rear disc brakes for mopar 9 1/4 rear differential

Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member
On a recent trip to a salvage yard with a buddy who is looking to replace the busted rear differential in a 1968 383 mopar, road runner , I noticed that theres damn few older cars to scavange the correct parts from, but I noticed several more modern cars with the 9 1/4" mopar rear differentials that looked like they might be a rather less expensive and readily available option.
the cars in fair shape but the differentials toast!
his car looks similar to these pictures but his is a burgandy wine color

1968rr1.jpg

1968rr2.jpg


the car originally had a chrysler 8 1/4" or 8 3/4" rear

http://garage.grumpysperformance.co...troker-probably-in-the-future.1111/#post-2201

http://www.summitracing.com/search/...end-components/make/plymouth/model/roadrunner

https://www.yukongear.com/DiffList....ModelName=Road+Runner&Side=Rear&DriveType=RWD
1968rr5.png

1968rr6.png


rear disc brakes for mopar 9 1/4 rear differential on the differential would be a great upgrade.
he does not have a great deal of cash, so finding a DANA 60 is very unlikely, but we were quoted
"under $200 for a complete 9 1/4" mopar rear differential of our choice."
which seems reasonable if we can find the correct replacement with similar over all dimensions , espectally if we get disc brakes thrown in on the price.

summit racing lists an upgrade kit, but at $700 plus its not real cheap, I'm wondering if any pick-up trucks came with that differential equiped with disc brakes and what my options are?
http://www.summitracing.com/parts/sum-bk1410-x/overview/make/dodge
SUM-BK1400.jpg
 
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Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member
http://www.planethoustonamx.com/main/chrysler_8_34_rearends.htm
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YES A THIN COAT OF GREASE , on the back of disc brake pads ,WILL WORK, to reduce vibration and noise
housingdiagram.jpg

obviously selecting and proper use of the correct lubricant tends to work better
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Chrysler 8 3/4” Axle Guide Updated 2015

The following conglomeration of information should help a person be able to locate, identify, and install an 8 3/4” Chrysler rear axle in their AMC product. Many topics are covered, and the text is compiled into one long document in order to speed locating the information you need. The topics covered are as follows:
General
Where to Find One
Axles and Housings
Center Section Types
Sure Grip
Universal Joint Yokes
Strength Considerations
Service Parts Information
Selected Parts Reference
Appendix A: 8-3/4 A-body axle upgrade to 4.5" bolt circle
Appendix B: How to Put One in a Javelin (or other AMC)


General

The Chrysler 8-3/4" rear axle assembly was introduced in 1957. It is a banjo-type (Hotchkiss) axle, ie. the differential is contained in a removable carrier assembly which is extracted from the axle housing toward the front of the car. It is retained by 10 nuts on studs in the housing. The differential “cover” (although permanent) as viewed from the back of the car is smooth and hemispherical; it is welded onto the main housing. The axle tubes are part of the overall housing. The axle has an 8-3/4" diameter ring gear. There are three basic types available distinguished by their drive pinion stem diameter. The 8-3/4" axle was the primary axle assembly used in most Chrysler car lines through 1972.

Where To Find One

The first thing one needs to know in order to find the right axle for the job is the Chrysler platform code system. With an understanding of the different vehicles involved, you can then determine which one will best suit your application.

A-body models include:
1964-76 Plymouth Valiant, 1964-69 Plymouth Barracuda, 1970-76 Plymouth Duster, 1972-76 Plymouth Scamp, 1964-76 Dodge Dart, 1971-72 Dodge Demon, 1973-76 Dodge Dart Sport, 1969-76 Dodge Dart Swinger


B-body models include:
1965-70 Plymouth Belvedere, 1965-74 Plymouth Satellite, 1968-74 Plymouth Road Runner, 1970 Plymouth Superbird, 1967-71 Plymouth GTX, 1965-74 Dodge Coronet, 1968-71 Dodge SuperBee, 1966-74 Dodge Charger, 1969 Dodge Charger Daytona


C-body models include:
All 1965-74 full-size Chrysler models (Newport, New Yorker, Imperial), 1965-74 full size Dodge and Plymouth models (Polara, Monaco, Fury, Sport Fury, etc.)


E-body models:
1970-1974 Plymouth Barracuda and 1970-1974 Dodge Challenger


Axles and Housings

Because the 8-3/4" axle was available in most body lines, there are a variety of housings available. Following are SOME of the passenger car axle dimensions and notations. The 'Perches' dimension is the distance center to center between the spring mount perches. Dimensions are in inches.

Body line Track Perches Notes
------------- ---------- ----------- -----------------------
A-body, 65-72 55.6 43.0 4" lug bolt circle,
offered in heavy duty apps.
B-body, 62-70 59.2 44.0
B-body, 71-72 62.0 47.3
B-body, 71-72 63.4 47.3 station wagon
C-body, 64-72 63.4 47.3
D-body, 64-72 63.4 47.3
E-body, 70-74 60.7 46.0


The 8-3/4 was also available in the 58-74 D100/W100 trucks (and variants), the 64-70 A-100 trucks and vans, the 67-70 A-108 trucks and vans, the 71-74 B100/B200 vans and non-listed 57-64 full and mid-size car models.

Notes:
1) The axle centerline to yoke/universal centerline is 12.35" for the 8-3/4" axle.
2) Any 8-3/4" center section may be interchanged for another as an entire assembly.
3) All 8-3/4" axle shafts, 65-74, are retained by a bolt-on flange. Axles can be
interchanged within housings of the same width. The passenger side axle has a
threaded adjuster to set axle shaft end play.
4) There was a slight dimensional change in axle shaft length when the Sure Grip design
changed. If interchanging axles with the slight difference, the threaded end play
adjustment can be used to accomodate it.
5) The 57-64 8-3/4 axle driveshafts were tapered and used a keyway and locknut to retain
the brake assemblies and end play was set with shims. The 65 and later units use
flanged axle shafts and a threaded adjuster to set axle end play.
6) See Appendix A for information about the A-body 8-3/4" axle and bolt circle changes.


Center Section Types

The 8-3/4" axle was available in three basic types. The types are differentiated by the pinion stem diameter....1-3/8", 1-3/4", 1-7/8". The choice of axle pinion assembly was determined based on the application. Differential bearing setting (ie. backlash ) is set with threaded adjusters on all carriers. All 8-3/4" carrier assemblies can be identified externally by the casting numbers.

1-3/8" small stem pinion (aka. '741')
Carrier casting numbers: 1820657 (1957-1964), 2070741 (1964-1972).
This assembly was typically used in low weight/low horsepower applications through low weight/medium horsepower and high weight/low horsepower applications.
Pinion depth and bearing preload is set with shims.


1-3/4" large stem pinion (aka. '742')
Carrier casting numbers: 1634985 (1957-1964), 2070742 (~1961-1969).
This assembly was replaced by a phase-in of the 1-7/8" pinion starting in the 1969 model year. 1970 RW (Plymouth and Dodge mid-size) were the last models to use the 1-3/4" which appeared in a 2881489 case. This assembly was typically used in high weight/medium horsepower applications through high weight/high horsepower applications.
Pinion depth and bearing preload is set with shims.


1-7/8" tapered stem pinion (aka. '489')
Carrier casting numbers: 2881488, 2881489 (1969-1974).
This assembly was introduced in 1969 and was phased-in to relace the 1-3/4" unit through 1970. Note: the 1-3/4" pinion also appeared in some '489' carriers during this period. By 1973, the '489' was the only unit available in passenger car applications. This assembly was typically used in high weight/medium horsepower applications through high weight/high horsepower applications.
Pinion depth is set with shims, preload is set with a crush sleeve.


The '741' commonly has a large X cast on the left side, the '742' may have a large 2 cast on the left side, and the '489' has a large 9 cast on the left side. Through 1965, the factory ratio was stamped on the identification boss, followed by an 'S' if Sure Grip equipped. After 1965, a tag was affixed under one of the carrier mounting nuts to identify the ratio. If Sure Grip equipped, an additional Sure Grip lube tag was sometimes affixed; later years sometimes had the filler plug painted orange.

Gear ratios available on the 8-3/4" axle through the years include: 2.76, 2.93, 3.23, 3.31, 3.55, 3.73, 3.91, 4.10, 4.56, 4.89, 5.17, 5.57. On OEM gear sets, the ratio is usually stamped on the ring gear edge. Ratio may be determined by the number of teeth on the ring gear divided by the number of teeth on the pinion gear or by counting the ratio of the number of turns of the pinion relative to one turn of the axle shaft.

The 8-3/4" center section is removed from the front of the housing. To remove the center section, remove the wheels, brake drums, and drive shaft (note: pre- 65 units have a pressed-on brake hub...requires a puller for removal). Remove the axle shafts, 5 bolts on the backing plate flange on post 64 units, use puller for pressed-in pre-65 units. Remove the 10 nuts on the housing studs around the carrier perimeter. Remove the carrier...may require prying, fluid will drain when carrier gasket seal is broken.

Sure Grip

Sure Grip is the Chrysler name for a limited slip differential. It was optional on the 8-3/4" axles, 1958-1974. Two styles were used.

1958-1969 used the Dana Power-Lok (# 2881487). This unit utilized clutches for the differential locking action. The Power-Lok can be rebuilt using kit # 2070845 ( Mopar Performance [MP] # P4529484 ). In this assembly, axle driveshaft end thrust is taken by the thrust block assembly (replacement # 2881313). This Sure Grip appeared in the '741' and '742' assemblies. The axle bearings are: 25590 (Timken cone), and 25520 (Timken cup), (Chrysler numbers 1790523 and 696403). The Dana Power-Lok can be recognized by its bolt-together assembly, bolts around the side opposite the ring gear, and multiple openings exposing the cross shafts.

1969-1974 used the Borg Warner Spin Resistant (# 2881343). This unit utilized a spring-preloaded cone friction arrangement for the locking action. Axle end thrust is taken by the cross shaft. This Sure Grip appeared in '489' assemblies and 70 and later '741'/'742' assemblies. The differential axle bearings are: LM 104912 (Timken cone), and LM 104949 (Timken cup), (Chrysler numbers 2852729 and 2852728). The Borg Warner Spin Resistant unit can be recognized by its lack of bolts on the side opposite the ring gear (like the Dana), and two openings exposing the preload springs. Borg Warner sold this design to Auburn Gear who currently offers the replacement Sure Grip assemblies.

Non-Sure Grip differentials can be identified by the large openings in the differential exposing the differential (aka. spider) gears. There are no springs or clutches.

Interchange Notes:
The two Sure Grip types can be interchanged between the carriers if the matching differential axle bearings are retained. The outside diameter of the cups are the same between the '741'/'742' and the '489'; the inner cone differs. The Sure Grip differential can be used as a direct replacement for the non-Sure Grip within the carrier/bearing limits previously noted.


Universal Joint Yokes

The 8-3/4" axle was offered with two size cross & roller style universal joint. These are referred to as the '7260' (2-1/8" yoke ID) and the '7290' (2-5/8" yoke ID). Most Imperials and some C-bodies used a different univer- sal joint. The '1330' type joint was used on Imperials and others with a constant velocity joint. The '1330' uses outside snap rings instead of the inside snap rings used by the '7269' and '7290'. The cap diameter for the '7260' is 1.078". The cap diameter for the '7290' is 1.126". The '1330' style joint cap diameter is 1.063".

There are four different yokes that have been used with the 8-3/4" axle for the '7260' and '7290' style universal joints. The '741'/'742' assemblies used a coarse spline (10 splines) drive pinion. Most of the aftermarket gears also use this coarse spline yoke mount. There is a small yoke for the '7260' and a larger one for the '7290'. The '489' assembly used a fine spline (29 splines) yoke. Note: during the phase-in period of 69-71 for the '489' unit, there were several permutations of pinion size and yoke availability. 69-70 '489' units may be equipped with a coarse (10) spline pinion, particularly for the '7290'. There are two yokes for the '7260' and '7290' universal joints with fine (29) splines. Two additional yokes were used for the '1330' style universal joint in constant velocity applications, one for 10 splines and one for 29 splines.

Interchange Notes:
7260, 7290, 1330 yokes may be interchanged if the spline count is the same.
Note: the 9-1/4" axle (73-up) uses the same fine spline yokes as the 8-3/4" fine spline units (29 splines).


Strength Considerations

Pinions
The 1-3/8" '741' pinion is the weakest. It is still a capable unit in most moderate power, moderate traction street applications. For high torque applications with high traction tires, the 1-3/4" or 1-7/8" should be considered.
The 1-7/8" '489' is supposedly the strongest. Although the stem tapers down along it's length, it appears inherently stronger from a pinion stem perspective and the inherent strength of the fine splines (OEM gears).
The 1-3/4" '742' has a larger rear pinion bearing yielding greater strength in this area. The 1-3/4" shares yoke mount diameter and mounting nut with the 1-3/8".
For perspective, the 7-1/4" has a 1-3/8" pinion, the 8-1/4 has a 1-5/8" pinion, the 9-1/4" (70s) has a 1-7/8" pinion.


Sure Grips
The Dana Power-Lok is inherently stronger and provides better, equal torque transmission to both axles. It's locking capability is also proportionate to the applied torque. The Borg Warner unit is weaker, but is a more versatile unit for practical street applications in inclement traction periods. The Dana unit is the better of the stock sure grips for racing applications and has clutch rebuild kits available. An updated cone-type sure grip unit is available from Auburn Gear with 30% increased torque carrying capacity over the old version. Lockers and spools are also available from various sources.


Service Parts Information

Most replacement parts for the 8-3/4" axle are still available. Some items not available are new Dana Power-Lok assemblies, most OEM gears, most carrier housings and complete differentials and housings. A revised version of the cone-type Sure Grips are available from Auburn Gear. The Power-Lok clutch kits are available from MP and other sources. Gear sets (typically performance oriented ratios) are available from MP and the aftermarket for the '489' and '742'. Bearings and seals are readily available.

Some sources
Mopar Performance dealers, Chrysler dealers.
Moser Engineering, 1616 Franklin St, Portland IN, 47371 (219-726-6689).
Reider Racing, 12351 Universal Dr., Taylor MI, 48180 (313-946-8672).
Aftermarket for general replacements, ie. seals, bearings, etc.


Selected Parts Reference

Numbers listed for reference, some may be superceded or discontinued, some variances among models/years may occur. Reference factory or replacement parts catalogs for exact replacement details.

Universal Joint Items
Item Chrysler Precision Dana TRW
(Detroit ref.) (OEM or MP) (Moog) (Spicer) (FederalMogul)
-------------- ------------ --------- -------- --------------
7260 joint 4364400 315G 5-1306X 20030, 20030P
7290 joint 4057025 316 5-1309X 20059, 20059P
Combination * --- 347 --- 20226
1330 joint 2533202 354 5-213X 20064, 20064P
7260 strap kit P4120468 318-10 2-70-38X 20704
7290 strap kit P4120469 492-10 2-70-28X 20705


* This is a combination of the 7260 and 7290 universal joints to allow
mating of the two styles.


Yokes
3432485 -> 29 spline 7260 (2-1/8" ID), also P4529481
3432487 -> 29 spline 7290 (2-5/8" ID), also P4529483
3004872 -> 10 spline 7260 (2-1/8" ID), also P4529480
P4529482 -> 10 spline 7290 (2-5/8" ID), replaces 2808384, 3004873
2931813 -> 10 spline 1330, for constant velocity, ie. Imperial.
3432489 -> 29 spline 1330, for constant velocity, ie. Imperial.
1556556 -> pinion washer, concave, 3/16" thick, 13/16" hole diameter.
2070117 -> pinion washer, concave, 3/16" thick, 15/16" hole diameter.
1795175 -> pinion washer, flat, 3/32"thick, 13/16" hole diameter.
1795173 -> pinion nut, 3/4"-16 thread, 1-1/4" hex.
6027323 -> pinion nut, 3/4"-16 thread, 1-1/8" hex.
6028041 -> pinion nut, 7/8"-14 thread, 1-1/4" hex.


Sure Grip Items
Mopar Sure Grip axle additive - 4318060
Dana Power-Lock thrust block set - 2881313
Repair Kit, Dana Power-Lok - P4529484 (replaces 2070845)
Note: there is no repair kit for the Borg Warner/Auburn unit, but the internal cones have been remachined by others to successfully restore performance.


Shim Package
1-3/4" pinion -> P4452027
1-7/8" pinion -> P4452026


Ring Gear Bolts
P4529486 -> 71 and later (also 4131255, pkg. of 10)
P5249163 -> 70 and earlier


Note: the 71 and later bolts may be installed in the earlier units by drilling a shoulder relief in the attachment holes.

Gaskets, Seals
Position Chrysler National C/R Fel-Pro
--------------- -------- -------- -------- --------
Axle inner seal 4796698 8695S 15460 ---
Axle outer seal 2404216 8704S 19000 ---
Axle flange, foam 2070933 see flange kit see flange kit 55032
Axle flange, shim 2881314 see flange kit see flange kit ---
Carrier gasket 1673367 --- --- RDS 65833
Pinion seal, 1-7/8 2931862 5126 18708 ---
Pinion seal, 1-3/4 2931862 7216 18912 ---
Pinion seal, 1-3/8 2931862 8515N 18708 ---
Yoke repair sleeve --- 99187 99187 ---


Bearings
Position Cup/Cone, Timken, BCA Notes:
------------- --------------------- ------------------
Differential, side LM 104949/LM 104912 70-74, Borg Warner
Differential, side 25590/25520 57-69, Dana
Pinion, front M88048/M88010 1-7/8"
Pinion, front HM89443/HM89410 1-3/4"
Pinion, front M88048/M88010 1-3/8"
Pinion, rear M804049/M804010 1-7/8"
Pinion, rear M803149/M803110 1-3/4"
Pinion, rear HM89446/HM89410 1-3/8"
Axle, outer BCA A-7 65-74
Axle, outer C/R BR7 65-74


Axle bearing service kit: Chrysler # 3683966, one axle.
BCA differential kit: 1-7/8", # RA-301, 1-3/4", # RA-300.
BCA axle mounting flange repair kit: Left # A-7-LK, Right # A-7-RK.
C/R axle mounting flange repair kit: Left # A7-LK, Right # A7-RK.
Vent bolt - Chrysler # 4032798
Spring mounting pads (perches) - Chrysler # P4120074
'489' collapsible spacer (pinion bearing preload) - Chrysler # 2931687
Mopar gear lubricant - 4318058
Mopar wheel bearing lubricant - 4318064

Note: the 8-3/4" axle shaft outer bearings require packing with grease as they are not
lubricated by the gear oil.

Appendix A: 8-3/4 A-body axle upgrade to 4.5" bolt circle

The 65-72 A-bodies were available with the 8-3/4" axle. This was standard on all 340 equipped cars. It was also included in heavy duty packages such as 318 with manual transmission and towing options. It was often included in post 65 273 high performance manual applications.

The bolt circle (BC) on these vehicles was 4". All other Chrysler vehicles (except some Imperials and trucks) of this era were equipped with a 4.5" BC. It is commonly desired by A-body owners to change to the 4.5" BC when upgrading to later style disk brakes or to expand wheel choice.

A-body 8-3/4" axle shaft swap:
There are several methods to accomplish this. Custom axles such as Strange, Summers, Moser, etc. can be specified with the larger lug pattern for the A-body housing. Longer axles from a larger vehicle may be cut and resplined to fit the shorter A-body axle. Donors for this operation are C-bodies, D-bodies, trucks and vans with the 8-3/4" axle and 4.5" BC. Moser Engineering can perform the cut and respline operation. When selecting a donor axle shaft, look for one that does not taper along its length. Note: A-body 8-3/4" axles were equipped with 10x1-3/4" drum brakes. Replace these with 10x2-1/2" or 11-2-1/2" brakes and associated hardware from the donor vehicle or similar.

Appendix B: How to Put One in a Javelin (Or Other AMC)

AMC’s use a 43 1/2” perch to perch spacing for all models from 1964-78, and possibly even further. Narrow body cars (68-70 Javelin & AMX, Gremlin, Hornet, etc.) use a 57” track width, and wide body cars (71-74 Javelin, Rebel, Matador, etc.) use a 60” track width. Comparing these numbers to the table above, it would appear that all of our axle needs can be fulfilled with either A-body or B-body axles, depending on which AMC vehicle we own. The 1969 A-body axle that I installed in my 1969 Javelin measured 57 1/4” from drum face to drum face, although the listed track width is 55.6”.

The spring perches don’t need to be moved in order to install the axle. Most leaf springs will allow 1/4” of side movement to permit the installation easily. You can purchase new Mopar Performance spring perches from Jeg's for $11.69 a pair if you feel the need to relocate them.

You can use the stock AMC shocks, but you need the shock/spring mounting plates from the donor Mopar. Use the passenger side plate on your drivers side and vice versa (Chrysler mounts the shock on the outside of the leaf spring, AMC mounts it on the inside). Another mounting option is to use Lakewood's "Traction...Action" bars, which are a combination shock/spring mount and traction bar. Buy some u-bolts for a 69 Cuda and bolt the axle in.

The driveshaft and u-joint require no modification typically. Moroso makes a fine u-joint girdle set to replace the stock straps for about $22.

Brake lines will have to be modified to fit each application. On the rear end I used the distribution block was located on the drivers side. I relocated it to the passenger side and made new lines.

References

- Chrysler factory service manuals, various, 1964-1974
- Chrysler parts catalogs, various, 1957-1974 - Hollander Interchange Manuals, 40th
edition
- Mopar Performance catalogs
- Mopar Performance Chassis Manual
- Mopar Performance Oval Track Manual
- Mopar Action magazine, selected articles
- High Performance Mopar magazine, selected articles
- Chrysler Car Enthusiast, Engines, Etc magazine, selected articles
- BCA/National catalog # 510-1, 1995
- CR Seals & Bearings catalog # 457205, 1991
- American Bearing catalog # 710, 1980
- Fel-Pro Master Gasket Catalog, # 900-96, 1/1996
- Precision Universal Joint catalog # MC-86, 1/1986
- TRW Universal Joints catalog # X-4003, 1995
 
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Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member
http://www.hemmings.com/mus/stories/2005/12/01/hmn_feature25.html

http://www.drivetrainshop.com/Chrysler_9_25_s/83.htm

Chrysler 9-1/4-inch differentials




Feature Article from Hemmings Muscle Machines
December, 2005 - Jim O'Clair

A few months ago we discussed converting to an 8-3/4-in. Mopar differential. While it is a definite improvement to upgrade to the 8-3/4-in., those older 741 and 742 cases are getting tougher and tougher to come by, which also means they are getting more expensive if you do find one. Finding an alternative rear end that can be used in place of the 8-3/4-in. is relatively easy, if you know where to look. That substitute would be the Chrysler 9-1/4-in.
One of the key factors in considering this exchange is the ease of availability. Used extensively in C-body full-size and B-, R-, J-, and M-bodied mid-size cars, 9-1/4-in. rears were also in many light-duty pickup trucks and van bodies. The 9-1/4-in. axle assembly was also produced in both open-gear and Sure-Grip positraction for over 25 years. The large pinion shaft diameter and the beefy 31-spline axles make the 9-1/4-in. a workhorse differential that can be adapted to many driving conditions, whether it's propelling your classic luxury car to the car show, launching a street car down the quarter-mile, or helping haul firewood in your truck.



You can easily distinguish a Mopar 9-1/4-in. axle by the 12-bolt octagon-shaped cover on the rear of the assembly. This cover uses 7/16-in. left-handed bolts to hold it onto the pumpkin. Looking at the front, the spline diameter where the yoke is attached is 1.265-in. with 29 splines on the pinion shaft. The rear pinion-bearing mounting diameter is a sturdy 1.875-in.


Original differential ratios range from 2.71:1 to 3.90:1, and most that you find in passenger cars are 3.55:1 or higher. Truck donor rear ends range from 3.55:1 on up to 3.90:1. Aftermarket ring-and-pinion suppliers offer even larger options with 4.10:1 and 4.56:1 gears which can be retrofitted into an existing 9-1/4-in. There are some wider truck differentials that you will find with 3.90:1 gears that are rated specifically for the van bodies. These are built to run more quietly than those in a conventional pickup or car, because the van body amplifies the rear-end noise much more than the other vehicles. These are fine to use in other applications; however, these axles tend to be the widest ones you will encounter.


Axles are a standard 5-lug, except on the 4WD Dakotas or Durangos, where you will encounter 6-lug axles. Both 5- and 6-lug axles are 1.32-in. diameter, 31-spline and C-clip retained. The axles are comparable in size to a Dana 44; however the 9-1/4-in. assembly has a much larger pinion diameter. Most original and replacement axles use a 7/8-in. C-clip; however some 1980-'84 axles used a 3/4-in. C-clip, so this is important to check for compatibility if you are looking for a donor rear to use parts from. The 9-1/4-in. differential is a semi-float axle, meaning the axles bear a lot of the rear-end weight. Outer axle bearings are similar in style to the GM corporate axles, but larger in both inside and outside diameters. This is another good reason for converting to the thicker-axle 9-1/4-in. rear end, because of the larger axle diameter.


As with the GM corporate axle, the outer bearings tend to be their weakest link; however, repair bearings are available to save a bad axle tube. These bearings can save the expense of replacing the entire differential assembly because of a spun bearing or broken axle. The industry repair bearing number is TRP-1559-TV.


This axle can be found in many late-1970s and early-1980s cars and in pickups and vans from the mid-1970s well into the 1990s. The 9-1/4-in. has also enjoyed a resurgence in late-model Dakotas and Durangos. Here is a list of donor cars and trucks you should be looking underneath:


1997-'02 Dodge Durango (left axles are longer than right axles)
1998-'04 Dakota with 4WD or 5-speed M/T (left axles are longer than right axles)
1981-'00 D-100 and 200 pickups (Sure-Grip only available from 1981-'94)
1974-'93 Ramcharger and W150 and 250 pickups
1974-'80 B-100 and 200 vans
1982 and 1984 B150 and B250 vans
1992-'94 B250
1984-'94 B350
1995-'00 BR2500 and 3500 vans
1975-'83 Chrysler Cordoba
1977 Chrysler New Yorker Brougham
1975-'78 Plymouth Fury
1975-'77, 1980-'81 Plymouth Gran Fury
1980-'83 Dodge Mirada
1975-'82 Chrysler New Yorker
1975-'81 Chrysler Newport
1976 Plymouth Sport Fury
1979-'81 Dodge St. Regis



To identify a Sure-Grip rear end on the vehicle, jack up the rear of the car or truck and place it on jack stands. With the vehicle in neutral, spin one rear wheel counter-clockwise and observe the motion of the other wheel. If it spins in the same direction as the wheel you are turning, it is a Sure-Grip rear. If the other wheel does not spin, you have an open-gear differential. Most Sure-Grip rears would also still have the Mopar additive tag located on or near the rear cover specifying the use of 4318060 limited slip additive in addition to 3 quarts of 75W-90 GL-5 gear oil.


The Chrysler 9-1/4-in. differential can easily be adapted to your existing drivetrain, with the use of one of the two Mopar pinion yokes and an adapter U-joint. Chrysler used both the 7260 series and 7290 series drivelines to join their 9-1/4-in. to the transmission. Both yokes are easily available from ring and pinion suppliers, if you did not get one with your donor rear end. Both of these yokes are also used on the Chrysler 8-3/4-in. rear end. They retain the rear driveshaft u-joint by means of a flat strap with two 8-point 5/16-in. fine bolts. Both replacement strap kits are readily available where you purchase your U-joints. The 7260 series yokes fit 2-1/8-in. U-joints with 1-5/64-in. end caps, 7290 series yokes fit 2-5/8-in. U-joints with 1-1/8-in. end caps. Spicer makes an adapter U-joint to convert from one to the other too, part #5-527X.


As always, we recommend that you have your donor differential thoroughly checked before installing it into your vehicle. Seek out a rear-end specialist who has the proper tools to check pinion wear and, in the case of the Sure-Grip differentials, check that the friction discs (or in late-model differentials the rod and cone assembly) are in good shape. The 1994 and newer differentials used a toothed outer band on the ring gear to activate rear wheel anti-lock. This ring must be re-used on your vehicle if you want the ABS in the rear to continue to work.


Installing one of the Chrysler 9-1/4-in. rear ends will require a little bit of measuring on your part. Because most of the donor cars are large-wheel-track vehicles, a 9-1/4-in. may not be the best choice for your Falcon or Dart. The B-body (and later R-, M- and J-body) cars used a 57-3/4-in. flange-to-flange axle housing, which would be compatible with many other cars and trucks, and not just earlier B-body Mopars. Mid-1970s Torino/Montego bodies, mid-1960s full-size Chevys and 1949-'58 Fords can all benefit from using the 9-1/4-in. rear end.


B-body and C-body housings would have a 47-3/8-in. leaf spring perch dimension. So, for full-size or mid-size Chrysler applications, the 9-1/4-in. should line up and bolt in pretty easily. The pickup differentials will be 65 in. wide, making them compatible with earlier Mopar B-, C- and D-body cars.


The Dakota/Durango 9-1/4-in. differentials measure 63 in. wide; however, the left axle is longer than the right, and the axles are 6-lug. For ease of installation, we would not suggest using this rear end in other vehicles. But the 9-1/4-in. is a good candidate for replacing the 8-1/4-in. differentials used on these models from 1997-'04. Original axle width and spring perch dimensions for most American vehicles are available in the parts locator section of www.hemmings.com. This list continues to be updated monthly as new information is received from our readers and from car club enthusiasts.


Looking into a good used 9-1/4-in., you can find one from a 1978 Chrysler Cordoba for between $150 and $300 for an open-gear unit. Used open units from a 1979 Ramcharger with 3.90:1 gears sell for between $250 and $400. Even figuring in a master rebuilding kit ($110), an open 9-1/4-in. can be under your car or truck for less than $700. Not terribly expensive, when you consider a brand-new unit with no axles or wheel bearings will run you about $1,200. We have seen some completely rebuilt open-gear units, complete and ready to install for $950 with a 90-day warranty.


If the differential you find turns out not to be a Sure-Grip rear end, you can purchase aftermarket Spicer Trac-Lok carriers (part number 75102X) for about $175 from ring-and-pinion supply companies. Mopar Performance Parts sells replacement carriers as well. P4876117 fits differentials before 1983. P4876119 fits 1984 and newer differentials. Be aware that Chrysler carriers sell in the $360 range. The Trac-Lok carriers will accept the ABS ring as well for 1994 and up applications. For 9-1/4-in. limited slip differentials, Sure-Grip clutch repair kits are available (Spicer part number 706352X) for $75. New replacement axles, if necessary, are available for $130 to $190, depending on the length you need and C-clip diameter on the shaft. Generally, axle lengths are 31-5/8-in., 31-11/16-in. or 32-9/16-in.


Considering how sturdy the 9-1/4-in. is, it can be used for both daily driving or weekend quarter-mile running, and the costs involved in upgrading from your present differential to a Mopar 9-1/4-in. can easily be justified. With the abundance of donor vehicles at your disposal, and the relatively inexpensive new replacement parts available, it is entirely possible to find an open-gear differential for very little money and build it the way you want it. You can make it a 2.76:1 open gear rear-end for your daily driver, or add taller 4.11 or 4.56 gears and a locking differential and you are ready to go racing on the weekend.
 
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87vette81big

Guest
The Mopar 9-1/4" is Ok I think Grumpy.
They usually have C-clip Retained axle shafts.
Not the Best choice for You and Me because we want to push the Race Limits.
Dana 60 & Pontiac 9.3 still #1 choice for us.
 
8

87vette81big

Guest
I have rebuilt a few 9-1/4" rear diffs in Late model Dodge Ram pickups .
They rebuild easy.
Much easier than Dana Rears.
 

Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member
I've been helping one of the local guys off and on, with a 440 mopar engine build, for a 1969 road runner project car, as he slowly accumulates the necessary funds ,
its been a rather long term project as hes like most of us , usually lacking the funds to buy the parts required to advance the project.
well hes hardly done but its up and at least semi drive-able at this point.
but like many of the younger guys hes concentrated mostly on getting the engine built and ignored a great deal of the cars original sub-systems.
well he brought the car over to show off his progress, and he was very proud of the new intake manifold he had installed recently, he found at a local swap meet. complete with two suspect condition edelbrock carbs for $700 which is not a bad deal on the face of it.
heres a link or two I found
indymodmanintake.jpg

indymodmanintake.jpg

http://www.mopartsracing.com/parts/Indy-Intakes.html
http://www.indyheads.com/bbengines.html
now he gets on the accelerator, to demonstrate his new toys potential, and leaves two long black smokey stripes on the pavement in front of the house,
and probably got to 40 mph then hits the brakes, it took him about 800 feet to stop as the brakes are almost non-functional.
its the first time he tried to stop the car from over 20 or so mph...and luckily there was enough clear street in front of him to slow down.
he scared himself pretty good when the brakes were not very effective, this is a very common issue that younger guys seem to be facing.... not thinking things through, and checking the sub systems like
BRAKES,COOLING,EXHAUST LEAKS,SHIFT LINKAGE, OIL PRESSURE,GAUGES & SENSORS , ELECTRICAL CHARGING, turn SIGNALS, & HEAD LIGHTS , STEERING AND SUSPENSION
I strongly suggested he put the car up on jack stands,
and inspect and correct or upgrade the brakes,
as they obviously required detailed inspection and correction,and further suggested he think very seriously,
about,

up-grading the brakes from salvage yard components to save cost to disc brakes off a heavier car,
once hes done the required research into parts compatibility ,and interchangeability,
from something like a Chrysler imperial or dodge 3/4 ton pick-up.
reading links and sub linked info may not be fun,
but you may be amazed at the amount of wasted time and money,
you can save from being wasted with the info gained in the process
you may not find the link you need, specifically,
but the info you do read, should make you think,
and question the process, ask the related questions,
and look at all your options carefully.
and yes if your installing a suspension, measure accurately several times..
assume nothing is correct until its carefully verified several times,
and yes your very likely to make mistakes,
so Id suggest you measure with the suspension and tires sitting on the ground,
before, you decide on tires, clearances , Finnish welding of the suspension links , spring perches, drive shaft angles etc. are finalized/ begins


http://garage.grumpysperformance.co...asuring-for-a-new-drive-shaft.478/#post-67321

http://garage.grumpysperformance.co...ear-axles-and-differentials.11848/#post-73266

http://garage.grumpysperformance.com/index.php?threads/getting-a-camaro-or-firebird-to-bite.4067/

http://garage.grumpysperformance.co...c4-corvette-wheel-tech-info.12099/#post-75335

http://garage.grumpysperformance.co...nks-that-may-help-your-musclecar-handle.3526/

http://garage.grumpysperformance.co...ouve-got-a-camaro-nova-etc-this-may-help.460/

http://garage.grumpysperformance.co...-and-info-to-help-get-the-chassis-right.9012/

http://garage.grumpysperformance.com/index.php?threads/suspension-springs.5622/

http://garage.grumpysperformance.com/index.php?threads/disc-brake-kits.6579/

https://www.summitracing.com/search...kits/year/1969/make/plymouth/model/roadrunner

http://www.hotrod.com/articles/mopp-0610-plymouth-gtx-disc-brakes-install/

http://www.doctordiff.com/blog/documentation/disc-brake-kit-comparison/

https://www.carid.com/1969-plymouth-roadrunner-brakes/

https://www.performanceonline.com/6...uth-Disc-Brake-Conversion-Kit-Stock-Spindles/


http://www.wilwood.com/BrakeKits/Br...dge&model=B-Body&modoption=Drum+Brake+Spindle

http://www.streetmusclemag.com/tech-stories/brakes-suspension/killer-kong-project-update-speedway-motors’-speedy-disc-brake-swap/


 
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