So it was relief I learned this week that the gearbox internals were in good condition, and all it need was a few synchromesh rings - in fact about the least I could have hoped to get away with. It should be back with me in a couple of weeks.
An aside I was interested to hear a comment Jez made when we were inspecting the 'box, comparing the weight favourably to the later G50 units. From what I'm able to tell, the various weights as follows;
- G50 gearbox used in the later Carrera 3.2s ~70kg
- 915 gearbox with aluminium cases used in the SCs and first 3.2s ~58kgs
- 915 gearbox with magnesium cases used in the '72 and '73 911s ~50kgs
The stronger aluminium cases were adopted when Porsche started to worry about the torque of the bigger engines, but from what I can tell from other owner's experiences, with sympathetic use the mag alloy cases do just fine. Certainly losing 20-odd kilograms from the tail of the car can only be a good thing.
SS7
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For comparison, the weight for a 2012 Carrera S auto unit is 116.9kg. It is amazing that the driver can actually see the road and not just the clouds these days.
That's interesting Pat. I assume you mean the PDK 'box? Its a big lump of metal, even though most of it is well within the wheelbase of a 991.
I'd also be interested to know how much 18-way power seats weigh!
SS7
Hi Charles,
The mag 915 cases were used up until approximately april 1977- around that time Porsche was tooling up for the SC and the alloy gearbox case was stronger, but also cheaper to produce.
I noticed the changeover when researching the last of the Carrera 3 cars on the register: they were already equipped with the alloy-cased 915 gearboxes.
All the best,
Bert
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