Re: 741 742 489
[Re: Slanteye6]
#2169285
10/06/16 10:15 PM
10/06/16 10:15 PM
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Joined: Oct 2007
Posts: 936 own private Idaho
ngpSatellite
super stock
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super stock
Joined: Oct 2007
Posts: 936
own private Idaho
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The Chrysler 8-3/4" rear axle assembly was introduced in 1957. It is a banjo-type, 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.
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 (741) Carrier casting numbers: 1820657 (1957-1964), 2070741 (1964-1972). These numbers are found on the left side of the carrier assembly.
This assembly was typically used in low weight/low horsepower (Small Block as an example) applications through low weight/medium horsepower and high weight / low horsepower applications. Pinion depth and bearing preload is set with shims. Differential bearing setting (i.e. backlash ) is set with threaded adjusters.
1-3/4" large stem pinion. (742) Carrier casting numbers: 1634985 (1957-1964), 2070742 (1961-1969). This assembly was replaced by a 1-7/8" pinion starting in the 1969 model year. 1970 Plymouth and Dodge b Bodies 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 (i.e. backlash ) is set with threaded adjusters.
1-7/8" tapered stem pinion. (489) Carrier casting numbers: 2881488, 2881489 (1969-1974).
This assembly was introduced in 1969 and gradually replace the 1-3/4" unit through 1970 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 through high weight/high horsepower applications. Pinion depth is set with shims, preload is set with a crush sleeve. Differential bearing setting (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.
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Re: 741 742 489
[Re: crackedback]
#2169445
10/07/16 03:08 AM
10/07/16 03:08 AM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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I would Keep It Simple Sam and search for a 742 (preferred) or 741 sure grip which would from the factory both have the highly desired clutch type sure grip in the ratio you desire for your app. if the pinion yoke does not match your driveshaft there is a combo ujoint to easily solve that minor dilemma. EDIT there is also a 6.20 742 gearset (I have one)
Last edited by RapidRobert; 10/07/16 03:18 AM.
live every 24 hour block of time like it's your last day on earth
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Re: 741 742 489
[Re: moparx]
#2169647
10/07/16 02:48 PM
10/07/16 02:48 PM
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Joined: Jun 2005
Posts: 5,110 Western Md.
skicker
"The Champ"
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"The Champ"
Joined: Jun 2005
Posts: 5,110
Western Md.
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I destroyed a 5.67 that was purchased from Petty many moons ago... Several years back (20?)I know a 5.57 could still be bought for a 742...
...FAFO...
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Re: 741 742 489
[Re: Slanteye6]
#2169672
10/07/16 03:29 PM
10/07/16 03:29 PM
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Joined: Jan 2003
Posts: 25,899 Rio Linda, CA
John_Kunkel
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,899
Rio Linda, CA
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They all physically interchange but the yoke has three different u-joint profiles and the pre-'64 center thrust block might not work with '66 and later rear ends.
The INTERNET, the MISinformation superhighway
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Re: 741 742 489
[Re: dogdays]
#2169825
10/07/16 08:12 PM
10/07/16 08:12 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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Blazin' Bob, I need to remind you that 741 production carried over into the '70s and they came with the cone type Suregrip. I did not know that. I stand correct(ed)
live every 24 hour block of time like it's your last day on earth
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Re: 741 742 489
[Re: John_Kunkel]
#2169875
10/07/16 09:16 PM
10/07/16 09:16 PM
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Joined: Dec 2003
Posts: 4,952 northwest USA
NANKET
master
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master
Joined: Dec 2003
Posts: 4,952
northwest USA
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They all physically interchange but the yoke has three different u-joint profiles and the pre-'64 center thrust block might not work with '66 and later rear ends.
Open rear end only, the 64 and older thrust block is 1.25", 65 and newer thrust block is 1.5" so they will not interchange.
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Re: 741 742 489
[Re: Slanteye6]
#2169887
10/07/16 09:28 PM
10/07/16 09:28 PM
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Joined: Jan 2004
Posts: 9,066 Eugene, Oregon
minivan
master
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master
Joined: Jan 2004
Posts: 9,066
Eugene, Oregon
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JohnRR on here will recommend a cone type sure grip as being the best..
Last edited by minivan; 10/07/16 09:29 PM.
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Re: 741 742 489
[Re: pjc360]
#2170268
10/08/16 01:35 PM
10/08/16 01:35 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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what I would do is find/buy a good 742 sure grip in the ratio you want & you're set. it would have the desired clutch type from the factory & highly likely that has not been swapped (if you see no springs in there you are golden). I highly prefer a ring gear felpro gasket as opposed to using RTV. some heavy parts house gear oil (I forget the weight) with a bottle of furd sure grip additive. set your axle end play to .010
live every 24 hour block of time like it's your last day on earth
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