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| techtalk:ih:transfinal03f [2024/04/29 19:53] – [1957-1985 Transmission Trapdoor Pics and Information] hippysmack | techtalk:ih:transfinal03f [2024/04/29 20:02] (current) – [Transmission Trapdoor History] hippysmack | ||
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| - | The mid 54 through 1956 trans doors were attached to the cases via tapered dowel pins. This require | + | The mid 1954 through 1956 trans doors were attached to the cases via tapered dowel pins. This required |
| - | in 1957 the first interchangeable doors were introduced. Straight dowel pins . These doors remained unchanged until 1973. At that point the countershaft bearing area was reinforced. | + | In 1957, the first interchangeable doors were introduced. Straight dowel pins. These doors remained unchanged until 1973. At that point the countershaft bearing area was reinforced. |
| - | In 1975 HD was in the process of swapping these bikes over to left hand shift if you if you look at a 77 and up model crank case you'll see that the casting numbers are dash 75. For the 1977 model year the door was changed to accommodate the left hand shift shaft and the demise of the transfer valve. This door had the notch for the shifter shaft and a modification of the bottom profile of the door. The shifter shaft notches self-explanatory. The change to the bottom profile of the door was to allow the transmission and primary to share the oil. There is now a open area under the counter shaft were oil could migrate between the two compartments . | + | In 1975, HD was in the process of swapping these bikes over to left hand shift if you if you look at a 77 and up model crankcase |
| + | In 1977 when the door profile was changed, the crank cases were also changed. The area below the counter shaft drive gear in the crankcase was deepened: that changes the effective area open between the primary and the transmission. \\ | ||
| + | Previous to this in 1976 and down models the transfer valve allowed the transmission to fill up with oil when the bike was idle. With your 1976 down bike, once the transfer valve evacuated most of the oil out of the primary, the trans remained basically isolated so the idea being that the trans kept getting lubed. Without the transfer valve in 1977, there was no need for this any longer it was actually thought that it was better off that the primary and trans shared the oil all the time. This is the door was supplied through the parts department as replacement for all 1957-up bikes. I've never found the problem with using these later doors on a 1976-down motorcycle. HD also used them on under XR's built after 1977. | ||
| - | previous to this in 76 and down models the transfer valve allowed the transmission to fill up with oil when the bike was idle. with your 76 down bike once the transfer valve evacuated most of the oil out of the primary the trans remained basically isolated so the idea being that the trans kept getting lubed. Without the transfer valve in 77 there was no need for this any longer it was actually thought that it was better off that the primary and trans shared the oil all the time. this is the door was supplied through the parts department as replacement for all 57 and up bikes. I've never found the problem with using these later doors on a 76 and down motorcycle HD also used them on under XR's built after 77. | + | Bottom line is that any sportster with a generator can interchange any generator vintage door on any generator vintage bike. \\ |
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| - | Bottom line is that any sportster with a generator can interchange any generator vintage door on any generator vintage bike. | + | |
| ====== 1977-E1979 Trapdoor ====== | ====== 1977-E1979 Trapdoor ====== | ||
| HD Part# (34844-57B) \\ | HD Part# (34844-57B) \\ | ||
