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Technical Rebuilt my first 39 Ford transmission yesterday, questions for the experts

Discussion in 'The Hokey Ass Message Board' started by Roothawg, Aug 23, 2020.

  1. Roothawg
    Joined: Mar 14, 2001
    Posts: 20,205

    Roothawg
    Member

    So, The 39 tranny in the roadster. I previously had LZ gears but second was trashed. I bought a 47 side shift and transferred all of the guts over into my case. Everything looks OK, but on the bench it seems kinda clunky. Now it just has the assy. grease on it, the case is dry, since I am waiting on the gasket set.

    Just paranoid that I did something wrong or missed something. Are they generally smooth on the bench or sort of hard to get to drop into the next gear sitting statically? Eventually it gets smoother, but it seems like it is not lining up or something.

    Like I said it's dry, so that could account for part of it and it is sitting on the bench flopping around. Am I just being paranoid? I don't want to have to pull it back out, if I can remedy it on the bench.

    Thanks
     
  2. junkman8888
    Joined: Jan 28, 2009
    Posts: 501

    junkman8888
    Member

    If you're serious about finding meaningful advice, the first thing you need to do is post pictures so the expert you're hoping to find can help figure out what's wrong, (if anything). While your waiting for replies (and enduring sarcastic advice), bolt your transmission to a later flathead transmission adapter plate then bolt the whole mess to an engine stand so you can spin the input shaft while going through the gears, that will allow you get a "feel" for how well the transmission is working (or not). I've rebuilt an number of manual and automatic transmissions, some immediately successful and some eventually successful, in other words, I feel your pain.
     
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  3. Roothawg
    Joined: Mar 14, 2001
    Posts: 20,205

    Roothawg
    Member

    You wouldn't be able to tell anything form pics. Too many variables.
     
  4. alchemy
    Joined: Sep 27, 2002
    Posts: 15,869

    alchemy
    Member

    Did you follow the Mac Vanpelt book to the letter? That's the only way I'd do one of these transmissions.

    If ALL of the parts came from the same late transmission, you should be golden. If you had to replace some parts, you might need some adjustments.

    Mac sells the good syncros, bearings, and spacers. He also gives good advice over the phone. Getting the clearance on the main assembly just right seems to be the key, and hopefully your case isn't worn in the back surface inside.
     
    Atwater Mike and Truck64 like this.

  5. Roothawg
    Joined: Mar 14, 2001
    Posts: 20,205

    Roothawg
    Member

    I used it for reference I basically inspected the pieces, used the whole assy as a unit from the 47 tranny. I didn’t blow it apart other than to get it out. Dad says it’s fine, but he has always been a close enough guy. So, rebuilt was probably an overstatement.

    I reused the thrust washers that were in the 39 case, since it looked to be recently overhauled.
     
    Last edited: Aug 23, 2020
  6. AngleDrive
    Joined: Mar 9, 2006
    Posts: 826

    AngleDrive
    ALLIANCE MEMBER
    from Florida

    Looking good and measuring correctly are two different things. It is imperative that you keep the cluster gear end play and the second gear clearance on the main shaft on the low side of the spec. It is not easy as there are not a lot of choices with the shims that are available. Macs book explains it all in detail and he is available for tech support.
     
  7. Roothawg
    Joined: Mar 14, 2001
    Posts: 20,205

    Roothawg
    Member

    OK, I just went completely back through the tranny, step by step using Mac's book. There was only one area that was gray and please tell me I didn't just screw up big time....

    On converting to the later style synchronizers, he never says what to do with the ball and spring. He just says to install the new style plates and us the new spring clips. He mentions this is much easier than using the old spring and ball setup.

    Please tell me I wasn't supposed to put the springs and balls back in!!!!!!

    I will slit my wrists if I have to order more gaskets and tear this thing back apart.
     
  8. trey32
    Joined: Jul 27, 2014
    Posts: 285

    trey32

    Balls and springs go on the shop floor...
     
    rusty valley likes this.
  9. Roothawg
    Joined: Mar 14, 2001
    Posts: 20,205

    Roothawg
    Member

    Nice. That’s what I wanted to hear.

    The reason for the panic was a buddy said something about the balls and springs and the new plates .
     
  10. Mac VP
    Joined: May 13, 2014
    Posts: 328

    Mac VP
    Member

    I guess I assume that folks understand the process when I suggest using the later synchro insert kit instead of ball and spring type......I deal with these parts almost every day so my mind is two steps ahead of my hands half the time. To be clear, you would NOT use any of the earlier style kit (the 3 balls, the 3 little springs, and the 3 inserts/plates with the 1/4” holes in the centers). The later kit includes the 3 inserts with the little bump in the center and the two approx 2” diameter wire springs. You would use this kit instead of the earlier type.

    While you’re in the transmission fixing the issue just double check everything else to make sure that you haven’t missed something else that could be affecting the transmission. You’ll feel better having gone back through it
     
    JNKYARDDOG_1 likes this.
  11. Roothawg
    Joined: Mar 14, 2001
    Posts: 20,205

    Roothawg
    Member

    Thanks Mac. I didn't realize you were on the HAMB. I figured I was out of luck on a Sunday afternoon getting tech help. We read the manual and "thought" we had it correct, until a buddy mentioned that he thought the balls went under the new plates. He think now, that he must have confused the 2 different types. I was just afraid I had screwed up big time. I remembered in our conversation that you said that you don't even stock the earlier styles now.

    We did buy the later kit from you, and we did go back and check all our measurements, as per our phone conversation. I appreciate the info and just as constructive criticism, you might make a foot note on your next revision of your manual. It helps the first time rebuilders, like myself.

    I appreciate the time you spent to actually write the document for guys that aren't familiar with the Ford trannys. I feel like I have a better handle on it now and it's not that daunting task any longer.
     
    Last edited: Sep 14, 2020
  12. when you swapped the side shift gears in it did you put all new thrust washers in it? did you check you clearences at the thrust surfaces. some times the case is worn and can give you excessive play in the cluster gear. Wich would require different thickness thrust washers. When my 39 trans was on the bench and freash rebuilt it was very smooth to rotate, but it was clunky changing gears on the bench, it was better if you turned the input shaft. that being said, once in the car and running it shifts smooth as butter.
     
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  13. Darin Younce
    Joined: May 8, 2019
    Posts: 576

    Darin Younce

    Just curious but you said you are waiting on gaskets so did you install the front and rear bearing retainer plates? If not you could get some movement while you are trying to shift and that would certainly make things clunky Also , are you doing the shifting with shifter installed or just moving the synchro by hand ? moving the synchro by hand might feel a bit clunky . If your shifter is installed and are shifting with imput shaft movement ( spinning as stated above) it might also feel a bit clunky. Also condition of shifting tower can make it clunky, need well lubed movement and good detent balls and springs I know all this because in the last couple of months I built 2 39 Trans ( one twice because I decided to get a new synchro later) and both operated much better installed on truck with engine running than sitting on bench. Had to to a lot of work on the shifter/ tower , re welded and ground the end where sat in the forks , welded and ground the slot on the shifter where the 1/4 pin sets.
     
    Roothawg likes this.
  14. Roothawg
    Joined: Mar 14, 2001
    Posts: 20,205

    Roothawg
    Member

    Thanks for the input guys. My dad and I swapped everything over from a 47 sideshift case, but keep in mind he is 82 and doesn't like to talk a lot. He would rather "do". He has built tons of them in his old drag car, but I had to remind him that was 60 years ago, and parts are a lot more worn now.

    My wife and I tore it completely back apart and went through using Van Pelt's book, making sure that all of the specs were within tolerance. We converted to the newer style synchros and I ordered a few pieces from Mr. Van Pelt. It shifts way smoother now and I have a warm fuzzy about it.
     
  15. Atwater Mike
    Joined: May 31, 2002
    Posts: 10,264

    Atwater Mike
    ALLIANCE MEMBER

    I've done these for years, but Mac Van Pelt is the last word. Perfection plus.
     
    warbird1 likes this.
  16. AngleDrive
    Joined: Mar 9, 2006
    Posts: 826

    AngleDrive
    ALLIANCE MEMBER
    from Florida

    ditto
     

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