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Technical Her Rear End!

Discussion in 'The Hokey Ass Message Board' started by Joe Romano, Aug 21, 2015.

  1. Ok she's not complete but she does have a rear, but is it the right rear for her?
    It's a 1940 Chevy Coupe, stock 350 sb with a Edelbrock 600cfm carb. and a TH 350 trans.
    The rear is 2.73 open.
    Question is, is that a good rear for a driver, no long trips just local, around town and what about gas mileage? I don't know anything about this stuff, all I do know, is what I got....Joe

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  2. raidmagic
    Joined: Dec 10, 2007
    Posts: 1,438


    That is the ideal rear end for long trips. IF you are really concerned about fuel mileage swap out the 350 trans for a 700r4. The over drive will help more.
  3. Nope you want a 3.08 to 3.26:1 for a versatile around town and short trips rear. A 2.73 is what we always called an airplane gear, good for a 3 mile trip on the salt flats. :D

    it'll work but a little lower gear ( higher number) will work better for you. I used a 3.08 in my C-10 and it was a good trade off for around town and on the highway, better on the highway then around town. A 3.26-3.55 is actually a good around town gear for a small block in a fairly light car.
  4. TudorJeff
    Joined: Feb 13, 2007
    Posts: 1,131


    I have that EXACT combination in a '51 Pontiac, same carburetor and all. I agree it's a little sluggish around town but I have no trouble in stop and go traffic. Tire size can affect your choice a little but that combo works fine unless you plan to be a stoplight warrior. When I'm in the Pontiac I just know we are going to cruise low and slow with the stereo on and the AC blasting. Plus when I want to take a trip on the highway, it will keep up at 75-80 with no problems at all.

    A 700r4 is not your solution either. 2.73's with that overdrive is asking for trouble and poor gas mileage. 3.73's and a 700r is probably the best of both worlds.
    Hnstray likes this.

  5. 26 roadster
    Joined: Apr 21, 2008
    Posts: 2,015

    26 roadster

    just chucked my 2.73:1 in my truck for 3.07 much better for running to the store
  6. squirrel
    Joined: Sep 23, 2004
    Posts: 48,733


    I just swapped from 3.00 to 2.75 in my 55, and went for a drive yesterday. I like it. But I have a real motor, not a little mouse.

    A while back, I swapped the rear in my 350 powered 57 Suburban from 2.75 to 3.08. It's better around town, but not so good on the freeway. But then I got a free overdrive, and that fixed that problem.
    volvobrynk likes this.
  7. Well said, I'm using a 3.08 in my avatar, Nailhead / TH350, the perfect gear for my set up, 2500 rpms = 68 mph.
  8. Thanks every time I mention something like that the peckerwoods crawl out of the woodwork. I have actually received hate mail for a statement like yours. :D

    My mouse would pull it but a mountain motor would pull it better. When I get my A Boone on the road you and I need to find a place and hook em up. Winner buys the cheese burgers. ;)

    My sweet spot is between 3k and 3200 the 3.08 in the Pusher was perfect for highway cruising for me.
    1927graham likes this.
  9. Thank you all!
    Looks like a 3.07 or 3.08 is the answer.
    Now where to find one dirt cheap....
    Can anyone give me a lead on what to look for in the junk yard....
    What did they put these rears in?
    Again thank you for your support... Joe
  10. squirrel
    Joined: Sep 23, 2004
    Posts: 48,733


    If it was my car, I'd drive it with the rear that's in it now for a while and see how I like it.

    3.08 rears were common in many cars. The 3.08 8.5" ten bolt in my 57 Suburban came out of a 74 nova. Probably more important, is the width and wheel bolt pattern, and possibly the mounting setup.
  11. Thank you, so far it has less the 2 mile's on it.
    I think what I'll do is like you say give it a try, and if need be then move to a 3.08. I read some where that the engine, trans and rear should blend together for the desired use of the car, ie, in town, highway, just cruising...... That was the purpose of the inquiry, to get a feel for what all you folk think.. Thank you all.....Joe
  12. Actually, 2.73 was not that uncommon for Fords of the '60's.
  13. squirrel
    Joined: Sep 23, 2004
    Posts: 48,733


    Chevy used ratios from 2.29 to 4.11 over the years...and if you're used to driving modern cars with overdrive, the 2.73 may be ok.
  14. I'm in agreement with Squirrel. There were a lot of cars built with 2.70-2.73 gears with 350 turbos and a helluva lot more weight and 25 inch tires. You said your 350 was bone stock. That combination will work great with your light car and I see in the photo you do not have a tall [29-30 inch] tire on the back. You'll be fine until you get bit with the horsepower bug.......then you'll change everything! Drive the sumbitch and spend the gear money on car wax and tire dressing. .
  15. 325w
    Joined: Feb 18, 2008
    Posts: 5,563


    Well my coupe has a 2.78 and 350/350. When it had the TPI it all worked good but got less fuel mileage than a friend with a 32 sedan and a carb. He ran a 3.50 rear gear. I had good 3.07 ish in the coupe and found this
    Real good 2.78 and switched them out. My take off is fine but not as good as it was. At 65 on the hi way it's fine I guess.
  16. BamaMav
    Joined: Jun 19, 2011
    Posts: 4,871

    from Berry, AL

    I had a 2.79 in my Linc, switched it to a 3.00 this spring, same set up, stock 350 with a turbo 350 behind it. Only increased my highway RPM about 200 RPM, made take offs seem better, can't really tell much difference in fuel mileage, but haven't really checked it. My rear is a 8" Ford, so your results may differ.

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