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

breaking a dana 25/27

Discussion in 'Early CJ5 and CJ6 Tech' started by biggy, Dec 16, 2011.

  1. cj6/442

    cj6/442 Sponsor

    when on the 'Con this year with the ecj5 crew,,,, I saw alot of hopping and full throttle abuse going on ,,I just shook my head and was shocked there was no breakage going on . those 25/27 shocked me ........... ask POSI he saw alot of it on Cadillac. it was awsome .
     
  2. garage gnome

    garage gnome ECJ5 welder

    I've been kicking it back and forth whether to put a locker in my 25. Between the 225 (soon to be built), T18, D18, 5.38s, and a PM to nickmil, I decided against. HOWEVER, my D41 rear is locked and haven't broken it yet, so I must be doing something right. :)
     
  3. djbutler

    djbutler Sponsor

    Steve, you're not talking about me are you?

    Don
     
  4. biggy

    biggy New Member

    its nice to hear from people with experience. it sounds like the spider gears are a weak link. Can a person still get a power loc for a 25?
     
  5. nickmil

    nickmil In mothballs.

    They are out there but getting harder to find. Hermtheoverdriveguy has a kit to put a 27 powerlock in a 25 but even these are getting harder to come by. He usually has a couple though so worth checking.
     
  6. cj6/442

    cj6/442 Sponsor

    maybe,,,,,,,,,,:D
     
  7. oldtime

    oldtime oldtime

    Absolutely true. My buddy races his F-134 . It's extremely built and likely puts out say 120 HP.
    He prefers open carriers up front. Runs a spool in the rear D44.
    I sell him all my open differential gears for D25. He blows them up every few races.
    Yes D25 and D27 Powr Loks are few, far between and never to be had for cheap.
     
    Last edited: Dec 17, 2011
  8. biggy

    biggy New Member

    Those of you who have used a lock right to replace the spider gears, do you begin breaking other parts/which ones?
     
  9. cj6/442

    cj6/442 Sponsor

    well I have had cases with hairline cracks off the openings,
    I think throwing a lock right in there would break them open .
     
  10. I haven't! seems that the power to the wheels is divided so you dont get the torque on either axles assembly like you would otherwise. I may be wrong but it sounds logical in my mind. my wife wedding ring is stronger than those spiders:)
     
  11. nickmil

    nickmil In mothballs.

    Actually it puts more stress on the individual components like shafts, u joints, case, etc because there is less give between the components. A powerlock still has give depending on how tight it's set up
     
  12. i'm sure your right, but then again you dont have to put as much juice to it to get through somethin at least thats what i've seen, I can idle through stuff one legged trucks have to blast through.
     
  13. biggy

    biggy New Member

    What is the biggest tire you would use on a 25 used some on trails and some on rocks. I would say a 6.5 out of 10 with 10 being rough rock crawling?
     
  14. oldtime

    oldtime oldtime

    The Jeep must be envisioned as a complete synchronous system.
    Your question in part depends on the engine and the clutch size.
    You can only dump so many foot pounds of torque onto the axle due to clutch pressure limit.

    Increasing tire surface contact area (size) or decreasing air pressure both increase traction and decrease tire slip.
    That overall will increase the stress on the drive train.
    I believe you can get by running the biggest tire that fits your Jeep if you only have an F-134 with 8-1/2" clutch.
     
    Last edited: Jan 15, 2012
  15. biggy

    biggy New Member

    I have an 8.5 inch clutch with an amc 196 from a rambler and a t98. How does a limited slip or locker affect tire size?
     
  16. oldtime

    oldtime oldtime

    Back to the complete synchronous system.
    Think of it this way... A chain.
    Anytime you install a stronger link into the chain, that strong link will not break.
    Only the weakest link will break.

    A limited slip, increases the stress upon the drivetrain as compared to an open differential.
    A limited slip decreases the stress upon the drivetrain as compared to a locker.

    For reference; the typical 8-1/2" clutch in good condition provides about 165 ft lbs of torque.
    Regardless of engine specsifications. The engine cannot deliver more torque than the clutch will allow.

    The T98 basically doubles the available torque as compared to a typical 3 speed transmission.
    In simple terms the T98 is a double strong link in your Jeeps chain.

    Increasing tire surface contact area increases drivetrain stress.
    Decreasing tire pressure increases stress because traction increases.

    Its already been stated the weak link in the D25/27 is usually the spiders.
    Powr Lok is a fix.
     
    Last edited: Jan 15, 2012
  17. oldtime

    oldtime oldtime

    My books show that the AMC 196 produces 150 to 185 ft lbs torque depending on the compression and carburetion.
    I suspect the use of an 8-1/2" clutch is a very weak link.
     
  18. MikeT

    MikeT New Member

    I run 33x12.50x15 TSL swampers with 44 rear and 27 front both with lock rites and 5.38 gears. Mild built 225 with t-14 trans and d18 case. I have had great luck with this set-up but I only use as much skinny pedal as needed to make an obsticle. I like to crawl and let the tires work.
     
  19. I have the same except with 3.73 gears works great haven't broke anything...yet.:)
     
  20. biggy

    biggy New Member

    That is good info. What kind of terrain?