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Projects Switching from 7.25" to 8" rear end,help

Discussion in 'The Hokey Ass Message Board' started by StarDiero75, Sep 20, 2017.

  1. StarDiero75
    Joined: Jan 15, 2017
    Posts: 170

    StarDiero75
    Member

    Howdy everyone,

    So I gots a 65 Ranchero with a 200, 3spd, and a rear end that's getting worse. It's got a decent amount of play and I gots what sounds like crap dropping in the back when doing 50+mph (specifically on the passenger side). It's a 7.25" and I'm switching to a 8", out of a 66 Mustang. Is there anything I need to do (excluding brakes) other than drop out and drop in? Like driveline mods? Leaf spring adjustments? Crap like that. Please help, the noise is getting worse and it's my daily driver and the last thing I need is to have a bearing lock up on me and really leave me stranded.

    Thanks guys!
    Ryan
     
  2. StarDiero75
    Joined: Jan 15, 2017
    Posts: 170

    StarDiero75
    Member

    Also, are there any issues with keeping the 4 lug in the front and having 5 in the back, Other than keeping 2 spares? I just rebuilt the fricken front end and I aint doing that crap again for awhile.
     
  3. I think your front end lug pattern is just an easy swap to hubs and drums with 5-lug? Not a Ford expert, but the V8 cars had the 5 lug, and I am sure the basic suspension is identical.

    Since no direct experience swapping rearend in that vehicle, some general things to look out for. Perch width, is it the same? Pinion angle, needs to match the orig installation; you can get shims to adjust the angle. Total rearend width, the Mustang is probably close. Driveshaft length may or may not need modifications. Pinion U-joint may or may not match the driveshaft yoke size; but conversion U-joints are available. Shock mounts, are they on the U-bolt plates or rearend?
     
  4. Sheep Dip
    Joined: Dec 29, 2010
    Posts: 1,572

    Sheep Dip
    Member
    from Central Ca

    I believe your yokes will be different, that means a driveline modification for the new 8" yoke. Plus as mentioned check spring perch centers for compatibility before you start.
     

  5. StarDiero75
    Joined: Jan 15, 2017
    Posts: 170

    StarDiero75
    Member

    If the perches are slightly off, how can that be fixed, easliy?
     
  6. evintho
    Joined: May 28, 2007
    Posts: 2,380

    evintho
    Member

    Measure carefully, cut off and reweld. If your welding skills aren't up to par, any local welding shop can do it cheaply.
    '66 Mustang rears are 57.25" wms to wms (wms = wheel mounting surface). It's a pretty simple swap. Shouldn't be too hard. As far as the front, do a search for '65 Ranchero 5 lug swap. There should be tons of into out there.
     
  7. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,333

    gimpyshotrods
    ALLIANCE MEMBER

    The front spindles are different for the 6-cylinder cars, in terms of how the backing plates mount, and the tie rod taper.

    They are geometrically identical.

    Scarebird makes a disc conversion that converts 4-to-5 in the process: https://scarebird.com/index.php?route=product/product&path=65&product_id=126

    The Mustang parts needed to swap to 5-lug-drums and a pair of tie rod taper spacers are not exactly rare, or expensive.
     
  8. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,333

    gimpyshotrods
    ALLIANCE MEMBER

    This is true too. The 6-cylinder Falcon uses a diminutive 1210 u-joint. A custom driveshaft will need to be made.
     
  9. NewGuyOldFord
    Joined: Jan 17, 2011
    Posts: 596

    NewGuyOldFord
    Member

    Gimpyshotrods is right. I did this swap and there was "bastard" u-joint to be found to connect the 6 cyl driveshaft to the 8 inch rear. I ended up welding one up with another driveshaft that I had made that had the right tranny yoke on it. Other than that, the spring perch spacing between mustang and falcon were identical.
     
  10. Flathead Dave
    Joined: Mar 21, 2014
    Posts: 3,968

    Flathead Dave
    ALLIANCE MEMBER
    from So. Cal.

    I did something similar when I did my V8 Pinto. The 1957-59 rear end pinched in perfectly. I did have to have the drive shaft cut down about 13 inches. I beefed up the front end slightly but was able to keep the front end as original with out going to larger hubs.

    I think in your case, if you can use your drive shaft, may be, just may be, change out the u-joint and slightly trim your drive shaft to length.
     
  11. StarDiero75
    Joined: Jan 15, 2017
    Posts: 170

    StarDiero75
    Member

    This is something that if I go to a driveline shop then they can do it right? I don't have any welding stuff, nor a rear yoke for a 8".
     
  12. StarDiero75
    Joined: Jan 15, 2017
    Posts: 170

    StarDiero75
    Member

    Did you have to trim the driveline at all to make it fit or just cut off the yoke and replace with the 8" one? I have another driveline but it's set up for a FordOMatic and a 7.25 in the rear. Mine is a 3 spd man.
     
  13. NewGuyOldFord
    Joined: Jan 17, 2011
    Posts: 596

    NewGuyOldFord
    Member

    I had a fordomatic driveshaft. If I remember right the 8 inch was 3/4 - 1 closer to the tailshaft than the 7.5 was. I then did a V8 swap and had to start all over again. Sorry I can be of more help.

    Sent from my SM-N920V using The H.A.M.B. mobile app
     
  14. StarDiero75
    Joined: Jan 15, 2017
    Posts: 170

    StarDiero75
    Member

    Can I drive in the meantime with 4 in the front and 5 in the back? Other than having to carry 2 different spares theres no issue right?
     
    Alonzo "Lon" Wilson likes this.
  15. I put a Maverick 8" rear in a '77 Pinto cruiser wagon to take the power of a 5.0 and C-4 swap. Used the stock Pinto driveshaft with "bastardized" U-joints. Car still has the 4 lug front hubs and 5 lug rear. The 10" Maverick brakes worked fine with the front discs.

    Sent from my SAMSUNG-SM-G930A using The H.A.M.B. mobile app
     
  16. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,333

    gimpyshotrods
    ALLIANCE MEMBER

    No issues. You'll be fine.

    I ran a rock rig with 5-lugs on the front, and 8-lugs on the back for a long time.
     
  17. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,333

    gimpyshotrods
    ALLIANCE MEMBER

    A good shop should be able to modify the existing shaft to make this work. Worst case scenario, they would have to make a new shaft, with the requisite stuff on it.
     
  18. StarDiero75
    Joined: Jan 15, 2017
    Posts: 170

    StarDiero75
    Member

    Nice. I may do the disk conversion for the front since it's my daily and I also plan on getting power brakes as well so that'll work nicely.
     
  19. StarDiero75
    Joined: Jan 15, 2017
    Posts: 170

    StarDiero75
    Member

    Ouch on the worst case. What would you think a decent shop would charge to cut the rear yoke off and weld the 8" on? I tried calling a local one but they didn't answer. I'd like to know what is fair and what's a rip off, y'know.
     
  20. StarDiero75
    Joined: Jan 15, 2017
    Posts: 170

    StarDiero75
    Member

    Nice. What did you have to do to the u-joints?
     
  21. Sheep Dip
    Joined: Dec 29, 2010
    Posts: 1,572

    Sheep Dip
    Member
    from Central Ca

    Down here in Kalifornia last October I had the drive shaft for the 40 coupe made to go from a Turbo 350 GM to a Ford 8" and it was roughly $350 and change. I supplied the 350 yoke and they supplied the rest. They also balanced the whole completed assembly.
     
  22. StarDiero75
    Joined: Jan 15, 2017
    Posts: 170

    StarDiero75
    Member

    Oh crap, this might get expensive. So I have another driveline, the front is set up for a 2spd automatic and the back for the 7.25, can I flip the driveline and use my 3 spd man yoke on the small rear end side and the larger auto transmission yoke for the 8" rear end?
     
  23. Sheep Dip
    Joined: Dec 29, 2010
    Posts: 1,572

    Sheep Dip
    Member
    from Central Ca

    They should be able to make it for you. Just let them know you are on a budget and what you got to work with money wise. Definitely have new u-joints installed though
     
  24. oldolds
    Joined: Oct 18, 2010
    Posts: 3,408

    oldolds
    Member

    Balancing a drive shat can range from $75-$150. Depending on the shop and what they have to do to balance the shaft. It is money well spent. Cutting and changing the end maybe an hours time plus parts.
     
  25. If memory serves me right, I used a pair of 1310BC u joints in it. Try www.driveshaftspecialists.com to see a list and pix of what's available. The "BC" joints have 2 different widths to match different yikes to the driveshaft.

    Sent from my SAMSUNG-SM-G930A using The H.A.M.B. mobile app
     
  26. StarDiero75
    Joined: Jan 15, 2017
    Posts: 170

    StarDiero75
    Member

    I called them and the guy said $150 for cutting and welding the new 8" end on, I think that includes a balance. I'm hoping it does. I try to not let people know that I'm in a spot b/c that's when they take advantage of you. I'm 19, this is my daily, and I don't have a lot of cash b/c the car sucks it up.
     
  27. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,333

    gimpyshotrods
    ALLIANCE MEMBER

    That's a fair price.
     

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