- Category: Research & Identification
356 Registry Technical Column, Reprinted from Vol. 16, #1 (1992)
Vic Skirmants, Editor
Way back in Vol. 13, #4 (Apr/May `89). I asked for transmission serial number data. Here's a repeat of the request. I would like to ask the readers to send me information on their transmissions, as well as the chassis number of the car if the trans is believed to be original. I can use all the data possible. Including empty trans cases out in the chicken coop. I can't promise a complete list to every respondent, but I can try to answer your questions as to what your gearbox really is. With enough input, I might even write an article explaining some of the mysteries.
Now for the hard part. On original, non-show cars the numbers I want you to dig up will be under a lot of greasy crud. The serial number is located in a fore-and-aft direction on the bottom center ridge of the tunnel-type transmissions. It will be a five-digit number. The number on the split-case transmissions is in a similar location and can be three, four, or five numerical digits, as well as having a possible additional letter and number, such as "H5". On the split-case transmissions the number is also located on the top of the transmission by the starter mounting bolt. I also need to know if the housing is the "crashbox" type, i.e., having a huge protuberance for the horizontal oil filler.
The tunnel transmissions have several more numbers of interest. On the forward bottom crossridge, (directly behind the intermediate plate), are several numbers. There will be a two or three-digit number, (indicating month and year of assembly,) and then the four gear letters on the 644 transmissions, or the transmission type on the 716 and 741 transmissions (716/O, 741/2A, whatever). The part number cast into the left side of the trans housing will be 644..., 716..., or 741.... I just need the first three numbers, as well as the last two for the 741...00 or 741...10. Just forward of the cast part number is a circle with the week and year of casting (3/58. 43/59, 6/65, etc.).
First, I would like to thank everyone who responded. especially multiple contributors Mike Robbins. Ron Roland, Richard Miller. and Ken Wunsche.
Now for a short history of transmissions.
The first transmissions used by Porsche were VW crashboxes, using the standard Volkswagen serial numbers. The numbers I have range from KDO244975 to 0359615. I only have four data points for these! Sometime in 1952, Porsche introduced their all-synchro 519 transmission. The magnesium VW crashbox housing was still utilized with some internal re-machining and a change of all the internals, including a new nose to cover the reverse gear which had been the main housing on the previous transmissions. The nose is aluminum, although I have seen one in magnesium. These first 519's had steel shift forks and slider sleeves that looked like the late 741 style, but were not interchangeable. Also, the ring & pinion was an 8:35 and the differential carrier was the very earlyVW style. The numbers in my file start at 454 Hl and go to 1885 H4. Six data points,
In 1953 VW changed transmission housings and Porsche used what was available. The housing was still magnesium, but no longer had the big bump for the oil filler. The internal parts were still the same. At some as yet undetermined numbers the shift forks were changed to brass [the steel ones wore themselves and the shift sleeves terribly) and the shift sleeves and spiders were changed to what I'll call the 644 style. Numbers KD 2899 to 7526 H5. 29 data points. Hl, H4, H5? No H? Evidently a code for the gear ratios. The H5 quite often appears in speedsters with BBAB gears and Hl has BBBC. However, this is not always consistent.
With the introduction of the 356 A, the 519 carried on, with a new dual mount nose and the addition of a second stud by the pinion rear bearing for better clamping. Numbers 8077 H5 to
10536 H3, fourteen data points. H5 now seems to indicate BBBC gearing, and only one of the numbers is from a speedster. Incidentally, three of the transmissions are from 550 Spyders, numbers 10014, 10063 and 10067.
In 1956, transmission information gets interesting. Porsche introduces its own aluminum tunnel case for its transmissions. but the internals are identical to the last 519 gearboxes. The housing now has the week and year of its creation cast directly into the left side near the part number. The housings were subsequently machined in batches, not necessarily in order of casting. The month and year of completion were now stamped on the front bottom cross-ridge, followed by the gear ratios. Example: serial #11404; on cross-ridge, 96 BBAB (completion in September of 1956). Casting number 32156: case was cast in 32nd week of 1956 (end of August). This is getting exciting, isn't it? OK, I'm easily amused. Numbers on file, 11048 to 16634 (?). 33 data points.
One change occurred in the casting of the 644 cases around that last number. The side-cover stud holes had more material added internally to make them "blind" holes, rather than "through-holes". The 644 case now remained unchanged until superseded by the 716 case. Numbers 17042 to 23599 (casting unknown) although #23118 was cast in 30158, assembled Nov., 58. 25 data points.
The housing and synchronizers were changed with the introduction of the 716 transmission in December 1958. The synchronizers were re-designed to be much more effective. The housing had some material added for eventual installation of a throw-out bearing guide tube, although the tube didn't appear til late `59 on the first 741 transmissions. The gear ratios were no longer stamped after the completion date, instead the transmission type (716) appeared, followed by a number code for the ratios; 0 for BBBC, 2 for BBAB. Numbers 25023 to 29627; 25 data points. Incidentally, #25023 is missing, and Ed Venegas would like to know its whereabouts. August of 59 seems to be the end of the 716, with the first 741's completed in September of 1959. Does anyone have a trans numbered 30,000 to 31,999?
The first 741 transmissions still used the 716 case and 716 synchronizers. The only change was the `B' model throw-out bearing guide tube and the ineffective single front mount (even Porsche can goof-up). The stamped transmission type was now 741, followed by 0 for BBBC gears, 2A for BBAB gears, 2 for BBBD gears, and 1 for BBAA. The 741 transmissions completed in 1959 of course carried a 9 for the month number. The 1960 transmissions did not carry a "0", for the year but instead a 6, which stood for 1960. For instance, 16 meant January 1960. These "6" numbers should not be confused with 1956, because as you have learned, the 1956 housings were 644, right? Serial numbers 32147 (Sept. 1959) to 34503. (34473 completed Jan., 1960). 14 data points.
Next change, the re-introduction of a dual mount nose, of course with the low shifter as introduced with the first 741. Numbers 35044 (Jan. 1960) to 42274, (Dec. 1960), 28 data points. I also have #42332 to 43273, type of housing (716 or 741) unknown; five data points.
Around the 49th week of 1960, the first 741 housing was cast, #741.301.010.00. Internally identical to the 716, externally differentiated by different ribbing and a cast-on pad for the S-90 camber compensator. Also, at an as-yet undetermined date the 3-4 shift fork was strengthened. The synchronizer blocks, bands, and clip were also improved, but that may not have occurred until later in 1961. First 741 housing, #43328 (Feb. 1961) to 50596 (Sept. 1961). 33 data points. 741/0 meant BBBC gearing, 741/2 BBBD gearing. The factory spec book differentiates transmissions after #50000 as 741A. This may be the synchro change referred to above. 741/0A, BBBC gears; 741/2A, BBBD gears; 741/20A, BBAB gears.
Around the 34th week of 1961, the 741.301.010.10 cases were first cast in place for the rear mainshaft and pinion bearings. It was also located slightly rearward to provide more space for the wider, stronger first gear that appeared around this time. Number 51074 (Oct. 1961) to 70451 (July 1963). 53 data points.
The 741 trans for the 356 C debut in August 1963. Identical to the 741 A, but having a 12 bolt ring & pinion. 741/2C, BBBD gears; 741/OC, BBBC gears. Numbers 70931 (Aug. 1963) to 86517 (March 1965). 77 data points.
In this last batch of transmissions is Apparently what happens here is that a group that shows once again that we're all human, even Porsche. During the casting weeks of 9 to 18, 1964, someone cast 741.301.010.00 on the housings. The ones examined internally so far all show that they really are 741.301.010.10.
So there you have it. More than you ever wanted to know about 356 gearboxes. Now send me your info, even if it seems like it would only fit in the "common" ranges, one never knows what might crop up. I do need as much information as possible. Merely the trans number off the Kardex doesn't really tell me anything, but go ahead and send it anyway.