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Is there an easy way of checking a four speed 2SYN box to check that its ratios are definitely standard?
It has no 'S' marks, but it's a box which was sparkly clean, came with a nicely shortened lever, and whilst its not on a car so I cant do the wheel revolutions thing, it would be nice to determine if it's ever had anything changed internally. There is a good diagram in the PWA7C book for the 3 speed cogs, but I cant find one for the 4...
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Location: Auckland, NZ
It is far easier to count the ratio direct than disentangle from the diff ratio. 1, 1.66, 2.64, 4.37.
From these ratios can deduce the equivalent of whatever considered prudent in top. The 3rd gear is much as 2nd of powerful 3 speed cars. Just 30 in 3rd is equiv 50 in top hence the din.
Joined: Aug 2017 Posts: 3,247 Threads: 360
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can't select the gears just with the stub, hence wondering about what cogs once could see.
I'll see if I can make an extension attachment for the lever to give a bit more leverage.
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Location: Port Elizabeth, Sunny South Africa
Car type: '26 Chummy, '28 Top Hat, '33 Type "65", single seaters
Sockets & long extensions work well as temporary gear levers
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It is simple to select gears with the top removed, using a stout screwdiver on the selectors. Fit a clutch centre plate into splines, mark the centre plate and rear flange to determine ratios,by counting revolutions.
Joined: Aug 2017 Posts: 3,247 Threads: 360
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thankyou John - that is extremely helpful. (All those readily at hand and yet the brain doesn't engage when one hasn't done it before).
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Location: Near Cambridge, UK
Car type: 1928 tourer (mag type), short chassis Gould Ulster
I had a lever break when I was out once long ago; a Mole wrench got me home enabling selection of all the gears.
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Location: Auckland, NZ
Be careful attempting to engage gears with the interlock plate removed. May risk synchro balls popping out.
