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Scored a 9 inch out of an early bronco

Discussion in 'The Hokey Ass Message Board' started by 74bowtie, Mar 26, 2012.

  1. 74bowtie
    Joined: May 18, 2010
    Posts: 257

    74bowtie
    Member

    I finally found a rearend to use in my roadster pickup, it came out of a pre 1977 Ford Bronco, I measured it at 58 inches between the wheel mounting surfaces. I don't know to much about it, someone had wrote posi on it in but it does not work properly I will know more when I take it apart.

    I don't see s tag on it to get any other info off it, did Ford stamp any numbers somewhere on the housing to decode it better,
     
  2. 65COMET
    Joined: Apr 10, 2007
    Posts: 3,086

    65COMET
    Member

    No numbers stamped to verify what it is.It could be a Traction-Lok being that it came from a Bronco.
     
  3. 74bowtie
    Joined: May 18, 2010
    Posts: 257

    74bowtie
    Member

    There are no brakes at all on the rear end no drums, no shoes, just has the backing plates, how do i know what size drums to go with.
     
  4. Hnstray
    Joined: Aug 23, 2009
    Posts: 10,961

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    The drum friction surface diameter will be about a 1/2" or so smaller than the outside diameter of your backing plate. Usually there is a "lip" on the drum, a bit bigger than the friction surface, that rides inside the flanged lip of the backing plate. Whatever you come up with that is closest to an even number...i.e. 10" or 11" should be what you need to know.

    Ray
     
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  5. Not to be the bearer of bad news, but that rearend is going to be a little wide for your rpu. Mine nine inch is at 53" and it sits about three and a half inches from the body.
     
  6. phat rat
    Joined: Mar 18, 2001
    Posts: 4,308

    phat rat
    Member

    Unless your 9" is narrowed you're measuring between the backing plates. 74bowtie is measuring wheel mounting surface to wheel mounting surface
     
  7. Deuce Roadster
    Joined: Sep 8, 2002
    Posts: 9,520

    Deuce Roadster
    Member Emeritus

    [​IMG]

    Look at your axle bearings. If you have the small bearing ... you need the 10 inch brake drums and backing plates. IF you have the larger bearing ... you need the 11 inch brake drums and backing plated ( like a late 60's to early 70's F-100 )

    If your Bronco is a 1977 ...
    it should measure 58 inches wide ... from the wheel mounting flange to the wheel mounting flange.
     
  8. pincher
    Joined: Sep 12, 2007
    Posts: 378

    pincher
    Member
    from Saginaw

    I have a early Bronco rear in my Model A, when i tore the rear apart it had 411 gears in it, rear end fits great on my A. The drums are 10" Good luck with the build...........PINCHER
     
  9. al bundy
    Joined: Jan 4, 2007
    Posts: 128

    al bundy
    Member
    from bay area

    the early broncos had the narrowest rear end ,,,and if those backing plates are 10 in drum by 2.5 wide.. they are the same backing plates used on early shelbys..$$$
     
  10. phat rat
    Joined: Mar 18, 2001
    Posts: 4,308

    phat rat
    Member

    66-77 Bronco is 58"

    78-86 Bronco is 65 1/4"

    57-59 Ford is 57 1/4"
     
  11. Beau
    Joined: Jul 2, 2009
    Posts: 1,884

    Beau
    Member

    No.
     
  12. The37Kid
    Joined: Apr 30, 2004
    Posts: 26,288

    The37Kid
    Member

    If you have a bare housing what would the flange to flange width be on a Bronco? [​IMG]
     
  13. Hnstray
    Joined: Aug 23, 2009
    Posts: 10,961

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    Remedial Reading Classes @ 9:00 am sharp, Tuesday. Get some rest.


    Ray
     
  14. I have an early bronco rear also and they're small bearing, 10" or 11" drum and 28 spline. Mine came in pieces, housing, backing plates, shafts and then I found a 3.00 center chunk for it.
     
  15. Aquaroscoe
    Joined: Apr 13, 2006
    Posts: 315

    Aquaroscoe
    Member

    Mine was 3:5 posi, small bearing, 11" 28 spline They are very popular with late 30/early 40 installations.
     
  16. malkintent
    Joined: Sep 3, 2007
    Posts: 442

    malkintent
    Member

    [​IMG] Early Bronco Rear Axle School

    Let's cover some basics. The rear end refers to the entire rear axle assembly. The different parts of the rear end are the brakes, axles, axle housing, and the third member. The most common question we are asked is "How do I tell if I have a large or small bearing rear axle?" You can easily identify if you have large or small bearing axles by examining the ends of the axle housing.

    Photo 1 shows a small bearing axle housing. If you look close at the housing right where it meets the backing plate, there is no noticeable size invcrease where the axle bearing pocket is. Photo 2 and 3 show a large bearing axle housing and you can see a noticeable size increase where the axle housing meets the backing plate. If you have loose axles laying around, you can simply measure the outside diameter of the bearing. The small are 2.835" or just under 3" and the large are 3.150" or just over 3".

    [​IMG]
    There are 4 different sets of rear axles that would have come stock in 66-77 Broncos. The original applications are as follows:
    1. 66-75 small bearing,
    2. 66-75 large bearing,
    3. 74-75 medium duty large bearing, and
    4. 76-77 large bearing.
    Each of these sets have a driver and a passenger side axle. Each of these sets use corresponding backing plates and brake drums. The backing plates and drums are particular to each set and are not interchangeable with the exception of the 66-75 small bearing and 74-75 medium duty large bearing using the same brake drum.

    So, how can you identify which large bearing set you have? it can be narrowed down this way: The inside diameter of the Bronco rear brake drum is approximately 10" or 11". So, if you have a large bearing and a 10" brake drum, you have what we call a 74-75 medium duty setup. That leaves us with the 66-75 large and 76-77 large. Both use an 11" brake drum. The 66-75 uses a narrower drum and corresponding brake shoes. We identify this as 11 X 1 3/4". The 76-77 uses an 11 X 2 1/4" drum and shoe. Note the difference in the backing plates * in photos 2 and 3. Photo 2 shows a 66-75 large bearing with 11 X 1 3/4" brakes. Photo 3 shows a 76-77 with 11 X 2 1/4" brakes. If you look close you can see the backing plate of the 66-75 appears wider. Please note that all of the original axle sets were 28 spline. See Photo 4. With an increase in spline count comes an increase in outside diameter of the axle and so you get an increase of strength. A very common upgrade is to install a set of 31 spline axles. All that is necessary to do this is a set of axles and a new differential and we would recommend a third member rebuild kit. 35 spline axles are another step up in the strength department but usually require a new differential housing. The 35 spline axle is common for the extreme rock crawlers.

    The third member, also known as the differential housing, hogs head, and chunk, holds the differential, ring and pinion gears, and bearings. This is the part that bolts into the center of the axle housing. See photo 5. You have three choices of gear ratios that were stock. They would be 3.50 which is the most common, 4.11 and 4.56. There are many other ratios that can be used as well. The differential refers to the ring gear carrier and came stock either open or limited slip "posi" type. There are numberous upgrades such as Detroit Locker, ARB air locker, electric lockers, etc.
     
  17. malkintent
    Joined: Sep 3, 2007
    Posts: 442

    malkintent
    Member

    props to wild horses4x4.com for the previous post!!
     
  18. 74bowtie
    Joined: May 18, 2010
    Posts: 257

    74bowtie
    Member

    I do have the complete rearend the only parts missing are the brakes, no shoes or drums. I measured from axle flange to flange and Came up with 58 inches.

    A lot of great information from everyone, Thank you.
     
  19. Gabby
    Joined: Apr 14, 2007
    Posts: 217

    Gabby
    Member

    My son just delivered to me Bronco rear he found in scrap metal yard. It is a posi unit, haven't checked ratio yet. They cut it out for him, total cost $75 SCORE. Going in a model A PU
     
  20. Drums can be a B...to find!! I redrilled 78 Ford PU backing plates to fit, had to weld up the holes. Centered good though, then all the 78 PU parts fit. Tucked the whole assy. under a 40 Chevy coupe,had room for 15x8 rally wheels
     
  21. Fenders
    Joined: Sep 8, 2007
    Posts: 3,922

    Fenders
    Member

    Posts 7 and 18 both 58" but one is WMS other is axle flanges......
    I am keeping a list and would like to know which is correct.
    Thanks.
     
  22. Beau
    Joined: Jul 2, 2009
    Posts: 1,884

    Beau
    Member

  23. Speadfreak1
    Joined: Jan 19, 2008
    Posts: 32

    Speadfreak1
    Member
    from Wisconsin

    I too just scored an early rear for a whopping $125. Unit was complete drum to drum with a 3.50 locker carrier. The guy I bought it from is a mud dragger - blows my mind that he didn't know what he had.
     
  24. Beau
    Joined: Jul 2, 2009
    Posts: 1,884

    Beau
    Member

    In LaCrosse?
     
  25. 6-71
    Joined: Sep 15, 2005
    Posts: 539

    6-71
    Member

    Yes I did the same thing.I found 11" brakes from a later Bronco.I was at the LKQ yard in St.Pete FL. someone had removed the center section,the backing plates were just hanging there,brand new wheel cyls.shoes and hardware,the drums were in excellent condition.I think I paid $40.00 for the whole works. The center hole is the same size as the earlier bronco,so it centers well,I just redrilled the bolt holes.I drilled the axles and drums to chevy bolt pattern. I have one of these rear ends under my 39 chevy coupe,with 15x8 ralleys and 275-60-15 tires.It is actually a little too narrow.my tires just touch the inner fenders when making a sharp turn into a driveway etc.
     
  26. rottenleonard
    Joined: Nov 7, 2008
    Posts: 1,950

    rottenleonard
    Member

    I just replaced all of the brake hardware,drums and shoes in my late 60's bronco rear I got for my next build, rockauto had everything, cheap too.
     
  27. I have 3 of those rear ends, one in the t-bucket, one in the Henry J and one spare. I got drums from Autozone but shoes from a different auto parts place which name escapes me at the moment.
     
  28. 6-71
    Joined: Sep 15, 2005
    Posts: 539

    6-71
    Member

    Our local Auto zone quoted me $99.00 each for drums,If they could get them(they couldn't) and I would be damned if I would pay $99.00 each for them.
     
  29. I paid 34 each I think, I know napa and advanced auto couldn't get them or the shoes, auto zone couldn't get shoes either.

    I think Bronco Graveyard wanted 300 for everything including backing plates.
     
  30. tommyd
    Joined: Dec 10, 2010
    Posts: 11,320

    tommyd
    Member
    from South Indy

    Will those axles be 5 on 5 wheel stud spacing and not 5x4.5?
     

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