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MG Midget and Sprite Technical - Gearbox ID

given there don't seem to be any useful marks on the input shaft, what's the best / quickest way of telling if a smoothcase box is A35 ratios or Genuine AH or MG with the close ratios?
TIA
David Smith

The way I do it is mark the input and output shafts with typex and put in say first gear, then count turns / part turns of input to get one complete Rev of output shaft.
Repeat for second etc.

R.
richard b

In case you don’t have the ratio’s to hand

Mk1
3.627
2.374
1.412

MK 2 (or close ratio set in Mk 1)
3.2
1.916
1.357

I believe the A35 is the same as a frog but I’m sure someone will confirm.

R.


richard b

My Haynes A35 manual gives the same ratios as Richard does for the Mk1'.
Dave O'Neill 2

ETA: once again Dave posts whilst I check hyperlink, but Richard's table is useful for other boxes.

Richard Wale, Oxfordshire, United Kingdom
Posted 21 October 2017 at 10:25:11 UK time

"Apart from the original Frogeye, which has the same construction, with the same ratios as the 948 Minor/A35/A40, all the other Sprite/midget gearboxes have 'close ratios', including the Sprite MkII/Midget MkI 948.

The 1098/1275 close ratio boxes also had needle roller bearings for 2nd and 3rd gears. The 1275 had a different helix angle as well, which makes it very different from any other in-line A-Series gearbox, and as a result 'stronger' than any of the others."

Table for other boxes here (scroll down page) - http://www.mg-cars.net/mg-midget-sprite-technical-bbs/gearbox-differences-2017101920423826611.htm
Nigel Atkins

thanks all (so far) - I have the manuals with the ratios in. I can't count turns as the box is seized :-(
I guess I'm really after any tooth counts so I can take the side plate off and ID it by inspection.
David Smith

If you are lucky with the side cover off you might see a number on the lay shaft.

22A287 Frog/A35

22A207

From the Richard Wale list Nigel linked to.

Best of luck as I always find them difficult to read.

R.
richard b

The gearbox input shaft id number that this BBS alerted me to, which
I could not see mentioned anywhere else was G40 (or perhaps G4N?) for a late model Morris Minor - ‘Morris 1000’ - with a 1098c engine. I found that a short number is easily missed, particularly when I was initially looking for a longer one starting with 22.

The Richard Wade table already mentioned is handy as are the gearbox and clutch info ones from Gerard’s Garage:

http://www.gerardsgarage.com/Garage/Tech/TransPartsIndex.htm

http://gerardsgarage.com/Garage/Tech/TO_Bearings/tobearings.htm

Cheers
Mike
M Wood

This thread was discussed between 25/03/2021 and 26/03/2021

MG Midget and Sprite Technical index

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