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Registered
Join Date: Feb 2024
Posts: 1
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912 Driveshaft Confusion
Hi all, I have a 1968 912 SWB Targa and its a bit of a Frankenstein as I build it up.
It came with no engine or box so had to source. The box I found is a 902/14. Other numbers on the box are: 5091388 and 901.301.311.2R. It came with 100mm Gearbox flanges but I understand I needed 90mm ones so sourced these together with 415mm Drive shafts and the 90mm stub axles. The problem(s) i have are as follows, the 90mm gearbox flanges don't fit as snug as the 100mm ones. On measuring the 2, there is a 1mm difference and hence the little bit of play i can feel. The other problem i have is that the 90mm gearbox flanges kind of protrude more and as such, the driveshafts dont fit. (See photo of 100mm and 90mm) Im at my wits end and would love some advice, in fact if some one can solve it i'll gladly pay or donate some money to charity!   
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04-14-2025, 12:03 PM
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Registered
Join Date: Jan 2001
Location: Carlsbad,Ca.
Posts: 1,106
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Hello, give a member named Sterling a ping at https://www.912bbs.org/forum/whats-new/ he will be able to answer your question.
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1981 911SC Targa-1966 912 -1989 Alfa Spider Graduate 1967 912-1985 Toyota FJ60 Landcrusier 1985 Toyota SR5 4x4-1965 Baja Bug-1997-4Runner-4x4 1966 Bug stock-2004 Toyota Rav4-1989 XJ6 Jag 1975 914, 1965 Norton N15CS 750, 1975 Husqvarna 360 CR GP 1982 Honda 500 XLS |
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04-15-2025, 02:42 AM
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Banned
Join Date: Feb 2025
Posts: 27
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Consider either reverting to the 100mm system fully (CVs, stub axles, etc.), which at least gives consistent fitment. Or try to find the correct early 90mm flanges for the 902 box that match both the internal splines and the CV interface depth for SWB. Measure your flange-to-flange width and compare it to factory SWB specs; this will help with shaft selection too.
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04-30-2025, 01:26 PM
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Ken Wunsche
Join Date: Dec 2009
Posts: 130
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Porsche made many changes in transmissions, axle flanges and axles from 1965-69 including changing the wheel base in 1969.
SWB 911s and 912s were only delivered with aluminum case transmissions and used the long axle flange with the small flange diameter you show in your picture. The short flange you show is for a magnesium case transmission. The magnesium case was introduced in the middle of the 1969 model year and used the large flange diameter. The aluminum case differential is about 12mm shorter than that for the magnesium case which is why its axle flanges are longer. I know this is confusing but bottom line is I don't know how you can fit a mag case transmission into a SWB car using stock parts. It would be best if you found a aluminum case transmission. I am American but live in Germany. Contact me if you have any questions. |
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05-09-2025, 12:12 AM
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