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Technical CHASSIS, Modern Axles for Ford Banjo Rearend - Redux w/ pics

Discussion in 'The Hokey Ass Message Board' started by modernbeat, Apr 17, 2003.

  1. modernbeat
    Joined: Jul 2, 2001
    Posts: 1,241

    from Dallas, TX

    Okay, so this wasn't the place to experiment with firewall settings. So, here it is again, this time with the pics hosted somewhere more reliable.

    What follows is another one of those great tech features in a hard to find magazine. This one, a how to put a quick-change in a late model Sedan by adapting modern axles to an early Ford banjo rear end, has a different purpose today in this era of hefty OHV engines in our '30s Ford bodies with vintage running gear. This was taken from a November 1960 Hot Rod, so it's not exactly new-tech. NealinCA sent me this after the subject came up on the HAMB. So, without further ado, here it is...........

    Quick-Change for Late Sedans

    Early Ford rear axle housings, a quick-change center section and late Ford axle shafts fit together with a little ingenuity to make an ideal rear end for hot competition machines

    Photo story by ERIC RICKMAN

    There are a lot of pieces from Henry Ford's older models that just never lose popularity and unless we miss our guess, the one piece which will be around the longest is the '48 and earlier Ford rear axle unit. The reason for the popularity is, of course. the fact that quick-change center sections are available to fit the early Ford housings. Competition machines have to be able to vary gear ratios to fit track, tire, horsepower and driver so the quick-change will be here for a while and so will the early Ford rear axle.

    Despite quick-change adaptability, there are a few drawbacks to the early Ford rear axle. Axle drive gears form the inner part of the axle shaft so the whole rear housing must be disassembled to change axles. Also, these early Ford axles have a tapered outer end that fits into a hub drum unit which is usually "mean" to remove. The hubs are not of the safety variety so if an axle breaks, the car often loses a wheel and this is not a good idea at speed. Last but not least, the axle shafts designed for early Fords just don't have enough "meat" to hold the horsepower being turned out by today's big over-head V8's.

    A logical solution for competition machines all the way from dragsters to Gas sedans would be to combine the quick-change features of the early Ford axles and the easy change, safety hub, stronger axles featured in later cars. Just so happens that is exactly what we had in mind to show you. We contacted Irving Cohen at Wedge Engineering in Gardena, California, for pictures and information so here is how the job is done.

    Two rear axle assemblies are needed to make the conversion, a '48 or earlier Ford unit and a '49 to early '51 Merc axle assembly. If you plan to use a quick-change center section, ratios can, of course, be varied but if a quick-change is not planned, select the gear ratio best suited for your car when buying the early axle unit. The reason for the '49 to early '51 Mere rear axle is to obtain the 5.5 inch bolt circle on the axle flange which will fit early Ford, wide-base Imperial or magnesium wheels commonly used for competition. These rear ends also use a larger outer bearing than Ford rear end axles of the same years. Ford pickups of the early fifties vintage also use the 5.5 inch bolt pattern and have the added advantage of more strength in the shaft itself so are the best for an all-out competition car.

    Disassemble the two rear ends and carefully check the following parts from each. Early Ford: everything except the axle shafts, hubs, and brake assemblies. Merc or late Ford pickup: axles, axle gears, backing plates and brake assemblies. Replace any bearings or other pieces not in perfect condition. Also, the outer portions of the Merc axle housing will be needed. 'The best way to attack this item is with an acetylene torch, cutting them next to the spring seat, which will leave plenty of material for machining in a lathe.

    The early Ford housings must also be cut so that the later housing flanges can be welded to them. The early housing and the late housing ends must happens be machined to give a combined length of 26.5 inches (flange to flange) so that the Merc axle shafts will fit. If a narrowed rear end is desired, this is the time to make the extra cut. The axles will then also have to be cut and resplined. The housing pieces are next welded together to form new housings for the Merc shaft. One hole on the inner end of the early housing should be positioned to align with the flat portion on the Merc outer flange so that the backing plates will be properly aligned when installed.

    Next comes the job of adapting the Merc axle drive gears to the Ford ring gear and spider gear carrier. Early Ford ring gears and carrier are one piece and are hardened steel so must be annealed when machining is required. Remove carrier bearings and heat the inner part of the ring gear to a cherry red as quickly as possible so that the heat will stay toward the center of the gear. Allow to cool slowly and the gear can then be easily machined. Machining operations required on the ring gear are also needed for the other half of the carrier but it is not hardened like the ring gear so does not need to be annealed. Three cuts are needed on each piece. The center of each piece must be bored out to a diameter of 1.625 inches and a depth of approximately 15/16 inch to accept the hub of the Merc axle gear. This hole is not bored all the way through the pieces since it would leave a thinner shell to fit inside the carrier bear-ing. The second cut is to enlarge the remaining part of the bore by .020 inch so that the Mere axle shafts will slip through into the axle gears. The third cut needed is to remove .035 inch material from the inner face of the carriers against which the axle gear rides. This is necessary to spread the thicker later axle gears .070 inch wider so the early spider gears will fit between them.

    Merc axle gears will not fit in the early carrier in stock form since they are approximately 3/8 inch larger in diameter than the space available. So the gears are simply ground down in diameter so that they will fit into the carrier bore with ample clearance to prevent bind. The amount removed is just about equal to the beveled amount on the back side of the gear. The reworked gears will now fit into the enlarged bores in the carrier and the early spiders, although of slightly different tooth angle and size than the axle gears, will fit between them just right.

    The next step is to determine whether the differential should be locked or left unlocked. If unlocked, you are now ready for assembly but if you desire to lock them for use in an all-out drag machine, the spiders must be modified to prevent differential action. This can be done in two ways. The common method used for many years was simply to arc weld the spider gears so that they wouldn't turn. A new and better method is to install a pair of spider gears made by Wedge Engineering that have only two full teeth on each side of otherwise blank gears. The teeth lock the axle gears together while the blank area prevents turning. Only two of the four spider gears need be replaced with these special locks and they can be removed at any time should the owner wish to "unlock" the differential.

    Now all that remains is to assemble and install the rear axle unit in the car. If used in a car with an open driveshaft, the front of the early Ford center section or quick-change will have to he converted by using a pickup hearing retainer or other available pieces. If used on a chassis with semi-eliptical leaf springs, pads will need to be welded to the housing at the proper spacing. Whatever the application, there is a way to make the pieces fit, and the advantages are many.

    Spring perch end of early Ford housing being cut off in the
    lathe. Notice that cut is made exactly at the weld point.
    New perches to match car it's used under are added later.

    These are the parts of '48 and earlier Ford rear end which
    are saved for conversion. Note spring perches have been cut
    off. However, a complete rear end is needed to start with.

    This is what you need from 1949-50 or early '51 Mercury rear
    end assembly. Check '51 wheel stud pattern. Only ends of axle
    housing are retained. Check bearings at this time.

    Thrust bearing face of ring gear must be heated to soften
    surface hardening as a cut must be made across this face.
    Try to confine heat to center area as much as possible.

    Center of Ring gear is bored out to 1.625 inch and
    approximately 15/16 deep to accept hub of Merc axle gear.
    .002 to .003 inch clearance is needed here. A .035 inch cut
    is taken on thrust face.

    Spider gear carrier housing must also be bored to take Merc
    axle gear. It needn't be heated since it hasn't been surface
    hardened. Thrust bearing face was machined. Use same specs as
    ring gear.

    Outer diameter of the axle gears must be ground down to permit
    gears to fit into carrier housing. Approximately 3/16 inch of
    material is removed.

    Reason for grinding the outer diameter of the gear is now
    quite apparent. Free-hand grinding on a bench grinder is
    sufficiently accurate. Be sure that the gear is free to
    rotate in the housing.

    Completed housing showing Merc bearing carrier housing end
    welded to a Ford axle housing. Merc ends are cut to length
    in lathe so matching faces are aligned.

    The rear end assembly may be used with stock center section
    and a wide range of early Ford ratios or with quick-change,
    as shown. Circle of Safety retainers, featured in the April
    '60 issue of HRM, are recommended. This particular installation
    is in Wedge Engineering '55 Chevy two door D/Gasser; it turned
    163 mph at Bonneville.
    kidcampbell71 likes this.
  2. Petejoe
    Joined: Nov 27, 2002
    Posts: 10,655

    from Zoar, Ohio

    Great article! thanks for sharing. Now that you have pics its time to print it out.

    A Streetrod has a Smallblock up front and a can of Wax in the trunk.
    A Hotrod has a Flathead up front and a box of Tools in the trunk.
    Fred Offenauser
    Id rather be wrenchin- than shinin
  3. Thanks for the post 'beat! I printed it off at work today. I also found a rearend, just have to tell the guy what I will pay.
  4. Deal was struck!!!!! I have a 50 Merc rearend, does it make my ass look huge?

  5. modernbeat
    Joined: Jul 2, 2001
    Posts: 1,241

    from Dallas, TX

    Tman, I bought my first one for $10 as a pity purchase when a guy lured me 60 mile out of town with his story of flatheads and Merc cranks for sale. They were a big batch of barnacled and burnt blocks. Got my second (spare axles) from Honest when he decided to use the special Wilson Welding axle gears and go with slightly shorter nine-inch axles. FWIW, Honest is the one I envy.
  6. Lets just say I traded a slightly larger amount of parts for mine. I still came out OK. Deal was goo for both sides.
  7. atch
    Joined: Sep 3, 2002
    Posts: 4,583



    tech-o-matic, please
  8. Good story and pictures. I also did mine, but with 28 spline late Ford axles and bearing cups.
    Used the same procedures. One tip though, if you cut the ring gear with a carbide tool, it saves
    heating it to anneal it. Somewhere I have a disk with the newer feature on it as well as a cross
    sectional drawing of the spider carrier dimensions, if anyone's interested. Thanks for sharing the article.
  9. NealinCA
    Joined: Dec 12, 2001
    Posts: 2,882


    [ QUOTE ]
    One tip though, if you cut the ring gear with a carbide tool, it saves
    heating it to anneal it.

    [/ QUOTE ]

    Thanks for the tip on the ring gear/Carbide cutter. That part had me a little concerned.

    [ QUOTE ]
    Somewhere I have a disk with the newer feature on it as well as a cross
    sectional drawing of the spider carrier dimensions, if anyone's interested.

    [/ QUOTE ]

    I heve the parts to do the 50 Merc conversion, but I would be interested in the late model conversion as well.


    BTW, Modernbeat - I am glad you got the copy OK. Thanks for taking the time to make it available to everyone.
    kidcampbell71 likes this.
  10. modernbeat
    Joined: Jul 2, 2001
    Posts: 1,241

    from Dallas, TX

    HotrodA, what axle gears are you using? I'd love to be able to do the conversion on the next one with nine-inch axles instead of the Merc axles.

    Yeah, sorry Neal, I should have sent you a message that I got it. I appreciate you sending me the info.
  11. I used the 28 spline late model Ford axle gears, ground down. The late model stuff was from a 69 Cougar. Still looking for the disc and pics. Been on the road for 8 years with no problems.
  12. modernbeat
    Joined: Jul 2, 2001
    Posts: 1,241

    from Dallas, TX

    Tech-O-Matic please...
  13. [ QUOTE ]
    One tip though, if you cut the ring gear with a carbide tool, it saves
    heating it to anneal it.

    [/ QUOTE ] Carbide wasn't readily available in 1960.Now they are dirt cheap,compared to all the time and hassles they can save.Might as well use technology when we can.
  14. modernbeat
    Joined: Jul 2, 2001
    Posts: 1,241

    from Dallas, TX


    Tech Time for this....
  15. NortonG
    Joined: Dec 26, 2003
    Posts: 2,117

    Member Emeritus

    This defenitly needs to be in the tech o matic. I'm not to this stage with my car yet but it will be good to have around.
  16. Elrusto
    Joined: Apr 3, 2003
    Posts: 1,285


    Oh yeah, definatly tech worthy!!!
  17. raven
    Joined: Aug 19, 2002
    Posts: 4,614


    Is it possible to cut off the ends of an 8" or 9" and weld them to the tubes?
    Then shortend and re-spline the later model axles?
    Has anyone done this?
    Pics, procedures?
  18. Paul
    Joined: Aug 29, 2002
    Posts: 15,066


    great post!

    that kiddies, is traditional hot rodding.
  19. Steve
    Joined: Mar 5, 2001
    Posts: 1,010


    nice article thanks. if you go to I have scans of an article from street rodder on basically the same conversion. they are labeled wrong the say 9in in banjo but its not its the 49 merc axles.
  20. modernbeat
    Joined: Jul 2, 2001
    Posts: 1,241

    from Dallas, TX

    Update links to images...

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    IronFord, bct and kidcampbell71 like this.
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