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High Horsepower Front Axle Swap Ideas

Discussion in 'Early CJ5 and CJ6 Tech' started by 66_Cj5_Explorer, Nov 3, 2019.

  1. Nov 3, 2019
    66_Cj5_Explorer

    66_Cj5_Explorer New Member

    Huntsville, AL
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    I have a 1966 CJ5 that has Summers Brothers aftermarket 1 piece flanged axles in the dana 44 rear and dana 27 front with t-10 4 speed, warn overdrive unit, and dana 18 transfer case. My father had engine swapped a previous 350 sbc to a solid tappet 406 small block chevy that makes approximately 500-550 flywheel hp. It was only broken in about 20 years ago then sat in my parents garage. I just got it running again and broke the dana 27 in my gravel driveway very quickly... the pinion snapped and part of it went through the iron housing. I was wondering if I should swap a lower horsepower motor into it like a fuel injected v6 or what front axle would be sufficient to not break again without going 37s? The jeep currently sits on 33x12.5r15 Mudstar tires and I'm not really interested in running super a wide stance. Side note, it has 1966 Corvair Steering Column from what I can tell. It has the stock 5.38 gearing with limited slip rear. Also I'm not sure if the 1 piece dana 44 axles are course spline or if that carrier was swapped out at some point with the newer axles. I'm guessing the former. The drum brakes on all 4 corners are 11x2 inch. also.

    I was looking into dana 60 front axles but the housing sits so low and everyone seems to recommend against it with less than 37s due to reduced ground clearance. I'm concerned that a dana 44 or 10 bolt front axle would be marginal with the torque put out by this motor.
     
  2. Nov 3, 2019
    RATTYFLATTY

    RATTYFLATTY I think you need a little more throttle

    Central MN
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    If you actually have that much HP my opinion is to look into a different power plant as you will just be chasing broken parts till you no longer enjoy driving the Jeep. Or put a block under the gas pedal.
     
    Jrobz23, tcfeet, Alan28 and 1 other person like this.
  3. Nov 3, 2019
    colojeepguy

    colojeepguy Colorado Springs Sponsor 2019 Sponsor

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    You're also well over the HP/torque rating for that overdrive.
     
  4. Nov 3, 2019
    Twin2

    Twin2 wasn't me Sponsor 2019 Sponsor

    Virginia Beach, VA
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    welcome to forum
    I would do option #2 4.3 FI
    or go with a smaller motor 283/327/307 stock HP
    front is toast . get a NT30 with disk brakes
     
  5. Nov 3, 2019
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

    Apopka, Fl
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    I guess just being careful with the throttle isn't an option?
     
  6. Nov 3, 2019
    jeepstar

    jeepstar Sponsor Sponsor

    Sheboygan
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    That's funny.
     
    Jrobz23 and Twin2 like this.
  7. Nov 3, 2019
    Jw60

    Jw60 Recovering Jeepaholic

    Sedalia MO.
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    What do you want to do with this jeep?
    In my opinion A dana 30 front with a 4.3 will go a lot of places just YouTube jpet and bam bam.
    If you want to go fast and break stuff keep the v8.
     
    tcfeet likes this.
  8. Nov 3, 2019
    garage gnome

    garage gnome Rust polisher Sponsor

    Western MA
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    My fire chief used to race a 2A with a Nitrous injected 350 that made 500 some odd hp. He had a flanged offset d44, D30, th350 and a D18. The d18 he said was the weak link. Now the 500 hp monster is gone, and he put a 383 stroker with a mild cam in so it is a little more drivable.
     
  9. Nov 3, 2019
    txtoller

    txtoller Member Sponsor 2019 Sponsor

    Weatherford, TX
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    I would put a d30 or 44 in and re-motor!
     
  10. Nov 3, 2019
    66_Cj5_Explorer

    66_Cj5_Explorer New Member

    Huntsville, AL
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    Thank you for the responses. I really needed the other opinions.
     
  11. Nov 3, 2019
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member Sponsor

    Denver, CO
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    I'd say pull the motor, dump the jeep, and find something fun to put that motor in...
     
  12. Nov 3, 2019
    Mcruff

    Mcruff Earlycj5 Machinist Sponsor

    Albertville, AL
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    Where
    Where are you located in Huntsville. I only live about 40 miles away in Albertville. You PM me if you want!
     
  13. Nov 3, 2019
    ITLKSEZ

    ITLKSEZ Volvophilic

    Post Falls, ID
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    What are your plans for this rig? Street only? Trails?
    ___% street
    ___% trails

    If street only, the front axle is irrelevant.
     
  14. Nov 3, 2019
    66_Cj5_Explorer

    66_Cj5_Explorer New Member

    Huntsville, AL
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    I already have a matching engine in a chevy II. The Jeep will be a fun toy to drive rarely to work, occasionally around the area and occasionally on trails. Probably 70% trails 30% street. I'm unsure if it will ever see hard core trails though. Just standard Jeep trails in the moderate level. My previous vehicle to put around on forest roads and trails was a 1995 manual Corolla so this is a big step up in capability. I had to backup a steep incline when I tried to go down the hard difficulty trail once with the corolla after coming across a 5 foot drop off a granite bolder. I'd like to eventually not have to back up but I'm not sure how much down the road that is.
     
  15. Nov 3, 2019
    Rich M.

    Rich M. Shoe pusher

    Maryland
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    Dana 27's are a dime a dozen. Junk the broken 27 for another one, repower with something mild and enjoy. The 30 is a nice upgrade but causes some scope creep. For your purpose not needed. I agree about finding something to enjoy the high horsepower in though :sneak:
     
  16. Nov 3, 2019
    Alan Rogers

    Alan Rogers New Member

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    My 69 cj5 had 410hp sbc t10 d18/overdrive 27a front offset 44with ff axles. I was 18 then. I ran 15" wide paddle tires on each corner and played in the sand. Only broke front end twice, cuz i got air born. Now it is detuned with a th350. 33" tires
    The t10 will never be a good "off road' trans.
    How about putting a mail jeep 2wd front axle, keep it low. Dump the d18 and make it a "hot" street jeep.
    If you keep 4wd To keep that overdrive happy. Remove the fill plug. Get a 90' elbow at hdw. Store.put it in where plug was. It will increase your oil capacity. Put your plug back in the elbow.
    Be careful with your right foot. Enjoy
     
  17. Nov 3, 2019
    duffer

    duffer Rodent Power Sponsor 2019 Sponsor

    Bozeman, MT
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    As noted above in several posts, it's all in how you use that right foot. I kept a D25 alive in my 3B for 3+ decades behind first, a warmed over 1970 LT 1 engine and then the 381-both 400 hp+. I cringed just airing down the tires let alone ever installing a traction device in that front axle. It was never an "if". Only a when. And when did happen. I'm just now finishing the install of the replacement. It started life as a F250 D44 and was cut down to standard wide track Jeep width. It has Reid knuckles, Dutchman chrome molly shafts, Scout II disc brakes/outers, and an ARB. This axle will be subjected to the new engine (441 sbc) so it will be a test (Dyno Sim indicates about 489 Hp and 570 ft lbs but the reason I put it together is 425 ft lbs at 1000 rpms).

    As far as your engine, what do you want out of it? That much HP out of a NA 406 means a somewhat nasty cam and most likely a big sacrifice of low end torque. To me, the ideal Jeep engine is something that you really don't need the skinny pedal for. Something that will just idle over anything. Hopefully, the 441 will do just that.

    The Warn OD is rated for 300 ft lbs. I know for a fact that if you drive sanely, they are good for at least 100 ft lbs more than that. The D18 is also good for at least 400 ft lbs and something I have never had problems with. That said, the large index case is notably more beefy than the small index cases. And I really wish someone made some fine splined output shafts-----

    But the bottom line is that there isn't ANYTHING you can't break if you try hard enough.
     
    FinoCJ and RATTYFLATTY like this.
  18. Nov 4, 2019
    colojeepguy

    colojeepguy Colorado Springs Sponsor 2019 Sponsor

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    I thought that a power lock diff was stronger than stock in a 25/27
     
  19. Nov 4, 2019
    duffer

    duffer Rodent Power Sponsor 2019 Sponsor

    Bozeman, MT
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    Absolutely. You eliminate the spider gear weakness but are virtually assured a busted axle shaft. My 25 (Spicer shafts) did the classic shear on the short side shaft right at the side gear. But it wasn't by any means a clean shear and shed all sorts of about 1/8" squarish shards (near perfect match for the splines) which totally destroyed the inner seal seat. My best guess is that almost an inch of that shaft just exploded.
     
  20. Nov 4, 2019
    Norcal69

    Norcal69 Out of the box thinker 2019 Sponsor

    Cottonwood, Ca
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    For you to instantly break it in the gravel drive way makes me wonder. Was it already damaged? Are you sure that the front and rear ratios are the same? If the rear has been modified it may not match the front.
    Something would have to bind up pretty hard to cause the damage you are talking about.
    Lots of incidental things can get forgotten about after 20 years of sitting around.....
     
    MJRedJeep, Vanguard, 47v6 and 2 others like this.

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