1. Registration trouble? Please use the "Contact Us" link at the bottom right corner of the page and your issue will be resolved.
    Dismiss Notice

'80 CJ5 lugging along

Discussion in 'Intermediate CJ-5/6/7/8' started by Dano50, Feb 5, 2007.

  1. Feb 5, 2007
    Dano50

    Dano50 New Member

    Keno, Oregon
    Joined:
    Dec 19, 2006
    Messages:
    38
    Hello everyone:

    Played with the jeep and looking over the old girl for future ideas and upgrades. Generally, I want a light (read timber) trail/ weekend driver for summer open top fun and camping. My mechanic says that it had a 2.5 lift installed, currently I am running 235/75/15s, SR4 transmission and Dana 300 transfer.

    While waiting for the new parts to arrive, had a chance to get some details. One of the POs had put in a re-built GM 2.5L 4 banger. Some interesting things:

    1) It has a hydrolic clutch. From what I've read, this is standard for a 4 cylinder of this era.

    2) The (I am assuming) Dana 30(?) differential is a 3.54 after cleaning the tag . The AMC 20 (rear) is marked "N" on top of the case which appears to be the code for a 3.54 gearing. I'm glad they match.

    Someone had mentioned that the 4.10 gearing ratio was usually standard for the most efficiency...especially since GM 2.5L is gutless in fourth gear using the 3.54(s). Was the 4 cylinder matched with the 3.54 originally...could there have been a change. It may/will be couple years out before I can install a 6 cylinder.

    Questions:

    1) What is the most energy efficient/compatable gearing. How hard is it to change the gearing from 3.54 to (I don't know) 3.73s, 4.10s for light highway / offroad use? Which would you suggest, both mileage and efficiency wise? I haven't opened up either one to see if there was a change to a lower gearing by a PO...but, I sort of doubt it.

    2) If I were to change tires (say 31s or 32s), would this enhance or detract from its efficiency. Planning on using the 235s until they wear out...looking to the future when I buy new ones.

    3) I may get extravagant in the future and look for a beefier transmission (currently I have both the SR4 and a T-4, currently thinking about switching in the T-4 in order to tear apart and rebuild the SR4). Possibly use both for trade (again, sometime down the pike)

    some updates...

    Waiting for my new spindle kit and socket wrench. Should be in this week.

    Re-surfaced the rotors on the front brakes. The PO had it sitting so long that a fine film of oxydation and discoloration had built up creating a smooth surface (braking took far more time to complete than I liked).

    Replacing brake hoses on the front brakes, old ones were cracked and starting to fall apart.

    Hoping to get it driveable. This summer I hope to fix the tub rust (several spots in the usual places) by welding in metal, then painting and herculining the inside.

    Aren't these things fun? Thanks for all your help.
     
  2. Feb 5, 2007
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
    Joined:
    Jul 30, 2003
    Messages:
    8,513
    the hydraulic clutch for that year is factory
    the 3:54 ratio was standard; 4:09 optional
    The T4 is probably more desireable than the SR4 IMO
    any taller tire without gear ratio change will hurt you even more IMO
    The "N" code indicates a locking diff in the rear as well; have you looked?
     
  3. Feb 5, 2007
    Dano50

    Dano50 New Member

    Keno, Oregon
    Joined:
    Dec 19, 2006
    Messages:
    38
    JPFlat:

    Thanks for your reply. Right now the front end is jacked up waiting for this weekend when (I Hope) I can finish repacking the bearings and reinstalling the brakes, so I will see if I can test the rear differential to see if it is a locking type. It appears that a locking type would be prefered over another, correct?

    Question, I would assume I have a locking rear if both wheels spin in the same direction when in neutral (after jacking up off the ground, of course). Is that correct?

    If I would try for a lower gear ratio, how difficult is it to change out the gears in the differential(s) I have? Major expense and time?

    Thanks once again.
     
  4. Feb 5, 2007
    CJ-X

    CJ-X Member

    Ohio
    Joined:
    Aug 6, 2006
    Messages:
    816
    I never trust the tags.
     
New Posts