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Differential Options?

Discussion in 'Intermediate CJ-5/6/7/8' started by aasbra, Jul 30, 2022.

  1. Jul 30, 2022
    aasbra

    aasbra New Member

    Tigard, Oregon
    Joined:
    Jul 25, 2022
    Messages:
    5
    I recently picked up a ‘73 CJ5. Has the stock Dana 30 front (open) and 44 rear (worn out trac loc) with 3.73 gears. 304, t15, Dana 20. 33” tires.

    Hoping to use it for running on trails in the woods, in the sand dunes, could see some snow, and some cruising on pavement. Not a daily driver, but will see some limited street driving. Considering what differentials may serve me best?

    I’ve used the spicer powr lok in the front Dana 44 of an old IH Scout II I had years ago and liked it. I’ve had a Detroit locker in a 9” rear for years in a street/strip muscle car, so I’m familiar with how it works with the noise and clunking when engaging and disengaging/cornering manners. I see a couple companies make a new production Power lock (Nitro for example); how do these compare to the old spicer units like I had prior? Are they good quality and robust? Was considering a power lok or truetrack in the front, and a Detroit locker or powr lok in the rear. Also may consider e lockers, which would give a lot of flexibility, but I like the simplicity of the other options. Thinking I may swap in some lower R&P gears, say 4.27, but wondering if I would I be better of keeping the 3:73 gears and going with the terraalow gear kit in the transfer case? I have a Ford T18 I plan to swap in, which would help for slow speed work on trails.

    I’ve heard some caution against the Detroit in the rear of a short wheelbase CJ, especially in ice or snow. Thoughts of those who have more experience with the CJs? This is my first. Thanks in advance for sharing your experience.
     
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  2. Jul 30, 2022
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Medford Mass USA
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    23,604
    It is possible to rebuild the Trak-Lok. They work pretty well as limited slip when new, and are very well-mannered on pavement. They have a reputation for wearing out, and they can break from impact load. However, if you expect to putt around and don't hammer the axle, it may serve you well.

    Selectable is the premium solution. Nothing will drive as nice on pavement or in ice and snow as an open differential.

    I would look at what's available; Randy's Ring and Pinion is a well known source.
     
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  3. Jul 30, 2022
    Sierra Bum

    Sierra Bum Member

    The High Sierra
    Joined:
    Oct 23, 2017
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    234
    You will hear lots of opinions on this and it really boils down to preference. For the 30 spline Dana 44, and the 27 spline Dana 30 there are many options in lockers and limited slip units. You can even upgrade the Dana 30, to 30 spline. I think it comes down to intended use and budget. If you're looking at lockers and low gears (truck four speed, t-case gears etc), we'll assume your doing some real four wheeling.

    My jeep is both a mountain cruiser and a four wheeling jeep. I run selectable front and rear (ARB Air Lockers), 4:88's and a truck 4 speed (SM420). I really like low gears. A 100:1+ crawl ratio is not too much for me...in fact I'd even go a little lower. But I have an early model cj with an overdrive and I split all the gears. So this is my preference.

    If I were to do it again, I'd run OX lockers with the manual shifters. I dig the simplicity and the mechanical nature of it. The ARB's are strong, mostly reliable and the selectable option is great. However I've had some air leak issues which can be a PITA to sort out ...especially when its internal. Eaton makes e-lockers for these axles as well...people like those too.

    I am a fan of the Power Lok. I had those front and rear for quite a while. They are easy to rebuild and customize clutch pressure. All-around performance is quite good. I cannot speak to the newer units. I only switched to the ARB's because I wanted options. I drive on back-roads in 4WD open-open quite a bit. The ARB's are obviously superior in difficult, technical four-wheeling situations. These selectable lockers are really either totally open or spools...they do not allow for any differentiation like a Detroit or Lock-Rite, or slippage like a limited-slip.

    Budget options include the "lunchbox lockers" which will install into an open carrier. They have a learning curve for street driving like the old Detroit locker and are a bad idea if winter driving on the street (snow & ice) is part of your driving plans.

    What is right for you?... you'll have to explore that. In my mind rock crawling gearing starts around 70:1. If you're not into that then a 60:1 ratio is pretty good for all around four wheel driving. Your dana 20 t-case does not have the option for an OD, so maybe ring & pinion for street use is a bigger consideration. 3.73 - 4.10 and 33's seems to work well.

    Can you set up gears and do the diff work yourself? Axle work is expensive...both parts and labor. Also consider what size tire you want to run as this will ultimately affect everything including effective gearing. So then suspension plays in. 33x12.5x15 is the practical max size without getting into fender trimming, custom suspension, fabrication etc. Its all within reach but it helps to think it though before spending a bunch of money. Many things to consider.
     
    Last edited: Jul 30, 2022
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  4. Jul 30, 2022
    duffer

    duffer Rodent Power

    Bozeman, MT
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    Sep 17, 2009
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    3,721
    Yes, a lot of opinions. I absolutely hated the Detroits in the rear of my 3B. I even gave them two chances. The Powr-Loc was good but came up a little short in the rocks. The B currently sports ARB's on both ends and I would go selectable again.

    I would stick with your 3.73's for the present and go with the TeraLows. The TeraLows are definitely a big improvement, especially so in the D20 with the wimpy 2:1 low range. I think with the TLows and a T18 you will be fine for just about anything and still work reasonably well on the road. As for the 70:1 CR, it depends----- If a pentapanty 3.6 is under the hood, even 76:1 comes up way short. The flip side is if you have a lot of low end grunt (ie a 360/401), IMO, you don't even need 70:1.
     
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  5. Jul 30, 2022
    bigjohn

    bigjohn Member

    Kelso Wa
    Joined:
    Mar 18, 2010
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    921
    I’m a big fan of power loks and true tracs. My 75 has power locks and they’ve been all over. I loved the true trac in the 74 and feel like it was almost better than the power lock at times. The best is being able to seamlessly transition from low traction flexes to turning without binding or pushing through the steers. And street manners are superb. That said neither are lockers. And if you don’t have lots of suspension travel, the tougher trails will be more difficult once tire’s are in low/no traction situations.

    As far as gears, spend some time with both the crawl ratio calculators online and the rpm/speed calculator to figure out the best compromise. 33”s 3.73’s and a 58:1 crawl ratio was awesome for my 75. Now 35’s are a little much.

    Also 4.27 gears are spendy. Just did that last year in my 74. 4.10 or 4.56 are much more price friendly. 4.27 are much less common these days and thus more expensive.
     
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  6. Aug 4, 2022
    jeepdaddy2000

    jeepdaddy2000 Member

    Eagle Point oregon
    Joined:
    Jun 24, 2004
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    805
    Tru trac or powr lok are the best of the "conventional" LS units. The tru trac is seamless and the powr lok is rebuildable and slightly adjustable. I think the powr lok would be a bit sturdier in the front, especially with the bigger tires.
    My distaste for the trac lok knows no bounds.
    E lockers and ARB's are the best of both worlds but retard expensive.

    Sand? where are you?
     
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  7. Aug 4, 2022
    Jw60

    Jw60 WRPD855 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Sedalia MO.
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    I'ld go Tera low and keep the current gears. I've had my spartan lunchbox since spring but so far it's been great Considering the cost and ease of installation.
     
  8. Aug 4, 2022
    colojeepguy

    colojeepguy Colorado Springs

    At the foot of...
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    I just put a lunchbox locker in mine & I despise it. It's great off road but for anything else it's terrible.
    I'll probably spend the $ for an Eaton soon.
     
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  9. Aug 4, 2022
    cayenne

    cayenne Member

    central Texas
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    Dec 24, 2006
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    My input:
    I have a lunchbox in the front and used to have a lunchbox in the rear. Now I have a Eaton E-locker in the rear, but I thought they quit making it?
    I have no problems with front lunchbox and the only downside was it was extremely hard to steer (if not dangerous) with manual steering (but any locker would be).
    I never really liked the lunchbox I used to have in the rear, but got the job done. However, the selectable removed all the negatives of a locker for me.

    For gears: I do not have a terralow, but after all the work that was involved with swapping in a sm465 for the low first gear...the terralow has got to be easier. I am at 86-1, but I rarely use the lowest. I have 5.38s and with my overdrive (when I can get it engaged and it doesn't pop out) I end up with something close to 4.10s, and I still want something higher. I would think with dunes, you want higher?

    I guess my only advice it to be honest with yourself on how you will use it when selecting ratios and lockers. I built it mine for much more aggressive offroading than I actually want to do and that money could have probably been better spent on making it comfortable to cruise in (but my life/family has changed alot over that time).
     
  10. Aug 6, 2022
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
    Joined:
    Sep 23, 2002
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    12,176
    Powerlock or Tru-Track are probably the best of the limited slips as said above. The new Powerlock’s are not as good quality as the originals but seem to work and hold up fine. I’ve had both on the workbench side by side and you can see the quality difference and feel the weight difference. Good used original units are getting harder to find however which is why they are being made by the aftermarket. As said above you can manipulate the clutch packs to tune them to your needs. I have a Tru-Track in the back of my ‘04 Silverado 1/2 ton extended cab and love it. Very seamless. Kind of apples and oranges comparison though. All the customers I’ve installed them for seem to really like them.
    I’ve run Lock-Rites front and rear for probably 25 ish years in my ‘59 CJ-5 and like them but they definitely have handling quirks on pavement and not too fun in ice or hard pack snow. I’m switching to ARB’s during this rebuild.

    Where in Oregon are you? I’m in Clackamas/Happy Valley just south of Portland.
     
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  11. Aug 7, 2022
    aasbra

    aasbra New Member

    Tigard, Oregon
    Joined:
    Jul 25, 2022
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    I’m around the Portland area now. Used to live in Eugene, and grew up riding ATVs and motorcycles on the Oregon Coast. Although not as convenient as it used to be, I’d like to take the Jeep over to the coast occasionally.
     
  12. Aug 8, 2022
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    Sep 23, 2002
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    Nice! BigJohn is in Kelso, WA and meets us for breakfast occasionally (this morning), along with Damon. MB44z (Zack) is in Oregon City, Richard of the original R&P is between Oregon City and Canby and I usually meet him for lunch about once a week. If you’d like to meet up I’m between Clackamas Town Center and Sportsman’s Warehouse off 82nd Ave.
    I’ve spent a lot of time on the Oregon coast. Even have an ORV Host patch for Sand Lake. Been quite a few years though. Went to tons of poker runs in Tillamook State Forest.
     
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  13. Aug 8, 2022
    aasbra

    aasbra New Member

    Tigard, Oregon
    Joined:
    Jul 25, 2022
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    Thanks! I'll send you a private convo to coordinate meeting sometime.
     
  14. Aug 9, 2022
    jeepdaddy2000

    jeepdaddy2000 Member

    Eagle Point oregon
    Joined:
    Jun 24, 2004
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    805
    We are avid sand riders and do a big vacation a couple of times a year. We are older now so have graduated from dirt bikes to quads. Back in the 80's I ran my CJ a couple of times out in the dunes but found the various dribbles and leaks gathered tons of sand.

    That being said, you can run sand with open diffs. The trick is to air down till you get a fat pooch in the sidewall (usually about 10/15 PSI) and drive it like you stole it......

    We're heading over to Riley ranch for ten days in late Aug. Feel free to come out and break some parts:beer:
     
  15. Aug 9, 2022
    aasbra

    aasbra New Member

    Tigard, Oregon
    Joined:
    Jul 25, 2022
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    Yes, the sand does stick to everything with grease and oil on it, and dropping the air pressure on your tires is key. As a kid, I remember seeing lots of people trying to drive their 4WD vehicles out of the paved parking lot into the OHV riding area only to find they were leaving huge ruts and getting stuck real quick. Once they figured out the key of dropping air pressure, and carrying a bit of momentum (don't try to stop and then start out again on a hill) they did much better. And don't nose the truck down into a spot you can't drive out of. I remember trying to help quite a few people who ventured to places that they couldn't get back out of. Much easier to get around on an ATV or even a dirt bike, than a big truck that is not equipped for where you are trying to go.

    Thanks for the invite to tag along later this month. You are heading over the mountains to Riley? That should be fun. I need to do some more work to get the CJ road and trail worthy. Until I picked it up a month or two ago from its prior owner of the last 20-25 years, it has been sitting for the better part of the last 10. So it needs a little TLC, and probably a few upgrades, before I would trust it out on the trails. But another time....it is pretty country over there!
     
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