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Projects 1964 wanting to swap out rear end

Discussion in 'Traditional Customs' started by Brodbeckh, Jan 10, 2022.

  1. Brodbeckh
    Joined: Apr 22, 2021
    Posts: 33

    Brodbeckh

    looks like its a 12 bolt and looks like from other forums saying so and i want better highspeed driving and want to swap out rear end what are good diferentials that have a 3.73 and fit a truck and are sorta new 1980-now
     
  2. We need a whole lot more information. What is it in? What do you want to accomplish, lower RPM? What engine trans combination? From your title and info you gave I would say put a 9" Ford in it.
     
    Pist-n-Broke and Gizzy like this.
  3. For the cost of buying parts and doing a gear change correctly. If in fact you have a GM 12 bolt, you may be better off just going to taller tires if you can. 3.70 to 3.50 are what I call good street gears if you have any kind of performance under the hood. Changing tire size is much the same as changing gear ratio. Ther's actually a written formula to tell you what the effect is from one size to another.
     
  4. Brodbeckh
    Joined: Apr 22, 2021
    Posts: 33

    Brodbeckh

     

  5. Brodbeckh
    Joined: Apr 22, 2021
    Posts: 33

    Brodbeckh

     
  6. squirrel
    Joined: Sep 23, 2004
    Posts: 50,966

    squirrel
    Member

    64 Chevy pickup...what I did was to get a rear from a 70s van that had 3.07 gears. I then set up the 3.07 gears and differential into the older housing. It worked great. I was running a mild 454 and TH400 transmission.

    If you don't know how to set up ring and pinion gears, it can be kind of challenging....so you might want to get some help from a drivtrain shop.

    Also, Chevy trucks used the 12 bolt rear until about the early 80s. The 10 bolt gears won't fit, and car 12 bolt gears won't fit. The differential case has a different offset depending on the ratio, I think the cutoff is at 3.73, so if you get 3.07 through 3.55 gears you'll need a different differential. Vans were more likely to have mild gearing, most trucks had 3.73

    Since the truck has coil spring suspension and trailing arms and a panhard bar, swapping in a 9" ford is not quite as easy as it could be.

    You'd have to get 41" tall tires to get the same RPM reduction as this gear swap...so just ignore the tire size comments.
     
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  7. Brodbeckh
    Joined: Apr 22, 2021
    Posts: 33

    Brodbeckh

    my car has a 250 with a saginaw 3 speed so i do need some of low end power but also high end speed like im okay with throwing a 2000s chevy rear end due to more common and more common foinding a 3.73 if it fit
     
  8. manyolcars
    Joined: Mar 30, 2001
    Posts: 8,671

    manyolcars

    brodbeckh is 23 yrs old
     
    X38 likes this.
  9. junkman8888
    Joined: Jan 28, 2009
    Posts: 814

    junkman8888
    Member

    I've said it before and I'll say it again; a vehicle is not just a collection of parts but a system, in this case if you replace the rear end to go faster to be safe you also need to upgrade the front brakes. The best solution is to buy a donor '73-87 Chevy pickup for the rear end, entire front suspension cradle, the steering box, master cylinder and brake booster, ect.
    But then again, 41" tall tires would make your truck look so "donk"
     
  10. squirrel
    Joined: Sep 23, 2004
    Posts: 50,966

    squirrel
    Member

    The thing about a later rear is that you have to deal with the panhard bar, and the trailing arm mounts.

    How are your fabrication skills? Study how the rear in your truck is mounted. Go to a junkyard and look at the rear in a possible donor truck. Do you think you could do the cutting and welding needed to add a panhard bar mount, and swap the existing leaf spring perches for the correct trailing arm mounts? I don't know your abilities, or what facilities you have available to do this kind of work.

    I was able to do stuff like this when I was 23. I was also able to set up ring and pinion gears.

    And you can keep the drum brakes up front, IF you make sure they're working well, AND you drive appropriately. That's a big IF and AND.
     
  11. Moriarity
    Joined: Apr 11, 2001
    Posts: 23,087

    Moriarity
    SUPER MODERATOR
    Staff Member

  12. squirrel
    Joined: Sep 23, 2004
    Posts: 50,966

    squirrel
    Member

    Also make sure it's 4.11, I've never seen one, but I've seen a lot of 3.73s in those trucks.
     
  13. junkman8888
    Joined: Jan 28, 2009
    Posts: 814

    junkman8888
    Member

    Back again. There are several Chevy pickup forums on the "interweb", you might want to check there to see what is popular and easy when it comes to rear-end swaps.
     
  14. Moriarity
    Joined: Apr 11, 2001
    Posts: 23,087

    Moriarity
    SUPER MODERATOR
    Staff Member

    you could look for a rear end from one of those trucks that was born with an automatic trans, that should have taller gears and bolt right in.... check yours first to see what you have, do you have a tach? how many rpms are you running on the freeway? We have a tendency to get used to our modern cars that run 70 mph at 1800 rpms and think the old cars should be the same. Believe me that your truck doesn't care as much about this as you do....
     
  15. guthriesmith
    Joined: Aug 17, 2006
    Posts: 6,495

    guthriesmith
    ALLIANCE MEMBER
    1. H.A.M.B. Chapel

    Pretty sure I may have a 3.73 rearend behind the shop that we could give away out of my sons 63 C10. But, not sure I would go to all the work to go from a 4.11 to a 3.73 since they are pretty similar in drive-ability as Moriarity mentions. Also, knowing where you live might help someone near you help you out.
     
    Last edited: Jan 10, 2022
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  16. guthriesmith
    Joined: Aug 17, 2006
    Posts: 6,495

    guthriesmith
    ALLIANCE MEMBER
    1. H.A.M.B. Chapel

    A 3-speed OD might do you as much or more good to put in the pickup.
     
  17. KenC
    Joined: Sep 14, 2006
    Posts: 717

    KenC
    Member

    With a stock 250 as the engine, I'd want to keep the 4:11 and swap to an OD trans of some sort. My choice would be an A833, OD version from a later Chevy. Rare, but a good solution. Others would be a T5 with chevy case and MDG. Pickup weight, small six torque and higher rear gears just don't do it for me.
     
  18. finn
    Joined: Jan 25, 2006
    Posts: 985

    finn
    Member

    Sounds like an overdrive transmission is in your future. Not sure what fits best, though. Does the 64 still have the old four point mount system?, or is it side engine mounts and a rear transmission crossmember?

    I suspect four point, with the transmission hanging off the bellhousing, swinging in the air.
     
  19. Squablow
    Joined: Apr 26, 2005
    Posts: 15,886

    Squablow
    Member

    Do you want to keep it with 6 lug wheels? Because any 64-72 Chevy 2wd truck rearend will bolt onto the 64's rear trailing arms with no modifications, but 71-72 2wd rears are all 5 lug. The 73-87 rears are identical except for the mounts for leaf springs instead of trailing arms, I believe. They're an easy swap. You can bolt in the whole front suspension cradle from a 71-87 pickup and get 5 lug, power steering, and factory style disk brakes, without cutting or welding anything, it's a very popular thing to do, I had that setup on my '66 Suburban and it worked well

    If you want it all to bolt in, you want a 71 or 72 donor, the rearend bolts right in and so does the cradle, and front disk was standard at that point. Even your parking brake cables will fit. Trying to adapt some 2000's era stuff doesn't really gain you anything that you couldn't get from the bolt-in earlier stuff, and it'd be a lot of work.
     
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  20. squirrel
    Joined: Sep 23, 2004
    Posts: 50,966

    squirrel
    Member

    where do you hang the panhard bar?

    and yes, the transmission hangs in the breeze...swapping to an automatic requires finding a transmission rear crossmember, and dealing with the parking brake cable situation.
     
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  21. Personally I would just drive the truck the way it is….it’s worked fine for 58 years so far.
     
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  22. indyjps
    Joined: Feb 21, 2007
    Posts: 4,850

    indyjps
    Member

    From your profile info: 1964 c10 longbed fleetside custom

    Can you fill in location in your profile. Lot of members here have parts available, they may be close
     
  23. Find a 3 spd with o/d, direct bolt in to your bellhousing (linkage also) and you'll need to shorten the driveshaft and make the speedo cable longer. You'll get the low gear in 1st to help the 250 around and the o/d to help on the highway. I put a good used one in my '64 Chevy panel with a 230 (235/75r15 tires) and it dropped it almost 1000 rpm in o/d on the highway (at 65-70mph).
     
    Last edited: Jan 10, 2022
    Joe Travers likes this.
  24. Squablow
    Joined: Apr 26, 2005
    Posts: 15,886

    Squablow
    Member

    Not sure. I'm not sure if builders are putting in the complete rearend and swapping/fabbing mounts around or if they're just pulling the axles and center section out of the later rearend and putting them in the earlier case to gain the 5 lug to match the front and whatever gear ratio the later ones had.
     
  25. F-ONE
    Joined: Mar 27, 2008
    Posts: 3,092

    F-ONE
    Member
    from Alabama

    It looks like the subject is a 1964 C-10, correct? I have reviewed your posts; nowhere does it mention this truck actually running and driving. So, does this truck run and drive? I see you are getting a lot of info from forums but until it's on the road...it's all "pie in the sky".
    If it's not running and driving, get it running and driving. This way you can truly make an informed decision on what it needs.

    ^^^^ I agree. If it's not running or driving, getting it to run and drive is the first priority.
     
    Last edited: Jan 10, 2022
    X38 likes this.
  26. ekimneirbo
    Joined: Apr 29, 2017
    Posts: 2,499

    ekimneirbo
    Member
    from Brooks Ky

    Probably don't want to hear this, but as a few others mentioned above, you need to change the transmission, not the rear end. The problem is that you will be swapping one problem for another when you change the rear end gears. This is especially true with a small six cylinder engine. Look at how well many of todays cars perform with small engines. They will dust your truck even with its 4.11 gears and run off and hide from you on the xway. While there is some other technology involved, ALL of these cars and many trucks have gone to transmissions with lots of gears (6 or 8). Your six is never gonna be a whiz-Bang hot rod, but if you upgrade the transmission you will find it a lot more enjoyable to drive.
    I went to a swap meet over the weekend for Model A parts (mostly). There was a guy there selling stuff to put 5 speed manual transmissions in them. He even had one that put a 5 speed behind a 2 speed so he could choose from 10 gears. You aren't gonna solve your problem for $150......you are just gonna trade one problem for another.:)
     
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  27. Truckedup
    Joined: Jul 25, 2006
    Posts: 4,430

    Truckedup
    Member

    According to the info on the GM Heritage brochure, the 64 standard C10 rear gears were 3.73 , 4.11 was optional
     
  28. squirrel
    Joined: Sep 23, 2004
    Posts: 50,966

    squirrel
    Member

    The rears got wider in 70, then went to 5 lug in 71. You can swap the later axles into a 70 housing, but not the 63-69 housing.
     
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  29. Budget36
    Joined: Nov 29, 2014
    Posts: 8,439

    Budget36
    ALLIANCE MEMBER

    With a 3 speed, I’d limit it to a 3.50 gear, otherwise you would be a bit hard on the clutch taking off.
     
  30. 26Troadster
    Joined: Nov 20, 2010
    Posts: 680

    26Troadster
    Member

    i had a 63 12 bolt and the spider gears have a different spline as well from the newer ones. when i tore it out there wasn't much left, so i ended up putting a off topic trans am rear in my 63 with 241 gears with the 4 speed and later a auto trans. works great but it will never haul anything but ass now.
     

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