Should I do limited slip diffs in front and rear??
#1
Newbie
Thread Starter
Join Date: Sep 2016
Location: Thornton, CO
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1999
Model: Cherokee
Engine: 4.0
Should I do limited slip diffs in front and rear??
Hello everyone, my first post here. I actually got around to setting my account even though I've been lurking since I got the Heep 4 years ago .
Anyway to the real question. The Heep is my DD and I plan on throwing a 5.5 inch lift and 35's on there in the spring. While I'm doing this I will be regearing to 4.88's and thinking about locking up the axles. Since I live in Colorado and I like the 242, I'd like to maintain the full time option which is why I'm leaning towards a limited slip on front and back. My question is will the limited slip hurt me off road vs the benefit of not having a locker on the road. Right now the Heep is about 70% on road and 30% off road. Thank you for any opinions, feelings and the like.
Anyway to the real question. The Heep is my DD and I plan on throwing a 5.5 inch lift and 35's on there in the spring. While I'm doing this I will be regearing to 4.88's and thinking about locking up the axles. Since I live in Colorado and I like the 242, I'd like to maintain the full time option which is why I'm leaning towards a limited slip on front and back. My question is will the limited slip hurt me off road vs the benefit of not having a locker on the road. Right now the Heep is about 70% on road and 30% off road. Thank you for any opinions, feelings and the like.
#2
CF Veteran
Join Date: Jan 2012
Location: Ocean County, NJ
Posts: 2,208
Likes: 0
Received 3 Likes
on
3 Posts
Year: 1998
Model: Cherokee
Engine: 4.0L
You are much better off using a selectable locker at least in the front than an lsd unit if you want to use the full time option in your 242. It'll perform much better in the snow. I would run selectables front and rear if I lived in CO. An lsd unit will certainly be more street friendly than a locker. They're not as aggressive but also don't offer the same performance as a locker. You have to pick which is better for what you use the jeep for.
I will also recommend only going as big as 4.56's in a D30 for sake of the pinion or swap the d30 for a d44. If you don't go too hard offroad the D30 will survive with 4.88's but that tiny pinion will always be a weak link.
I will also recommend only going as big as 4.56's in a D30 for sake of the pinion or swap the d30 for a d44. If you don't go too hard offroad the D30 will survive with 4.88's but that tiny pinion will always be a weak link.
#3
Newbie
Thread Starter
Join Date: Sep 2016
Location: Thornton, CO
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1999
Model: Cherokee
Engine: 4.0
I understand what your saying. My whole reason for going with 4.88 gears despite the pinion weakness in the Dana 30, is that I would like to have those deeper gears so I can get more torque when crawling. I would prefer not to to run an air system for an ARB so would something like an OX locker be better? Also would the Dana 30 even be worth throwing something like an OX or an ARB in there? And lastly, just to confirm, would a luchbox locker in the front would cause the 242 to loose its "Full Time" abilities. Thanks for any replies.
#4
CF Veteran
Join Date: Jan 2012
Location: Ocean County, NJ
Posts: 2,208
Likes: 0
Received 3 Likes
on
3 Posts
Year: 1998
Model: Cherokee
Engine: 4.0L
My whole reason for going with 4.88 gears despite the pinion weakness in the Dana 30, is that I would like to have those deeper gears so I can get more torque when crawling.
Torque is exactly what breaks pinions...
I would prefer not to to run an air system for an ARB so would something like an OX locker be better? Also would the Dana 30 even be worth throwing something like an OX or an ARB in there?
You definitely want to run something where you can control it if you plan on using the Full Time feature of your 242. And personally, no a Dana 30 isn't worth throwing a bunch of money into but they can be a stout little axle if you're smart with your right foot. I run one because I got a hell of a deal on the parts to build it. I'm also not running an ARB in the front though.
And lastly, just to confirm, would a luchbox locker in the front would cause the 242 to loose its "Full Time" abilities.
You absolutely DO NOT want to run a traditional locker like a lunchbox in the front if you're going to use the full time feature of your tcase. It will be extremely hard to steer the jeep. Locked front ends like one direction, straight. They make life very difficult. I've NEVER heard my lockright ratchet or "unlock" when in 4wd and making any kind of turn. It just scrubs the tires which puts a ton of stress on front end components. Performs just fine when in 2wd. I don't even notice it. But this is something you definitely don't want.
Torque is exactly what breaks pinions...
I would prefer not to to run an air system for an ARB so would something like an OX locker be better? Also would the Dana 30 even be worth throwing something like an OX or an ARB in there?
You definitely want to run something where you can control it if you plan on using the Full Time feature of your 242. And personally, no a Dana 30 isn't worth throwing a bunch of money into but they can be a stout little axle if you're smart with your right foot. I run one because I got a hell of a deal on the parts to build it. I'm also not running an ARB in the front though.
And lastly, just to confirm, would a luchbox locker in the front would cause the 242 to loose its "Full Time" abilities.
You absolutely DO NOT want to run a traditional locker like a lunchbox in the front if you're going to use the full time feature of your tcase. It will be extremely hard to steer the jeep. Locked front ends like one direction, straight. They make life very difficult. I've NEVER heard my lockright ratchet or "unlock" when in 4wd and making any kind of turn. It just scrubs the tires which puts a ton of stress on front end components. Performs just fine when in 2wd. I don't even notice it. But this is something you definitely don't want.
#5
CF Veteran
Join Date: Jan 2016
Location: Newport News, VA
Posts: 1,242
Likes: 0
Received 38 Likes
on
37 Posts
Year: 96 & 88 4 dr Cherokees
[COLOR="Red"] I've NEVER heard my lockright ratchet or "unlock" when in 4wd and making any kind of turn. It just scrubs the tires which puts a ton of stress on front end components. Performs just fine when in 2wd. I don't even notice it. But this is something you definitely don't want.
I've had 4 axles (2 - d35's, and 2 - 9 1/4's) now with lunchbox style lockers in them, and I have heard every one of them ratchet.
I've also heard them ratchet in D44's & other axles when I was standing by them when they turned.
And it should not scrub the tires.....unless something is wrong. The only tire that can 'scrub' is the outside tire, and it should be free spinning when turning unless under power.
#6
Seasoned Member
Join Date: Jan 2014
Location: Springfield, MO
Posts: 302
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1996
Model: Cherokee
Engine: 4.0
I recently was deciding on lockers for my 96. It is not a DD, but I do drive it a fair amount on the pavement. I didn't want to run an air line or a cable, so I decided on the Eaton E Locker for the front. Very easy to wire up and don't have to worry about kinked air or cable.
In the rear I run a Detroit. in many instances before that would require 4 wheel drive, I can easily handle in 2 wheel drive because of the rear locker.
In the rear I run a Detroit. in many instances before that would require 4 wheel drive, I can easily handle in 2 wheel drive because of the rear locker.
#7
CF Veteran
Join Date: Jul 2013
Location: Monett, MO.
Posts: 7,554
Likes: 0
Received 14 Likes
on
14 Posts
Year: 1999
Model: Cherokee
Engine: 4.0
You could go with a Eaton e locker for the D30 or the OX both work without air the e locker is electric. Either of those with a LSD in the rear would work fine for off road use.
I run 33 & 35" tires with a 4.56 gear and works fine but the 4.88 may be a better choice for CO. in the mountains with long steep grades on the highways.
I run 33 & 35" tires with a 4.56 gear and works fine but the 4.88 may be a better choice for CO. in the mountains with long steep grades on the highways.
Trending Topics
#8
Seasoned Member
detriot in the rear, e-locker in the front, you will hardly notice it on the street,offroad it is amazing you will do 90 % of off road driving w/ the front open. steering isnt affected then, kick it on only when needed. imo limited slips are a waste of money.
#9
Newbie
Thread Starter
Join Date: Sep 2016
Location: Thornton, CO
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1999
Model: Cherokee
Engine: 4.0
You could go with a Eaton e locker for the D30 or the OX both work without air the e locker is electric. Either of those with a LSD in the rear would work fine for off road use.
I run 33 & 35" tires with a 4.56 gear and works fine but the 4.88 may be a better choice for CO. in the mountains with long steep grades on the highways.
Thanks for all of the opinions brought to the table I'm open to other suggestions, if anyone has any other recommendations what they have ran/used.
#10
CF Veteran
Join Date: Jan 2012
Location: Ocean County, NJ
Posts: 2,208
Likes: 0
Received 3 Likes
on
3 Posts
Year: 1998
Model: Cherokee
Engine: 4.0L
Really ?? Do you run your radio loud maybe ??
I've had 4 axles (2 - d35's, and 2 - 9 1/4's) now with lunchbox style lockers in them, and I have heard every one of them ratchet.
I've also heard them ratchet in D44's & other axles when I was standing by them when they turned.
And it should not scrub the tires.....unless something is wrong. The only tire that can 'scrub' is the outside tire, and it should be free spinning when turning unless under power.
I've had 4 axles (2 - d35's, and 2 - 9 1/4's) now with lunchbox style lockers in them, and I have heard every one of them ratchet.
I've also heard them ratchet in D44's & other axles when I was standing by them when they turned.
And it should not scrub the tires.....unless something is wrong. The only tire that can 'scrub' is the outside tire, and it should be free spinning when turning unless under power.
but yeah I drive with noise cancelling headphones on.... I'll clarify. When in 4wd, the front diff will not unlock even when turning. It acts more like a spool and forces both tires to turn at the same speed which causes the scrubbing.
in 2wd the locker does open and I can hear it ratchet on tighter turns than anything.
And since the inside tire turns slower than the outside tire, it would be the inside tire that is unlocked/free-spinning, not the outside boss man.
Last edited by Jeepin'_Aint_EZ; 09-29-2016 at 04:35 PM.
#11
CF Veteran
Join Date: Jan 2016
Location: Newport News, VA
Posts: 1,242
Likes: 0
Received 38 Likes
on
37 Posts
Year: 96 & 88 4 dr Cherokees
First, we are speaking of front differentials, not rears. They act totally different, so if you've never driven one with a locker then you really can't contribute.
but yeah I drive with noise cancelling headphones on.... I'll clarify. When in 4wd, the front diff will not unlock even when turning. It acts more like a spool and forces both tires to turn at the same speed which causes the scrubbing.
in 2wd the locker does open and I can hear it ratchet on tighter turns than anything.
And since the inside tire turns slower than the outside tire, it would be the inside tire that is unlocked/free-spinning, not the outside boss man.
but yeah I drive with noise cancelling headphones on.... I'll clarify. When in 4wd, the front diff will not unlock even when turning. It acts more like a spool and forces both tires to turn at the same speed which causes the scrubbing.
in 2wd the locker does open and I can hear it ratchet on tighter turns than anything.
And since the inside tire turns slower than the outside tire, it would be the inside tire that is unlocked/free-spinning, not the outside boss man.
I know what axle you were talking about. An axle is an axle...on every vehicle I have owned (and at 52, that's been quite a few), they work the same as far as basic function front or rear....which is what is being discussed. Some things are different due to the different axle shaft lengths and steering parts, but as far as a locker, nah. Power form the engine lock sit up....power from the ground due to different wheel speeds when turning unlocks it.
Noise cancelling headphones.....money, money, money.........I meant with your radio so loud you can't hear......like most people these days.
Boss Man huh.....well, dude....the Boss man is correct (read how a locker works, cuz you'll find you are backwards)
So you insist the inside tire is the one that free wheels....well, when the locker unlocks, it is functionally an open differential until it locks up again. In truck with an open rear diff, when turning...which tires spins ?? inside or outside ? Well, it can only spin if it is powered by the engine, and as we all know, it's the inside tire that will spin (except in certain circumstances with very low traction and high power, then both MAY spin). Same with a locker that is unlocked.....the inside tire spins until it locks up again, and that is because it is the one that is powered, and is NOT the one that free wheels.
But I'll also explain how a locker works here for ya....
When driving straight:
Under power, the driveshaft spins the pinion, which spins the ring gear, which spins the carrier.
The carrier spinning also forces the center pin to rotate, and as the center pin rotates, it forces the inner 1/2's of the locker OUT due to the wedge action that is present between the locker pieces & the center pin
The inner locker 1/2's moving out forces the engagement of the inner & outer 1/2's of the locker, and since the outer 1/2's are splined to the shaft, this action also locks the axles together
Now, when you turn.......
The inner & outer wheels/tires will travel different distances in the same amount of time...which means 1 of them has to increase it's rpm...right ??
This rpm increase is due to the OUTER wheel being driven/powered by the ground, NOT the driveshaft anymore
Well, as the OUTER wheel/tire speeds up the inner & outer 1/2's of the locker on that side will spin faster than the carrier & center pin slightly
This slightly faster speed lets the inner 1/2 of the locker on that side only move faster than the center pin and overcome the wedge action & move INWARDS towards the center pin.
Because it is moving faster on that side only, the center pin can not force it out.....giving a slight gap between the inner & outer locker 1/2's
This gap is what allows the inner & outer locker 1/2's to 'slip' over each other...letting the OUTER axle spin faster
THIS is what -
a) gives you the ratcheting noise
b) lets you differentiate when turning
c) lets you chirp the inside tire if you want (can't do that if it's free wheeling)
This would not work if the inner tire/wheel was the one that freewheeled, as that would mean the inner tire/wheel would have to be slowed down by the ground not accelerated....and that would in turn force the inner locker 1/2 into the center pin even harder, since the locker CAN NOT power the faster turning outside shaft without also forcing the locker 1/2's into lockup on the inner axle shaft. It can only power the slower spinning wheel/tire while the faster spinning wheel/tire disengages. It is not physically possible to work the other way.
Now, if your front diff doesn't unlock when turning, something is not set up correctly (likely not the proper clearance). If it was, then the change in wheel speeds that results from turning would unlock the locker, unless both tires are spinning. It may be a more violent unlock due to the added length of the long side axle shaft and the torsional effects the locker puts on them.
.
Last edited by TRCM; 09-29-2016 at 11:40 PM.
#12
Senior Member
Join Date: Feb 2014
Location: Southgate, Michigan
Posts: 793
Likes: 0
Received 2 Likes
on
2 Posts
Year: 1997
Model: Cherokee
Engine: 4.6 I6
I am locked front and rear with auto lockers. When I coast around corners they unlock but if I give it gas the rear will lock in while the front stays unlocked because it is not being driven by the pinion. The whole nature of an auto locker is when being driven by the pinion the locker will stay locked unless you are going around a very sharp corner.
Try going into a parking lot and throw your Jeep in 4 wheel hi. Now try to turn, that front locker didn't unlock did it?
Try going into a parking lot and throw your Jeep in 4 wheel hi. Now try to turn, that front locker didn't unlock did it?
Last edited by shooptube; 09-29-2016 at 10:16 PM.
#13
CF Veteran
Join Date: Jan 2016
Location: Newport News, VA
Posts: 1,242
Likes: 0
Received 38 Likes
on
37 Posts
Year: 96 & 88 4 dr Cherokees
I am locked front and rear with auto lockers. When I coast around corners they unlock but if I give it gas the rear will lock in while the front stays unlocked because it is not being driven by the pinion. The whole nature of an auto locker is when being driven by the pinion the locker will stay locked unless you are going around a very sharp corner.
Try going into a parking lot and throw your Jeep in 4 wheel hi. Now try to turn, that front locker didn't unlock did it?
Try going into a parking lot and throw your Jeep in 4 wheel hi. Now try to turn, that front locker didn't unlock did it?
If you give any locker, front or rear, enough gas to lock up, they will spin/power both axles equally assuming nothing is broken. There are other situations that will cause it to unlock, even under power...like different size tires, or ANY turn...not just a sharp one. You just normally don't hear or feel it under shallow turns at power due to road & engine noise.
I also know from experience, that if the clearances in the locker aren't within spec, it can not lock up, or not unlock.... properly. The gaps needed to allow the teeth to over run during disengagement must be within spec, or the locker won't work correctly. Mine was too tight & it wouldn't let the teeth fully disengage, and it would not unlock correctly.
For it to NOT unlock/disengage whenever you turn, sharp or shallow, under power or not, you would have to have one of a few things happen:
1) locker breaks
2) axle shaft breaks
3) center pin breaks
4) tire slips
You simply can not have hard metal parts spinning at different speeds like occurs when turning be completely locked together....not physically possible without breakage....that's why they designed them to disengage to let the difference in speeds occur when needed...and it happens a LOT more than most of yall realize.
If the distance traveled by the outer tire causes the axle shaft rpm to be higher than the rpm the pinion is spinning the carrier & center pin at, the inner 1/2 of the locker WILL unlock. front or rear axle...don't matter. That is how they are designed. The added axle shaft length of a front axle on the long side will delay the lock/unlock slightly since that shaft will twist a bit more before locking/unlocking (mainly unlock tho). Also, due the the ability to turn the front wheels, the rpm difference on the axle shafts isn't always as big as it would be on a rear axle...but the difference is still there.
On my rig, if I raise engine speed by more than 100 rpm, I am either finishing the turn faster than I can straighten the wheel back up, or I am spinning/chirping the inside tire.
If I make a turn with the inside tire on a 10' diameter circle ....the inside tire will have to roll 7.85' to make a 90 deg turn......but the outside tire will have to roll 11.8' in the same time (it's a 15' diameter or 10' plus the 60" axle length). So.....my inside tire would have to do ~ 1 rev to travel the distance, while the outside tire would have to do 1.5 revs...so the outside tire would have to spin faster by ~50% for the duration of the turn, which is definitely more than enough to unlock the locker quickly. So the whole circle would require 3.9 revs of the inside tire, and 5.8 revs of the outside tire.
It only takes a difference in rpm, not a set #, but the higher the difference, the easier & faster it unlocks. Think hard u-turn vs a gradual turn on the highway. Also remember, if the outside shaft is turning faster, but only by maybe a fraction of an rpm, like in a long slow turn on the highway, each revolution will add up, and it will eventually unlock if you stay in the turn long enough without accelerating.
10' diam = 3.14*10= 31.4, then divide by 4 to get 90 deg, gives you 7.85'
15' diameter (10' plus wheel to wheel distance or 5') = 3.14*15, which gives you 47.1, divided by 4 gets you 11.775'
31" tire circumference = (31"*3.14)/12= 8.112' per revolution
.
Last edited by TRCM; 09-30-2016 at 06:15 AM.
#14
Senior Member
Join Date: Oct 2011
Location: St. Albert
Posts: 731
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1989
Model: Cherokee
Engine: 4.0L I6
First of all... you shouldn't be having to figure out whether or not a lunchbox unlocks when turning in 4x4, because 4x4 isn't designed to be used on the street anyways, which is where you would notice tire scrub.
Secondly, if you're turning in 4x4 with the front and rear axle speeds locked in rotation speed by the xfer case, the lunch box WILL NOT unlock when you're turning. This is because the TOTAL distance both front tires has to travel in a turn is greater than the total distance the rear tires have to travel. Due to this difference, there will be tension or torque on the driveshafts, which as we all know is what keeps the locker engaged, and causes the tires to scrub if you were to do this on the street in 4x4. Just because the torque isn't caused by the engine doesn't mean it is not torque. And that's just science.
Secondly, if you're turning in 4x4 with the front and rear axle speeds locked in rotation speed by the xfer case, the lunch box WILL NOT unlock when you're turning. This is because the TOTAL distance both front tires has to travel in a turn is greater than the total distance the rear tires have to travel. Due to this difference, there will be tension or torque on the driveshafts, which as we all know is what keeps the locker engaged, and causes the tires to scrub if you were to do this on the street in 4x4. Just because the torque isn't caused by the engine doesn't mean it is not torque. And that's just science.
#15
CF Veteran
Join Date: Jan 2016
Location: Newport News, VA
Posts: 1,242
Likes: 0
Received 38 Likes
on
37 Posts
Year: 96 & 88 4 dr Cherokees
First of all... you shouldn't be having to figure out whether or not a lunchbox unlocks when turning in 4x4, because 4x4 isn't designed to be used on the street anyways, which is where you would notice tire scrub.
Secondly, if you're turning in 4x4 with the front and rear axle speeds locked in rotation speed by the xfer case, the lunch box WILL NOT unlock when you're turning. This is because the TOTAL distance both front tires has to travel in a turn is greater than the total distance the rear tires have to travel. Due to this difference, there will be tension or torque on the driveshafts, which as we all know is what keeps the locker engaged, and causes the tires to scrub if you were to do this on the street in 4x4. Just because the torque isn't caused by the engine doesn't mean it is not torque. And that's just science.
Secondly, if you're turning in 4x4 with the front and rear axle speeds locked in rotation speed by the xfer case, the lunch box WILL NOT unlock when you're turning. This is because the TOTAL distance both front tires has to travel in a turn is greater than the total distance the rear tires have to travel. Due to this difference, there will be tension or torque on the driveshafts, which as we all know is what keeps the locker engaged, and causes the tires to scrub if you were to do this on the street in 4x4. Just because the torque isn't caused by the engine doesn't mean it is not torque. And that's just science.
Well everything I said above is science too. And if you look at the parts, and understand correctly how they work, then you will see as well.
The locker staying locked has nothing to do with the transfer case...it has to do with the rotational speed differences between the locker parts & the center pin. The forces from the engine or ground are what change this relationship by changing the force with which the parts are driven.
The difference in distance traveled between the front & rear tires has no bearing on the lockers staying engaged.....it does have a bearing on the t-case as most 4wds have different gearing in the front & rear axles, and this can quickly bind up and cause this scuffing you talk of.
The front locker being locked or not is only affected by the front tires and the front pinion rotation. The rear locker only has to do with the rear tires & pinion. The difference front to rear means nothing to the lockers, but it can bind a t-case up.
If you are driving along in 4wd, with both lockers locked, and your t-case suddenly binds up.....BOTH lockers will unlock, since the tires are no longer being driven by the driveshaft, but are now being driven by the ground, which means the locker 1/2's are spinning faster than the center pin, and will move & unlock.
I had a brake issue once, where the drivers side rear drums basically didn't work. I got pissed off and stomped on the brakes hard enough to stop the driveshaft spinning. When I did, the driveshaft stopped rotating, and the passengers side wheel started to slide in the mud since the brakes on that side locked up the wheel. But the drivers side just kept rolling along with the ground as I slowed down.....and the locker was unlocking/ratcheting the whole time because the center pin was not moving, but the ground was spinning/driving the tire/axle & locker pieces. I guarantee you there was torque/tension on that driveshaft, but it didn't matter.....the center pin wasn't rotating, but the drivers side axle was...so it unlocked.
No matter what you may think.....any time the locker inner 1/2 is spinning faster than the center pin, it WILL slide towards the center pin and unlock....and it doesn't matter if you are in 4wd, 2wd, on the highway going straight, or making a u-turn in a parking lot.
Yes, there is torque present, and that is why sometimes the locker will unlock violently...but it WILL still unlock. And the torque/tension you mention on the driveshaft has no bearing on any of it unless the driveshaft is rotating the pinion. And that torque not produced by the engine is what speeds up the axle and allows the locker to unlock while turning.
What keeps it locked is the center pin pushing both inner 1/2's out.....and any speed difference caused by a difference in distance traveled by 1 tire over another, will let 1 of the inner 1/2's move towards the center and unlock.
Like I said above, the locker unlocks way way more often than people realize........and yes, even in 4wd. It's not magic....just simple physics (or science if you will).
.
Last edited by TRCM; 09-30-2016 at 06:04 PM.