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+--- Thread: Close ratio gearbox (/showthread.php?tid=6062)
Close ratio gearbox - DaveT - 03-05-2021
Currently on eBay is this gearbox,
https://www.ebay.co.uk/itm/194081052008
What would be the difference or improvement in the performance of this close ratio 4-speed 'synchromesh" gearbox?
Fitted with an input of 21 and layshaft of 30, compared to a standard 4-speed box as fitted to a 1935 MK1 Ruby?
Or are these modifications only beneficial fitted to a sporting 7
RE: Close ratio gearbox - JonE - 03-05-2021
You might be interested to read the comments on the Nippy gearbox for sale [post] on the forum; the Ruby is a fair bit heavier so if you haven't got engine mods, you might find you need the gearing you have at times if hilly...
RE: Close ratio gearbox - Chris KC - 03-05-2021
It would be something like 12% higher geared in 1st, 2nd and 3rd compared with a standard 4-speed synchro box.
Whether that would be beneficial rather depends on how you plan to use the car, but most A7 drivers concur that standard 1st gear is a bit too low to be useful and the gap from 3rd to top is too great, so it probably wouldn't do any harm. As CR boxes go the Nippy ratios are not extreme.
The price of a new CR gear set is around £200 so as it stands that box is a bargain, assuming it's in good order.
RE: Close ratio gearbox - Derek Sheldon - 04-05-2021
I fitted Nippy ratios to my standard four speed box that is installed in my APE (Opal) and in my opinion it has made a world of difference. I particularly like the third gear.
RE: Close ratio gearbox - Bob Culver - 04-05-2021
The standard step 1.66;1 between 4 and 3 is more akin that 3 to 2 of medium and large 3 speed cars. Some 1950s smaller 4 speed were 1.5:1 but most 1.4 or so. It is useful to divide what you consider prudent top speed in 4th by the ratio step to find equivalent in 3rd. Stock 50 mph gives 30 mph. In the day few would exceed 45 mph corres just 27 mph. Neverthelss not as tedious as the many small 3 speed cars near 2:1 down to 2nd. As above the low 1st gear enables starts on steep gardients loaded even with stock engine (clutch permitting).
Bit of a gamnble but unusual for input or layshaft 3rd gear to fail and most else replaceable.
RE: Close ratio gearbox - Martin Baker - 04-05-2021
I agree with Derek, I have fitted a Nippy ratio four speed box to my 1938 Pearl and think it makes it a much more driveable car.
I previously tried a box with true close ratios (Super Accessories). This was not good for a relatively heavy car despite the engine being mildly tuned.