Mid Sixties 8 3/4 Help Me Sort Out What I'm Doing Here

1966 -1967 Mopars

  1. Auggie56

    Auggie56 FBBO Gold Member FBBO Gold Member

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    I'm involved in a total restoration, and thought I'd tackle the rear axle, while the weather is bad. What I don't have in a center section, and need to know what would be the best route to go.

    I'm finding "drop outs" and "rebuilt drop outs," exactly what he (ebay) means by rebuilt I don't know.

    I have a pair of axles, that I have yet to count the spines, are there different splines ? Axle bearings, I find a complete set (pair) of Timkin off ebay for $190. Any better deals out there ? Can I buy a center section and not worry about the size of spline, or are there different axle spline ?

    Yokes, I want the larger one, I see course and fine spline one's. In my experience I have only seen the fine spline. Are the course one's pre-1966 cars or trucks ? Are there different numbers of fine spline pinions ?

    Rebuilt, I want a 3:25 ratio, can you just reuse an old set of gears If good, and replace the bearings, and still get a good results ? I'm having a local shop do the work, who is highly experienced in axle building.

    Thanks
     
  2. ply64post

    ply64post Seinor Member

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    Guide to the Chrysler 8-3/4"



    Part I of this guide was authored by Gary Lewallen (aka. Vaanth) for the MML and Internet community. It was originally published in January 1998. Part II was authored by Doug Ahern as a supplement to Part I.

    A Chrysler 8-3/4" Rear Axle Guide
    Part I.

    Author: Gary Lewallen (aka. Vaanth)
    Date: 12 January 1998
    Updated: 20 January 2000
    Introduction

    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. 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 car lines through 1972, and saw continued use until 1974.

    8-3/4" Axle 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.

    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. Differential bearing setting (ie. backlash ) is set with threaded adjusters.

    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. Differential bearing setting (ie. backlash ) is set with threaded adjusters.

    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. Differential bearing setting (ie. backlash ) is set with threaded adjusters.

    All 8-3/4" carrier assemblies can be identified externally by the casting numbers. Additionally, 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. It is retained by 10 nuts on studs in the housing. The rear of the housing is smooth, the back is welded onto the main housing. The axle tubes are part of the overall housing. To remove the center section, remove the wheels, brake drums, and drive shaft (note: pre-1965 units have a pressed-on brake hub which requires a puller for removal -- see Part II, Appendix B). Remove the axle shafts and the five bolts on the backing plate flange on post 64 units (use puller for pressed-in pre-1965 units). Remove the ten nuts on the housing studs around the carrier perimeter then remove the carrier (which may require prying), fluid will drain when carrier gasket seal is broken.

    Interchange Notes:

    Any 8-3/4" center section may be interchanged for another as an entire assembly, with the exception of center sections manufactured prior to model year 1964 (See Part II, Section 1: "Thrust Block Variations").

    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.

    Dana Power-Lok
    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.

    Borg Warner Spin Resistant
    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.

    There is an interchange problem with differentials and axles manufactured prior to 1964 (See Part II, Section 1: "Thrust Block Variations").

    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 universal 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.

    Note: the axle centerline to yoke/universal centerline is 12.35" for the 8-3/4" axle.

    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 better for racing applications and has clutch rebuild kits available.

    Axle and Housing Notes

    Because the 8-3/4" axle was available in most body lines, there are a variety of housings available. 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.

    See Part II, Section 3: "Part Numbers and Dimensions of Axles and Housings" for axle housing part numbers, sizes, and more detailed interchange information of axles and housings.

    Interchange Notes:

    Any 8-3/4" center section may be interchanged for another as an entire assembly except for a thrust block difference of non-Suregrip units built before 1964 (See Part II, Section 1).

    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.

    Note: 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.

    Note: 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.

    See Part I, Appendix A for information about the A-body 8-3/4" axle and bolt circle changes.

    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. 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).
    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
    (Detroit ref.) Chrysler Precision
    (Moog) Dana
    (Spicer) TRW
    (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.



    Chrysler Part Numbers
    Yoke Items
    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
    4318060 Mopar Sure Grip axle additive.
    2881313 Dana Power-Lock thrust block set.
    P4529484 Repair Kit, Dana Power-Lok (replaces 2070845)
    N/A Repair Kit, Borg Warner/Auburn unit. see note below.
    Shim Packages
    P4452027 1-3/4" pinion Shim Package
    P4452026 1-7/8" pinion Shim Package
    Ring Gear Bolts
    P4529486 71 and later (also 4131255, pkg. of 10)
    P5249163 70 and earlier, see bote below
    Miscellaneous
    4032798 Vent bolt
    P4120074 Spring mounting pads (perches)
    2931687 '489' collapsible spacer (pinion bearing preload)
    4318058 Mopar gear lubricant
    4318060 Mopar Sure Grip axle additive
    4318064 Mopar wheel bearing lubricant
    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.

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



    Gaskets and 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 Bearings

    Chrysler BCA C/R
    Axle, outer; 64-74 A7 BR7
    Axle mounting flange repair kit, right A-7-RK A7-RK
    Axle mounting flange repair kit, left A-7-LK A7-LK
    differential kit 1-7/8" RA-301
    differential kit 1-3/4" RA-300
    axle bearing service kit 3683966
    Part I, 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.

    B-body axle in the A-body:
    Another alternative can be used to replace an existing 8-3/4" or the smaller 7-1/4" or 8-1/4" axles. An axle from a 66-70 B-body can be installed in the A-body (note: a 62-64 axle can be used, but it does not contain the flanged axles of the later units). The later sport coupe style cars, Duster, Demon, Dart Sport, have the roomiest fenderwells. The 67-76 sedan and hardtop models have less. The 60-66 appear to be the tightest fit. The A-body has a spring perch spacing of 43.0", the 66-70 B-body is 44.0". To mount the B-body axle on the A-body springs, the perches need to be removed and new ones welded in place 1/2" inward from the original location on each side. The B-body track width is greater than the A-body. This may be a concern depending on the wheel/tire combination. The wider track enhances handling and aesthetics to some degree. This has been performed on the author's 73 Duster, now equipped with 15x6.5" rallye wheels and P255/60R-15 tires with 11x2.5" brakes. Originally setup with 15x7" rallye wheels and P275/60R-15 tires will rolled fender lips. The larger tires exhibited scrubbing when loaded on dips/bumps. If replacing a 7-1/4" or 8-1/4" axle, the driveshaft must be changed as the axle centerline to yoke centerline is greater for the 8-3/4" (12.35" vs. 10.09" for 7-1/4" and 11.69" for 8-1/4"). If changing a 7-1/4" axle the shock plates and u-bolts/nuts must be changed to the larger units from an 8-3/4" car.

    A Chrysler 8-3/4" Rear Axle Guide, Part II

    Section 1: Thrust Block Variations

    There was a difference in thrust blocks prior to 1964 that make center section interchange, as well as axle interchange problematic. The thrust block, or "axle shaft thrust spacer", it thr block that both left and right axles butt up against inside the center of the differential. Prior to 1964, all open differentials used a thrust block was approximately 1/8" to 1/4" thicker than units made after 1964. The Sure Grip thrust block prior to 1964, however, was indentical to all 1964 and later Sure Grips and open differentials. In 1964, the thrust block width was changed to match the Sure Grip thrust block width.

    This difference in thrust blocks between Sure Grip differentials and open differentials required that two different axles be produced for each 8-3/4" housing manufactured. This is true of all 1959-1963 cars with 8-3/4"s.

    A 1964 and later differential, or any Sure Grip differential, cannot be used with 1959-1963 rearends and axles originally equipped with an open differential. The original axles must be machined or original Sure Grip length axles must be used.

    Section 3 contains housing and axle sizes and part numbers for these early 8-3/4" rearends.

    Section 2: Flange Axle Taper and Flange Differences

    Besides the obvious bolt circle lug pattern difference between the A-body 4" BC axle and all other passenger car 4.5" BC axles, there is a sometimes unexpected difference in the flange that tends to cause confusion. The distance from the axle housing flange to the wheel flange of the axle is 1/4" smaller on A-body axles than on the standard 4.5" passenger car axle. On an A-body axle this measures 2", on 4.5" BC axles its 2.25".

    This slight difference will cause problems when one attempts to adapt brake systems (drum and backing plate together), or a brake drum from a 4.5" BC axle to a 4" BC axle. If you are using original A-body axles, regardless of what BC is may have been redrilled for, you can only use the original 10x1.75" drums (redrill the drums as well).


    The diagram above illustrates 8-3/4" axles. The top is a 66-72 A-body axle. and the other two are longer axles that generally resemble the B and C-body and truck axles. As Gary wrote earlier, C-body and truck axles can be shortened and resplined by a quality machine shop, however it is important to note that not all C-body/Truck axles are created equally. the bottom axle illustrates how many mid-60's axles taper as they near the splines, these can not be used as A-body short axle donors! The middle axle shows that at the location of where the new splines will be (26" from bearing retaining plate to the end of the axle, see measurement #2 in the diagram) the outside diameter (OD) must be larger than what the OD of the spline needs to be.

    Section 3: Part Numbers and Demensions of Axles and Housings.

    The following chart can be found in the Mopar Performance Chassis Manual. the distance between spring perches is an accurate reference, however the Track listing is the source of a lot of misconceptions. Track is the distance between the two tires, and includes a proportion of the actual tire track, or patch where it contacts the ground. The chart below tends to lead people to believe that all 62-70 B-body 8-3/4 rearends are the same width, not true!



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


    Axle Housing and Axle demensions

    The following is a listing of flange to flange widths for various year 8-3/4" housings. This is a measure of the bare housing, with brake backing plates removed, from the outside of the flange across to the outside of the other flange. Chrysler part numbers are listed as well for the purpose of showing a distinction between some housings and axles.

    Part# Application Flange to Flange Width Notes
    1045744
    1945745
    2070259
    2070269
    2070270
    2070960
    57-62 fullsize 63-64 Chrysler/880 55-5/8" (est.) 8-1/4" axles 57-61 have different housing part numbers.
    SG axle shorter than open rear axle, except for 1964 models.
    65 C-body unknown axle 2404228 same as A-100 vans and trucks.
    2800175 66 C-body unknown
    2881003 69 C-body 56-7/16"
    2881310 69 C-body wagon 59-7/64"
    70 C-body 57-3/4"
    2070231 60-62 Imperial unknown Imperials: 57-63 SG, all 64 axle 1829267
    2070961 63-64 Imperial unknown Imperials: 57-63 open axle 1675449
    2404208 65-66 Imperial unknown different from above axles, 2404139
    2800224 69 Imperial unknown
    2070539 62-63 B-body
    64 Max Wedge 53-1/4"
    Parts Manuals list four different axles for this housing:
    2070573 - 741 case w/o SG 30-1/2" overall;
    2404003 - 742 case w/o SG 30-1/2" overall;
    2070695 - 741 case SG 30-7/16" overall;
    2404050 - 742 case SG 30-7/16" overall;
    2404271 64 B-body except Max Wedge. 55-5/8" (est) 1/8" - 1/4" narrower than 2070270 (fullsize Chrysler) housing. axle length 31-1/2" overall.
    2404143 65 B-body 54-1/2" uses axle 2404223
    2643409 66-67 B-body 54-1/4"
    2852838 68-69 B-body 54-15/16" same as 1970 B-body, 1/32" difference
    3432295 70 B-body 54-29/32" same as 1968-69 B-body, 1/32" difference
    3507502 71-73 B-body 57-47/64"
    3507501 71-73 C-body
    71-73 B-body SW
    59-1/8"
    2800227
    3432647
    3432295
    66-72 A-body 52-13/64" (70-71) 52-37/64" (72) 4" bolt circle, used 10x1-3/4" drums. These demensions come from 1970,71,72 Factory Parts Manuals
    2852882 70-74 E-body 56-7/16"
    Section 4: 8-1/4" Carrier Housing

    From 1957 to 1964 Chrysler manufactured a front loading center section similar to an 8-3/4". Its ring gear diameter was 8-1/4". This is not related to the Spicer built 8-1/4" rearend used in Chrysler products in the Seventies. The 57-64 was more or less designated as the the six cylinder rearend whereas the 8-3/4" was designated for V-8 cars. The 57-62 8-1/4" used a case with a casting number 1828448. It appears that in 1963 and 1964 this gearset was installed in a 741 case. The 1828448 may have used a different housing flange pattern as it calls for a different housing (1045744,2070269). These rearends were for extreme light duty and were only used in six cylinder applications. six cylinder station wagons used 8-3/4"s. Along other available gear ratios, there was a 3.31:1 for manual transmissions and a 2.93:1 for automatic transmissions.

    Section 5: Aftermarket Components

    Auburn Gear limited-slip differential is available new from Auburn Gear. This unit is essentially the same design as the factory 68-74 Borg-Warner Spin Resistant unit, however Auburn Gear continues to make engineering improvements. Like the original design, the new unit is non-rebuildable. It can, however, be used with all 8-3/4" housings so long as 69-74 differential bearing cones and cups are used. AG Part No. 542051.

    Detroit Locker limited-slip, or "No Spin", differentials are also available. The origins of these heavy duty units dates back to Ford Motor Company's racing program of the Sixties. Tractech manufactures the Detroit Locker with some improved streetably features. Tractech's Part No. 187SL-14A.

    Powertrax Locker is a small drop-in locking differential that replaces the spider gears in an open differential housing. Two versions are available: a street friendly Lock-Right model and the beefier Performace Locker. Powertrax Part No. 1240 and VX124A (respectively).
    Green Bearing Company builds a bearing kit that replaces the cone-type wheel bearings. These are sealed roller bearing units that do not require end play adjustment, however they offer no side to side support, and fail quickly in street applications. These are drag race bearings only (the manufacturer even lists them under the "Racing" segment of their catalog). Green Part No. RP400.

    Part II, Appendix B: Torque Reference

    Fastener Foot-Pounds
    Axle Shaft Nuts (tapered axle end nuts) 145 (min)
    Brake Support Plate to Housing Mounthing Bolt Nuts 30 to 35
    Differential Carrier to Axle Housing Bolt Nuts 45
    Rear Axle Drive Gear to Case Bolts 60
    Differential Bearing Cap bolts 90
    Rear Axle Drive Pinion Companion Flange Nut 240 (min)
    Rear Spring "U" Bolt Nuts 50
    Source: 1963 FSM

    Part II, Appendix C: OE Ring and Pinion Sets

    Tooth Count Ratio Carriers
    41-14 2.93 '448', '657', '741', '742', '489'
    41-13 3.15 '448', '657', '985',
    35-11 3.19 '448', '657'
    3.23 '741', '742', '489'
    43-13 3.31 '448' (57-61), '741' (62-63)
    37-11 3.36 '448', '657'
    39-11 3.55 '448', '657', '741', '742', '489'
    41-11 3.73 '448', '657', '985', '741'
    43-11 3.91 '448', '657'
    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.
    - Chicago Rawhide (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.
    - Mopar Mailing List (MML) postings.
    - Memory.
    Acknowledements

    Hope this will help

    Jeff
     
    • Like Like x 5
    • Auggie56

      Auggie56 FBBO Gold Member FBBO Gold Member

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      Awesome amount of information, much thanks and Merry Christmas.
       
    • mike.c

      mike.c New Member

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      HI ,i have read this 7everal times and the question i have is can you use a 1 3/4 in pinion in a 471 ,i have a 2070471 with stock factory 1 3/8 pinion and want to up grade to the 1 3/4,any help would be greatly appreciated thank you.
       
    • Demonic

      Demonic Well-Known Member

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      Hi Mike,

      The short answer is no. The casting # on the carrier designates the ring and pinion set it requires. You'll won't have to worry about the 1 3/8 pinion until you buy a set of slicks.
       
    • 33 IMP

      33 IMP FBBO Gold Member FBBO Gold Member

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      I think i read somewhere that you can use a 742 gear in a 489 case, with a bearing change. I dont know if that is true. With a 741 case, you are stuck with 741 gears. Other than poor new gear ratio selection, that is not a bad thing (or a bad case!). If you go to Dr Diff's site, you can see where he shows that the weak point on 741 pinion is EXACTLY THE SAME on 742 and 489 too.
       
    • Fran Blacker

      Fran Blacker FBBO Gold Member FBBO Gold Member

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      One thing that is missing is yokes on 66 Hemi and 67 cars with 440 and Hemi cars. They came with 1330 u-joints automatic's had 1330 10 splines 4 speeds Dana 60's 1330 29 spline yokes.
       
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      • 4406bbl

        4406bbl Well-Known Member

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        Even with slicks a 741 with new bearings will last a long time, like forever in a normal auto equipped car. The yokes were hit and miss thru the years, most aftermarket gears back in the day used the 10 spline, so the 10 spline big joint yoke became a popular item at swap meets, always sold all I could find.
         
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        • Cranky

          Cranky Banned Staff Member FBBO Gold Member

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          Some years back a buddy of mine said you could do something similar between the 41 and the 42 but never heard about swapping between the 42 and 89. I guess you could mix and match bearings on any of them (?) to make it work. And I used to sell all the 89 and 42 stuff and kept the 'weak' 41's junk for myself and never broke one. Yup about Dr Diff's site shows the weak points on them is all the same and researched that a lot of years ago before Cass put it up on his site.
           
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