Register now to get rid of these ads!

Technical 9” 3rd member

Discussion in 'The Hokey Ass Message Board' started by Firedup, May 18, 2019.

  1. Firedup
    Joined: Feb 2, 2018
    Posts: 116

    Firedup
    Member
    from Oregon

    72E71890-ADD2-4A05-8E9F-E7A4E498B0C8.jpeg A406F6F9-A878-4E03-BF40-B13CE8DA83FE.jpeg CAC9128D-44CD-4799-8D28-5639B7A34CBB.jpeg 5F16E047-11D9-433F-AF9D-1D63A9AE582E.jpeg So I picked up this 3rd member from a guy, it was advertised as a 4.4:1 ratio. I couldn’t pass on it for the price. Looks to be in good shape. Coming to closer inspection I see that it is stamped with a 42-10 ratio, witch should be 4.2 ratio. I’m curious about these oddball ratios and not a whole lot of information on them from the searching I’ve done. I plan on trying this 3rd member out with my gasser build. BBC 454 with TH400 tranny and roughly 30-31” tires. What do you guys know about these?
     
  2. Early Bronco 6 cly. ?
     
    Firedup likes this.
  3. squirrel
    Joined: Sep 23, 2004
    Posts: 41,958

    squirrel
    Member

    ring gear is from 1971 or later, according to the engineering number

    might work ok, I'd probably check the tooth contact pattern, inspect the bearings, and replace the differential with a locker or spool or something, depending on intended use
     
    Firedup likes this.
  4. RmK57
    Joined: Dec 31, 2008
    Posts: 854

    RmK57
    Member

    Early Broncos had either 4.11 or 4.56.

    Ford had a 3.91 and 4.30 for their hipo ratios but they should be in a N case carrier.
    Could be someone put that together from spare parts.
     
    Firedup likes this.
    Register now to get rid of these ads!

  5. saltflats
    Joined: Aug 14, 2007
    Posts: 9,121

    saltflats
    Member
    from Missouri

    Have you counted the teeth?
     
    sidevalve8ba and Firedup like this.
  6. Firedup
    Joined: Feb 2, 2018
    Posts: 116

    Firedup
    Member
    from Oregon

    Definitely a locker or spool in the future. I may just run it though
     
  7. That's why I placed question mark. Goggle can not always be trusted. That said. There are several other people asking the same question in regards to 4:20 gears. So they are out there.
     
    Firedup likes this.
  8. Firedup
    Joined: Feb 2, 2018
    Posts: 116

    Firedup
    Member
    from Oregon

    Not yet lol.
     
  9. Firedup
    Joined: Feb 2, 2018
    Posts: 116

    Firedup
    Member
    from Oregon

    I will count the teeth when I get a chance. o_O
     
  10. gimpyshotrods
    Joined: May 20, 2009
    Posts: 15,891

    gimpyshotrods
    Member

    For some reason, that seems to light up a memory of being a 2.75:1 gear.

    That would be 44-teeth on the ring, and 16-teeth on the pinion.
     
  11. ^^^^^ That did come up during the short while I googled 4:20 Ford gears.
     
  12. onetrickpony
    Joined: Sep 21, 2010
    Posts: 340

    onetrickpony
    Member
    from Texas

    That 4210 is part of the engineering number. You should have counted the teeth before you bought it.
     
  13. gimpyshotrods
    Joined: May 20, 2009
    Posts: 15,891

    gimpyshotrods
    Member

    If it is a 2.75:1 gear set, I have a 2.50:1 gear set, if you want to make it worse. :rolleyes::p
     
    swade41, mgtstumpy, Just Gary and 2 others like this.
  14. oj
    Joined: Jul 27, 2008
    Posts: 6,037

    oj
    ALLIANCE MEMBER

    That case isn't very strong, it has just the single web. I wouldn't spend any money on it to use in a gasser, it won't last long launching a big block.
     
  15. flamedabone
    Joined: Aug 3, 2001
    Posts: 4,350

    flamedabone
    ALLIANCE MEMBER

    Judging only by how thin the ring gear is, I'm betting it is a 2.87 or 300:1. Definitely a single spinner because the ring gear bolt area is flat instead of bumpy. I'll go one further and guess it is 28 spline, only because they are more common.

    I don't swear my information is 100% accurate, because sometimes I'm full of shit, but I bet it's pretty close.

    Hang on to it, you will need it for something someday.

    -Abone.
     
    mgtstumpy and Just Gary like this.
  16. Yep, the 'basic' part number, probably found on all ring gears regardless of ratio, although I suspect this particular number is for 9" axles only.

    The 'D' is the decade ('70s), '1' is the year (in this case, '71), the 'A' is generic Ford, and the 'W' is axle/driveshaft group. Then the 'standard/basic' part number from within that group, and lastly the 'A' is the first revision.

    If it was a body part, it would be six numbers instead of four for the 'basic' number, with the first two identifying the specific model (Ford, Mustang, Fairlane, 2-dr, 4-dr, etc), and may have a color indication after/in place of any revisions.

    Some mechanical parts (primarily distributors and carbs) would have the basic part number, then an additional number denoting the specific application, either stamped in or on a separate tag. Some OEM-installed engines/transmissions would also have a partial VIN stamped on them, but not all.

    Also keep in mind that Ford didn't change casting or part numbers yearly; they merely denote the first appearance of that particular part. As long as the part was substantially unchanged, a part would keep the same number.
     
    Last edited: May 18, 2019
    deucemac, oj and gimpyshotrods like this.
  17. Charlietruck62
    Joined: Apr 2, 2019
    Posts: 9

    Charlietruck62

    As has been said the D1AW 4210 A is the engineering number that tells me it was designed in 1971. Probably used for several years thereafter until the next redesign. The C6AW number was designed in 1966 and used for many years and the case was done in 1967 etc. Count the teeth and divide by pinion teeth. From looking at it its probably a 2:75 or so gear from a 70's ford car and not a locker.
     
  18. Ive found 390 and 411 ratio 9 inch in old late 50's and early 60,s stick shift cars & trucks. the auto trans had 300 and a six auto a 350. the FE stick trucks had 325 ratio.
     
    anothercarguy likes this.
  19. big duece
    Joined: Jul 28, 2008
    Posts: 5,403

    big duece
    Member
    from kansas

    If they were 4:11 or lower, that ring gear would be awfully dam thick...
     
    Last edited: May 18, 2019
  20. DIYGUY
    Joined: Sep 8, 2015
    Posts: 569

    DIYGUY
    Member
    from West, TX

    I see a bunch of rust in photo 3. I wouldn’t use them.
     
  21. Marty Strode
    Joined: Apr 28, 2011
    Posts: 3,899

    Marty Strode
    Member

    We ran a 7.33 gear in a circle track car, it was real thick !
     
    swade41 and gimpyshotrods like this.
  22. Kan Kustom
    Joined: Jul 20, 2009
    Posts: 2,198

    Kan Kustom
    Member

  23. big duece
    Joined: Jul 28, 2008
    Posts: 5,403

    big duece
    Member
    from kansas

    Never heard of a 4.4:1 ratio, so the selling was all wet. Count the teeth.
     
  24. Jalopy Joker
    Joined: Sep 3, 2006
    Posts: 21,658

    Jalopy Joker
    Member

    would not run as is for that ride - never seen a 9" with that type of webbing but, I am no expert - kevinstang.com is good source for Ford differential info
     
  25. saltflats
    Joined: Aug 14, 2007
    Posts: 9,121

    saltflats
    Member
    from Missouri

    People have different ideas of what a gasser is. ;)
     
  26. raven
    Joined: Aug 19, 2002
    Posts: 4,062

    raven
    Member

    I’ve got a 4:11 in a locker third member if you’re interested.
    I even have a 4:56, too.
    r


    Sent from my iPhone using H.A.M.B.
     
    Firedup likes this.
  27. Firedup
    Joined: Feb 2, 2018
    Posts: 116

    Firedup
    Member
    from Oregon

    I was after some 4:11 gears . I saw the 4.4 and 4.2 ratio and thought I’d give it a go. Obviously I know nothing about them:confused: I think I did alright for $120
     
  28. choffman41
    Joined: Oct 30, 2012
    Posts: 2,245

    choffman41
    Member

    There may be another stamping on the ring gear designating the tooth count.
     
  29. Ericnova72
    Joined: May 1, 2007
    Posts: 81

    Ericnova72
    Member

    IMO you got hosed...not the gear you were told it is, weak single rib case, open differential....not even worth $50 bucks
     
  30. RmK57
    Joined: Dec 31, 2008
    Posts: 854

    RmK57
    Member

    If there 28 spline axles your 454 is going to make short work of them, even shorter if you have slicks. The C7AW case is probably the weakest one in the 9 inch pecking order also.
    One good thing is your using an automatic.
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2020 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.