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76 or 84 14bFF...

Discussion in 'The Garage' started by babyburb, Feb 24, 2007.

  1. babyburb

    babyburb 1/2 ton status

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    Need some advise. I have two 14b at my disposal. My original is my 76 3/4 ton burb or an 84 out of 3/4 ton Crew cab C20. Planning on a disc swap, shackle flip with 56s instead of 52s, 5.13 gears and a Detroit locker. I guess my question is, is there a difference between the two or one better than the other?

    One other, I have also aquired a 454 with a turbo 400 tranny in good condition. Would this swap right in for a 400 and turbo 350?

    Any advise would be great.
    Thanks
     
  2. u2slow

    u2slow 1/2 ton status

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    The crewcab has 1-ton spring spacing even though its a C20.

    Backing plates changed in '84 for the new cable arrangement. Won't matter much if you are going disc.
     
  3. rdn2blazer

    rdn2blazer 1 ton status Premium Member

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    take the 76', the 84'/85' year 14 FF's had the small pinion support bearings. I unfortunatly did not know this when I hunted mine out of the junk yard. I could not find a master install kit for a 14ff axle with the small pinion bearing. they all come with the bigger pinion bearing. so I had to buy the individual bearing itself which cost 62 bucks alone.

    the difference is because the rollers in the bearing are smaller they turn a faster rpm then the larger bearing rollers, hense more wear and because they are smaller they dont handle as much abuse.
     
  4. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    With the exception of spring perch spacing and shock mount location all the 14ff were the same up until 1987. 1987 and earlier used a small pinion bearing and 1988 and later used a larger pinion bearing.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    All else being equal, the newer one PROBABLY is in better shape. Yes, 14FF's are considered bulletproof, but treated equally, newer (all parts being equal) would always be better.

    IMO anyways, my '86 465 is much tighter than the '74 it replaced. :)
     
  6. 79k20350

    79k20350 3/4 ton status

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    Mile would have more to do with it than year... But yes older has more potential for mileage...

    The oldr one will have the correct spring spacing and cast perches which are nice....

    Honestly though id pop em both open and make sure neither has a gov lock. If they are otherwise the same, id take the older one...
     
  7. bigbluesuburban

    bigbluesuburban 1/2 ton status

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    Can someone reconcile this information for me? Somebody here is wrong... Who is it?
     
  8. koldsimer

    koldsimer 1/2 ton status GMOTM Winner

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    I always thought 85 was the split for the big/small pinion bearing.
     
  9. JIMMY76

    JIMMY76 1/2 ton status

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    let me know what motor your not going to use I'll come get it of your hands
     
  10. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    I'm looking in drivetrain warehouse's catalog and for a master install kit it is listed...

    G/G 35-2023 for Master install kit up to 1988
    G/G 35-2023A for Master install kit 1988 plus

    I know first hand that those year breaks are correct as i've had both kits in my hand and the only difference is 1 of the pinion bearings.
     
  11. babyburb

    babyburb 1/2 ton status

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    So they are both the same except for spring spacing?
     
  12. koldsimer

    koldsimer 1/2 ton status GMOTM Winner

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    Good to know, thanks man. Was there any difference between pre/post 85 or 86 models? Maybe it was the housing? Then again, I have been known to just make up stuff in my head.
     
  13. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Someone correct me if i'm wrong but i think the webbed housing started in 1988 as well.
     
  14. txfiremank5

    txfiremank5 1/2 ton status

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    Mines an 88 or 89 (I'd have to double check) and it has webbing, and I too think that 88 was probably the first year. I also remember the guy asking the year becuause of the bearing, when I bought my master install kit. I'll probably be doing the gears pretty soon.. so I guess I'll see if I got the right one or not. :o At the time I knew the year, so hopefully I have the correct one.
     
  15. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    This is of course assuming that the original pinion support is being used with the housing. Anyone could easily put an earlier pinion housing in a later diff and vice versa.
     
  16. txfiremank5

    txfiremank5 1/2 ton status

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    True. I doubt that's the case with this one though. I think all the previous owner did to it was put in a detroit, and relocate the spring perches. It still has the stock 3:73 gears in it, and stock strap style yoke. But, you never know for sure until you get inside and find out.
     
  17. onetonbb74

    onetonbb74 1/2 ton status

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    to answer your question about the 350 to 400 tranny swap, it wont just swap over, you pretty much need to find a transfercase with the 400 to make it work otherwise your finding adapters, input and output shafts, shifters, etc. As for the 14 bolt, look at the spindles and pick the housing with the best looking spindles, thats the only thing that matters with the housing once the spindles are shot, the housing is useless. Spring perches are not that hard of a job to sweat which housing you going to use solely based on that.
     
  18. rdn2blazer

    rdn2blazer 1 ton status Premium Member

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    I got my info from Pirate's BillaVista's 14FF Bible. I do know the axle I got out of the junk yard is a 84' out of a k20 pickup truck. it has the small bearing. the 84 axle could have seen way more abuse then the 76. unless you know the history of both axles and trucks they both came out of you will never know how much abuse either one has seen. just based on age alone, yea you could say the 84' is better then the 76' but there are other factors to consider.

    there both "old" axles per say. after 20/30 years whats the difference. unless there is rust dammage to take into account. if not I would choose the 76' since it has the bigger pinion bearing, but hay thats just me.

    also look at the condition of the spindle diameters, the threads at the end of the axle, the axle flanges where the backing plate and disc conv. would be bolted up to. look inside at the gears, there should be gear oil in them, look at general overall condition and make a good educated choice from there, that the best you going to be able to do.
     
  19. babyburb

    babyburb 1/2 ton status

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    Oneton
    You said I need to find a transfer case with the 400. The problem is it cam out of a C20. What transfer case would work with a 454/400 swap from a 400/350/203. I really want to find a 205 and rebuild it like the 454/400 combo. So what is the adaptibility of a 454/400/205 combination.

    This is what it looks like so far. I will have my tranny (400) rebuilt with a Transco Shift Kit and heavy duty sprag. The 454 will be tore down to the block and have it machined and tested at a local engine shop. I will rebuild it with a new engine kit, heavy duty cam, roller rockers and a set of Headers. In the mean time I need to sell the 84 14bolt for some funds and try to pick up a good working 205.

    Any other advise fella's?
     
  20. onetonbb74

    onetonbb74 1/2 ton status

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    I believe you have to find a transfercase and adapter that originally came behind a th400 transmission in a k20 or 30. You might have to get an output shaft for the tranny as well, not quite sure if the 2wd output is the same as the 205 output so id check that out as well. You remove the entire end slip yoke housing and the tc adapter bolts to the 6 bolts on the back of the casting.
     

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