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Technical How much does a powerglide rear really help

Discussion in 'The Hokey Ass Message Board' started by mtdriver, Jan 24, 2015.

  1. mtdriver
    Joined: Aug 14, 2012
    Posts: 13

    mtdriver
    Member
    from Montana

    So I've been reading and reading and reading until my eyballs are dry and my head is even more confused with ideas than before I started.
    A little about me, my wife and I used to have a survivor 49 deluxe but had to sell when the septic failed at our house and the nice man that gave us our toilet privileges back needed about 10k for his time and expertise, so off the car went. We are now the proud owners of an original survivor 52 styleline deluxe. The car had 53900 when bought in September and now it has 56200 on it. We love driving it. She calls it therapy when she drives it. It is a 216 babbit "massager" car with the 3 on the tree and the 4.11 and 205 70 15 tires. The car runs great, especially after a valve adjustment. I daily drive it in town as well as we recently drove it on a 350 mile trip from Billings to Bozeman through rain, wind, and snow over the pass. Love this car!

    So her in lies the question. The car goes just fine down the interstate at 60-65 but the rpm's are up there as you can imagine. I've read oodles of switching to open driveshaft and the correct rear and a t-5. I don't want a t-5. Part of the reason we enjoy this car so much is the 3 on the tree. So, does going from the 4.11 to 3.55 really make that much difference in cruising rpm? I dont want to go through bunches of work to drop 300 rpm or something small like that. The other thought was to swap to a later model 3 speed to run an open shaft and keep my tree shifting and have infinite rear gear possibilities. If none of this will make a noticeable difference I'll just keep cruising what I got and enjoying it. Life in the slow lane is a good life. :cool::)
     
  2. Yes,it will make a big difference. HRP
     
  3. clem
    Joined: Dec 20, 2006
    Posts: 2,589

    clem
    Member

    Its a mathematical equation to find the difference in diff ratios. Taller rear tyres help, which is what I did for a 4:11 rear end. Different style car though! Still not enough so one day I hpoe to go with a (dare I say it),Toyota 5 speed which has a final g,earing of .85 or so, therefore compensating for the 4:11 gears in the rear.
     
  4. steel rebel
    Joined: Jun 14, 2006
    Posts: 3,604

    steel rebel
    Member Emeritus

    I'm not an expert on early '50s Chevy's but going from 4.11 to 3.55 will make a big difference in highway cursing but it will also made a big difference in takeoff. You will have to race the engine slip the clutch a lot more. It's a tradeoff.
     
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  5. clem
    Joined: Dec 20, 2006
    Posts: 2,589

    clem
    Member

    perhaps that is why people go to a 5 speed, to have better all round drivability.
     
  6. clem
    Joined: Dec 20, 2006
    Posts: 2,589

    clem
    Member

    If you are clever you can adapt a floor shift to column shift if it is that important to you.
     
  7. 302GMC
    Joined: Dec 15, 2005
    Posts: 5,886

    302GMC
    Member
    from Idaho

    It will make a completely different car out of it ... that & a split manifold. They got a pretty good heater, too.
     
  8. BadgeZ28
    Joined: Oct 28, 2009
    Posts: 1,011

    BadgeZ28
    Member
    from Oregon

    Yes, that would be an improvement. You would be about 3,000 rpms with 26 inch tall tires at 65. You are around 3,000 rpm with a 26 inch tall tire at 50 mph.
     
  9. Moriarity
    Joined: Apr 11, 2001
    Posts: 15,801

    Moriarity
    SUPER MODERATOR
    Staff Member

    I had a 52 with a 235 (54) motor and 3 on the tree years ago and did the powerglide rear swap and it made it into a wonderful car for the freeway. the difference in takeoff was tolerable. It made a huge difference. I would highly recommend it......do it, torque tubes rule, leave the modern crap for the street rodders....
     
    arkiehotrods likes this.
  10. 48FordFanatic
    Joined: Feb 26, 2011
    Posts: 1,336

    48FordFanatic
    Member
    from Maine

    3.55/4.11=0.86 so whatever your rpm is now with 4.11's just multiply that value by 0.86 and that will be the rpm with 3.55 gears.
     
  11. mtdriver
    Joined: Aug 14, 2012
    Posts: 13

    mtdriver
    Member
    from Montana

    I would rather keep the car close to original as I can or maybe some period correct mods. It seems like its geting rarer to see un-rodded or customized cars. Not that I don't like those as we each have our own tastes and can appreciate the love of cars no matter what people do to theirs. I thought about the 235 swap as there are a few of them in cars in the wrecking yard still. Sounding like 3000 rpm is an acceptable number? The take off doesn't seem like thats as big of a deal as sometimes I forget it in 2nd when I take off from a light and it gets itself underway easily enough.
     
    Moriarity likes this.
  12. R Pope
    Joined: Jan 23, 2006
    Posts: 3,310

    R Pope
    Member

    Where you are turning 4110 RPM now, you will be doing 3550 with the gear swap. Or, 35.5 mph now will be 41.1 mph after. Of course, the speedometer will be out that much too. I don't think there are the right drive gears to correct the error.
     
  13. mtdriver
    Joined: Aug 14, 2012
    Posts: 13

    mtdriver
    Member
    from Montana

    For my own peace of mind what is a good 6 volt tach to get so I cam keep tabs on things?
     
  14. v8juice
    Joined: Dec 28, 2013
    Posts: 280

    v8juice
    Member

  15. 302GMC
    Joined: Dec 15, 2005
    Posts: 5,886

    302GMC
    Member
    from Idaho

    With your current tires, you're pushing 4000 at 60-65.
     
  16. 3030
    Joined: Dec 21, 2010
    Posts: 199

    3030
    Member

    I'm removing a powerglide rear from a 51 wagon right now if you are interested.
     
  17. mtdriver
    Joined: Aug 14, 2012
    Posts: 13

    mtdriver
    Member
    from Montana

    I am interested, cost and shipping of course being a factor. I'm in Montana at 59105. How does one send something like that?
     
  18. 3030
    Joined: Dec 21, 2010
    Posts: 199

    3030
    Member

    Have to do some figuring then I will PM you.
     
  19. Many moons ago I switched to a PG rear in my 50 vert(pic) that was running 2 97s & Clark headers on bored 270 jimmy (302)with a 3/4 50chevy convt.jpg cam & over size Goodyear double eagles. Had a continental kit hanging over the bumper for mo traction. I didn't loose too many street races
     

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