I have a 2004 TJ 4.0L with automatic transmission, 4" lift & 33" tires. I will mainly be using the Jeep for running forest trails in west central Minnesota. Very little highway miles. What would be the best options to equip my differentials for this application, they are Dana 30 in the front and Dana 35 in the rear. Also I would assume I should upgrade axles as well. Thanks for any help.
Suggestions for differential locker or limited slip
- Thread starter Turf
- Start date
I’m not sure of the terrain on those forest trails. My thought is a lunchbox locker up front would be sufficient for anything you encounter. As long as you stay on 33’s I think your Dana 30 and Dana 35 would be fine. Might check with @Tj04, as I think he’s in those parts and could chime in.
If you go for a full locker, I like the Eaton E-locker because it is selectable, simple and reliable. I like the Detroit for a non-selectable, because it’s simple and reliable. ARB is good too, I just don’t want to do all the air on board stuff.
If you go for a full locker, I like the Eaton E-locker because it is selectable, simple and reliable. I like the Detroit for a non-selectable, because it’s simple and reliable. ARB is good too, I just don’t want to do all the air on board stuff.
Firstly, do not add a locker to rear on stock shafts. With up to moderate wheelin on 33's, a locker and 27 spline alloy axles will work. If going for more hard core stuff, a Super 35 kit with whatever locker you like will work.
The Dana 30 works well on stock shafts with 5-760 ujoints and a lunchbox locker, eg Aussie, No Slip, etc. If do harder stuff adding alloy axles would be a wise choice.
The Dana 30 works well on stock shafts with 5-760 ujoints and a lunchbox locker, eg Aussie, No Slip, etc. If do harder stuff adding alloy axles would be a wise choice.
1999tj
Member
I'm in the same dilemma here. So, go with a Detroit Trutrack on the rear, but staying stock up front on the Dana 30 is probably ok for standard off road stuff?
I appreciate the replies. I should also mention I will be going with 4:88 gears. I am not apposed to upgrading to the rear super 35 if you all feel a rear locker is the way to go. Thanks again.
Yes, it should be. I wheel some pretty difficult stuff and no lockers front or rear. If you get serious you could blow the Detroit Trutrack on a Dana 35. The Dana 30 is stronger and that's where I'd put a lunchbox locker if it was in my build plans, which it may be, just not decided yet.
If you are going to have one diff fully locked, the one to lock is the rear.
If you are going to do a lunchbox, I say put it on the front.
Since you're in Minnesota where it gets very icy with lots of snow, correctly choosing between a locker and limited slip differential becomes especially important. Automatic lockers like lunchbox lockers and Detroit Lockers can be a real handful on roads or offroad trails that are slick from ice or snow. Automatic lockers which cannot be turned off with a switch are not a good choice for those conditions. Selectable lockers are a better choice for those types of conditions... they allow you to turn the locker(s) off when it's too slick from ice/snow for a conventional automatic locker.
If you want to wheel on icy/snow-covered trails and use 4x4 on the streets in the dead of winter and the road conditions are terrible as they can get there, I'd go with a Detroit Truetrac limited slip differential in the rear. LSDs were made for such conditions and are more effective and easier to drive with when the roads are slick from ice or snow. Perhaps up front too. You would not need to upgrade the rear axle for 33's and a Detroit Truetrac LSD like you would with a locker.
So is your Jeep strictly a fair-weather wheeler you put away for the winter? Or do you need to get out on the streets and use 4x4 when the snow and ice conditions are bad?
If you want to wheel on icy/snow-covered trails and use 4x4 on the streets in the dead of winter and the road conditions are terrible as they can get there, I'd go with a Detroit Truetrac limited slip differential in the rear. LSDs were made for such conditions and are more effective and easier to drive with when the roads are slick from ice or snow. Perhaps up front too. You would not need to upgrade the rear axle for 33's and a Detroit Truetrac LSD like you would with a locker.
So is your Jeep strictly a fair-weather wheeler you put away for the winter? Or do you need to get out on the streets and use 4x4 when the snow and ice conditions are bad?
It for the most part just for trail running and hunting, will not be driven in the winter. With that info what would you recommend. Also I will be changing gears so whatever I need to do I should do at that time.
I don't know how uneven the trails are you'll be on but if they're not uneven enough to be regularly lifting tires off the ground, I'd go for a Detroit Truetrac in the rear and a lunchbox locker up front. An Aussie lunchbox locker would be great. Most lunchbox lockers slightly click/ratchet when you make turns in 2wd so if you don't want any clicking, spend $100 more to get the No-Slip lunchbox locker instead of the Aussie. The No-Slip is pretty much unnoticeable in 2wd, it only locks up when you shift into 4Hi or 4Lo.
For your 33" tires, I'd go with 4.88 or 5.13 gearing. While 4.88 or 5.13 may seem like too low of an axle ratio (too high numerically), it's the right choice when you have the 4-speed 42RLE automatic transmission you have. The 42RLE lowers cruising rpms much lower than most transmissions do making lugging of the engine common unless the axles are geared with a slightly lower ratio. 4.56 would be a bad choice, don't let some yahoo at a 4x4 shop who doesn't know about your particular transmission's traits talk you into 4.56 or 4.10. You'd hate either of those ratios. Actually, more and more people are going 5.13 with 33's and the 42RLE automatic transmission as you have. Highway rpms would be fine with either ratio. Personally I'd go with 5.13 which will be fine on the highway, nope it will not cause excessively high engine rpms. Yep that ratio would indeed cause excessively high engine rpms with other transmissions like the 5-speed or 3-speed automatic, but not with your 4-speed automatic.
I don't know how uneven the trails are you'll be on but if they're not uneven enough to be regularly lifting tires off the ground, I'd go for a Detroit Truetrac in the rear and a lunchbox locker up front. An Aussie lunchbox locker would be great. Most lunchbox lockers slightly click/ratchet when you make turns in 2wd so if you don't want any clicking, spend $100 more to get the No-Slip lunchbox locker instead of the Aussie. The No-Slip is pretty much unnoticeable in 2wd, it only locks up when you shift into 4Hi or 4Lo.
For your 33" tires, I'd go with 4.88 or 5.13 gearing. While 4.88 or 5.13 may seem like too low of an axle ratio (too high numerically), it's the right choice when you have the 4-speed 42RLE automatic transmission you have. The 42RLE lowers cruising rpms much lower than most transmissions do making lugging of the engine common unless the axles are geared with a slightly lower ratio. 4.56 would be a bad choice, don't let some yahoo at a 4x4 shop who doesn't know about your particular transmission's traits talk you into 4.56 or 4.10. You'd hate either of those ratios. Actually, more and more people are going 5.13 with 33's and the 42RLE automatic transmission as you have. Highway rpms would be fine with either ratio. Personally I'd go with 5.13 which will be fine on the highway, nope it will not cause excessively high engine rpms. Yep that ratio would indeed cause excessively high engine rpms with other transmissions like the 5-speed or 3-speed automatic, but not with your 4-speed automatic.
Jerry,
I really appreciate your detailed info. The trails I run are not to uneven, they are mainly old logging roads. I feel you have given me enough information to move forward. I will do exactly as you suggested. Just to verify you feel I should do the Truetrtac LSD in the rear differential ?.
Thanks
Greg
That's what I'd do Greg. You won't even notice its presence on the street. I used to have front and rear Detroit Truetracs many years ago and they were invisible on the street, no quirks at all.
They're entirely different. I only mentioned I used to have f/r Detroit Truetracs (many years ago) when describing you can't tell they're there.
The No-Slip lunchbox locker is a more aggressive device, being a true locker and all that. That will only become a locked device when you're in 4x4 when offroad, you won't notice its presence on the street when you're in 2wd. Having that locker up front (in addition to the rear Detroit Truetrac) will make your Jeep nearly unstoppable on tougher offroad terrain. Think of that combination as having the best of both types of devices, lockers and limited slip differentials.
Jerry,
So you are recommending the no slip lunch box up front and the Truetrac LSD in the rear withe 5.13 gears ? Can I stay with the stock rear 27 spline axles or should I go to the 27 spline alloy axles unless you recommend going to 30 spline axles. Just trying to clarify all the information that has been shared.
Greg
@Turf, sounds like we use ours in the same kind of terrain; trails, back country hunting stuff. I have found the Truetrac and Aussie combo are working out fantastic. I have even done some tougher stuff, off camber, etc and it works great.
The 27 spline shafts with 33's and TT should work fine. Adding some 27 spline alloy shafts would add some peace of mind. The TT only comes in 27 spline.
I have run the No Slip previously and the Aussie currently. The NS will be quiet, the Aussie has a light "tick" while turning in 2 wheel, which isn't enough for me to say the extra 100 for the NS is worth it. Either will work great.
5.13's will work real nice with your combination.
The 27 spline shafts with 33's and TT should work fine. Adding some 27 spline alloy shafts would add some peace of mind. The TT only comes in 27 spline.
I have run the No Slip previously and the Aussie currently. The NS will be quiet, the Aussie has a light "tick" while turning in 2 wheel, which isn't enough for me to say the extra 100 for the NS is worth it. Either will work great.
5.13's will work real nice with your combination.
Lots of great posts in this thread. I followed Jerry's advice years ago, did the lunchbox locker in the Dana 30 and the Detroit Truetrac in the original Dana 35 and then again when I upgraded to a Dana 44. I'm on 35's with a 5.5" lift and I was able to drive 4 hours to the Rubicon Trail, run the whole thing, and then drive back home with zero damage or mechanical issues.
Depending whether you intend to do your own work or not and how long you intend to keep your Jeep, this may also be the right time to swap out the infamous Dana 35 rear axle. If I knew then what I know now, I would've first tried to find a used Dana 44 on craigslist for about a grand (or less) and only then spend the money for the Trueurac and installation. You probably won't absolutely "need" to swap out the Dana 35 for the wheeling you currently do but it's a well known weak point of the TJ and I personally feel like I made a mistake putting any money into the Dana 35. I definitely wasn't going to do the Rubicon Trail with a Dana 35 but in reality they're known to break on much easier stuff too. The peace of mind after the Dana 44 upgrade was well worth it for me... ymmv
Depending whether you intend to do your own work or not and how long you intend to keep your Jeep, this may also be the right time to swap out the infamous Dana 35 rear axle. If I knew then what I know now, I would've first tried to find a used Dana 44 on craigslist for about a grand (or less) and only then spend the money for the Trueurac and installation. You probably won't absolutely "need" to swap out the Dana 35 for the wheeling you currently do but it's a well known weak point of the TJ and I personally feel like I made a mistake putting any money into the Dana 35. I definitely wasn't going to do the Rubicon Trail with a Dana 35 but in reality they're known to break on much easier stuff too. The peace of mind after the Dana 44 upgrade was well worth it for me... ymmv
Sunder
TJ Enthusiast
Truetrac LSD in the rear is a good choice. Great for winter, and because they don't fully "lock", it will be less prone to breaking a 27 spline rear axle. (less prone than a locker, but more prone than an open diff)
As for the front - you live in Minnesota...so I would NOT recommend an automatic locker. (lunch box). Nope.
The lunch box works great for people who do not drive in the snow. But a lunch box locker can be unpredictable and dangerous in snow or ice. (You can be driving along nicely, then be immediately turned around 180' due to the auto locker deciding to engage on it's own).
In the summer, it will be awesome...but in winter...it will be fine for "most" of the time, until the one time it spins you off into ongoing traffic. If you do put a lunch box up front, do not engage 4x4 in winter on the streets or highway.
For the front, I'd recommend either a selectable locker, another TrueTrac up front, or keep it as an open diff.
I personally have a TrueTrac in my rear, and will have a TrueTrac in my front by tomorrow (I hope). I also live north of you.
The Detroit TrueTrac (not to be confused with the Detroit locker), is a LSD, and therefore works nicer in snow or on ice than an auto "locker".
The selectable locker is good up front because YOU decide when it's locked or unlocked. It can provide arguably superior traction when engaged and 4x4'ing and driving straight, but you can lose traction (laterally) and have difficulty steering.
An open diff isn't going to help you much when 4x4ing (what you have right now), but is not going to do anything unpredictable in snow or ice.
I chose a TrueTrac up front over a selectable locker because of a few reasons:
1. price
2. reliability (some people have issues with moisture freezing the air compressor lines. The TrueTrac does not have that issue - it doesn't even have clutch packs to wear out. It's just always going to work.)
3. it's (arguably) better in snow/ice, especially if steering in tight trails.
4. My Jeep is my daily driver.
As I've never 4x4'd with it yet (I plan to this Sunday), I cannot comment if I made the right choice or not. But that was my reasoning vs a selectable up front.
I'd also say that a 5.13 gear on a Dana 35 is a really small pinion. That might be too low for that axle combo in some people's opinions, but I can't say for sure.