Is my transmission truly correct and orignal to my 63??? - NCRS Discussion Boards

Is my transmission truly correct and orignal to my 63???

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  • Wayne M.
    Expired
    • March 1, 1980
    • 6414

    #16
    Re: Is my transmission truly correct and orignal to my 63???

    Here's the two designs of brass synchros that Bill mentions; later ('66-up) on left, early (mid-63 to '65) on right.
    Attached Files

    Comment

    • Joe L.
      Beyond Control Poster
      • February 1, 1988
      • 43205

      #17
      Re: Is my transmission truly correct and orignal to my 63???

      Originally posted by Donald Ayers (57880)


      I tell the guy and he says it will be months before he can look at it.

      .


      .

      Don------


      You mean to tell me that this guy has that many folks in line to have their transmissions screwed up by him?



      If you have any question as to whether the transmission is a wide ratio or close ratio, it's very easy to POSITIVELY discern which you have:

      Remove the side cover (very easy to do; put the transmission in 2nd gear first). If the main drive gear (i.e. the gear on the end of the input shaft) has 24 teeth, then it's a wide ratio. If it has 26 teeth it's a close ratio. It's not always reliable to tell by the circumferential rings (or lack of them) because some SERVICE and aftermarket gears didn't have the rings regardless of ratio.
      In Appreciation of John Hinckley

      Comment

      • Wayne M.
        Expired
        • March 1, 1980
        • 6414

        #18
        Re: Is my transmission truly correct and orignal to my 63???

        Originally posted by Donald Ayers (57880)
        .....I get the car finally going and from the first test drive I knew things did not feel right from a shifting standpoint i.e. the gears felt too close together between first and second. .....

        ..... During this time I get to drive other cars and even bought another (70 LS-5, which has a wide ratio & 3:36 rear) and they are a blast to drive and shift "just right" from gear to gear. ........
        Donald --- you mention closeness of the gears. The gap (or ratio delta) between 1st to 2nd, and 2nd to 3rd are the same, whether close or wide ratio.

        for example, you will see no difference with two identical cars; except one equipped with a wide ratio and 3.08 final drive, and the other with 3.55 gears and close ratio. It's only on the 3-4 shift that you will be able to tell which one has the M20 versus M21.

        I suspect your experience with the 454 is mostly due to big block torque .

        Also, no difference in the first 3 gears between two (otherwise) identical cars, one with M20 and 3.55 gears, and the other with M21 and 4.11's.

        Comment

        • Harry S.
          Extremely Frequent Poster
          • July 31, 2002
          • 5292

          #19
          Re: Is my transmission truly correct and orignal to my 63???

          Don, the 340 hp car and the 360 hp car all came with close ratio. You did not have to order it as an option. The 250 and 300 hp cars came with the wide ration.

          Saying that, is the close ratio really that bad or was it a crappy rebuild job? Being a purist I'd leave the close ration and sometime in the future cjange the ring and pinion to a 3.55 ot a 3.70. I know it's additional cost for the work but the same posi unit will take up to a 3.70 gear set.


          Comment

          • William C.
            NCRS Past President
            • May 31, 1975
            • 6037

            #20
            Re: Is my transmission truly correct and orignal to my 63???

            Easy way to determine if close or wide ratio without taking the trans apart. Drive the car, run up to 2200 rpm in low and shift directly into 4th. A close box will read 1000 rpm on the tach. A reading of 900 or less indicates a wide box. I agree with the previous comment about people standing in line for him to screw up their transmissions. I've done hundreds over the last 40 years, they aren't that hard.
            Last edited by William C.; July 12, 2014, 06:15 PM. Reason: enhance
            Bill Clupper #618

            Comment

            • Donald A.
              Expired
              • January 7, 2013
              • 239

              #21
              Re: Is my transmission truly correct and orignal to my 63???

              ThE person that "rebuilt" my transmission is well known here and has a NCRS number in the 3,000 range.

              He he came highly recommended by a longtime Friend in corvettes. However my experience witH this person has been very disappointing. He is a bit of a Jekyll / Hyde character, at least he was with me. He got my money and then was in no mood to hear there were issues or in a hurry to make good on it.

              I'll hold my tongue until we determine for sure the status.

              Comment

              • Donald A.
                Expired
                • January 7, 2013
                • 239

                #22
                Re: Is my transmission truly correct and orignal to my 63???

                OK, Status update. If you are reading for the first time go back and read post #15.

                Tranny is out of the car and it was verified to be a wide ratio. At this point I have to start over and think about how I set the car up different from when I bought it.

                Again, when I bought the car it had the original 4.11 rear end and a Close ratio box. I then changed the rear to a 3.36 and the box to a wide ratio. From day one the shifting is not what I would call a smooth transition from 1st to 2nd and 2nd to third.

                I don't know how to describe this in technical terms but imagine it like this. When you do a normal run up in first gear and you shift to second (letting foot off gas pedal and not adding power) the rpms jump up, like down-shifting and this causes the car to decelerate. Same thing when you go from 2nd to third but not quite as bad. It's like the perfect shifting combo for normal driving is to shift from 1st to 3rd and leave out 2nd all together. It's like the gearing is too close together. I hope this makes sense to someone.

                For example, I got to drive a friends 65 that has a Close Box and a 3.70 rear and it was great with very smooth transitions. With my new 70, the shift points are fantastic and so easy to drive and it has a 3.36 and a wide box?????

                I'm just about lost on all this stuff.

                So this leaves me with decisions I have to make because I hate the car the way it is and I have to change something or everything to get the car to drive better.

                Can anyone chime in here with what boxes and rear combos deliver what I am looking for???
                Attached Files

                Comment

                • William C.
                  NCRS Past President
                  • May 31, 1975
                  • 6037

                  #23
                  Re: Is my transmission truly correct and orignal to my 63???

                  OK, the close/wide ratio discussion has NO relationship to the issues you have described, as the 1/2 and 2/3 shifting parts are the same for a close or wide box, the only difference is the input and cluster gears. Frankly, a 340 hp car is never going to be as "low noise" as a 250-300hp car just due to the mechanical lifters, but that issue is unrelated to the difficult shifting you describe. The first question you need to answer to yourself is am I really happy with a high-performance mechanical lifter engine and accompanying drivetrain or not. Once you are satisified that a noisy, somewhat tempermental hi-perf engine is what you want, then proceed with the trans issues, or replace the car with a 250/300hp version and have fewer issues and less noise.
                  Bill Clupper #618

                  Comment

                  • Donald A.
                    Expired
                    • January 7, 2013
                    • 239

                    #24
                    Re: Is my transmission truly correct and orignal to my 63???

                    Bill;

                    Thanks for the reply. My engine has been rebuilt and "detuned" from the original 340 hp configuration. Basically it is exactly the same set up as original 340 hp with the exception of flat top pistons (compression ratio around 10.25 to 1), Stock 300 hp cam (929H from comp cams) with hydraulic lifters.

                    Comment

                    • William C.
                      NCRS Past President
                      • May 31, 1975
                      • 6037

                      #25
                      Re: Is my transmission truly correct and orignal to my 63???

                      BTW, if the stamped number on the side of the case 15xxx? matches your VIN, at least the case is original to the car.
                      Last edited by William C.; July 26, 2014, 11:07 AM. Reason: spelling
                      Bill Clupper #618

                      Comment

                      • Donald A.
                        Expired
                        • January 7, 2013
                        • 239

                        #26
                        Re: Is my transmission truly correct and orignal to my 63???

                        Bill;

                        It is the original transmission with VIN stamp

                        Comment

                        • Stuart F.
                          Expired
                          • August 31, 1996
                          • 4676

                          #27
                          Re: Is my transmission truly correct and orignal to my 63???

                          Just another voice chiming in on this; I have an original 340 hp (L-76) w/close ratio 4 speed (Muncie) and a 3.36 posi rear end. I love it just the way it is. I would never screw up the original engine with flat top pistons or any other cam other than the original Duntov. My engine has never been apart, nor has my clutch, transmission, or rear end (other than to replace a leaking pinion seal). Yes, after 47,000 miles, my tranny makes a little noise like a rock crusher box (whining) while loafing along through our village at 25 or 35 mph, and my clutch has seen better days such that I initial start the engine with my tranny in reverse and the clutch in (to save wear and tear in the vulnerable reverse gear). But, I have so well tuned my AFB that my car will practically idle away from a dead stop without feathering the throttle or slipping the clutch. I can run it up to redline in 1st, 2nd, and 3rd anytime and wind away from any other stock Corvettes with 4.56's, 4.11's, 3.70's, or 3.55's (except maybe Duke's L-76 with 3.08's). Why anyone would want to change such a perfect combination as that beats me. Don; Sorry for your troubles, but I think you have been given a lot of bad advice.

                          Comment

                          • Loren L.
                            Extremely Frequent Poster
                            • April 30, 1976
                            • 4104

                            #28
                            Re: Is my transmission truly correct and orignal to my 63???

                            I can't get by "...shift to second...rpms jump up" (with foot off the gas); to me that should only happen if 2nd gear is higher (numerically) than 1st; it's time for a transmission guy other than the one who built it to get a look at the insides.

                            Comment

                            • Chris D.
                              Very Frequent User
                              • November 1, 2002
                              • 198

                              #29
                              Re: Is my transmission truly correct and orignal to my 63???

                              Don, your dissatisfaction with the shifting / RPM response may have more to do with your engine changes. The 300 hp setup runs out of breath at a much lower engine speed than you were previously accustomed to with the 340. If you were shifting at 5500 or higher, you were just making noise and falling off the torque band sweet spot. Try shifting between 4500 and 5000 and see if this responds more to your likeing. Of the combinations you have already played with, my vote would go for the pure stock 340 pistons and cam, stock close ratio box, and the 3.36 rear. Better highway running and still passes for a factory delivered combination.

                              Comment

                              • Donald A.
                                Expired
                                • January 7, 2013
                                • 239

                                #30
                                Re: Is my transmission truly correct and orignal to my 63???

                                Stuart; When I got the car the engine had already been screwed up as you would put it. I thought long and hard regarding a return to stock but decided not to. That's another topic. You do bring up a good point about your combo. I could change the box back to Close Ratio and leave the rear end at a 3.36 and see how it drives. Then if I still want to change the rear that would be a separate work order.

                                Chris; The car is not being driven hard in fact the highest shift I've ever done was 4,500 rpm. My wife who wants to drive the car is very easy on it shifting gears more in the 2,500 to 3,000 max range. i.e. she's no hot rodder.

                                I have driven another car that is close to my house with a close box and a 3.70 and I thought it was great.

                                Please keep the thoughts coming!!!!

                                Comment

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