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Help on rear end

Discussion in 'F-J-M: Volare, Diplomat, etc, 1977-89' started by Rogue, Jul 13, 2016.

  1. Rogue

    Rogue New Member

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    ok so I have these to casting numbers
    2723676
    23258

    Ok it's a 7.25 rear end and it's got 2.76 in it I'm just curious if it's the original rear end
    It's 77 Plymouth Volare with a new high compression 360
     
  2. valiant67

    valiant67 Rich Corinthian Leather
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    What was the original engine?
    The 7.25" rear axle is weak and only found behind the slant 6 and some 318s.
     
  3. Rogue

    Rogue New Member

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    It was a slant 6 it's got them low gears so I kept it for gas mileage reasons
     
  4. valiant67

    valiant67 Rich Corinthian Leather
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    The 2.7 ratio was standard with the slant 6 and an automatic transmission.
    you should be able to find a much stronger 8.25" axle or even an older B body 8.75" axle when the 7.25" axle breaks (which it almost certainly will behind the 360). Finding economy rated gears like 2.7 (or the common 2.2 used in later 8.25" axles) should not be hard.
     
  5. ImperialCrown

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    Is there anything currently wrong with it now? Noisy?
    If you want to try and get maximum life from the 7.25" differential gears/bearings, change the hypoid oil to a 75W-140 synthetic hypoid lube:
    68218657_420.jpg
    Drive the 360 gently as the 7.25" isn't made for the torque of this engine.
     
  6. gary longo

    gary longo Active Member

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    I had an 77 Aspen that had a 318, that I swapped a 360 into it....it had the 8 1/4" rear end in it,that held up to the motor pretty good. I had a .455 lift cam in it,so the motor had some grunt. So if the motor Isn't too radical...this should work for you. Otherwise look for a late 60's b-body 8 3/4" rear end :)
     
  7. Rogue

    Rogue New Member

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    I have done reading and I've seen that about 500hp is most you've wanted to put on a 7 1/4
    I'm sure my engine doesn't make that, if it is I'd be surprised like crazy, and yes I'm currently looking for a bigger rear end, and the rear end is quiet and seems fine I believe we changed the fluid in it when we did the engine change witch wasn't that long ago
     
  8. Rogue

    Rogue New Member

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    And my dad (we're both MOPAR guys) has a 65 valant and it has a upgraded 318 with some nice heads and intake and he runs a 7 1/4 in it o think it had 3.23

    Put that things had a lot of abuse and is still perfect
     
  9. valiant67

    valiant67 Rich Corinthian Leather
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    It's your money, but there is no way the 7.25" rear axle is good for 500 HP. A stock slant 6 with all of 90-95 HP will kill one.
     
    Adventurer55 and hemirunner426 like this.
  10. CudaPete

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    Been putting 300 HP from my modified 318 through a 7.25 for 15 years now. No problems. Got the 8.75 for when it breaks.
     
  11. floridaman2013

    floridaman2013 Active Member

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    Wow, it's 2 of these and 2 of those! I've repaired a few 7.25 rears, mainly spider gears. They are alright to a point! Take care of it and don't shift gears in snow or mud too fast and you should do alright for while. Look for a larger one though for security in the long run.
     
  12. 2012srtchallenger

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    had 77 aspen r/t, shoe horned 440 ,4 spd and 9.25 out of 77coronet police car. the 8.25 didn't break but swapped 9.25 to be sure.just had to relocate spring perches but fit in body fine.i agree you would have to be very careful with 7.25
     
  13. CudaPete

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    I haven't been careful....
     
  14. pt006

    pt006 Active Member

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    Just lucky!!!

    I've changed out [2] 7.25's rear ends. Both were small blocks. Both were severely abused. Both had blown up spider gears which got in between the ring and pinion gears. Need I say what else went wrong?
     
  15. floridaman2013

    floridaman2013 Active Member

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    Been there, done that!That's why we advise what to do is change it to a better Rear!
     

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