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MG MGB Technical - wonderful upgrade

Just have to hoot. Drove the "B" today after installing 3.2 rear end gears. Holy Cow! wonderful improvement. Now travel at 55 MPH and 2500 RPM. Cost about 1/3 of a 5 speed but........not for the faint of heart. The entire rear end needs to be disassembled.
Tom
Thomas McNamara

Hasn't the change to 3.2 ruined whatever acceleration it had before?
Mike Howlett

Mike
It's just like being in overdrive all the time, yes it knocks a little grunt out of 4th but 3rd gear is there.
I did a 2.89 ready for a v8 conversion for a fella and drove it as a 4cyl and honestly it was great. very tall in 4th but 3rd was very useable. It's still like it now, the owner was going v8 for high mileage cruising and after he drove it he said why bother, this is exactly what I'm after.

willy
William Revit

Interesting Willy. I suppose that's the advantage of having a 4-speed with widely spaced ratios. My 3.9 litre BV8 has a Ford 3.14 diff and it could go higher. The torque means I hardly ever use first gear anyway. The 4-pot doesn't have that much torque but it's obviously enough to make the car work with a high ratio back end.

I never understood why so many MGBs were sent to the USA without overdrive. With the long straight highways an O/D would be so necessary there. Here in the UK with our twisty roads the majority of cars had O/D from new. I wouldn't want to drive an MGB without it.
Mike Howlett

I've read that customers didn't specify it because they didn't know what it was and didn't want to pay extra. Who knows now.

Wouldn't be without mine, to the extent of not wanting a 5-speed conversion unless it really was the only way to keep them on the road.
paulh4

Dear all, just to be clear, the change to 3.2 has no downside. First gear has lots of "grunt", acceleration is good through all gears. I live in a very hilly area and find myself in 4th most times. now the big question; why did I wait so long? Be well , Tom
Thomas McNamara

I suspect that any engine improvements (compression ratio, cam, etc.) that would improve midrange torque would complement the 3.2 nicely. I recently rebuilt the engine in the midget with the aim of improving performance with the 5 speed transmission. The car can now accelerate and maneuver at highway speeds safely.

My B with overdrive is a slug by comparison.
Glenn Mallory

I have an MGA which has a 5 speed Ford T9 gearbox, it used to have a 3-bearing MGB 1840 cc engine which had around 105 bhp. It went fairly well, but when climbing a long steep hill, it would run out of steam when in 3rd gear, but when I then changed down to 2nd gear, it would be revving its head off which really annoyed me. So, I would be continuously changing up and down between 2nd and 3rd to get the best out of it.

My solution was to install a very much more powerfull 1950 cc engine which had half as much power again and this will climb almost every hill you throw at it without often having to select anything lower than 3rd gear.

Now, I have really come to love this engine and the power and accelleration that it delivers.

So, would I fit a higher ratio diff like Thomas has, to lower the revs at higher road speeds?

No way, the extra power is now so good in this car and has been so hard fought for that I don't want to lose any of it by installing a higher ratio diff.

I may be in the minority here, but I prefer my MGA to feel more like a sportscar than a tourer.

Cheers


Colyn Firth

"I never understood why so many MGBs were sent to the USA without overdrive. With the long straight highways an O/D would be so necessary there. Here in the UK with our twisty roads the majority of cars had O/D from new. I wouldn't want to drive an MGB without it."

I never understood that either.
I have no idea if it is true, but I did read somewhere once, many years ago, that the reason the MGB was rarely fitted with overdrive for the North American market before 1968 was that the distributors feared that MGB's with overdrive would eat into sales of the big Healeys.
If this was indeed so, it reflects odd thinking, with a failure by Hambro's and BMC to appreciate the different types of buyers the two cars would appeal to. The B was always a softer riding, more spacious tourer than the Healey ever tried to be, especially pre-BJ8.

It was exactly the same in Australia, as in the USA. Australia is another country with vast distances compared to that of the home market UK cars. I covered 800 to 900 miles in a day in my MGB several times, and a couple of times even more... without overdrive. The car incidentally tolerated it perfectly well, but my ears much less so.
Overdrive wasn't available in Australia, at all, not even as an option, till the 1968 cars were built. (They incidentally built MGB Mk I cars in Australia until August 1968, about a year after the Mk I was discontinued in the UK. It is difficult to escape the conclusion that the UK factory dumped redundant superseded stock onto their lowly colonial offshoot to deal with. The UK parent company had done exactly the same in 1961 when they sent a large number of MGA 1600 cars to Australia after they introduced the MGA Mk II to the home market).

As many have also said, the fitting of an overdrive gearbox to my 1965 MGB transformed the car completely.
Interestingly, as Colyn alludes to, I have found the adding of a 5 speed (T9) gearbox to my MGA Mk II much less transformative. Indeed with its 4.1:1 differential and 15" wheels (vs MGB 14"), the car actually feels overgeared with its 0.82:1 top gear ratio.
The MGA just feels a much more "point, squirt and grin" car than an MGB, at least to me! :)
But for a longer journey, I would choose my MGB over my MGA, every time!
T Aczel

MGB on tour (with my wife and me).
MGA heading out for some fun, with two of our (of four) children.





T Aczel

This thread was discussed between 31/05/2024 and 29/07/2024

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