shifting issues

Discussion in 'The "Juice Box"' started by yachtsmanbill, Jan 1, 2014.

  1. yachtsmanbill

    yachtsmanbill Well-Known Member

    Got myself a cloned GSX 455/400 turbo. It was originally a 350/350 GS and built again in about 1990. When I got it there was a chevelle shifter cable and trans trunion installed that made for poor shifting (manually) and couldn't pull it down into L1. Got all that switched out and now have perfect control.
    The issue now is that when on the gas and I shift into L2 it wants to stay in L1. I don't want to over rev it of course so I back way off and itll shift. 1-2-3. Being refit, theres a welded on bracket for the 400 kickdown. The 350T had a switch on the carb. Is this a kickdown problem or a vacuum leak on the modulator? Hose at carb base may be cracked. Any ideas are welcomed. What happens if the kick down switch is taken out of the picture? Bill in TR

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    The vacuum port for the modulator is at the back bottom of carb and home made bracket is show as well...
     
  2. LARRY70GS

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

    First, you have an automatic transmission. It does not have a manual valve body, so if you move the shifter and the transmission calibrations "disagree" with your gear selection, the transmission disregards your choice:grin:, and follows it's own calibrations. The kickdown is simply electric. Apply 12 volts to the vertical tang on the driver's side of the transmission and it will kick down. Get under the dash, and floor the gas pedal. See if the switch is being operated correctly. Test the switch with an ohmeter, and make sure you have 12 volts at the switch and transmission. The system is very easy to troubleshoot with a test light or meter. The THM350 uses a cable from the gas pedal to the transmission to operate the kick down. If you eliminate the gas pedal kick down switch, it will never kick down, and the transmission will short shift at WOT. The vacuum supply for the modulator comes off the rear of the intake manifold, towards the passenger side. Even the aftermarket intakes have provisions for this. The rear center vacuum tap at the rear of the Q-jet will work, but it is supposed to be connected to the vacuum storage tank on the fire wall, for the climate control.
     
  3. yachtsmanbill

    yachtsmanbill Well-Known Member

    Thanks Larry, that's pretty much what Ive come to find over the years. However, I can see the kick down being disconnected and causing a same gear BOG with the secondaries opened. That's a simple matter of pulling the shifter down one or two gears. I use that term as in a "passing gear" situation.
    That's gonna bring us to a dual control situation. The electric versus mechanical governor. Even if the "magic" number is attained, irregardless of the switch position, the governor should cause an MAX RPM attained shift... at least it did on past owned 3/4 ton Suburbans (2x4s) and a few other 400Ts Ive owned. Hows the magic number determined where the electric stops and the mechanical takes over? In other words, there should be a set point for the switch, being either on or off.
    The only part I disagree with you is about the short shift. HYDRAULICALLY, the trans should stay in low if that's where the selector is, at least until the magic governor speed is met. I should be able to redline in first, hold the pedal down and shift into second. That's what is not happening right now. On the short shift, sometimes traction conditions can warrant that as well. I had a LS7 chevelle with a close ratio super T10 that ate short shifts alive. She loved it and minimized tire slip, keeping the engine speed in the power band.
    So I AM gonna change the vacuum porting, as the previous owner had stuff running all over the place and most of it not working, especially no defrosters with the vacuum pod on the firewall having NO SUPPLY! . The modulator was ported to the carb tho. I don't recall seeing an available port on the manifold on the passenger side tho... The pic below shows a silver block off I made for the defunct EGR, (no lectures please!) and I think there may be a hose with a screw plugging it just behind the carb.
    Now to make a long story short, whats the adjustment criteria on the electric switch itself? OFF then ON at Wide Open Throttle? Maybe Im just a control freak??? Bill in TR

    Vacuum tap plugged just forward of brake booster line. Vertical hose with screw inserted???


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  4. LARRY70GS

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

    Bill,
    An automatic like the 350 or 400 works off 3 inputs. The governor indicates vehicle speed. The modulator indicates engine load, and the kick down switch indicates throttle position. The valve body uses those inputs to determine shift points. It's like a tug of war between the inputs to determine shift point. If the kick down signal is not present, the transmission will shift at a lower RPM at WOT. If you attempt to manually shift into the next gear, and the governor says no, it will not shift. Same with the other 2 inputs. It will not shift unless it wants to. A full manual valve body will give you full control of your shifts. There is no adjustment on the kick down switch. The only thing you can do is put a piece of 3/8" hose on the switch so that the switch activates earlier, but it is just an on or off thing. Being that you have a weld on bracket, the gas pedal may not be activating it at the proper throttle opening. That's why I advised you to actually look under neath the dash as you push the gas pedal with your hand. It should operate the switch between 1/2 -full throttle. There is an adjustment procedure in the chassis manual. If you push the switch in the opposite direction it normally moves in, it will snap into a locked position. You then make a full throttle gas pedal application, and the switch will make a 1 time adjustment. Like I said, the transmission needs all 3 inputs, and they need to be correct inputs. The governor weights and valve can be gummed up. The governor gear can be damaged. The modulator may be leaking fluid or vacuum. The kick down switch may not be getting 12 volts, or it may not be passing the 12 volts down to the transmission, or the kick down solenoid may be defective and not working. Any of those things will affect shift points.

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    The correct modulator tap is right above the #8 . Below the #7 is the power brake tap. Your EGR block off may be covering the hole. If the hole is open, you will have a sizable vacuum leak. Vacuum connection varied by year, but the modulator and power brake connections were the same.
     
  5. yachtsmanbill

    yachtsmanbill Well-Known Member

    MAN!!! Finally got some concise answers here, and I thank you! I didn't realize that the governor was driven by road speed. I had a plastic drive gear bust (it was -40F and broke on initial moving of truck) and I had a 25 mile drive in rush hour Chicago traffic home in LOW gear only; had that and reverse.
    I think the modulator is OK as theres no smoke out the back from sucking up trans fluid. A fogger was always a clue the diaphragm was cracked. Im gonna take a better look at the manifold, but the plug locations may have changed with the advent of the EGR location.
    Utica Geoff has offered me a spare kick down switch mount, at which time Im gonna check for correct throttle cable length. I still don't know why the PO had to butcher one together, but Ill bet a penny to a dozen donuts its not right. The guy was a real Carneador.
    On the switch picture, youll see a small resistor (?) which I don't get. That should be 12V in and 12V out and 12V at the trans plug right? Ive changed out governors before, but is the KD solenoid accessed from the outside or is it internal? Id really hate to hafta pull the trans out... having a double knee replacement in 3 weeks and thatll put the KAY-BOSH on any further underneath work for some time! Thanks again... Bill in TR
     
  6. ap1672

    ap1672 Silver Level contributor

    Were driving your car today 1-1-14 in Chicago?
    455 in the snow.
    You Wisconsin guys carry a big set of stones and a thick wallet to pay for gas.
     
  7. yachtsmanbill

    yachtsmanbill Well-Known Member

    Small world aint it??? Moved to Two Rivers, Wi. from Darien 4 years ago. Used to live at 302 Janet ave. Just south east of Clarendon Hills Road and Plainfield! Alas, that wasn't me tho... made that very trip 100s of times in 455 GS's at 18mpgs. Where in Darien are you at? Bill in TR

    ---------- Post added at 09:26 PM ---------- Previous post was at 09:19 PM ----------

    Just braved the frozen tundra to go take this pic... cant even find the value of the resistor in my books. Bill in TR

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    So I cranked the motor over (had a drain, now fixed!) and the stooped key buzzer stays on... had to pull the battery cable... Hmmm...
     
  8. LARRY70GS

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

    That resistor does not belong there. Never saw that before. Just apply 12 volts from the battery to the transmission connection and listen for the solenoid click. If you don't hear a click, it could be the solenoid, or the wiring inside the pan. The solenoid comes off with 2 bolts and is easy to change, just gotta drop the pan.
     
  9. yachtsmanbill

    yachtsmanbill Well-Known Member

    Yeah that resistor looks like a feed from 12V to ground... on the trans side of the KD switch; doesn't make sense being in parallel... series I can see it causing a voltage drop.
    Soooo..... I should be able to unplug the KD switch, turn the key on and jumper the two yellow wires to the black/green and hear the solenoid click. Kinda weird that the PO was a mtce. guy at a large (5000 head) dairy up here. I wonder if he worked for NASA and did the O ring job on the Challenger??? Theres another resistor that's been removed as well on some kinda control for the AC / heater box. Henceforth, all removed. I have a local shop here to do a fluid and screen job (last time unknown) and can have them do a solenoid and governor job if needed. They days of me laying on a floor that's 20F are over LOL... Bill

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  10. yachtsmanbill

    yachtsmanbill Well-Known Member

    Didn't do too much other than clean the shop and put some tools away... that's an ongoing issue around here! I did change the heater fan relay with another used one and now have 5 fan speeds... outstanding! Did some more researching and found out a few things; the EGR manifold has different vacuum ports than a non EGR. My OEM modulator tap was capped off and the hose split and probably leaks. Im gonna cap off the carb tap and re-use the OEM tap on the manifold... but wait, it gets better!
    Back to the issue of a kick down switch, I stuck between two hard rocks and a damn hard spot in the middle. Hmmm. From what Ive found out (this is gonna get confusing)The 1968 cars with a 350 OR a 400 turbo used the same accelerator/switch mount bracket. The 350 is mechanical and the 400 is electric. In 1969 to 1972, two different brackets were used, each specific to the trans in the car. As far as I can tell, mine has a 350 bracket with a 400 switch holder welded on and PROBABLY a 350 gas pedal Z bar. The geometry is different on those as well. But wait, that's still not all, if you are the next caller, I can tell you that the full sized cars all use the same 350/400 bracket and gas pedal.
    So now, todays trick question is: are the big cars gas pedal mount the same as the skylark sized mounts? After reading the description from Mr.Buicks page, the skylark (usually a wagon model with a 400T) or GS with a 400 turbo takes the same bracket as the big cars for the sake of mounting the KD switch. Anyone care to comment/confirm this? I am now on the quest for a correct gas pedal and mount for a 400 turbo. Never simple is it?? Heres some of todays pics... Bill in TR

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  11. yachtsmanbill

    yachtsmanbill Well-Known Member

    Havent figured out how to shift here either. Made this post at 1530 hrs today and it still shows 2 days old. Hmmm.... Bill in TR
     
  12. mrolds69

    mrolds69 "The Cure"

    Can't answer your questions, but I see a few things now from the back of the carb. The small bracket on the PCV hose You have attached to the car bolt. That should mount on the middle bolt of the choke stove on the intake, 'cuz there is heavy heat there. The short split hose with the bolt is where the modulator metal line should be. The metal line should be shaped like a cane handle on the end, it should go higher than the gas level in the float bowl and straight down into the hose/fitting. I forget exactly...something about modulator lines, there's a reason they need to be high like that. I don't know if it doesn't make good vac there, or if it can suck gas, I forget...but it's definitely something. Where you have it now is NG, that's where the vac hose goes for the Climate Control. Looks like the vac hose on your secondary pulloff might be split, too.
     
  13. yachtsmanbill

    yachtsmanbill Well-Known Member

    Great points and all valid... I think the "cane" is a vacuum trap, in the event that the modulator has a slight leak it doesn't get sucked directly into the intake... like an upside down P trap under the sink. I will absolutely move the PCV hose... another great idea! That's where the PO had it so that's where it went back... SMOOTH MOVE EX-LAX!!! I was gonna T off the carb base, but I think Ill change the fitting and use a piece of brake line and cut the existing and use a compression union there. The carb base fitting should run the vacuum pod for the heater doors... right now theres no hose to it and theres no defrosters!
    The more I go through this car the more I realize the guy mustve had the major body work done. The whole back end was replaced with GM sheetmetal in about 1990 and really does look good. If theres any countenance between his electrical and body working capabilities it sure didn't lean towards the electric! Id still rate the car as a 7 even though its a clone... Bill in TR

    [video=youtube;8Lw7aNJ-2E8]https://www.youtube.com/watch?v=8Lw7aNJ-2E8[/video]
     
  14. yachtsmanbill

    yachtsmanbill Well-Known Member

    CALLING ALL EXSPURTS !!!!


    So well now.... its been established that the throttle pedal bracket is different from the 350 to 400T to incorporate the electric kick down switch. Of course, mine is home made. IS THE THROTTLE PEDAL SHAFT DIFFERENT AS WELL ??? MrBuicks' answer is "could be" but I need a more definite answer than that. If this thing is gonna come apart for the bracket I sure as hell wanna put the correct shaft back in there.
    A member here has agreed to loan me a bracket to see the actual difference between the 350-400 but I need to see a pedal shaft to duplicate or revamp mine. If anyone has one to loan me, (or sell preferably!), Ill pay the shipping both ways and GUARANTEE its safe return within a few days. Any help is appreciated!! Bill in TR
     
  15. 69GS400s

    69GS400s ...my own amusement ride!

    Not unless his name is Allan McDonald - who was the Director of Space Shuttle Solid Rocket Motor Project at sub-contractor Morton Thiokol.

    But neither he nor the booster rockets were to blame. In fact, the night before the launch he refused to sign the "Launch Recommendation" over safety concerns that below freezing temps might inpact the integrity of said O-rings. He went on to testify during the presidential investigation that Morton Thiokol had been so concerned about the O-rings that they recommended to NASA that no shuttle be launched in temperatures below 53*F.

    .. and they were ignored.

    Allan McDonald has recently released a book detailing what really happened and it is on my short list to read



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    Last edited: Jan 6, 2014
  16. yachtsmanbill

    yachtsmanbill Well-Known Member

    That's the guys name all right, but he was in charge of changing out the O rings at the dairy on the teat sucker things... the whole plant lost vacuum and the cows stampeded....NEVER disappoint a cow at milking time!!

    So... for having the '69 step child (transition year on these brackets) whats your take on the pedal shaft? BTW... we have friends with a big dairy in Door County, Wi. Had the ex wife up there a few decades ago and told her I could milk a cow... She didn't believe me. She grabbed a teat like it was my... ah... er.... and got the same results! I got alongside ol' Bessie and we took a gallon of fresh off the tap milk home... yes, we did boil it first. She couldn't drink it... "Its gross"... where'd she think it came from? DOMINICS. She wasn't the sharpest knife in the drawer, but what a looker! Now back to our regularly scheduled
    Q & A's... Bill in TR
     
  17. 69GS400s

    69GS400s ...my own amusement ride!

    I would not think a big car bracket is the same as an A-body one. As far as 68/69 Abody vs. 70-72 ? as long as the donor had a TH400 I would think they are the same but I don't know fer sher. My only focus for more than 30 years now has been the StepChildren and even so Im still learning things all the time.
     
  18. LARRY70GS

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

    Bill,
    I think you are over analyzing this. As long as the switch gets activated, it doesn't care whether you bracket is original or fabbed up. Just look and see what's going on when the pedal is on the floor. You want the switch at the end of it's travel when the pedal is on the floor. Have a look and see what is happening. Like I said, you can slide a piece of 3/8 fuel line hose onto the switch peg, and/or bend the gas pedal rod so that it activates properly.
     
  19. yachtsmanbill

    yachtsmanbill Well-Known Member

    OVER-ANALYZING ! Always been my curse of being a German Virgo ! LOL... I thought that switch was more like a rheostat, with the final increase to 12 volts at the end of the stroke, where in reality, its an on-off switch. That stoopid resistor is what was throwing me and its gonna get the Kleins next time Im out there. So I really only need 12V supply, floor the pedal at 100% have continuity through the switch, and I should hear the solenoid in the trans click. I feel like a friggin' cave man that stayed at a Holiday Inn last night AND had the free continental breakfast!
    If I don't hear the solenoid click, Ill cross that bridge when I get to it! The rocket scientist (O ring specialist) mumbled something about that switch a few times and I never really did understand what he was saying. Now that I have carnal knowledge of it, Im beginning to understand it a bit better. I can change a clutch and rebuild a T-10 and be driving the same day, but electrical stuff stumps the heck outa me!. I worked as a steam turbine overhaul engineer for 30+ years, yet when the themocouples or vibration probes needed to be set they would call in the magicians with the white latex gloves (read electricians) and they were veryyyyy secretive about their stuff.
    I have a pedal mount from a 66 GTO coming from a pal here to size it up, and unless the geometry is grossly incorrect, Ill probably do as advised. I THANK YOU! BTW... I got my drivers license in my moms '68 GS but always like the '69s better! Step children can teach old dogs new tricks... sometimes! Bill in TR
     
  20. LARRY70GS

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

    Yes, it might be a bit awkward to try and activate the switch and then listen for the click under the car. You can have someone activate the switch while you listen if you like. Just work backwards if you don't hear the click. Apply 12 volts directly from the + battery terminal with a jumper wire. If you don't hear the click, you'll have to go inside the pan. Inspect the wiring from the inside of the case connector to the solenoid. You can use the jumper wire again at this point. If you can't get the solenoid to click, replace it.

    If you do hear the click by jumping it externally, then check for 12 volts at the wire to the transmission. Again, have someone operate the switch while you probe the wire with a test light or meter. No voltage, check up at the switch. One side should have 12 volts any time the ignition is on. The other side should with the switch operated.
     

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