1973 Mercury Comet Ford 9 inch Conversion

Discussion in 'Technical' started by Deerhog, Dec 10, 2017.

  1. Deerhog

    Deerhog Member

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    I am looking to swap my comet over to a Ford 9 inch rear end. Has anyone here done this and can help me out? The rear ends I am finding online are for mustang. The one I am looking is for a 1967-1970 mustang, will this work as far as driveshaft placement, width, and leaf spring perches? (The perches are easy to move anyway). If anyone has any experience in doing this it would be great to hear how this goes.

    I am also interested if anyone has a Ford 9 In for sale.. Thanks.
     
  2. dyent

    dyent Member

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    I used the same Ford 9" from 69 Mustang back when I had my 74 Comet. Spring perch location same, the overall width is approx 2" wider (1" per side), but you can compensate by using wheels with deeper offset. I actually had my rims center section moved 1", but again, looking for correct offset wheels would be easier! I used a Mustang driveshaft from my 65 Mustang which was larger in diameter than on Mav/Comets, but you may have to shorten it. Depends on the 9" yoke, there where 2 versions, short and long, so you would have to see what is on the 9" you are looking for.
    Are you purchasing a used unit or new? There is a company called Quick Performance that manufactures brand new Ford 9" housings the same widths as on our Mav/Comets and then you can use the same axles (providing they are OK). Charges approx. $295. you still would need the center section, but you can check out site below and can get complete set up too.

    https://www.ebay.com/itm/9-Inch-For...m33d5256be3:m:mkUhyaa6y0_XkgcaeXJ0brA&vxp=mtr

    you can have them custom make to whatever width for same price.......I purchased mine from them back in 2012. Several other members have purchased from them too, not sure about phone number, may have changed.
    Brydon Papenberg
    641-751-8060
    staticz2229@gmail.com

    David
     
    Last edited: Dec 10, 2017
  3. Deerhog

    Deerhog Member

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    This helps thanks.
     
  4. yellow75

    yellow75 MCCI Oregon State Rep Supporting Member

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    Thanks for the info dyent thats good to know, I have purchased other stuff from that seller and he is top notch
     
  5. Hotrock

    Hotrock Rick, an MCCI Member Supporting Member

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    Why are you moving to a 9" 3rd member? Is your 8" a 4 lug unit?

    Just some advice, do not make all these modifications at once. Install the 302 or 9" then road test the car for vibrations moans etc. Should you end up with a vibration or moan diagnosis becomes much easier when a single modification has been made rather than multiple.
     
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  6. Acornridgeman

    Acornridgeman MCCI Wisconsin State Rep Moderator Supporting Member

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    I used a 9" from a 57 Ford with a Bronco Traction Lok center. The 57-59 housing is a direct bolt on, but is about 3/4" wider on each side. The axles used 28 spline, which is why I went with the Bronco as that is also 28 spline. The one that threw me was when I put the stock length driveshaft back on and it was 1" too short. The Bronco center chunk had the shorter pinion yoke. Needed to buy the longer pinion yoke and swap that out to get the slip yoke installed to proper depth.
     
  7. Deerhog

    Deerhog Member

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    My car is a 5 lug unit. The reason I am switching is I am doing a 347 striker and a t5 swap and I don’t think the stock rear end that was originally powered by a 200 in line 6 will handle around 475 horsepower.
    What is the stock rear end called? If there is some heavy duty center sections with the gears I want and some beefy axles out there in the aftermarket by all means I will save some money and keep this rear end.
     
  8. Acornridgeman

    Acornridgeman MCCI Wisconsin State Rep Moderator Supporting Member

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    Stock is an 8", which is a very good rear end. But Ford put 9" in anything over like 250 horse. That tells me that if you are seriously going to be north of 300 horse - build a good 9" and be done with it.

    With the HP you are planning, maybe take a better look at using that T5. They have their weak spots too.

    JMHO .......... :)
     
  9. yellow75

    yellow75 MCCI Oregon State Rep Supporting Member

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    You are confusing some of us, if the car is stock and came with a 200 6 then it would have 4 lug axles, now if it had a 250 6 it would have 5 lug axles.

    If you are serious about wanting to change things up why not think about an 8.8 out of an Explorer and have disc brakes in the rear as well, lot easier to find and lots of after market support, less driving friction. May cost a little more but is a win win situation. Here is a little info on it.

    http://thefabricatorseries.com/search?q=explorer
     
  10. Deerhog

    Deerhog Member

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    The t5 will be upgraded for sure
     
  11. Deerhog

    Deerhog Member

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    Do you know what spline the explorers used
    How wide is the explorer rear end stock?
     
  12. Krazy Comet

    Krazy Comet Tom

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    AFAIK 1973 & up all had 5 lug... The four lug stuff is a '70-'72 6cyl feature...
     
  13. RMiller

    RMiller My name is Rick

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    I have always wondered why nobody uses the 8.8 out of the 94-98 Mustang GT. They are plentiful, have disc brakes and should have a trac-loc. Sure, the Explorer had 31 spline axles but how many of our cars really need them? The width is pretty close and either one will require some welding.
     
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  14. Deerhog

    Deerhog Member

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    I’m pushing around 475 hp so I will take the 31 splines. Also niether the mustang or the explorer have the gears I want so I will be getting a new center section for both of them. The explorer axle is cheaper too.
     
  15. Deerhog

    Deerhog Member

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    What is the bolt pattern for the front stock. It’s 5 lug.
     

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