4:11 Vs, 4:59 Rear Ends

SuperDaveSuperDave Posts: 3,370Senior Contributor

I  hope I picked the correct category. "Hudson" was not available..

I just finished installing a 4:11 gear in my 49 Commodore eight with OD. The original 4:59 had the engine  "happy" at 50 MPH but a bit stressed at 60MPH. I live on the FLAT east Coast of Florida. The steepest thing we encounter are the high rise bridges over the Indian river and Interstate overpasses. If you don't have a lot of hills in your neighborhood.. I highly recommend the swap. It took a while to acquire all the seals, gaskets, speedo drive gear etc.Thanks to the help of other forum contributors. It was well worth the effort.  I used the royal Purple 75-150 gear lube ($20.00 a qt.) Also I used a Ford/Mercury wheel bearing grease. It was recommended by a friend and experienced mechanic. He said he has quieted several rear wheel bearing noises on Ford pickups even after installing new bearings! The only difficulty encountered, was setting up the end play. After a few more miles, I am going to re-check to make sure it's not too tight or loose.  Thanks again guys !


  • Ol racerOl racer Posts: 2,488Senior Contributor
    edited January 2016
     Sounds like you made the right gear choice for your area. You will find your speedometer will be off slightly now so drive accordimgly.or locate another speedo gear.
  • Park_WPark_W Posts: 2,545Senior Contributor
    Did the same with my '47 C8, a factory OD car.  Nobody needs a 4.11 rear end these days.
  • SuperDaveSuperDave Posts: 3,370Senior Contributor
    Park,I have the correct gear now. Life is great!  :)
  • airbrushguyairbrushguy Posts: 310Member
    Congratulations, seems like alot of work to save maybe 500rpms at about 60 mph, doesn't it?
    Are there any other lower (numerically) gears available?
  • SuperDaveSuperDave Posts: 3,370Senior Contributor
    edited January 2016

    All my grease seals and pinion were leaking, so I had to take it apart anyway.

    3:54 was used in the first HydraMatic cars. That is the lowest number available for the Hudson built differential. There isn't a speedometer gear that can be used to correct it. I had one in my 49 Superdore 262 w/od and twin H. Worked well but had a ton of error. I used my GPS to watch speed.

    I may have an extra 3:54 in my parts stash. I have a couple 4:59s if anyone wants to go drag racing..:)

    I put a 1953 3:07  Dana in my 49 Two door. But it also has the dual range HydraMatic to match, so the speedo is very close.

  • airbrushguyairbrushguy Posts: 310Member
    Dave, do you think OD would be too much for a 3:54? If not I may make you an offer in springtime!
  • Lee ODellLee ODell Posts: 2,700Senior Contributor
    Airbrushguy with 4.11's  in  overdrive at 60mph the  engine rpm is 2070, at 70 mph rpm is 2420.  With 3.54 gears in overdrive at 60 mph rpm is 1785 and at 70 mph rpm is 2080. This may be helpful with your decision.
    Overdrive also gives you the benefit of having 6 forward  gears to chose from to help on mountain roads.
  • allanallan Posts: 196Member

    I am running a 3:54 with overdrive in my 52 Hornet and it's a little tall on the take off, but the rest is fantastic.


  • PerPer Posts: 169Member
    I feel that about 2400 is a good cruising rpm for 8 cylinder and Hornet engines, which both have a 4 1/2 inch stroke, so I think 70 mph works well with these engines as Lee's figures show.  

    With the 3.54 ratio, this engine speed happens at about 80 mph.  With Hornet power, this certainly must  be fantastic, Allan!

    In the 49 Commodore that I have driven across the country recently, there is a 4.11 ratio with overdrive and a Pacemaker engine.  Driving at about 65 to 70 mph on flat roads the engine was happy, but slight hills slowed the car down, and needed a lot of use of 3rd gear at 45 to 50 mph.  When this engine was in its original somewhat lighter car, with a 4.59 ratio and overdrive, its performance was better.  I think Pacemakers with overdrive are the only cars where a 4.59 ratio makes sense.  The Pacemaker's shorter stroke of 3.875 inches gives it a cruising rpm of about 2700, which occurs at about 70 mph with the 4.59 ratio.

  • EssexAdvEssexAdv Posts: 602Expert Adviser, Moderator
    I have a bone stock 49 super six with low mileage. It has an Aluminum head and OD The car runs great everywhere I drive it. Well, there is one exception, I put the 3.54 rear in it. As most OD cars will hit hills where you have to kick it out of OD, this one is no exception. I might have to shift it out of OD a bit sooner than one with a lower gear, but it isn't a big deal. The original 262 is now speed deamon when compared to a Hornet engined car, but I have had no issues with acceleration from a stand still. I don't expect it to keep up with my Hornet so I am happy. I like quiet and the decrease in motor noise is welcome. Your happiness will depend on your expectations but it certanatly won't hurt the car
  • SuperDaveSuperDave Posts: 3,370Senior Contributor

    Yes a quiet smooth drive is what I am after. I have been down the 308 road with Twin H etc.... Still got outrun by Jap cars!  The 4;11 in the 49 eight convertible and the 3.07 in the 49 Super, wide block 262 with dual range HydraMatic both deliver a quiet smooth ride.

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