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Technical 1965 c10 gears ratio

Discussion in 'The Hokey Ass Message Board' started by Vincentnova, Oct 19, 2017.

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  1. Vincentnova
    Joined: Nov 6, 2015
    Posts: 80

    Vincentnova
    Member
    from san diego

    Hello
    I feel like i cant find any precise information about it
    I have a 1965 c10 4speed low gears
    Never use the fisrt gear
    All original
    And like most know on highway....60 mph engine screaming loool
    Im pretty sure i have 4.11 at the rear end..
    Well i dont want swap rear end
    And dont want swap tranny either

    What kind of rear end are those ?
    Where can i find gears ?
    Im between 3.42 and 3.08
    Can i find a set of gears that could feet the actual diferential ?
    If no please let me know what to use and where to look
    Thanks
     
  2. a50merc
    Joined: Apr 20, 2008
    Posts: 998

    a50merc
    Member

    Before you start Changing Gears why Not go with Higher Tires
    like if your Tire size is 27" in Dia. change it To 30" in Dia to see
    if it Helps Before changing Gear's

    Just my 3.5 cents

    Live Learn & Die a Fool
     
  3. Vincentnova
    Joined: Nov 6, 2015
    Posts: 80

    Vincentnova
    Member
    from san diego



    im having this nice set of white wall firestone old school g78-15 look..i look how they look and they are not cheap
     
  4. RR
    Joined: Nov 30, 2008
    Posts: 94

    RR
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  5. a50merc
    Joined: Apr 20, 2008
    Posts: 998

    a50merc
    Member

    vincentnova Get a Used set of rear tires just to see if it Help's
    unless you Got Money to Burn.

    Just my 3.5 cents

    Live Learn & Die a Fool
     
  6. Most 64 thru 66 chevy trucks have a GM 12 bolt rear end. 410 or 390 gears. Many years ago I installed taller gear's from a 12 bolt car( 1970 chevy caprice) rearend into one. That was before I was informed that they would not fit? And its still working in a 66 GMC with a six and powerglide. My 1/2 ton 66 GMC has the factory granny 4 speed and a Dana44 rear end mounted on leaf springs. and it has 336 rear gears.
     
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  7. InstantT
    Joined: Aug 15, 2012
    Posts: 668

    InstantT
    Member
    from SoCal

    Mine has a granny 4 with 3.70s in the rear. Rear tires are 820x15s and I'll do 70 on the highway at 3k rpm or so.
    A little less might be nice, but I don't want to go much faster in this thing. G78s seem too small for a truck IMO.
    [​IMG]

    Sent from my LGLS992 using The H.A.M.B. mobile app
     
  8. squirrel
    Joined: Sep 23, 2004
    Posts: 44,635

    squirrel
    Member

    car 12 bolts are not the same as truck 12 bolts. Among other things, the inner pinion bearing is smaller on the trucks. The mid 60s trucks I've had came with 3.73 gears, but there were other options.

    I had a 66 Suburban with the 3.73 gears, I found a 1970s Chevy Van 12 bolt rear end, that had 3.07 gears. I installed the 3.07 gears and differential (the diff housing has a different offset) in the Suburban, and it worked out nice.

    if you don't know how to set up ring and pinion gears, you might want to have someone do it who knows how, and has the necessary equipment, which includes a press, bearing separator, dial indicator, shim assortment, etc.
     
  9. That is what Ive been told. exactly what squirrel stated that the car rearend parts will not fit in a truck housing. however I did it and made it work. I dont remember just what I did but it can be done. In addition to a dial indicator I use a ink called Prussian Blue to be able to visually check tooth contact. I learned to set up rearends from info gleaned from a old book called Fix your Ford.
     
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  10. Vincentnova
    Joined: Nov 6, 2015
    Posts: 80

    Vincentnova
    Member
    from san diego

    What king of van ? G10 g20 ?
     
  11. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,581

    gimpyshotrods
    Member

    More gears is more better.

    I would swap the transmission. The gap between 1st and 2nd ratios is still too big, and will still be there with new rear end gears.
     
  12. RR
    Joined: Nov 30, 2008
    Posts: 94

    RR
    Member

    A 70's van is going to use leaf springs. A 65 C10 has trailing arms. You will have to change (weld) the perches on the rear end to make the van housing fit. Your better bet is to go thru the junk yard or Craigslist and find a rear from a 67-72 C10 with the ratio you want. They used the same trailing arm setup as the 60-66. Also note that a 73-87 (squarebody) 3/4 C20 ton or 1 ton C30 is going to use a 14 bolt that will be wider than your current rear and have a different bolt pattern for the wheels. A 67-72 3/4 ton (C20) uses an Eaton HO-72 rear which is larger than the 12 bolt and has a different bolt pattern. And as mentioned, will need to have the perches replaced.
     
  13. I'd swap the Trans too.
     
  14. Swapping the SM420 is a chore. The e-brake is on the back of the transmission.

    I drove them for years and started out in 2nd gear. The truck is probably geared as a 4.11 or 4.56. I had one with 19.5" wheels, tall tires that was all wound up at 55, probably had a 5.14 or 5.38 gear set. Measure up the tire height, plug and chug into an RPM calculator and you'll get an idea of a good ratio.
     
  15. I prefer the 64 thru 66 GMC mostly because they have leaf springs on the rear. And its simpler to swap in a complete rear end. In 66 the E brake was moved from the transmission rear to under the dash. I think the OP wants to keep his granny 4 speed. So taller tires or a faster rear gear set are his choices.The one I changed the rear gears in is a factory powerglide. and it originally had 410 gears. My eldest son was driving it to little rock two day per week to attend UALR college. So he needed a better ratio.
     
  16. squirrel
    Joined: Sep 23, 2004
    Posts: 44,635

    squirrel
    Member

    I did not suggest swapping a van rear into the truck. I suggested swapping the guts from a later Van rear end into the truck rear end.

    The donor van will have a 12 bolt cover on the rear end, not a 10 bolt cover, and you need to make sure what ratio it has, by counting turns, counting gear teeth, etc. The quick way is to turn one axle two revolutions and count the turns of the pinion yoke (or if you want, you can turn each axle one turn).

    if you don't understand why one axle turning two revolutions is the same as two axles turning one revolution, I invite you to read up on how automotive differentials work.

     
  17. Jim is correct one turn only gives you 1/2 of the gear ratio. A improperly set up rear end will quickly fail. and most times sounds like a siren at speed.
     
  18. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,581

    gimpyshotrods
    Member

    On a C10?

    I honestly don't remembered one with a tailshaft parking brake.

    Newer:
    [​IMG]
    Earlier:
    001.jpg


    I am remembering only 15 and 16-wheels.
     
    Last edited: Oct 20, 2017
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  19. squirrel
    Joined: Sep 23, 2004
    Posts: 44,635

    squirrel
    Member

    Three quarter and one ton trucks might have the parking brake on the trans, but the half tons don't.

    Swapping the transmission is a good way to get what you want, if you can find one that fits and has the speeds you want. Swapping the rear gears is another way.

    Learning to drive it like folks drove them when they were new, is yet another way. Never seemed to be a problem in the old days, that the engine revved a bit on the highway. It's still not a problem, if you don't let it be a problem.
     
  20. Mr48chev
    Joined: Dec 28, 2007
    Posts: 26,223

    Mr48chev
    ALLIANCE MEMBER

    You are looking at two ways to do it.
    Find a rear = 66/72 that will bolt in the truck that has better gears. Note that 69-72 are a bit wider than the 68 and earlier. That shouldn't be a problem with the tires you have if you don't have super deep reverse rims. We pulled the 3.7 rear out of my wrecked 70 Chev C-10 and put it in my friend's 66 short stepside back in 1989 and it was a bolt in but his big tires on 15x8 rims fit inside the wheel wells with enough clearance to not rub. 3.7 probably won't help that much with your tiny for a truck tires though. You need 3.0 or 3.3 and that is hard to find unless you do as Jim suggested and hunt down a donor rear for the gears or buy new gears with the ratio you need.
    Here is a quick tire size vs gear ratio /speed calculator that is easy to use.
    https://www.ringpinion.com/calculators/Calc_RPM.aspx
     
  21. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,581

    gimpyshotrods
    Member

    Well, if it were mine, it would already have a NV3500, sourced from a 4.3l equipped 4x2 S10 (has better ratios than the C1500 one). It is perfectly fine for a mild V8. The last one I bought was $150. The speedometer drive box cost more than the transmission (I am partial to the Dakota Digital ECD-100).

    I would love to be able to drive like it was 1965, but I currently live in 2017. Having a 4-speed, with three useful gears at worst, or feels like it is missing a gear between 1st and 2nd at best, do not sound like a viable list of options.

    I don't know where the OP lives, but where I am, traffic is bumper-to-bumper, stop-and-go, or it is doing 85.

    Outside of the metro areas, the freeway was built on the same road bed where the county road once was. That means there is no "back way" to take. You use the freeway. Even those daring enough to ride a bicycle here have a bike lane on the freakin' freeway!
     
  22. Mr48chev
    Joined: Dec 28, 2007
    Posts: 26,223

    Mr48chev
    ALLIANCE MEMBER

    Randy's ring and pinion has new gear sets for that rear axle for about 250 That may be a better option in the long run than trying to swap used gears. Bearings seals and all would probably run under 500 plus the cost of having a local shop swap gears.
    https://www.ringpinion.com/DiffWizard.aspx
     
  23. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,581

    gimpyshotrods
    Member

    I have had good luck with used gear sets, but I have only used them when I was able to put the donor axle/pumpkin on the bench, and then painstakingly duplicated the setup.
     
  24. squirrel
    Joined: Sep 23, 2004
    Posts: 44,635

    squirrel
    Member

    strange how that works...I've had better luck with used gear sets, than new ones.

    But as usual, we see things completely different, and both ways work.
     
    Old wolf likes this.
  25. How many Revs are you turning at highway speed?

    My '65 was originally a 3 speed 6 cylinder truck and had a 3.08 gear stock. That actually was as common a gear o as the deeper gears.
     
  26. oldolds
    Joined: Oct 18, 2010
    Posts: 2,895

    oldolds
    Member

    People today have no idea how cars used to rev. 60's cars used to cruise 60 mph at 3,000 rpm or more. I once has a 65 Malibu 327 4spd with 4:56 rear and g-60- 14 ( less than 26" tall) on the rear. I had no tach because I was young and broke. Shifted when the lifter began to float. Drove it on a 4 lane highway every day, kept up with 60 mph traffic. That 327 would scream along! Wasn't the fastest car in town but would give most a run for the money.
     
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  27. ebfabman
    Joined: Mar 10, 2009
    Posts: 637

    ebfabman

    In my '72 C10 there is the stock 12 bolt 3:73 rear with a 250 ci 6. I swapped the standard three speed on the column to a 2004r and auto column. 27ish tall rear wheels. At 70 mph, the 6 is spinning about 2150 rpms. Cruises real nice.
     
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  28. fiftyv8
    Joined: Mar 11, 2007
    Posts: 4,892

    fiftyv8
    Member
    from CO & WA

    Just change the tranny and be done with it.
    That way you will still have low diff gears for hauling and choose a 5 speed with O/D and that will give you great highway top end.
    I'm sure there are several kits out there and a tranny would not be so costly and you are done.
     
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  29. Vincentnova
    Joined: Nov 6, 2015
    Posts: 80

    Vincentnova
    Member
    from san diego

    Let say i want keep it manual wich tranny will be better....i like manual
     
  30. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,581

    gimpyshotrods
    Member

    See my previous post.
     
    Sixhundred sixteen likes this.

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