TH400 trans rebuild

Discussion in 'The "Juice Box"' started by Luxus, Sep 26, 2019.

  1. 1969RIVI

    1969RIVI Well-Known Member

    For the shifter shaft bore I would just lightly smooth out the rough edges on the outer edge and the gouge in the inner chamfer with a red scotchbrite pad to prevent them from causing a knick in the new seal when putting it in and you should be good. As for the "maze" there's nothing to worry about there the case is cast aluminum which will never be 100% perfect and the chips were probably there from when the housing was cast and the gasket surface was first machined. It looks to me that the gasket surface is still nice and flat and not all pitted or have any low spots the could create any internal leaks within the valve body.
     
  2. Luxus

    Luxus Gold Level Contributor

    I'm just about ready to start putting it back together. I'm wondering about what kind of trans fluid to use. Just regular store brand should be OK, right? Or should I look for something better.
     
  3. Bens99gtp

    Bens99gtp Well-Known Member

    I use plain type f in mine, but any dex/merc should be good
     
  4. 1969RIVI

    1969RIVI Well-Known Member

  5. Luxus

    Luxus Gold Level Contributor

    So it's not normal for the rollers to fallout of the low one way roller clutch, correct? I'm assuming I should replace it.
     
  6. Bens99gtp

    Bens99gtp Well-Known Member

    You can just put them.bsvk in as long as the little thin spring that pushes then isn't missing or damaged
     
  7. Luxus

    Luxus Gold Level Contributor

    So I'm working on the output shaft assembly and there's a couple of things. The outermost gear (speedo gear?) looks OK except for the end which looks to have a very rough surface. Almost like something cracked off. That being said the teeth look OK and there is a very nice looking chamfer where the teeth end on that side. Kind of looks like a factory screw up they let through because it wouldn't affect anything.

    Second issue is the new bushing I got is taller and has a couple holes whereas the old one is shorter and has no holes. Both bushings have the same style ID lubrication grooves. BTW, the new bushing still looks like it will fit.
     
  8. Luxus

    Luxus Gold Level Contributor

    I found out the taller bushing is OK and actually preferred. Next the forward gearset has some light grooving on the outside diameter. Not sure if it needs to be perfectly smooth or if that's OK.
     
  9. Bens99gtp

    Bens99gtp Well-Known Member

    So pictures of questions. Like this help, one idea of light grooving can be different. Plus it helps show exact locations
     
  10. Luxus

    Luxus Gold Level Contributor

    gear1.jpg

    This is a picture of the OD. Hopefully you can see what I'm talking about. There's a lot of stuff that has marks but you don't feel anything when you run your finger against it. This you can feel.

    gear2.jpg

    This a picture of the side of that speedo gear BTW.
     
  11. Bens99gtp

    Bens99gtp Well-Known Member

    On that geat set, those circular Mark's are caused from the gaps in the low/reverse band. You nothing to worry about, if you want you can take a scotch brite pad to the outside to knock the glazing off, just clean it very well after to make sure nothing stays inside or tiny gritty parts are left, especially if anything gets in the pinion gears


    Never seen a speedo gear like that, but they ate easy and cheap to replace
     
  12. Luxus

    Luxus Gold Level Contributor

    I've been busy lately with other things, but I finally got some time to work on the trans so here is an update.

    center section snap ring.jpg
    The gearset and the center section have been cleaned and gone thru and are back in the case. (how's the positioning of the snap rings BTW?). Very soon I will be coming to the things that need to be modded. :)

    Man that low one way roller clutch was a bear to get back in. The rollers kept falling out, but after the application of some expert profanity I finally got it back in. Also very pleased I was able to change the center section bushing. That thing is like 6" long and I thought I wouldn't be able to knock it out. Fortunately I found a socket that was just the right diameter and I pushed out the old one.

    Next the clutches!
     
  13. Bens99gtp

    Bens99gtp Well-Known Member

    Stop......that snap ring needs moved.......I circled yours in single red circle. You need to move it to where both ends are tucked under the lugs,,,,,,,like over where the double red circle is. In fact anywhere as long as vith ends are under the case lugs,,,,,not one end just open and flexing. See yellow line,,, as long as both open ends are in the yellow area you will be ok.......I prefer to center it as much as possable


    This goes for all snap rings in this area of the trans
     

    Attached Files:

  14. Luxus

    Luxus Gold Level Contributor

    Thanks, I appreciate the expert eye. I will adjust.

    Different topic - the kickdown solenoid. I actually have two to use but on both of them the insulation on the wire is cracked and coming off. I assume I need to get a new one?
     
  15. Bens99gtp

    Bens99gtp Well-Known Member

    No expect here......if the solenoid still functions, I would guess some liquid black tape, or some wiring shrink tube should keep anything from shorting out
     
  16. BRUCE ROE

    BRUCE ROE Well-Known Member

    That look nice and clean.

    I believe the early solenoids were about 18 ohms, but later somebody decided
    to save wire by making them (less efficient) 10 ohms. I prefer the early, some
    I have been able to use a replacement tefl-n wire on.

    The problem with that steel speedo drive gear, is it is very difficult to change
    in the car. I would take this opportunity to replace it with a plastic gear,
    which can easily be changed as needed to calibrate your speedo. Bruce Roe
     
  17. Luxus

    Luxus Gold Level Contributor

    OK, new problem. I'm preparing the intermediate clutch pack. I've measured the old clutch/plate stack up height and the new clutch/plate stack up height is something like 0.030" - 0.050" taller. Could this just be because the old clutches are worn? By individual clutch plate the new clutch plates are 0.010" thicker.
     
  18. 1969RIVI

    1969RIVI Well-Known Member

    You are test fitting and measuring the tolerances dry right? You may have to swap a few clutch plates back and forth to get your tolerances right. I ended up having to use one of my old steel plates to get my tolerance right. Just make sure if there's any burnt spots on it to sand the plate evenly not just on the burn spots to clean it up and reuse it.
     
  19. Luxus

    Luxus Gold Level Contributor

    The new ones I'm measuring dry. The old ones I didnt bother to clean because the will go in the trash once I'm done with this part.

    I really am thinking its wear because the old steels are like 0.002" thinner than the new ones.

    BTW this clutch pack has a larger OD than the others. So my kit only has 3 and 3 of that size. No swapping around here possible.

    Finally to keep the wavy plate or not? Still deciding...
     
  20. 1969RIVI

    1969RIVI Well-Known Member

    Yes they'll definitely be thinner due to wear. Sorry my apologies you said intermediate clutch pack, yeh that's different you kinda gotta use what you have in the kit. I had the same issue with mine and the tolerances being bigger than what the specs say. Ben said the same thing to me it is what it is and that it should be fine as it's not as important to to stay right on specs with the intermediate as it is with the direct drum. Maybe he'll chime in to reassure what I've said is ok.
     

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