Please note that this page was copied in its entirety from AUTO HOBBY DIGEST
The writers of this page really did some digging to be this thorough, and they deserve all the credit in the world for it.
You can view the original page at this address: http://www.autohobbydigest.com/8_75.html
Guide to the Chrysler 8-3/4"
Revised: 16 June 2004
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
|7260 joint||4364400||315G||5-1306X||20030, 20030P|
|7290 joint||4057025||316||5-1309X||20059, 20059P|
|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.
|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.|
|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|
|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.
|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||---|
|Position||Cup/Cone (Timken, BCA)||Notes|
|Differential, side||LM 104949/LM 104912||70-74, Borg Warner|
|Differential, side||25590/25520||57-69, Dana|
|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|
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.
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.
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.
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!
|A-body, 65-72||55.6||43.0||4" lug bolt circle|
|B-body station wagon, 71-72||63.4||47.3|
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|
|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.|
|2881310||69 C-body wagon||59-7/64"|
|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|
64 Max Wedge
|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|
|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|
|3507501|| 71-73 C-body
71-73 B-body SW
|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|
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.
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
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.
|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
|41-14||2.93||'448', '657', '741', '742', '489'|
|41-13||3.15||'448', '657', '985',|
|3.23||'741', '742', '489'|
|43-13||3.31||'448' (57-61), '741' (62-63)|
|39-11||3.55||'448', '657', '741', '742', '489'|
|41-11||3.73||'448', '657', '985', '741'|
Thanks to Jeff Brown with his help on the yokes information (Lewallen), the Mopar Mailing List (MML), and the RAMM.