Narrowing A Differential

Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member
Im starting this thread, basically due to a call I got from a friend with a Pontiac firebird,
who succeeded in shredding his 10 bolt differential once he installed some decent slicks on the car.
hes now looking to upgrade his differential,
after seeing the result of added traction on his Pontiac

http://garage.grumpysperformance.com/index.php?threads/big-block-vs-10-bolt.4525/#post-37599

http://garage.grumpysperformance.co...ck-butt-pontiac-engine-combo.1472/#post-48277

http://garage.grumpysperformance.co...a-camaro-or-firebird-to-bite.4067/#post-10821

http://garage.grumpysperformance.co...ing-a-dana-60-to-disc-brakes.5083/#post-25173

now I've had this done for me a few times, and yes, using a dana 60 differential,
I got from a salvage yard in all cases, adding disc brakes in the process is a great idea
and then ordering the required custom axles and new differential gears,
after measuring the narrowed differential,
but I always felt more confident in having the work done by someone,
with decades of previous experience and access to the tools required.
and a good reputation for doing the job correctly

if you visit the local tracks and ask the guys with the faster cars,
(generally, the cars consistently running, 10 seconds and faster)
You're almost sure to get some info on the shops that have the tools and skills required.
keep in mind you'll need to have very accurate measurements for centering the differential pinion gear in the trans tunnel,
and locating spring seat locations, this almost always results in the two sides
or axles not being identical lengths


related threads
http://garage.grumpysperformance.co...ear-axles-and-differentials.11848/#post-98649

http://garage.grumpysperformance.com/index.php?threads/dana-60-all-the-same.12306/page-3#post-96227

http://garage.grumpysperformance.co...erential-spring-mount-issue.12104/#post-58114

http://garage.grumpysperformance.co...-60-rear-in-a-big-block-vette.667/#post-41879

http://garage.grumpysperformance.co...ifferentials-available.1282/page-2#post-56082

https://www.fourwheeler.com/how-to/154-0708-weakest-to-strongest-axles/

http://garage.grumpysperformance.com/index.php?threads/rear-differential-id.398/#post-5487






 
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https://www.doctordiff.com/strange-60.html



https://www.strangeengineering.net/product/s60-with-ends-and-leaf-spring-mounts.html/

yes you may not have a local shop that has the skills and tools
there are several shops that sell custom made differentials

a correctly built , high compression BBC , set up with a suspension that gets good traction and a set of decent race tires/slicks, add a few dozen hard launches at 2000 plus rpms, and that can rapidly turn a 10 or 12 bolt differential into scrap in my experience, where a DANA 60 or a properly set up 9" ford can shrug off the torque impact loads
 
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http://garage.grumpysperformance.co...strongest-rears-differentials-available.1282/

http://www.moserengineering.com/com...-dana-60-built-to-order-rear-end-package.html

http://garage.grumpysperformance.co...ing-a-dana-60-to-disc-brakes.5083/#post-25173

http://garage.grumpysperformance.co...fferentials-and-related-info.1261/#post-10180

http://garage.grumpysperformance.com/index.php?threads/narrowing-a-rear-differential.1934/#post-5126

http://garage.grumpysperformance.com/index.php?threads/the-dana-60-rear-differential.1035/



You can find a passenger-type Dana 60 in one of these donor cars if equipped with 426 or 440 engines:
o 1966 Dodge Coronet and Charger, Plymouth Belvedere and Satellite
o 1967-'72 Charger, Super Bee, R/T, GTX and Road Runner
o 1970-'71 'Cuda and Challenger

The industrial-type axles can be found in any of these truck applications:
o 1969-'88 Jeep J-20, J-2000 and J-4000 pickups
o 1967-'77 Chevrolet and GMC 3/4-ton pickups
o 1975-'87 Chevrolet and GMC 1-ton pickups and Suburbans
o 1979-'91 Chevrolet and GMC 1-ton vans with dual rear wheels
o 1955-'99 Dodge 3/4-ton pickups
o 1993-'01 Dodge 3/4-ton vans
o 1955-'93 Dodge 1-ton pickups
o 1955-'85 Ford 3/4-ton pickups
o 1980-'98 Ford E200/E250 vans with single rear wheels
o 1955-'76 Ford 1-ton trucks

These differentials came in two basic designs. The passenger-car configuration included a three-hole mounting surface on the front of the housing to mount a pinion snubber, which keeps the rear end in proper alignment with the drivetrain under heavy torque. The industrial version was used in all truck applications and does not have this mounting surface. Because most of the industrial rear end housings are built for trucks, they tend to be too wide for most passenger cars, but the Dana 60 can be narrowed by cutting the axle tubes to the proper length and installing the passenger car-style end hubs. New passenger- and industrial-style hubs can be purchased, and aftermarket axles are also available in 30- or 35-spline varieties to fit any reduced lengths. New axles may be your best option for adapting an industrial axle to fit a passenger car. Although the B-body Mopars used a five-lug bolt pattern, most industrial-style truck axles used a six-lug or an eight-lug axle, which will be difficult to redrill to a five-bolt pattern.

The passenger car version of the Dana 60 came equipped with the Mopar "Powr-Lok" semi-float limited-slip differential option from 1966 to '69. The Powr-Lok differential used 30-spline axles. Pinion input splines on the Powr-Lok differentials were 10-spline by 1-5/8-inch diameter. Later years featured the rod and cone-type semi-float limited-slip positraction configuration, commonly referred to as "Trac-Lok," and a 29-spline by 1-5/8-inch pinion shaft and 35-spline axles. The passenger car axles shared common components with the Mopar 8-3/4-inch rear end we featured in an earlier column. The axle bearings, seals and retainer packages are interchangeable. Because the Dana 60 axles on the passenger side are always slightly shorter than the driver's side, the 8-3/4-inch axles will not interchange directly into the Dana 60. The replacement pinion yokes for the Trac-Lok differentials (Spicer number 3-4-5731X) are 29-spline and accept the larger Spicer 1350 series (part number 5-178X) U-joints. The advantage of using the GM-style 1350 series U-joints is that you can also use the heavier U-bolt retainers for the end caps, instead of the flat straps that were used on the original Detroit 7290-style U-joints. The pinion yokes for the pre-'69 differentials are only available in the original 10-splines for the Detroit-style joints (Mopar part number P4876804). The industrial axles featured in truck applications can be found in either semi-float or full-float configurations and used a larger axle bearing than the passenger-style rear ends. Possible ratios can range anywhere from 3.54:1 right up to 7.17:1; however, most passenger-car and 3/4-ton truck ratios you will find readily available will be somewhere between 3.54:1 and 4.10:1 (4.10:1 being the largest ratio that can be used without changing to a different carrier). Passenger axles with the pinion snubber-mounting surface are getting very difficult to find and demand a high price tag. The industrial versions are abundant and less expensive, and many aftermarket Dana 60s being offered are remanufactured industrial axles without the snubber mounting.

When scavenging through the aisles at a swap meet or at your local salvage yard, check your donor assembly thoroughly. Although these rear ends are super strong, they do occasionally have problems with spinning the side bearing races inside the housing. The driver's side of the case housing is the best place to check for this wear as this bearing race takes most of the load stress. This problem can be fixed; however, it is time consuming and expensive. It is best to stay away from axles with this condition if possible.

Needless to say, it is important that the donor differential be carefully checked for this kind of wear as well as any other components that can wear over time. You should consider changing the fluids, seals and axle bearings, at a minimum. Aftermarket suppliers have developed an axle-bearing package, which eliminates the need to adjust the end play of the assembly from the outer passenger-side axle flange, as is the case with the Chrysler 8-3/4 inch. The Mopar part number for this package is P5249444. It is very important to remember to keep track of where the shims are removed and how many are removed, when you are disassembling the differential. Shims are located in several places and it will be much easier to put a Dana 60 back together and check clearances if you can get back to where you started from using the same number of shims in the same locations.

As you can see from the list of donor trucks, installing a Dana 60 into any full-size pickup will be relatively straightforward. Most of the vehicles listed will have drum-to-drum axle lengths of between 60 and 68 inches. This also makes them a great candidate for installing in mid-'70s Chrysler B, C, and E-bodies as well as mid-size Fords from 1967-'73 and full-size Fords from 1960-'64. With an original axle width at 62 inches the Dana 60 is also a good candidate for 1955-'59 Chevy pickups. Spring perches will probably have to be relocated; however, these can be removed and rewelded, or new 3-inch-diameter spring perches can still be purchased from rear axle parts suppliers along with the other upgrade items we have mentioned. At 13-1/2 inches long, front to back, the Dana 60 may also require you to shorten your driveshaft as much as 2 inches on any Salisbury-style (non-removable carrier) axle. This is not necessarily the case when swapping with a banjo-style (removable carrier) axle such as the Ford 9-inch.

Doing some checking into locating a good used donor rear end, we found virtually no used passenger-style Dana 60s. We did, however, find many of the truck axles available relatively cheap. A 3/4-ton Dodge differential can be as inexpensive as $200, with most selling in the $400 to $500 range. This is a far cry from purchasing one of the complete remanufactured units currently being offered. A remanufactured unit with drum brakes can sell for between $2,100 and $3,600, depending on the length of the axles and the gear ratio. Replacement differentials with a rear-disc brake option are offered for between $3,000 and $3,800.

However, as you can see, with a little information in hand and a little hunting around, you can easily find a used unit and have it built to your own specifications for less than $1,400, including new axles, a limited-slip differential rebuild kit, and new ring and pinion gears. The added advantage of using what is considered to be the strongest passenger car differential assembly also will allow you to make many changes as engine performance changes, regardless of horsepower rating. Although the Dana 60 has been around for over 50 years, it is still a great way to upgrade your

 
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