviews

It really depends on what you're going to do with your rig.

Yes lots of people get by with 40's on D44's. The trick is, no wheel speed. The ground-traction torque only increases linearly with tire diameter, so you're looking at a 14% increase in torque going from a 35 to a 40. Not that big a deal. If you cross the line you can absolutely still cause damage, but it's quite likely that if you break on a 40 in a static loading scenario, you also would have broken with 35's or 37's. Note it gets a little worse if aired down really far on high traction rock, because your ground traction also increases with surface area as the tire size increases.

Add wheel speed, and you have a serious mess. Moment of inertia increases with radius squared, the tire's tread weight increases linearly with radius, and sidewall weight increases with r^2. That's an a*r^3 + b*r^4 relation with tire size to moment load torque. That means going from 35's to 40's increases your moment-loads by notably more than 50%. That's a tremendous change, get a little wheel hop going or try to use wheel speed to get up a high traction environment, and your D44 will snap like a twig on 40's where 35's would have been fine. The torque spec of a D60 vs. D44 is just enough to cover this difference, hence why you can absolutely still break a D60 with 40's, just like you can break a D44 with 35's. Of course there's also great variety in tire weight between different brands that you have to factor in too, but that's the general concept.
christensent is offline  
post #14 of 30 Old 06-02-2017, 10:36 AM
JKO Addict!
 
thedirtman's Avatar
 
Join Date: Aug 2010
Location: southwest reno, nv
Age: 51
Posts: 4,343
Feedback: 0 reviews

I guess hard wheeling is a relative term and you may have not broken yet, yet being the relative word. I have broken a 35 spline shaft on a pro rock 60 as well as 1480 u-joints in said axle. I typically run with buggies though and never see JK's on the actual hard stuff.

You get by with 3.5" bs wheels because you are so high with your lift and have lots of bump stop. Do you know your actual lift height? If you were at 3.5-4" of actual lift and properly bump stopped for max articulation there is no way you get by with 3.5" bs and retain full steering without rubbing hard on front corner and likely the frame and lower control arms.

Like I said in my post, you can go high with lots of bump and get by. You will be more unstable and have limited up travel and actually limit yourself to total suspension travel because of driveline angles. IF you want to limit your overall travel to like a 12" max shock it will help with rubbing but you are likely going to have to have so much bump stop for wheel clearance that a 12" total travel shocks in factory locations is only going to have about 9"-10" of actual usable travel.

Some build info here:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


[COLOR="Red"]New to jeeps, check this link
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
thedirtman is offline  
post #15 of 30 Old 06-02-2017, 12:00 PM
Rock God
 
Dkjeep's Avatar
 
Join Date: Aug 2010
Age: 39
Posts: 1,017
Feedback: 0 reviews

There are LOTS of people around the DFW area rolling around on 40's with d30 front axle. Some of them do actually use their jeeps as well and I am amazed when they dont break, some of them do break though. You are not going to grenade a d30 the second you put 40's on it but it definitely becomes the fuse in your driveline. A nice 44 axle will buy you even more time. If you ever plan to be a "hardcore" wheeler then do everything dirtman said. If you plan to just play occasionally you can get away with way less. Just be aware that you will be looked down upon by "real jeepers" with anything less than tons and a 40" tire.
Texas_Jester likes this.
Dkjeep is offline  
post #16 of 30 Old 06-02-2017, 12:58 PM Thread Starter
Granite Guru
 
Texas_Jester's Avatar
 
Join Date: May 2017
Location: Texas
Age: 55
Posts: 188
Garage
Feedback: 0 reviews

@chistensent I got dizzy reading this the first two times before I had to put a pen and pencil to it to make sense of it, good feedback and thanks for the technical insight,
I would never have looked at it this way. Great info!

Quote:
Originally Posted by christensent View Post
It really depends on what you're going to do with your rig.

Yes lots of people get by with 40's on D44's. The trick is, no wheel speed. The ground-traction torque only increases linearly with tire diameter, so you're looking at a 14% increase in torque going from a 35 to a 40. Not that big a deal. If you cross the line you can absolutely still cause damage, but it's quite likely that if you break on a 40 in a static loading scenario, you also would have broken with 35's or 37's. Note it gets a little worse if aired down really far on high traction rock, because your ground traction also increases with surface area as the tire size increases.

Add wheel speed, and you have a serious mess. Moment of inertia increases with radius squared, the tire's tread weight increases linearly with radius, and sidewall weight increases with r^2. That's an a*r^3 + b*r^4 relation with tire size to moment load torque. That means going from 35's to 40's increases your moment-loads by notably more than 50%. That's a tremendous change, get a little wheel hop going or try to use wheel speed to get up a high traction environment, and your D44 will snap like a twig on 40's where 35's would have been fine. The torque spec of a D60 vs. D44 is just enough to cover this difference, hence why you can absolutely still break a D60 with 40's, just like you can break a D44 with 35's. Of course there's also great variety in tire weight between different brands that you have to factor in too, but that's the general concept.
Texas_Jester is offline  
post #17 of 30 Old 06-02-2017, 05:26 PM
Rock God
 
ChuckTheRipper's Avatar
 
Join Date: Mar 2014
Location: Chester, WV
Age: 27
Posts: 925
Feedback: 0 reviews
Need Help - 40's on JK Unlimited - What Lift?

There's a guy I wheel with here who has a 4 door on a RK 5.5" long arm kit and 40" maxxis stickies and beadlocks who is running 44s with the stock 4.10 gears and chromoly shafts (not RCVs). He wheels the absolute piss out of his rig. Relative term or not, I beat on my Jeep pretty damn hard, yet nothing like this guy. Since upgraded his shafts he is yet to break anything other than like 20 rock krawler shocks. Ive seen him rip the shafts out and blow the shafts through the body so many times, each time blowing apart his bump stop. I honestly have no fucking clue how his 44s hold up, I'm amazed.


Sent from my iPhone using Tapatalk
ChuckTheRipper is offline  
post #18 of 30 Old 06-02-2017, 07:11 PM
Rock God
 
Join Date: Jun 2011
Location: Delray Beach, FL
Age: 45
Posts: 768
Feedback: 1 reviews

These threads always crack me up. There are so many opinions on this but the facts are 40's on factory axles and/aftermarket 44's is just a dumb idea.

Op, if you must run 40's get some Dana 60's.

Personally I think it's dumb for you to run 40's at all when you say you are 5% trail use and 95% highway use. Seriously... 40's are dumb for that. No one with common sense will say otherwise. Even on Dana 60's it's dumb to run 40's for 95% highway use, you just added 800lbs-1000lbs minimum of steel and rubber to slow you down 95% of the time.

Run 37's on your original plan of a beefed up rear 44 and pro rock front 44. That's the sweet spot for a DD JK. I know because I daily drive one set up like this 20k miles a year for the last 5 years and it's a trail killer and mall crawler all in one. Keeps the rig lighter with less stress on drivetrain. Better street performance mileage/acceleration/highway use. A proven reliable set up that will go anywhere a JK on Dana 60's and 40's will in my experience, less than 3/4" difference in ground clearance under Diffs between the 2 set ups.
bigworm36 likes this.

Last edited by Biginboca; 06-02-2017 at 07:28 PM.
Biginboca is offline  
post #19 of 30 Old 06-02-2017, 09:09 PM
Super Moderator
 
j3ff3ry_j33p's Avatar
 
Join Date: Jul 2012
Location: Nashville
Posts: 5,895
Garage
Feedback: 1 reviews

Quote:
Originally Posted by TCdawg View Post
3.5" RK suspension.

Love the height and stance. You cantallerti make things easier but with a little clearancing work and proper bumpstops, 3.5 works great

Either I have never seen a "full Jeep profile" image of your pig or it's been a long time, dude. That looks righteous ,srry to veer off topic OP,
On subject - edit here - ',boca speaks the truth up there ; light weight is key with tarmac centric JKUs . 37s-38 lights (ko2,mtr/k,a few others) tops on built oem housings is as big as ya wanna go without dedicating to spending beaucoup $$$ on new everything...and for 95%" getting to trails" you're gonna be investing at least what the Jeep cost itself to do so


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Last edited by j3ff3ry_j33p; 06-02-2017 at 09:19 PM.
j3ff3ry_j33p is offline  
post #20 of 30 Old 06-02-2017, 09:43 PM
Rock God
 
Nucleophile's Avatar
 
Join Date: Mar 2012
Posts: 821
Feedback: 2 reviews

Quote:
Originally Posted by Biginboca View Post
These threads always crack me up. There are so many opinions on this but the facts are 40's on factory axles and/aftermarket 44's is just a dumb idea.

Op, if you must run 40's get some Dana 60's.

Personally I think it's dumb for you to run 40's at all when you say you are 5% trail use and 95% highway use. Seriously... 40's are dumb for that. No one with common sense will say otherwise. Even on Dana 60's it's dumb to run 40's for 95% highway use, you just added 800lbs-1000lbs minimum of steel and rubber to slow you down 95% of the time.

Run 37's on your original plan of a beefed up rear 44 and pro rock front 44. That's the sweet spot for a DD JK. I know because I daily drive one set up like this 20k miles a year for the last 5 years and it's a trail killer and mall crawler all in one. Keeps the rig lighter with less stress on drivetrain. Better street performance mileage/acceleration/highway use. A proven reliable set up that will go anywhere a JK on Dana 60's and 40's will in my experience, less than 3/4" difference in ground clearance under Diffs between the 2 set ups.
Nailed it. 40s for 5% trail use......no way.
Nucleophile is offline  
post #21 of 30 Old 06-03-2017, 09:03 AM
JKO Addict!
 
thedirtman's Avatar
 
Join Date: Aug 2010
Location: southwest reno, nv
Age: 51
Posts: 4,343
Feedback: 0 reviews

Thats generally why I recommend going no bigger then 35's on a JK, but if money is no issue then knock yourself out.

Some build info here:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


[COLOR="Red"]New to jeeps, check this link
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
thedirtman is offline  
post #22 of 30 Old 06-03-2017, 09:32 AM
Rock God
 
Dkjeep's Avatar
 
Join Date: Aug 2010
Age: 39
Posts: 1,017
Feedback: 0 reviews

Quote:
Originally Posted by ChuckTheRipper View Post

Cant believe I have to be the first to say.... nice funbags.
HUNTER likes this.
Dkjeep is offline  
post #23 of 30 Old 06-03-2017, 09:32 AM
Rock God
 
coilrod's Avatar
 
Join Date: Feb 2010
Location: Lower mainland
Age: 52
Posts: 1,661
Garage
Feedback: 0 reviews

Quote:
Originally Posted by christensent View Post
It really depends on what you're going to do with your rig.

Yes lots of people get by with 40's on D44's. The trick is, no wheel speed. The ground-traction torque only increases linearly with tire diameter, so you're looking at a 14% increase in torque going from a 35 to a 40. Not that big a deal. If you cross the line you can absolutely still cause damage, but it's quite likely that if you break on a 40 in a static loading scenario, you also would have broken with 35's or 37's. Note it gets a little worse if aired down really far on high traction rock, because your ground traction also increases with surface area as the tire size increases.

Add wheel speed, and you have a serious mess. Moment of inertia increases with radius squared, the tire's tread weight increases linearly with radius, and sidewall weight increases with r^2. That's an a*r^3 + b*r^4 relation with tire size to moment load torque. That means going from 35's to 40's increases your moment-loads by notably more than 50%. That's a tremendous change, get a little wheel hop going or try to use wheel speed to get up a high traction environment, and your D44 will snap like a twig on 40's where 35's would have been fine. The torque spec of a D60 vs. D44 is just enough to cover this difference, hence why you can absolutely still break a D60 with 40's, just like you can break a D44 with 35's. Of course there's also great variety in tire weight between different brands that you have to factor in too, but that's the general concept.
Stop trying to use facts and science to prove you're smartlier then me! My opinions are solidly rooted in feelings! I feel that 40's n 42's should be ran, they're a good size for, the best size is really all about the wonderful Dana 44, an American made axle, bring back the greatness to the trails. And we know it will help the climate change.

I am a troll. Do not take my advice. It isn't going to help.
coilrod is offline  
post #24 of 30 Old 06-03-2017, 05:01 PM
Super Moderator
 
j3ff3ry_j33p's Avatar
 
Join Date: Jul 2012
Location: Nashville
Posts: 5,895
Garage
Feedback: 1 reviews

Quote:
Originally Posted by christensent View Post
It really depends on what you're going to do with your rig.

Yes lots of people get by with 40's on D44's. The trick is, no wheel speed. The ground-traction torque only increases linearly with tire diameter, so you're looking at a 14% increase in torque going from a 35 to a 40. Not that big a deal. If you cross the line you can absolutely still cause damage, but it's quite likely that if you break on a 40 in a static loading scenario, you also would have broken with 35's or 37's. Note it gets a little worse if aired down really far on high traction rock, because your ground traction also increases with surface area as the tire size increases.

Add wheel speed, and you have a serious mess. Moment of inertia increases with radius squared, the tire's tread weight increases linearly with radius, and sidewall weight increases with r^2. That's an a*r^3 + b*r^4 relation with tire size to moment load torque. That means going from 35's to 40's increases your moment-loads by notably more than 50%. That's a tremendous change, get a little wheel hop going or try to use wheel speed to get up a high traction environment, and your D44 will snap like a twig on 40's where 35's would have been fine. The torque spec of a D60 vs. D44 is just enough to cover this difference, hence why you can absolutely still break a D60 with 40's, just like you can break a D44 with 35's. Of course there's also great variety in tire weight between different brands that you have to factor in too, but that's the general concept.

yeah, what @christensent said !

(and I thought I was obsessive! well-explaint,dude)



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
j3ff3ry_j33p is offline  
post #25 of 30 Old 06-09-2017, 01:03 PM
JKowners Vendor
 
Rock Krawler Suspension's Avatar
 
Join Date: Apr 2009
Posts: 4,715
Feedback: 8 reviews

Chuck

Pretty sure our shock department is pretty familiar with that guy. He does beat the balls out of his jeep. Doesn't seem to care to put in limit straps or anything. Every once and a while he just sends them back. You can tell. LOL

Interesting pic too. Looks like his tire balls got misplaced and then boom - they were found...


OP

As far as height is concerned. We really like the 3.5-4.5" lift heights for 40's. It is not so much about height, just about how much you want to open up your rear wheel well. That is the key. The stock JK/JKU rear wheel well tucks a 37/38 very nicely. 40's will require a little trimming to achieve full stuff. So as long as you are not afraid of that, go for it. 40's are becoming more common place...

RK
ChuckTheRipper likes this.
Rock Krawler Suspension is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JKowners.com : Jeep Wrangler JK Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome