Difference between 37 38 2nd gear

hudson1948
hudson1948 Member
edited November -1 in HUDSON
Does any one out there know the difference between an intermediate gear for a 37 and one from a 38. I am doing a 1937 transmission and I have a new in the box 38-40 2nd gear (part # 155013) . I see in the parts book that the 37 gear is a 48800. I put the two gears side by side and can't see any difference, does any one know if it will work? Thanks, Charles S.

Comments

  • Park_W
    Park_W Senior Contributor
    Charles, it's not clear what the difference is, but it appears they don't interchange. Hudson's 1950 interchange book shows no interchange for that '35-'37 gear. The 155013 shows application as '38-'48.
  • Unknown
    Unknown
    Charles, I'm certainly not a parts expert and would not debate the info with Park, But I would look at it like this. Any # on the gears themselves ? Did the gear your replaceing fail ? How about the mateing gears, any damage there ? If so why, it's possable they had the wrong gear in it causeing it to fail. If that is not the case, then it is also possable that books can be wrong or just a matter of changeing a number sytstem or the new gear being in the wrong box. If your dead certain the gear your replaceing was the correct gear, then compareing ALL dimensions, tooth angles, # of teeth, everything, if the two are exactly alike in ALL respects then I see no reason it will not work. In the end, if the original gear was the right one and the replacement is exactly the same it will work, no reason for it not to no matter what the # on the box says. Bud
  • Jon B
    Jon B Administrator
    After you carefully compare the new and old gears you may indeed find a difference but it might be minor -- something you could remedy with a little machining. For example, the shaft size might have changed slightly. If (for example) a larger diameter shaft was used in 1938 then possibly you could open up the gear's bore to fit the new shaft. If, on the other hand, the number of teeth is different, that would not be so easy to adapt!
  • [Deleted User]
    [Deleted User]
    I think the improvement for 1938 -up was a larger gear shaft size.
  • Huddy42
    Huddy42 Senior Contributor
    Charles,

    According to my parts books they are not interchangeable,1935-6-7 differ from 1938-39.



    You may have to look very carefully at the profile of the inner hubs of both gears as that is where I think the difference will lie, some had square profile while others had radial profile.



    Also remember somewhere over the last 70 years the gearbox may have been changed for a different model, have seen this happen on numerous occasions.



    My parts book does make reference to the 1938 gear having recessed hub, so as previously said, this maybe the difference.



    Both gears are 23t..Helical dia 3 1/4".. 6 .spline.



    Hope this helps somewhat.
  • Geoff
    Geoff Senior Contributor
    Are we talking about the layshaft (countershaft) gear, or the 2nd gear assembly that sits on the extended drum of the input shaft?
  • Clutchguy
    Clutchguy Senior Contributor
    Charlie,I know that you have probably done this,but measure the depth where the snap ring goes-same-yes/no,it should be the same,the amount of teeth-same.I question the only difference could be where the inner teeth mesh.The inner mesh angle to the input or the thickness of the thrust is different?They were trying to make these transmissions shift smoother,and not grind,but as the engines made more power,they knew this trans.was going to be replaced.I didn't look,but I know the input shaft is a different part#.I do know one thing for sure-the parts book is a mess when you start looking at all the different parts for these transmissions.:eek:
  • hudson1948
    hudson1948 Member
    Geoff, It's the babbitt lined gear on the main shaft.
  • Geoff
    Geoff Senior Contributor
    hudson1948 wrote:
    Geoff, It's the babbitt lined gear on the main shaft.



    Okay, the only difference is the thickness of the circlip, and it is interchangeable with all other models '33-'40. You must use the correct circlip though.

    Geoff.
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