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Swapping 4.10 Gears into a Jeep CJ-7 Dana 30 Front Axle


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I have an 82 cj with a dana 30 low pinion with 2:73 gears. I want to put 4:10 gears in it. Can I use a carrier and ring and pinion from a TJ wrangler or 2000-2001 XJ Cherokee mentioned in the dana 30 rebuild how to. I'm sure my pinion is long. I'm not sure if they are in the models mentioned above. Any help would be appreciated.

 

Thanks,

 

Mike

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Mike, I've swapped a lot of parts back and forth, but I CAN't specifically answer you without error. I suggest you go to Quadratec or another parts source and chase down the parts overlap in their "Replacement Parts' sections. It Seems that the exchangeability of various parts for CJ-YJ-TJ Dana 30's is sporadic, but possible. I don't have all the data you have regarding the parts you started with and the parts you have access to, but YOU DO. I do not believe that the internal dimensions of the Dana changed over those years, so matching carrier and gears should swap in provided you have the right end clearance (shims) worked out for seating the carrier, You will need to verify the oil slinger and interchangeability of the yoke though, at least.

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Aside from outer wheel hub designs, the primary difference between Dana 30 axles is "high pinion" versus "low pinion".  The CJ is a standard rotation ring-and-pinion with a low pinion.  Other Dana 30s can be standard or the "reverse rotation" gear sets.

 

Another concern is the differential carrier, which you hinted about.  The carriers will only work for certain ratios.  On the CJ-7 Dana 30 front axle, the ratio break is between 3.54:1 and 3.73:1.  From what you share (2.73 gears, wow that is tall!), you currently have the carrier for up to 3.54:1.  If you go to 4.10 gears, you will need the 3.73 and up carrier.  I found a new Spicer bare carrier listed for $65 at one site, a genuine part, sounded like a reasonable price.  I'll provide a link if useful.  There are also aftermarket locking differentials like the ARB, taking care of the diff case at the same time.  I prefer a manual locker, if any locker at all, in the front axle.

 

I'll research this further, there's a tremendous amount of misinformation floating around in aftermarket parts catalogs.  I thought a quick answer was available by supplying parts outlet links, only to find three vendors with completely different breakouts for the CJ, XJ, YJ and TJ models!  Expect more details...

 

Moses

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Here's one supplier's quick overview...I'll look into this further, there are shim and crush-sleeve distinctions that require explanation, high and low pinion and so forth.  Many years of Jeep models left out.  This looks very generalized, a partial list at best...Maybe a place to start?  Expect my update...Moses

 

Jeep Dana 30 Diff Applications Include: [presumed to be "standard rotation"]
  • Jeep CJ Front - (72-86)
  • Jeep TJ Front - (97-Present)
  • Jeep Liberty Front - (01-Present)
  • Jeep ZJ - (96.5-Pres.)
  • Jeep WJ - (96.5-Present)
  • Jeep Jeepster Front - (72-73)
  • Jeep Wagoneer Front - (72-73)
  • Please call for all other Jeep Dana 30 applications.
  • Also Fits:
  • Eagle Front (80-87.5)
  • Aerostar Front (85-89)
  • Jeep Bronco Front (67-71)
  • International Scout Front (68-75)
Jeep Dana 30 Reverse Diff Applications Include:
  • Jeep XJ - (87-99)
  • Jeep YJ - (87-96)
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Thanks for the info so far. I was aware of needing the carrier which is for the 3:73 and lower ratios. Just didn't know if the ring gear was a different size or if the pinion was long or short in these other models. Looking forward to more info though. Thanks again.

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Here's a tidbit...I followed Gutthans suggestion and did a quick check at Quadratec.  (They've sold my Jeep books over the years and deserve a worthy plug!)  I pulled the Quadratec part number for the '72-'86 CJ model Dana 30 front axle ring-and-pinion with 4.10 gear ratio: Quadratec #52440.1012.

 

When I put this number in the site's search bar, the only reference that came up was the '72-'86 CJ application.  This could just be the parts numbering system at Quadratec, or it could indicate that '72-'86 is the only year range of Dana 30s that we can say with certainty will fit your front axle.

 

I would suggest taking a sampling of Quadratec's R&P gear set part numbers from the years and applications you inquired about.  See if there is any other part/set for a 4.10 ring-and-pinion that matches the '72-'86 application.

 

I'll compare Mopar factory part numbers for Dana 30 R&P gear sets from the CJ-7 era and up.  We'll start with the ring gear and pinion shaft, as these parts are machined for correct pinion length and depth, bearing locations, pinion spline type, ring gear fit to the carrier, pinion bearing preload method (crush sleeve or shims, which determines the machining on the pinion shaft) and the yoke flange seal design.  I emphasize each of these issues, as they would be on the check list when examining parts other than specific '72-'86 Jeep CJ Dana 30 replacement parts.  Any attempt to use parts from another application would need to take these machining issues into account.  Standard versus reverse rotation gear cuts remain important, too.

 

On a lesser note, axle shaft spline count plays a role with the differential carrier flange design and axle shaft bore sizing.  That's a carrier concern.  Overall, though, the best place to start is simply with the ring-and-pinion gear set interchangeability.

 

Moses

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  • 7 years later...

Ive also got an 80’ cj5 with 3:54’s. 
i want 4:10’s.  Im having a heck of a time finding whole gear sets. Or sets and bearing kits. I know i need 3:73 up carriers etc. i know the rear is the amc 20, and from what i can find it will hold a 4:10 ring and pinion without changing the carrier? And as for the front, my buddy is taking the 4:10’s out of his YJ and im hoping his ring and pinion will work and all i have to buy is a carrier. 

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Trentwood...YJ gears are reverse rotation (high pinion) design.  You have a low pinion axle housing in the CJ.  You need to use gears for a Dana 30 low pinion housing.  As you note, the carrier must be the 3.73-up design.

A quick search turned up low-pinion 4.10 ratio gears:

https://www.morris4x4center.com/svl-spicer-front-dana-30-ring-pinion-set-4-10-ratio-low-pinion-spc-2020819.html

The full installation kit (bearings, pinion nut, ring gear bolts, seal, etc.) is:

https://www.morris4x4center.com/master-overhaul-kit-dana-30-front-all-352065.html

Based upon the illustration, you'd still need to buy the inner axle shaft seals, not expensive, but at this price point, they should be included.  You may be able to price shop this master overhaul kit.  It does include enough parts to service either a crush sleeve or non-crush sleeve front Dana 30 axle, which does bump up the price.  Your axle does not use the crush sleeve;  pinion bearing preload is set with shims.  Note that this kit shows all the shims for the various Dana 30 front axles.

Below are some details from my oldest Mopar parts listing (1981), which covers your Dana 30 front axle as well.  The factory "kits" are obsolete, but note that your axle is a non-crush sleeve type that uses shims to adjust the pinion preload.  Note that the actual ratio for the factory "4.10" is not 4.10, it's 4.09:1.  This is common practice when there is a mix of axle manufacturers front and rear. 

It was also once believed that the slight ratio difference front to rear helped resist gear bind in four-wheel-drive.  Moot point, as 4x4 mode should be on loose traction surfaces anyway.  In the day, ratios were sometimes a direct match front-to-rear, at other times (based upon axle sources and manufacturers) they could be "close enough" like 3.73/3.70, 3.54/3.55, etc.  Do the tooth counts and divide pinion count into the ring gear count for an accurate ratio.  A true 4.10:1 is ten pinion teeth to 41 ring gear teeth.

 GEAR PACKAGE, Front Axle Ring and Pinion [Mopar factory illustration #13 "kits" shown below for Dana 30 front axle in a later CJ-5/CJ-7/CJ-8 Scrambler]
J8133063 1 2.72 Ratio
J8132601 1 3.31 Ratio
J8126518 1 3.54 Ratio
J0945345 1 3.73 Ratio
J8126494 1 4.09 Ratio
J8134385 1 4.56 Ratio

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