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MG MG Y Type - Overdrive for Y-type

There have been many articles about fitting 5-speed gearboxes to the gearbox associated with the XPAG but none that I can find about fitting an overdrive.

I did find a mention of someone modifying the gearbox housing and fitting to pre-T type gearboxes, but he has never been asked to do one for a Y.

Speaking as an engineering semi-illiterate I can see that the transmission tunnel would need modification, but the idea looks simpler (and cheaper) than the 5-speed and there are any number of overdrives available.

Any comments from the experts out there?
Michael Nicholson

i approached Quantum about adapting a D-Type overdrive to a TC transmission. They said it could be done without too much difficulty. Other than a bulge in the transmission tunnel,there would be no permanent change to the car. You would have the same driving experience except that you could flip a switch to gain higher gearing.

I don't like the idea of putting a bulge in the tunnel, but one could always keep the original tunnel in the attic for future owners and install a fabricated one in the car with the OD.

Just some food for thought.
Steve Simmons

Michael

Check out http://www.mgfivespeed.com/t-series.htm

Installation appears to fit without body modifications and is fully reversible. Need to contact them about the Y application. Let us know what you find.

HTH

Larry

Larry Hallanger

The downside there is that you change the driving experience somewhat. To some people it matters little but to me it's a big deal. When I drive a vintage car I want it to look, function and feel like a vintage car. The OD would accomplish that with a hidden switch to lower revs on the highway and allow higher top speed in modern traffic. Other than the speed versus RPMs being changed, there would be no difference in experience from driving a completely stock car.

The 5-speed would sure be more simple to install though.
Steve Simmons

The driving experience would be exactly the same, until you engaged OD. However with a 5 speed box it would be a totally different car.
JRA Arkley

That's basically what I was trying to say. To take it a step farther, I think the driving experience would remain the same with the OD engaged. It would be no different than having an alternate differential gear ratio.
Steve Simmons

Larry, the website that you detailed does not seem to mention an overdrive, but it does confirm what I thought, that a shortened propshaft is needed for the 5-speed conversion which would also be needed for an overdrive.

I can't see that the 5-speed conversion is easier to install, Steve. The engine would not need moving forward, I guess, so it would seem to be just removal of the gearbox and propshaft, modify and refit with overdrive.

To a mechanical moron like me, this sounds easier, and chaper, as an overdrive costs less than 500 sterling and a lot less from a breaker I imagine.

I like the idea of not altering the feel of the car which the 5-speed would inevitably do.

Is there anyone out there who can do the gearbox to overdrive conversion?

Michael Nicholson

I suppose you're right. I have never pulled the engine or gearbox from my Y-Type so I don't know which would be easier.

Assuming you don't want to ship the gearbox across the pond, maybe try Chris Betson at Octarine Service.
Steve Simmons

Is there a possibility of changing the rear axel ratio on both the YA and YB to give a higher cruising speed.
Bryan

Yes, it can be done.
Steve Simmons

I contacted Octarine Services but they do not offer the overdrive conversion and do not know anyone who does. They think that the conversion including a recon gearbox would be as dear as a 5-speed but I was not considering the gearbox recon.

That's it folks!
Michael Nicholson


Dear Steve Simmon
Regarding Brian Cardiff's question if a YA's gear ratio could be upgrade you answered with "yes". This is new to me and is interesting me a lot.
Up to now, I was only aware of the possibility to change the ratio on a YB which is the same as the TD/TF - whereas the YA's is similar to a TC crown wheel and pinnion.

Never have I heard of someone modifying a TC. Would you have details of ratios, part numbers etc.?
Anton Piller

Raising the rear axle ratio on a TC used to be, and probably still is, fairly common, and the crown wheel and pinion come from (I think) a TA. I do not know the ratio as I have a TD, but why don't you put a question on the TA/TB/TC thread.
Roger Wilson.
Roger Wilson

I should have been more careful. I didn't notice he wrote "both YA and YB". I'm not entirely sure about YA. I would however be surprised if it was not possible. Surely the YA axle was not used solely on YA, or even on only MGs.

The most common gear ratios available for the TC are 8/43, 8/41, 8/39 and 8/37.

8/41 is stock TC and gives a 5.125:1 ratio. 8/39 is TA and gives a 4.875 ratio. 8/37 is available and gives 4.625

I recently put the TA gears in my TC with stock transmission and tires. It's a perfect compromise for canyon driving and distance touring. I'm still considering an overdrive on it though, when the gearbox is ready for overhaul.
Steve Simmons

Was there EVER an OD for the TC/YA/YT gearbox? I have never seen a reference to one.

One advantage of the 5 speed is that the installation is completely reversible.

FWIW

Larry
49YT
Larry Hallanger

There were no factory options for overdrive. I have seen standalone overdrive modules for various cars. There is even a company making an inline overdrive module for Model As which would be perfect for a T or Y-Type. Unfortunately they have no interest in making a model which would fit into our cars.
Steve Simmons

Another thought on this theme to retain the original gearbox and gearbox cover etc but with OD! I recall seeing many years ago a TC with an OD unit fitted in front of the diff instead of behind the G/box. I can't recal exactly how it was fitted and a little engineering would be required but there is probably plent of room in that part of a Y to not require any body modification. Cheers Richo.
Richard Prior

Re raising the rear axle ratio on a YA/YT. I think it possible. I know next to nothing about the mechanics of the rear differential but from visual observation it looks the same as a TC. Roger Furneaux in the UK sells a range of higher ratio gears for the TC. He would probably know.
The problem with that as I see it is that if you live in an area with mountain passes,as I do, you are not going to be able to drive the car up 2 or 3 mile hills with a rise in elevation of 1500 to 3500 feet. As it is on one or two hills with an S curve at the base I can't start the climb with enough revs so am into second gear by a quarter of the way up. Terry
Terry O'Brien

Richard, if you come across any information on that TC, I would love to see it.
Steve Simmons

Thank you steve, for the various ratios - pitty though, that I have alreday overhauled my YT's diff with new bearings etc.
I'll keep this thrad, in case I need more hign way speed.

Anton
Anton Piller

This thread was discussed between 15/10/2007 and 13/11/2007

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