1946-47 Diff.

super651
super651 Senior Contributor
edited November -1 in HUDSON
What type of Diff. will fit under the 46 Hudson and only the spring pads would need to be relocated ?

It has an 8 and 3/4 mopar with 2.73 ratio now and i need to get a 3.56 -3.70 ( the mopar fits fine and is 60 inches wide from rim to rim mount flange)

Thanks toall Rudy.

Comments

  • [Deleted User]
    [Deleted User]
    Rudy

    I have one from a 1986 Iroc Camaro in mine. It fits perfectly, not sure of width.
  • super651
    super651 Senior Contributor
    Thanks Bad Hud.

    I failed to tell that i have a set of Magnum 500 wheels on it and they only fit Ford,Mopar,AMC.

    Do you know of a ford or amc that will fit ?

    Thanks Rudy
  • junkcarfann
    junkcarfann Expert Adviser
    You can get your ring and pinion changed by a rear axle shop. The aftermarket has 3:55 gears for the MoPar axle...I did just that to the MoPar axle in a 1940 I used to have.



    The cost will likely be close, and a lot easier, than putting in a new housing, as you already have the MoPar axle installed.
  • Unknown
    Unknown
    alot of the early-mid 70s 1/2 ton Dodge pickups have 3.55 or 3.91 8&3/4 rearends in them , shouldnt be hard to find a complete third member that you can drop in - shouldnt cost much either .
  • junkcarfann
    junkcarfann Expert Adviser
    The 8 and 3/4 mopar rear ends have three different models. One is #741, I cannot remember the others. The number is cast into the side of the third member.



    There are differences in the three, one difference being the number of splines on the axles, making interchange not a sure thing, so be careful. Also, the ring and pinions are not the same...I found out the hard way when I had a shop change the r & p of my 8 3/4 MoPar axle (#741). The ratio I wanted was not available for my version of the axle, but was for the other versions.



    Bottom line...be careful, do your homework before assuming interchangeability.
  • Unknown
    Unknown
    junkcarfann wrote:
    The 8 and 3/4 mopar rear ends have three different models. One is #741, I cannot remember the others. The number is cast into the side of the third member.



    There are differences in the three, one difference being the number of splines on the axles, making interchange not a sure thing, so be careful. Also, the ring and pinions are not the same...I found out the hard way when I had a shop change the r & p of my 8 3/4 MoPar axle (#741). The ratio I wanted was not available for my version of the axle, but was for the other versions.



    Bottom line...be careful, do your homework before assuming interchangeability.



    Any early 60s on up 8&3/4 all use the same spline axle , , in 1969 they went to a crush sleeve pinion and a fine spline pinion yoke, the center sections will interchange . when it comes to Mopars I did my home work long ago.
  • Unknown
    Unknown
    an 8&3/4 center section or two , ranging from 1962-1973
  • super651
    super651 Senior Contributor
    Thanks so much Stateline and Junkcar fann you both have been Great help on the Diff,Also the pictures are very helpful.

    HELP also is what MAKES THIS CLUB the BEST.

    Hudsonly Rudy
  • Ol racer
    Ol racer Senior Contributor
    FYI

    If you have not decided on a rear yet you might want to check out the Ford 9" Rear ends like I use (and even the newer 8.8 rears). Many have the same bolt circle(4.5) as Hudson.... They are very strong, yet light wt and vary from narrow to wide width. Posi's are easy to find too. Look at Bronco's and BroncoII to fit close. I also use the neat Bronco rear sway bar...
  • super651
    super651 Senior Contributor
    Ol Racer, The Ford 9 inch What did you have to change other than the Spring Pads ?

    Also on the Broncos What years ? Change Pads Only ?

    ( have been with stepdowns for so long the 46-47 is new to me)

    Thanks so much. Rudy
  • [Deleted User]
    [Deleted User]
    You can find 8 or 9 inch Ford rearends cheap its what has been used by drag racers for 40 years. There is any ratio you would ever need you find alot of stock rearends with ratios of 3.00 or 3.25 or for about a $125.00 you can buy another gear set
  • Ol racer
    Ol racer Senior Contributor
    Rudy,



    Regarding Ford 9"... They have removable pumpkins with 28 or 31 spline axles and they are Strong ...I have Ford 9" Posi's under my Terraplane and my Stepdown. I believe the very early Econoline ('67 -69) are the narrowest housings. Bronco's until 1988 had 9" then went to the 8.8 which are strong too but have integral gears; Ford trucks had 9" too but they have larger 5.5 bolt circle. Ford full size cars have 9" with disc brakes but wide housings. Additionally some years have un equal width tubes. I have used them as well with no problem.



    I never recorded the yrs Ford I got the housings from because its always a different width needed. I just go to the Wrecking Yard and look at the Fords until I find one with my desired width and 4.5 Bolt circle.



    The gears are usually 2.78 - 3.00 unless a real small motor or std trans may be lower. If you can find a '57 - '69 standard shift they will have 3.70 - 3.90. The Yoke flange bolts directly to Hudson U jnts. Of course flanges need cut off then re positioned. I set the housings side by side then weld the identical pinion angles. (be careful when welding dont overheat and distort tubes); If drag racing lower the angle more)



    The Posi Units are usually in the 'loaded' XL Vehicles, and they are tough too. I bought a clutch Kit and tore couple down just to find not worn.

    Emergency brakes are similarly connected.



    I have narrowed the housings at a local machine shop when could not find a real narrow one. Stock axles are shanked nicely so that they can be shortened and re-splined easily.



    The only weak link when racing is the pinion 'crush' collar (may) collapse and loosen pinion preload. This only happened once to a friend's 9 sec Camaro. To eliminate the possibility Ford sells a 'steel' pinion spacer in several different sizes..





    The early car or trk axles are 28 spline. I used to race them with 10"slicks with no problem .However all the newer ('80's & up) axles to be larger 31 spline.



    The Wheel brgs are installed with a 'Collar' on the axle acceptable to racing Regulation, however I 'tac' weld a couple spots inboard the collar for extra safety... I have used 10 & 12 Bolt Rears but they dont compare to the Ford 9"
  • Unknown
    Unknown
    Rudy, Randys Ring & Pinion should have whatever ratio for the mopar 8.75 , the head office is located at Everett Wa. but they do have a California and Tenessee parts depots. Phone # 800-297-6554 . At work we use them for R&P sets axles, install kits seals etc. Got an install kit for my 54 Hornet there too! If you are looking to replace whole assembly at 60 inches 71-73 Mustang/Cougar would fill the bill. Hudsonly Lou Cote
  • super651
    super651 Senior Contributor
    Chuck and Lou,Thanks so much ,you both have much Help for this Old Man (XXX Drag Racer)

    Now I will get to work so I can make the TURBO-262 Wake up at Blast-Off-Time. Hudsonly Rudy
  • Ol racer
    Ol racer Senior Contributor
    Rudy

    My Ford 9" Rears are narrowed more for real wide tires (slicks) so that measurement wont help but remembered I have a couple fresh narrow empty housings I found later stashed away.. One is 53 1/2 and the other 56 1/2 backing plate flange to flange (not axle flange) Additionally, I cut off shock brkt and use Hudson U Bolt Plate for shock....
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