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MG MG Y Type - YA transmission ratios

Does anybody have the gear ratios for a YA 1947 transmission? I am trying to compare it to a TD unit.
Sandy Sanders
conrad sanders

Conrad - log on to www.mgytypes.org, go to the Technical Centre, Technical Data page and select MG YA and YT General data.

You should be able to find it in there.

Paul
Paul Barrow

Conrad, just in case you do not have the TD ratios,TD,TF,YA and YT are all the same ratios it is the identical gearbox in all models. Only the overall ratio will differ depending on which diff ratio you are running. Cheers Richo YT3208
Richard Prior

Richard:
I thank you for that info. I think that I will change the shift rods and the output shaft and make a TD unit that I need.I do have the parts for that.
Sandy Sanders
conrad sanders

Richard; I have just checked the ratios and found out that first,second and fourth are the same but third gear in the Y series is 7.121 versus 7.098 in the TD-TF.
Sandy Sanders
conrad sanders

Sandy,
Those ratios are the overall ratios at the back axle and vary because the YA and TD/TF have different diff ratios. They would be identical for YB which has the same back axle. If you look at the gearbox ratios only, you will see they are identical for YA/B/T and TD/F. As a matter of interest I believe the Morris Ten gearbox has the same ratios and will fit into a TD/F YA/B/T gearbox but the bits are not interchangeable, you have to use all the Morry 10 bits. The gears are a different size but the ratios the same. If you are looking to drop revs at cruizing speed you will have to alter the diff ratio or go for one of these 5 speed Sierra g/box conversions.
Cheers Richo YT 3208
Richard Prior

Richard;
Today I stripped the YA gearbox.I do not think that anything in that box can be used with a TD-TF box. Although the box casting numbers are the same ,the box is not the same. Tha layshaft is larger by .040 and the laygear uses bronze bushings. There are no needle bearings on the input shaft to main shaft spigot( bronze bushing again) The cone for the 4th gear syncro on the YA is larger in diameter.4th gear on layshaft is almost 1/4"larger in diameter. I could go on and on . I needed a set of needle bearings for my TD and there are none in the YA. I have not disassembled the main shaft so there is a chance that there are some on 2nd-3rd gears.Externally the box is identical down to the casting numbers but that is where it stops.
Sandy Sanders
Hudson Florida
conrad sanders

Sandy,
Are there numbers on that laygear? I have had for forty years a brand new BMC laygear with bronze bushes. Part number 1B3694. Uses a stepped layshaft.
FRM
FR Millmore

I am not am not an expert on gearboxes but it seems to me that your YA box has been bodgered at some time in its lifespan. About 8-10 years ago I had my YT box completly rebuilt, new gears,bearings, etc. and used new parts for a TD box. Never heard there was a problem or for that matter any difference in the parts removed and replaced. Terry
Terry O'Brien

Sandy,
Loose needles are a common thing from bearing supply houses, in a million sizes and end configurations.
FRM
FR Millmore

UPDATE ON MY TRANSMISSION.. It appears that it is not an MG-Y transmission at all but one from a Morris 10. I never realized that it was not a Y unit until I started asking questions and nothing appeared right. Thanks to Dave Lawrence he put me straight. Now I must find an owner for a good Morris 10 box.
Sandy Sanders
Hudson Florida
Sandy Sanders

It's an easy mistake to make, Sandy, with so many small variations in spec; a friend of mine has a 1947 Riley RMA, which has yet another variant of the same clutch and gearbox as the YA. I'm amazed that they ever managed to keep the lines running with so many differing components and variations: it must have been a nightmare.
Tim Griggs

This thread was discussed between 02/09/2005 and 23/09/2005

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