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School me on Ford 9" axles, center sections

Discussion in 'The Hokey Ass Message Board' started by Leadsled51, Apr 22, 2012.

  1. Leadsled51
    Joined: Dec 21, 2001
    Posts: 333

    Leadsled51
    Member

    I need some schooling. Building a nostalgia gasser Falcon, and it came with a 9" out of who knows what. I've already ground off all of the useless brackets, and I'm getting ready to get the housing mounted into the car. Since it will be drag only, what are the pros and cons of using a 28 spline versus 31 or 35? Are they bigger? If you bought 28 spline axles from, say Moser, or Currie, are they strong enough? I'm shooting for between 400 to 450 H.P.

    What about the center section....would I be better off running a spool? Or better of running something else, like a locker, or limited slip?

    What gear? How would I go about figuring out what I would need? (4:11? or ?)

    I need some good drag racers advice.....this car will not see the street at all. Thanks!
     
  2. Leadsled51
    Joined: Dec 21, 2001
    Posts: 333

    Leadsled51
    Member

    excellent info, thanks! a good place to start
     
  3. boogeracng
    Joined: Feb 13, 2008
    Posts: 343

    boogeracng
    Member
    from Eureka,MO

    Tire size? Stick? Auto? Transbrake? Converter stall rating? Cam? Car weight? ??????????????????
     

  4. 61falcon
    Joined: Jan 1, 2009
    Posts: 772

    61falcon
    Member

    i ran 28 spline stock axles in my falcon running high twelves with drag radials and a manual trans. they had alot of passes on them before i found a very slight twist in the splines. i bought aftermarket 28 splines axles from moser and at the last inspection they were still perfect. the car weighs 2900 lbs and now runs 12.50's.
     
    Last edited: Apr 22, 2012
  5. Leadsled51
    Joined: Dec 21, 2001
    Posts: 333

    Leadsled51
    Member

    Tires are pie crusts 28"tall, 8" wide.....stick tranny, not totally sure of cam yet, thinking car should be around 2800lbs (total guess but should be close) Its a 63 Falcon, with interior totally stripped. Shooting for around 400-450HP when engine is done.
     
  6. usually the more splines the more strength in the axle.
     
  7. Slag Kustom
    Joined: May 10, 2004
    Posts: 4,312

    Slag Kustom
    Member

    with weight and power run the 28 spline axles. there is no need for the added weight of 31 or 35 spline axles.


    friend with a amx put a 9" in and ran 35 spline axles cause all the parts where the same cost. car went slower due to all the reciprocating mass
     
  8. rustednutz
    Joined: Nov 20, 2010
    Posts: 1,580

    rustednutz
    Member
    from tulsa, ok

    I'd build a 31 spline set up. If, as you say, drag only, go with a spool. You know eventually that 450hp won't be enough, so build the rear right the first time. With 2800lb car 31 spline should work to 550-600hp. There are plenty of websites for figuring gear ratio based on tire size, max rpm, desired mph. If you want to hit cruise night occasionally a locker works better for strip/street. Spools on the street suck. Just a few things to consider. I'm building a 39 Olds coupe gasser with BBC and tunnell ram that will still be streetable and I'm going 35 spline, aftermarket center section with Detroit locker and 4.30 gears. Estimated weight 3100lbs. The only reason for my choice of 35 spline is eventually putting a blower on the BBC. Good luck with your Falcon.
     
  9. Moser, Currie, and Dutchman will all tell you they don't recomend there 28 spline for Drag racing if your going to run slicks. N.H.R.A. says anything running 10.99 or quicker mandatory after market axles per rules and reg's 2:11 . Do yourself a favor and just install a Spool with 31 spline axles. Your car is light enough 35 spline is a waste of $$$ also you don't have enough horse power to need them. We run a 68 A.M.X. at 2200 lbs and 680 hp at the tires with 31 spline, 28" tall 12" wide slicks and a spool. No problems yet after 8 years.
    The Wizzard
     

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  10. squirrel
    Joined: Sep 23, 2004
    Posts: 47,478

    squirrel
    Member

    31 spline with a spool and aftermarket axles....you can probably get away with a stock Ford center section, but you might consider a nodular if you have a few hundred bucks extra to spend on it.

    Gear ratio depends on what the car needs, you'd need to get all the details and estimate what the mph will be thru the lights, as well as the engine's rpm at peak power, then you'll probably want to experiment a little to see if more or less gear makes it go quicker.
     
  11. trksmth
    Joined: Feb 10, 2009
    Posts: 372

    trksmth
    Member

    X2 Well said!

    Each spline is worth 11%, so going from 28 to 31 is 33% stronger. But have your stock axles checked, if you are using them. Mike
     
  12. theHIGHLANDER
    Joined: Jun 3, 2005
    Posts: 8,120

    theHIGHLANDER
    Member

    I ran Moser 31 splines and their spool and carrier for nearly 500 passes in a 3545# braket racer making 725 engine HP. 5500 stall, brake, 10.5X29.5 Mickeys, 60' times averaged 1.41. Go with the 31s. Stock Ford centers will break with 500HP small blocks. Had a guy break 2 of em before he stepped up. It's ugly when it happens. The pinion will drive out the front of the case. Good advice above, build the axle for the future. You'll never be satisfied. FWIW, the 12bolt GM, and even the 8.8 Ford are more efficient for power delivery due to pinion placement. More of a bitch to change around, where a 9" can be dropped out and swapped in easily. Mostly worth the difference in power delivery. For an hour of work you can drop in a street gear and hit the cruise night with a 9". You will let us see the car, right? :cool:
     
  13. Leadsled51
    Joined: Dec 21, 2001
    Posts: 333

    Leadsled51
    Member

    Hey, I thought this thread was dead! I went ahead and got the 31 spline axles, and a spool. A buddy of mine gave me a nodular center section, and I did some research, and I am going to start with 5.14 gears. An old timer I know here at work used to run a Falcon in the early 70's and he said I would need at least that gear, maybe more! I'm building this one strictly for the strip, so like most of you said, I will probably want to go faster in the future, so I figured buy the better stuff now. I'll try and find a pic of it.
     
  14. Good move. With the description of your project I think you'll find 5;14 pretty deep. They are more like 1/8th mile gears for your package.
     
  15. Leadsled51
    Joined: Dec 21, 2001
    Posts: 333

    Leadsled51
    Member

    Well, I figured I had to start somewhere, the nice thing is they shouldnt be too hard to change!
     
  16. Leadsled51
    Joined: Dec 21, 2001
    Posts: 333

    Leadsled51
    Member

    Here it is....go easy on me!
     

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  17. A 5.14 gear will puke out about when you hit the 1/8th mile mark. This is just fine IF you're running 1/8th mile but if you plan on running the 1/4 run a 4.33 gear.
     
  18. Mattilac
    Joined: Oct 27, 2007
    Posts: 1,145

    Mattilac
    Member

    If you're starting from scratch, it's just as easy to go with 31 splines as it is 28, so definitely go with the beefier 31-spline axle. Same cost, stronger parts.
     
  19. Drive Em
    Joined: Aug 25, 2006
    Posts: 1,748

    Drive Em
    Member

    Just remember that if you have a small bearing 9" rear end, going to 31 splines will gain you a small amount of strength at the splines only. The axle size at the bearing will still be the same size as the 28 spline, actually it will be the same size as an 8" rear end. I would rather go with a big bearing 28 spline rather than a small bearing 31 spline axle. Skip 31 spline stuff and go right to 35 spline as they don't cost any more, and keep away from small bearing axles and housings.
     
  20. Buckster
    Joined: May 3, 2010
    Posts: 229

    Buckster
    Member

    I don't think a small bearing (1.378 I.D.X 2.8246 O.D./part no. RW207CCRA) will accept a shaft diameter to get you a 31 spline axle.
     
  21. You can have a 31 spline axle with a small end bearing housing and the axle is not necked down. It can't be! Moser will make you any performance axle you want for around $350.00.
     
  22. filthy frank
    Joined: Jan 25, 2008
    Posts: 541

    filthy frank
    Member

    a ford 31 spline diamiter is 1.333 , so the normal size bearing is a 1.531 inside diamiter x 3.150 outside diamiter big bearing , the longer the shaft , the easyer it will break .a lot of bearing manufacturers stopped making the small ford bearing , so if you can use a pair of 31 spline axles , go for it ! and use the big bearing .
     
  23. Drive Em
    Joined: Aug 25, 2006
    Posts: 1,748

    Drive Em
    Member

    Yeah, and that axle bearing will most likely fail in about 1,000 miles because of the ultra tiny bearings that are needed to have the small bearing axle O.D. With the big bearing axle I.D. Those conversion bearings are fine for drag racing but will fail on the street in a short time.
     
  24. Humm...

    Well maybe I ought ta' change 'em 'cuz day mus' be bad 'cuz day been in dare for over tree years and tousands of miles. :rolleyes:

    Oh and I race it and yes it's fast!

    You buy shit you get shit..... Build it once, build it right!
     

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