Got the Transgo 1-2 shift kit, any suggestions before installation?

Discussion in 'The "Juice Box"' started by EEE, Jul 17, 2007.

  1. EEE

    EEE Straight out of lo-cash!

    I picked up the 1-2 kit, and also a b&m governor reaclibration kit. I'll hopefully be installing the shift kit tomorrow, and I was just wondering if you guys have any suggestions on installation, or maybe on additional modifications, additional drilling to the plate?
     
  2. 7 skylark 1

    7 skylark 1 Well-Known Member

    my opinion, if you want a really firm shift drill the spacer out to the largest size recommended, i wish i did on mine. i drilled mine a little smaller than recommended and the part throttle shifts are not as firm as i would have liked. the full throttle shifts are good.
     
  3. Smartin

    Smartin antiqueautomotiveservice.com Staff Member

    Get ready for a trans fluid shampoo..
     
  4. jakeshoe

    jakeshoe Well-Known Member

    TransGo is usually conservative with their orifice sizing but I wouldn't go with the largest orifice sizing.
    There is no reason to have hard part throttle shifts. It is only detrimental to the trans. WOT shifts will still be very firm with the orificing around .135 or so.
    It doesn't hurt anything to go to the full .157" on the 3rd feed hole because Transgo maintains the 2-3 accumulator so this can work without issue.

    I would setup the accumulator valve on the 2nd from firmest calibration. It leaves some room to go either way.

    New filter while there obviously. Double up the o-ring on the filter tube.
     
  5. skylarkroost

    skylarkroost skylarkroost

    I agree with Jake. Setting it up for hard partial throttle shifts is a mistake. You'll get really tired of replacing u-joint and pinion gears not to mention barking the tires next to Officer Friendly while trying to gently pull away from the light. Probably more harm to the rest of the drivetrain than the tranny in a 400THM. Driveablity just plain suffers.
     
  6. EEE

    EEE Straight out of lo-cash!

    Thanks guys! I'm sitting here with the instructions trying to figure out which parts to do, and which not to. I'm also a little confused by the terminology and what each part we're discussing is, does and is called. I'll try to make some kind of list and maybe you guys can help me understand what needs to be done. I'll scan the pages, then maybe we could go through them.

    Here's the link to the scan, I thought I'd save the site some bandwidth:
    http://lucidroom.com/transgo/transgo.html
     
  7. EEE

    EEE Straight out of lo-cash!

    On page "2" as it is called (the first page), I take it I will not do any changes to the pressure regulator, or? My car isn't exactly a full race car with over 450hp. ???

    How about the other items further down, do I do any of them? I've understood it as this is something you would do if the transmission is apart?

    - - -

    On page "3" as it is called, you install a new shift valve to be able to get into first gear at any rpm, any need for this? I don't see when you would downshift an automatic unless you are engine braking the car? Which seems kind of desperate in a car like mine.

    - - -

    On page 4, where you adjust the 2nd accumulator valve, any ideas on this? Which springs to go with, which version of the valve would be in my car (see bottom left of page)?

    "I would setup the accumulator valve on the 2nd from firmest calibration."

    (orange) has been suggested, I guess you leave the outboard spring off.
    - - -

    On page 5. We have three feed holes to size up here, A , B , C . Which range have you guys been using on all of those?

    WOT shifts will still be very firm with the orificing around .135 or so.
    It doesn't hurt anything to go to the full .157" on the 3rd feed hole because Transgo maintains the 2-3 accumulator so this can work without issue.


    So .135 on A & B, and .157 on C?

    - - -

    On page 6. There is no new modulator included in the kit, should there have been? Do I fit the pink spring to my existing modulator valve, or do I just skip thar spring?

    It says "don't forget front servo" (middle left of page), I have no idea what that means. Then there's the orifize passage, I take that that is what has been discussed earlier in this thread?

    Allison type filter, something I guess I don't need at this time. No o-rings are included in the kit, I get that from somewhere else I take it.
     
  8. John Eberly

    John Eberly Well-Known Member

    Kimson -

    You are right on not modifying the pressure regulator. Increasing the line pressure is very hard on your trans, and it is extremely difficult to reinstall the spring and plunger for the pressure valve with the trans in the car. Stick with the other modifications, leave the pressure valve alone.

    The shift firmness is up to you, but remember that you are pushing a lot of iron around. I'd say stay conservative - you can always go back into the transmission and drill bigger later.

    You might consider adding a drain plug to the trans pan while it is apart - save you from future baths in the pink skin lotion!
     
  9. EEE

    EEE Straight out of lo-cash!

    Sounds good, I also took this quote from Smartin on the buick centurion forum:

    "Don't install the spring behind the vacuum modulator as they say in the instructions. It almost makes 2nd gear non-existant when you are driving around. It will make 3rd gear kick in too soon."

    I guess we'll leave that out too.
     
  10. jakeshoe

    jakeshoe Well-Known Member

    No changes to pressure regulator. The stock spring in good shape will yield 160+ psi, this is adequate enough for 1000HP is other things are taken care of.

    You will not be installing the case snap ring or direct clutch return springs.

    The 1st gear at any rpm feature prevents an unwanted shift from 1st to 2nd at high rpm that stock TH400's do. Installing the valve and plug fixes this and makes the valve body a "manual/automatic", that is full manual control of downshifts and upshifts out of first. It will maintain automatic function in 3rd.

    Yes the orange spring inboard or maybe even the next lighter spring. I don't have the instructions in front of me and don't remember the colors. It's not terribly critical and is dependent on how hard you want it to shift.

    .125-.135 on the 2nd feed hole, I stay a bit more conservative on this hole because if it shifts too hard it hurts the intermediate sprag. On my racing units I install a 34 element sprag and do some other things to upgrade this area, but on a stock 16 element sprag, use caution with the hole size.

    .140-.157 on the 3rd feed hole. Transgo uses the 2-3 accumulator function, and they dual feed. The dual feed mod increases the capacity for power in 3rd gear, but the TG kit is too slow for race setups, so we do this mod internally.
    You'll notice your TG plate is a 3 piece design sandwiched together and riveted. The stock plate is not. They have a passageway cut into the center plate to re-route fluid from 3rd gear circuit to the reverse side of the direct drum. You'll also notice the "C" hole is smaller on the TG plate than the stock plate. This is the 2-3 accumulator feed hole IIRC. Being smaller restricts how fast oil is routed to the accumulator which softens shifts. So oil is routed faster to the 3rd gear clutches but your accumulator is still effective. Very smart on TG part but I do it a bit different on my builds. I don't use the 2-3 accumulator at all, but I keep the orifice sizing smaller, and the dual feed takes more fluid, so it acts like an accumulator somewhat.
    Again hole sizing is up to you, and I have found with plenty of power (450+ Hp) , the 3rd feed needs to be on the large size to keep the clutches alive using the TG kit, and it is still limited.
    .140" is a good place to start. even at .125" you'll find that at 3/4 throttle and above you will get a 3rd gear chirp on street tires and at WOT my Chevelle would chirp going into 3rd on 11" wide slicks at the track with the relatively mild 427.

    No modulator included in the kit to save $$. You can get one from a local parts house for about $10 usually. I don't save much getting them from a trans supplier. I pay about $7 for the regular red stripe at trans shop price.

    Leave the pink spring off. You can add it later to soften the shifts a bit if desired but it makes the part throttle shifts too early.

    Don't forget to re-install the front servo when you put the VB back on.

    I have brass screened high flow TH400 filters (late style) in stock. You might be able to get them from a parts store but most are fiber mesh. A trans shop can get you brass or fiber type.

    If you go to a trans shop, get a fiber pan gasket also. Accopack or Farpack type.
     
  11. nailheadina67

    nailheadina67 Official Nailheader

    This is coming from experience.......definitely leave the stock pressure regulator spring in there. If you stiffen it up then the part throttle shifts will be too harsh and adjusting the vac modulator will have no effect. Been there, done that. :Dou: If you keep the pressure down, you will always be able to adjust the modulator to where the part throttle shifts suit your taste.

    When you floor it, detent pressure which is higher takes over and makes the full throttle shifts firmer. By using that heavy regulator spring, it's like running on detent pressure all the time. At least that's my take on things anyway.

    As for the drain plug..........that's definitely worth it. :)
     
  12. EEE

    EEE Straight out of lo-cash!

    Thanks for the help guys!

    :beers2: :beer :beers2: :beer :beers2: :beer
     
  13. jakeshoe

    jakeshoe Well-Known Member

    Raising the pressure doesn't necessarily make the shifts harsher. All else being equal they will be harder, but the shifts become harder for two reasons. The increased fluid pressure forces the fluid through the orifice holes faster and applies the pistons with more force.
    You can reduce the feed hole size to compensate for the increase in pressure. I usually use a slightly heavier PR spring because many of my builds are for 600+ HP applications and I am using the manual/auto VB setup that will need greater minimal line at light throttle.
    My shifts aren't hard at light throttle. Crisp but not harsh.
    It is not like running detent pressure at all times. Detent is a seperate circuit that does just that, causes a downshift. Full line pressure with the detent activated is no different than full line without it.

    You're lack of ability to adjust your modulator has something to do with the additional hole you drilled. :)
     
  14. EEE

    EEE Straight out of lo-cash!

    There's always something, on p.3 it says you should change out the shift valve to another one with the same diameter. Well, in the kit there are two new valves, but both are larger than the original one. I know there has been a different shift kit installed in the transmission earlier, so this might have something to do with this, any ideas.. .I'm in the middle of this so a quick answer would be great.

    http://lucidroom.com/transgo/transgo.html
     
  15. jakeshoe

    jakeshoe Well-Known Member

    You can grind a land on the original valve. You need to grind two flats on opposing sides.

    In the pic:

    [​IMG]
     
  16. jakeshoe

    jakeshoe Well-Known Member

    Are you sure you have the right valve?
     
  17. EEE

    EEE Straight out of lo-cash!

    I got that one sorted out, the valve was just stuck in there and the small valve was an intermediate one that sits in front of the one I didn't see at first.
     
  18. EEE

    EEE Straight out of lo-cash!

  19. bobc455

    bobc455 Well-Known Member

    Some GREAT information here guys.

    As it happens, my TH400 just went "ka-blooey" so it is time for a full rebuild. I gave the trans shop a 100% stock (never opened) Th400 with about 80000 miles instead of rebuilding the one I have, for a few reasons. I have a ~450HP motor, but I also use an occasional 200-250HP hit of nitrous, so I need to set it up slightly differently. I also insisted on the Transgo shift kit, since it has been so highly recommended.

    Based on what I've read here, I've decided on the following:
    - 2nd feed hole: 0.135" (I am using a hardened sprag so maybe I should go larger?)
    - 3rd feed: 0.140"
    - 3rd accumulator: ??????
    - Do use the new snap ring & all 16 springs in direct clutch
    - 2nd accumulator valve: orange spring inboard, no outboard
    - Modulator: use pink spring

    Durability and reliability are KEY, and 1-2 tire chirps are nice (but emphasis goes to durability). The shop will be using "upgraded" frictions & steels, hardened sprag, etc.

    This car does spend a LOT of time on the street, which is why I will be using the pink spring in the modulator. For very very light throttle, early & comfortable shifts are just the ticket.

    Any insight is appreciated!

    Thanks,

    -Bob Cunningham
     
  20. Smartin

    Smartin antiqueautomotiveservice.com Staff Member

    I didn't put the pink spring in my modulator this time, as I didn't like the short 2-3 shift it had on the street when the spring was installed.
     

Share This Page