1-2 upshift early

Discussion in 'The "Juice Box"' started by puddle, May 24, 2023.

  1. puddle

    puddle Silver Level contributor

    I have a th400 out of a 1976 LaSabre behind a mild 455 and tag says BC. I have installed a transgo shift kit to the heavy duty level. I have played with the governor and the 2-3 shift is about perfect at 5200 RPM WOT. The 1-2 shift however is early at 4600. I would like to raise the 1-2 shift point to about 5400 RPM. Do I do that be shimming the 1-2 shift valve spring? I try to shift it manually, but find it difficult to time it right to hit that 5400 rpm with my old man reflexes and sloppy factory column shift.
     
  2. LARRY70GS

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

    How have you played with the Governor? Do you have the B&M kit? WOT shift points are controlled by the governor. You need more work there. You also need to verify that the kickdown is hooked up and working. The transmission will short shift if it is not.
     
    Last edited: May 24, 2023
  3. puddle

    puddle Silver Level contributor

    Kick down is working properly. I have a Superior Solutions shift point package #K018. Tried several combinations of weights and springs and dialed in the 5200 rpm 2-3 upshift that way, but whatever change I made, it moved both 1-2 and 2-3 upshifts together. Nothing I did moved the
    1-2 upshift without changing the 2-3 upshift, and increasing the 1-2 upshift RPM made the 2-3 shift point too high. Also lightened the primary weights, and that increased the part throttle shift points, but had no effect on WOT shifts. I have an adjustable vacuum modulator, and played with the adjustment, and that only affected the part throttle shifts. So to summarize, I have the transmission shifting as I like, except the 1-2 WOT up shift is too low.
     
  4. LARRY70GS

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

    The secondary weights are the ones that need modification/change. Also, the springs will will bring the shifts closer together (stiffer) or further apart (lighter). It's a time consuming process that requires a step by step approach. You haven't got the right combination yet. Change ONE thing at a time, and evaluate. The weights get you in the ballpark, the springs fine tune. I'll attach the instructions for the B&M kit.
     

    Attached Files:

  5. puddle

    puddle Silver Level contributor

    Thank you for posting the B&M instructions. Yes, I have tried many combination of secondary weights, but not so much with the springs. But like I said before, nothing I did seemed to raise the 1-2 shift without also raising the 2-3 shift, and wondering if I had exhausted possibilities there and needed to try something else, or something is amiss in the transmission. I will try again with stiffer springs and see if I can get there.
     
  6. Bigpig455

    Bigpig455 Fastest of the slow....

    I was messing with governors a few years ago, and had some good results. Problem was , what was good for my transmission didnt neccesarily repeat in the next transmission due to line pressure differences, etc..

    This thread was very helpful in establishing a baseline, and discusses an important concept of "noseweight" vs total weight. ..:

    https://www.v8buick.com/index.php?threads/governor-info.207490/page-3
     
  7. puddle

    puddle Silver Level contributor

    Thanks for posting the link to that other thread. Some good info in there and helps understand the workings of the governor. I was able to test a couple more iterations today between chores, errands, holiday traffic, and thunder storms. I have been able to get the 1-2 shift where I want it, but then the 2-3 is beyond 5500. I can also get the 2-3 up shift at around 5200, but then the 1-2 shift is way low. I have never run across a combination recently, or during any test sessions in the past, where the 1-2 and 2-3 shifts occurred at the same, or close to the same rpm. In every case, the 1-2 up shift has always happened at a considerably lower rpm than the 2-3 up shift. I have a few more general combinations to try, but I am running out of options with the governor.
     
  8. TrunkMonkey

    TrunkMonkey Well-Known Member

    It may be "Cap'n Obvious" territory, but make certain the vacuum line to the modulator and fittings have zero leaks. It can make for all kinds of swings in up shift RPM with 1-2/2-3 and kickdown. As well as checking the spool/spring behind the modulator (sticking/hanging)

    Try tests with/without the spring and take good note/comparisons to rule it out as any issues.
     
  9. puddle

    puddle Silver Level contributor

    Thanks, I will certainly check the modulator vacuum line for leaks, and check the valve, and test with and without the spring. I can say that the WOT shift points, and part throttle behavior is very consistent. Once a change is made to the governor, it will hit those same shift points every time. Looking at my notes, when the transmission is working the best, and hitting that 5000-5200 rpm 2-3 wot up shift, the weights and springs are very similar to what Jim Weiss puts in his TH400 transmissions to get 5300 1-2 shifts and 5000 2-3 shifts. Mine does that except the 1-2 wot upshift is 700 rpm lower.
     
  10. TrunkMonkey

    TrunkMonkey Well-Known Member

    Consistently is key. Then make small single change and "creep up" on the goal.

    You may be very close to dialing it in. (Some times that last bit can be a bit of a battle)
     
  11. puddle

    puddle Silver Level contributor

    Yes, by changing one secondary weight one step heavier or lighter, I can change the WOT shift point by 100 RPM or so. I can do the same changing one spring to the next strongest or weakest. What I can’t do is get the 1-2 shift and the 2-3 shift to occur at or near the same RPM. In every single combination I have tried, the 1-2 up shift always happens at least 700 RPM lower than the 2-3 up shift.
     
  12. puddle

    puddle Silver Level contributor

    For instance:
    (shift points rounded to nearest 100 RPM)
    Weights B and D, green and orange springs:
    1-2 WOT shift point 4400 RPM
    2-3 WOR shift point 5000 RPM

    weights C and D, green and orange springs:
    1-2 WOT shift point 4500 RPM
    2-3 WOT shift point 5100 RPM

    weights D and E, green and orange springs:
    1-2 WOT shift point 4600 RPM
    2-3 WOT shift point 5200 RPM

    weights D and E, green and red springs:
    1-2 WOT shift point 5000 RPM
    2-3 WOT shift point 5700 RPM

    weights C and D, green and red springs:
    1-2 WOT shift point 4800 RPM
    2-3 WOT shift point 5500 RPM
     
  13. puddle

    puddle Silver Level contributor

    Here is a really horrible combination:

    E and F weights, black and blue springs:
    1-2 shift 3200
    2-3 shift 4900
    Early 2-3 part throttle

    other end also bad:

    A and B weights, red and purple springs:
    1-2 shift 5500
    2-3 shift 6000+
    Late 2-3 part throttle
     
  14. rkammer

    rkammer Gold Level Contributor

    When I was playing with part throttle vs WOT shifting last month I discovered that there are several types of governors for our T400s. The original type for my 1970 GS455 with the number's matching T400 had solid outside weights while the second types (sent to me to play with) had a hole in the outside weights about 3/8" in diameter.

    I found that the governors with the holes in the outside weights wanted to WOT shift at almost 6000 RPM in both the 1-2 and 2-3. Rather than experiment with those I decided to try modifying my original governor very carefully. So, I shaved just a bit off the top of the two inside weights and an angled cut on each side of each weight. I reused the stock springs on each side.

    I guess I got lucky. The bone stock weights would shift both the 1-2 and 2-3 at just under 5000 RPM. The modified weights got me the 5500 RPM shifts that I was looking for on the first try. Both shifts were almost identical.

    In order to get the part throttle shifts where I wanted them I had to adjust the vacuum modulator all the way clockwise as far as the screw would turn. It is now perfect and increases shift points with the speed of the car.

    I realize your problem is not being able to get the 1-2 and the 2-3 the same but thought I'd inject my experience in hopes that the info might prove helpful in some way. Here's a written pic of how I modified my stock inner weights as I forgot to photograph them before reinstalling the governor.
    Governor Mod (2).JPG
     
  15. puddle

    puddle Silver Level contributor

    Very good and thanks for sharing! I appreciate everyone’s input!
    This morning I removed the vacuum modulator and removed the spring. Valve moves freely and smoothly in its bore. No vacuum leaks in line.
    Checked the specs on the stock governor springs, and they match perfectly what Jim Weiss likes: .950” free length, 9 coils, .020” wire diameter. With my calibrated thumb and index finger spring checker, they feel to be right between the green and orange springs. Threw them in just to see. Also put back in the D weight (about 9 grams and full material on the end) and the E weight (about 7 grams and quite a bit less material on the end). So these are about like the 8 gram ones Jim Weiss uses.
    Went for a test drive. With the spring removed from the vacuum modulator valve, Part throttle upshifts are later and firmer, especially at small throttle openings. No apparent effect on WOT shifts. Those are now about 4600 1-2 and 5100 2-3, so really no change over green and orange springs.
     
  16. puddle

    puddle Silver Level contributor

    My apologies to Jim Weiss. I have been misspelling your name. So sorry! Thanks for posting what weights and springs work in your transmissions.
     
  17. BQUICK

    BQUICK Gold Level Contributor

    You can also get an adjustable modulator that you can tune for earlier/later shifts and firmness.
     
  18. puddle

    puddle Silver Level contributor

    Shoot, and now my stupid smart phone auto correct won’t let me spell it right!
    Weise
    Weise
    There!
     
    TrunkMonkey and rkammer like this.
  19. puddle

    puddle Silver Level contributor

    Oh yes, I have an adjustable vacuum modulator, and have tinkered with it. Removing the spring seemed to do the same thing as cranking in the screw half a dozen turns.
     
  20. puddle

    puddle Silver Level contributor

    Well, after tinkering with the governor for the past three days, I have come to several conclusions, with this transmission, installed behind this particular engine, installed in this vehicle, using this particular spring and weight kit: swapping springs makes a bigger change than swapping weights. Stiffer springs used with lighter weights seems to spread the shift points further apart, but lighter springs in combination with heavy weights did not bring them closer together either, and these extreme combinations started affecting part throttle shifts. Weights and springs near the middle range work the best. Fairly satisfied that the answer does not lie in the governor, but probably in the valve body. I did install the special 1-2 shift valve that eliminates the forced shift of the transmission, if the shifter is left in low, so perhaps I don’t have something right in there. But that will be another day when I do a filter and fluid change as well. On a positive note, I got to go out and make a bunch of WOT blasts-Weeeeee! Boy that was fun, and the engine is performing great! My sweetie says I should just get a B&M Mega Shifter and shift manually. That would be fun, but then my sweetie would not be as comfortable sitting right next to me on that bench seat.
     
    Mark Demko likes this.

Share This Page