2.93 or 3.23? What to get?

Discussion in 'Got gears?' started by Mike Trom, Aug 18, 2007.

  1. Mike Trom

    Mike Trom Platinum Level Contributor

    I am going to have my rear rebuilt (on my GS :laugh:). It currently has the original posi with the 2.93 gears. I have an opportunity to have it rebuilt with 3.23 gears (for extra $, I would have to buy that gear set).

    Right now my GS will get 18 MPG on the highway with the 2.93's but it does not have that "pull" when you step on the gas at the start. Would the 3.23 gear be a little more fun for the around town cruising? (mostly what I do)..

    I know it will make my spedo read wrong with the different gears, not a big deal.

    What do ya think...

    :3gears:
     
  2. ibmoses

    ibmoses TORQUEMONSTERHASBEENSOLD

    When I had the 8.5 built to replace the factory 2:93 in my 70GS455 I had to make the same decision...
    From what I remember though a 2:93 was not available for the 8.5.
    I got the 3:08 and love it.

    Bert
     
  3. cjp69

    cjp69 Gold Level Contributor

    Mike should have the 8.2 rear in his 69, I think the 3.08's are only for the 8.5's. Come on guys, how about some input? I am thinking about doing the same thing with my 2.93's.:TU:
     
  4. kick71

    kick71 Mike

    Well i have a 3:23 in my 71' Skylark now. It originally was a 350 2bl pegleg car. I put in a mild built 400bbb th400 and 3:23 rear. Driving with that gear was a HUGE blast:3gears: speedo was of about 15mph, till i threw a rod in the 400. So I just had e new 455 built by engine shop and i am dropping that in a keeping the same rear. Although I do have a 3:42 gear set I may stick with 3:23. Its a street car and I really don't care about mpg.
     
  5. Mike Trom

    Mike Trom Platinum Level Contributor

    Yes I have the original 8.2...

    3.42 were the standard gears for GS400 with 3/4 speed manual transmissions. 2.93 came on GS400 automatic cars. 3.42, 3.64 and 3.91 were optional GS400 automatic trans ratios.

    What can I expect from a 2.93 to 3.23 gear change?
     
  6. flynbuick

    flynbuick Guest

    WQith a 3.23 gear set I run about 3000 rpms at 60 mph indicated with a TH 400/ 455 and 2.45/60 - 15 tires.
     
  7. ibmoses

    ibmoses TORQUEMONSTERHASBEENSOLD

     
  8. IDOXLR8

    IDOXLR8 Senior Member

    I would go with the 3:23 set. The differance between the 2:93 is not that great. Performance grains would be worth it and fuel milage would not be a real big differance eather. I went with 3:42 my self and this was a good set for performance and highway trips, AL.
     
  9. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member


    Jim,
    You trying to scare the guy:laugh: 3.42's with the stock tire (26.6")will turn about 2700 RPM at 60 MPH. 3.23's will be about 100 RPM less. The 2.93's will turn about 2300 RPM at 60, so there is roughly a 300 RPM difference between 2.93's and 3.23's at 60 MPH. The difference between the gear sets as far as low end scoot is something you will be able to feel. Gears are multipliers of torque.:TU:
     
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Mike, that is very easy to fix once you make the gear change. The hardest part is finding out how many teeth are on the speedo drive gear. After that it's just math to find out what driven gear you need to change to.
     
  11. 68 LeSabre 4dr

    68 LeSabre 4dr Well-Known Member

  12. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    That is a good chart. Note that those RPM's are at 65 MPH and don't figure in converter slip which shouldn't be more than 100-150 RPM.

    336/tire height X MPH X rear gear = RPM 336/26.6 X 60 X 3.23 = 2448 RPM, with converter slip, 2550-2600 RPM
     
  13. Mike Trom

    Mike Trom Platinum Level Contributor

    Thanks for the help.. I have 215R70-14 tires so my RPMs will be higher.

    I need to find someone in the area with 3.23's and hitch a ride to feel the low end difference. The 2.93's are smooth but the 3.23's might add a little more low end fun:Brow: Going from 2.93 to 3.23 is not a huge jump so I know the low end difference will not be major though...

    I think the 215R70-14 tires I have now are still shorter than the original f70-14 polyglass tires that the car came from the factory with so my spedo is not correct (it's close) anyway.

    I know the parts for an 8.2 are hard to get but I have a local Buick mechanic (guru) that I spoke with and he said he could get the parts when I'm ready...
     
  14. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Mike,
    I just went from 3.42's to 3.73's and I could feel the difference. You will be going with the same ratio jump.

    F70-14's were 26.24" tall, the P215/70R-14's are 25.85" tall, less than a 1/2" shorter.

    Make sure your mechanic knows that the 68-70 Buick 8.2 is not the same as the BOP 8.2 like in the 64-67 Buicks.
     
  15. wkillgs

    wkillgs Gold Level Contributor

    Mike if you can possibly find a pair of tires that are 2.5" shorter, that will give you the same efffect as changing the rear gears.
    Maybe a pair of 'space-saver' spares for a test drive????

    Just goggle 'gear ratio tire size calculator' to find what size tire you need for the test.
     
  16. Mike Trom

    Mike Trom Platinum Level Contributor

    He knows that for sure, he has been working on/racing Buicks for a long time :TU: I don't think he races anymore but he runs a shop that specializes on Buicks..

    I will be pulling the rear out once the car is put in storage (October) and that is when I will have to decide on the gear change...

    :beers2:
     
  17. 67 Post GS

    67 Post GS Well-Known Member

    go 3:23. i got 3:42 's in my 67 and there a great all around gear. You'll notice the difference.
     
  18. bobc455

    bobc455 Well-Known Member

    You don't say how often you drive on the highway.

    If highway driving is a serious consideration for you, then the 2.93 is a great gear. However if you don't actually drive above 55MPH for a long time very often, then go with a 3.23 or whatever. I drive my car on the highway quite a bit at 75-80, and when I go to Bowling Green (or whatever) the car is driven and not trailered.

    How you will use the car will give you the answer to the question.

    -Bob C.
     
  19. Mike Trom

    Mike Trom Platinum Level Contributor

    Only a few "long" road trips, mostly around town driving...

    I may get the 3.23's and save my original 2.93's just in case :TU:

    :beers2:
     
  20. Scot69GS400conv

    Scot69GS400conv Stepchild

    Last month I went from a 8.2" 2.93 open to a 8.5" 3.42 posi and MAN, that really woke up my all stock 400. As far as I'm concerned that 2.93 was a real TURD gear (in my humble opinion, of course). It feels like I gained 40 horsepower!!! It's a blast to drive now.

    I do notice a big difference on the highway. If you want performance, go with the numerically higher gear. If you're taking the family on vacation in the GS, go with the sluggish but economical 2.93 (economical / muscle car ... aren't those terms mutually exclusive?)
     

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