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MG MGB Technical - 5 speed conversion

Hi All

I,m thinking about converting to 5 speed trans and have the ford type 9 gearbox, i,m now looking to buy the conversion kit from Hi-gear engineering but want to know how good this kit is and are there any other kits out there.
your thoughts appreciated
Cheers Pete
PJ Thompson

I hate to be a party pooper here but I would be very reluctant to put a modern 5 speed gearbox into my Bs as it would spoil their whole character. The 4sp + overdrive is really a six speed transmission and the ability to flick in and out of overdrive when meandering through villages or country lanes thus avoiding declutching and changing gear will be totally lost thereby losing some of the character of the car. Don't forget that the four synchro gearbox is very robust and reliable and virtually bulletproof making its longevity on a par with that of the Ford.
Iain MacKintosh

I used to think the same untill i drove a 'B' with the ford box and after driving with overdrive for 15 years was really pleasantly suprised.
The 'B' is a lot nicer to drive with the ford box, smoother, quieter and easier on the motor.
I will leave the switch on the dash for nostalgic reasons and pretend :)
This conversion is reversable

PJ Thompson


I'm with you Pete. I've fitted an MX5 (Miata) gearbox to mine. Now drives like a dream.

Herb Adler

Party pooper # 2 reporting in here.
I have a 1965 Mk1 MGB that I fitted a 3 synch O/D gearbox to 25 years ago, and a 1600 Mk2 MGA that I just fitted the Hi Gear T9 based conversion to.
The Ford T9 has a much nicer spread of ratios, especially with Peter Gamble's taller first gear option. Despite this, and even with the huge gap between 2'nd and 3'rd gears with the MG box, and the crash first gear, I much prefer the "feel" of the old style gearbox. It just feels so nice when you get that gear-shift "just right". If I wasn't facing significantly modifying my MGA's transmission tunnel to fit an O/D gearbox to my MGA, and the MG O/D boxes weren't so hard to come by (here in Australia), I'd have preferred the MG O/D gearbox option for my MGA.
BTW the later 4-synch gearbox certainly is robust, but this is not the case with the earlier 3-synch boxes.
T Aczel

I fit HiGear kits to MGAs, MGBs and currently - a Magnette ZB.

The kits are complete and well engineered - I wouldn't go elsewhere for them.
Chris at Octarine Services

Why anyone wants to change an original OD gearbox (if that is what it is) to a 5 speed defeats me. Why go down from 6 speeds to 5, why lose OD 3rd which is a brilliant ratio on the 4-synch box for spirited driving on twisty bits or hills, and why lose the electric ratios which anticipated the much-vaunted modern paddle change (especially the column switch) by many years.

I wouldn't even fit one to my V8 which only has OD on 4th, let alone my roadster.
PaulH Solihull

Because the Ford box is so much nicer to use and the ratios are better spaced than the MG one.

Actually, 3rd OD is so close to direct 4th that you only have 5 gears in reality.
Chris at Octarine Services

Totally agree Chris
After driving overdrive equipped 'B's for 15 years 3rd o/d is useless and i stopped using it a long time ago.

PJ Thompson

Well you know what the advert says "why be like a golf when you can get the real thing ?"
Iain MacKintosh

Ive got a golf for everyday use, believe me i dont cared what improvements you make the Mg aint ever gonna be like a golf :)

PJ Thompson


Let's back up to what you said about fitting an MX-5 Miata box. Was that done custom or with a kit? What are the details. As most know, the type 9 is rare in the states, but Miatas are common.

C R Huff

I find the 5 speed ford box is much better both in ratios and gearchanges. It transforms the B and the conversion kit is very well made and easily fitted. Unless originality is the main requirement when doing a restoration a 5 speed conversion is one of the best improvements that can be made to the B particularly in the early cars without synchro on 1st.

Ron Stevenson, Ayrshire, Scotland
R Stevenson

Hi Charley,

Sorry about my post, what I meant was I fitted a Nissan Bluebird box, but Miata seats. Senility confusion early in the morning!

If you are considering the Nissan swap, I have an article, just let me know and I will email it to you.


Herb Adler

I agree with PaulH regarding the electrically operated o/d.

On a hilly and winding road it becomes a nuisance depressing the clutch and operating the shifter to drop in and out of fifth gear.

To me the electric o/d is a retro-modern feature.
Steven 67GT

"3rd OD is so close to direct 4th that you only have 5 gears in reality."

Close on the D-type maybe, but on the LH-type OD 3rd is closer to mid-way which is why it is so useful ... at least I've found it so over 20 years, but each to their own. Straight 3rd 5.4:1, OD 3rd 4.43:1, straight 4th 3.909:1.

And who, after going to the trouble and expense of fitting a 5-speed, isn't going to claim it's better heh heh.
PaulH Solihull

Wow Steven 67GT

It becomes a nuisance depressing the clutch to change in and out of fifth!

And reaching out to the dash to flick 3rd O/d (Useless) in then out depress clutch change to 4th and reach out again for 4th O/d is'nt a nuisance.

I think this is going off thread as many do i actually like o/drive, i was only asking about the Hi-Gear conversion kit and if there were any other kits out there, ive already had my answer off those that have experienced using these kits as i only take notice of those that have the relevant experience.

As ive said ive driven overdrive 'B's for 15 years now, the ford box is so much smoother and quieter.
Driving around town or long distance is so much nicer.

It's not about expense some people spend their money on power steering leccy windows etc for me its about making my 'B'enjoyable to drive, many people have said the 5 speed conversion is the best improvement you will make to a 'B'

For those who hav'nt driven a 5 speed converted 'B' test drive one if you can you'll be suprised.

PJ Thompson

If you drive the engine to 5000 rpm before changing up then 1st gear will take you to 26mph and a change into 2nd drops the revs to 3132. 5000 in 2nd takes you to 41.5 mph and a change into 3rd drops the revs to 3187. 5000 in 3rd takes you to 65.1mph and a change into OD drops the revs only to 4094, a change into top drops the revs to 3616.

Since max torque is around 3000 rpm I think the use of 3rd OD in the change up sequence is a waste of time!

Yes 3rd OD is useful on twisty roads where 3rd & 3rd OD provide gearchanges by switch rather than clutch but that is about all it is useful for!

Similar figures for the usual Ford N type box are - 1st to 24.66mph and a change into 2nd drops revs to 2698. 2nd to 45.7mph and a change into 3rd drops revs to 3477. 3rd to 65.7mph and a change into 4th drops revs to 3650.

Closer ratio Ford boxes are also available - not so with MGB boxes unless you go to straight cut gears - the Brown & Gammon helical close ratio gears are NCA.
Chris at Octarine Services


I have a vague memory of a Datsun Bluebird in the mid-60s here in the states that was a pick up truck. Is that what you used?

Often the same model has a different name on different continents. Maybe the Nissan Bluebird is common here with a different name that you might know of?

If it is the old pick up that I remember, that would be pretty scarce here now.

Either way, I would be happy to have your write up on it. Even if I never do it, the more people that have the info, the less likely that it will be lost. My e-mail is on my header line.

C R Huff

Hi Charley,

In the States it could have been the Maxima. A sedan, not a pickup truck.

See wikipedia

Herb Adler

Hi Herb,

I looked at the wiki link, but I'm still not sure what it is. That body style is pretty non-descript, so it's hard to recognize it. If it were the Maxima here, it would have to have been the early ones since for many years the Maxima here is a V-6 front wheel drive car.

Thanks for sharing your articles on the trans swap.

C R Huff

Dear All, Look at this thread! You have all demonstrated the true concept behind owning an MG, and that is you are all individuals. The MG was created to be tinkered with and modified. It is all a matter of personal taste. I myself still run the 4 speed with overdrive, would I like a better spread of ratios? You bet! My more modern car has a 6 speed close ratio box. It is a dream to drive fast, in traffic it can get tiring. If I can have this in the MG I would, ( and will someday. ) I just love mucking about! Don't you all? Mike
J.M. Doust

Hi All,

Well said, Mike, we are all different and do what we do to suit us.

Now if I were picky, I could point out that if using the OD switch is such a relief to changing gears, then invest in an automatic and then all you need to do is to decide if you want to go forward or backward.

Herb Adler

Try driving one, and you will see why an auto is a completely different kettle of swimming things to a manual with OD :o)
PaulH Solihull

I was considering putting in a Ford gearbox as my OD isn't working. I see a lot of MT75s for sale, are they the same as the type 9?
c cummins

On my 64 B I put in a HI gear kit. It was well engineered and installed easily. It may have taken some of the "charm" away from the car but it was sure a lot easier to drive. Ed
E kulick

I wonder, to what extent do our respective driving experiences shape our perspectives on this perennial issue? I have the 4 speed and overdrive and love it in and around Canberra. Not sure I would feel the same in any other Oz capital city - traffic congestion and urban sprawl. I can well imagine English lanes and country by-ways being well suited to my setup.

Down here though, if I'm on a club run Canberra to Bathurst, Albury, Hay plains et al, I might find attractions in the 5 speed conversion - especially when overtaking coaches or road trains on those regional roads. I might live with the marginal depreciation in flexibility I now enjoy in local urban 40/50/60/80 K zones.

Just a thought.

And a very Merry Christmas and the best of New Years to everyone on the board. Can't wait for Boxing Day!!


Roger T

OK, I toss my two cents in. My B has an overdrive, and I think that it just brings out the vintage nature of the car and makes it an even more fascinating classic than it is with a simple four-speed transmission. The MGB is not a modern car, and trying to transform it into one seems to defeat its very nature. I'll stick with the overdrive, heavy and complex though it is.

As for those Purists who are dead set against puting a five-speed transmission into an MGB, I must point out that the engineers at Abingdon installed a Rover five-speed transmission into a prototype MGB during the same period when they were fitting the proposed overhead camshaft O Series engine into another prototype MGB. If the car had continued in production, these features would certainly have made it to the production line.

MG owners have been improving their cars since day one. In fact, the entire history of MGs goes back to the days when mechanics at Morris Garages would take a standard Morris automobile and improve it for discerning customers who wanted a little better performance, then affix an octagonal MG emblem to their radiators to advertise where the car was serviced (now you know where the name MG comes from). MGs have always been enthusiasts cars, and it is just in the nature of things for enthusiasts to improve their cars. Only the most rabid of purists would object to an owner doing period-correct modifications to it. What entails period-correct modifications, you ask? Quite simply, anything that was being done to the cars when they were still in production, including some really interesting work done by the factory race team. This includes, but is not limited to, changes such as: camshaft, headwork, valvetrain work, carburetors, intake manifolds, air filters, exhaust system work, distributor modifications, changing transmission and differential gear ratios, suspension modifications including different springs, damper rate modifications, stabilizer bars (both front and rear), lowering the chassis, adding a Panhard rod, wheels, tires, and just about anything else that the mind had conceived of in those days, which is a lot. I have never met an MG owner who has actually done all of these things to his car, but if I ever do, you can bet he will be wealthy. I can see no reason for any MG enthusiast to have a problem with pointless ignition, better headlights, better brake friction materials, radial tires, or anything else that is a reversible improvement. To those enthusiasts who take pleasure and pride in tinkering with and improving their MGs I say: You are the true keepers of the MG Heritage. To those who insist that an MG should always be exactly as it was when it left the factory at Abingdon, I can only say this: You are missing the whole point of the Marque and its history.
Stephen Strange

"I must point out that the engineers at Abingdon installed a Rover five-speed transmission into a prototype MGB"

It would still have been changing a six-speed with two electric ratios (UK anyway) for a five-speed and so a reduction in facilities, probably for cost reduction. Not all the changes Abingdon made were for the best, you'll be telling be rubber bumpers were an improvement next ...

The RV8 *did* have a five-speed.
PaulH Solihull

No, Paul, I hate the rubber bumpers with a passion. However, as has already been pointed out, due to the uselessness of the 3rd gear overdrive ratio, the later four-synchro transmission when equipped with Overdrive is in reality a five-speed.

Yes, indeed, for Management one of the reasons was to reduce production costs and take advantage of "Economy of Scale". Another was reduction of inventory costs for both the factory and the dealers. The Marketing people thought that it would modernize the car and follow the trend in the marketplace toward five-speed transmissions, just like previous market trends had rendered the three-synchro transmission obsolete from a sales standpoint. I believe that the engineers at MG were enthusiastic about it because the change would've reduced weight and increased reliability.

By the way, I never once used the word "improvement". That matter is for the individual MG owner to decide upon.
Stephen Strange

I, personally, find that 3rd od is a very useful ratio, especially with the 4 synchro/lh od transmission. I use it all the time. Although my car is now equipped with a supercharger, albeit a non-factory item, the use of overdrive in 3rd gear gives me a very noticeable difference from 4th direct. The od trans is a very British part of the B experience, although many automobile manufacturers used overdrive transmissions well into the '80s. RAY
rjm RAY

Those rubber bumpers are useful for putting spanners/cups of tea/plates of biscuits on when you're working on the car. Don't knock em!

In fact do knock them! They're supposed to soak up damage up to 5mph though I'd rather not risk it. ;-)

Mike - no overdrive in my car unfortunately.

"as has already been pointed out, due to the uselessness of the 3rd gear overdrive ratio"

Pointed out maybe, agreed with definitely not!
PaulH Solihull

Re: MX-5/Miata gearbox.

A few years back there was on FleaBay in Quebec a 'B listed with an MX-5 gearbox. I communicated with the seller and he said he'd had the conversion done at a garage local to him. I did get the name of the garage but never followed it up. One of these days I'll have to dig up the contact info and see if he's still in business.

Another LBC garage in Montreal was offering conversion kits using the gearbox from the Nissan 240ZX instead of the more commonly used 280ZX. Anyone wanting to follow up on this an contact Britannicar @ 514-637-6661. Ask for Len.

And there was another local garage that did a one-off conversion with the Honda S2000 6-speed gearbox.
Derek Nicholson

Sorry, a correction. That's a Nissan 240SX, not a 240ZX.
Derek Nicholson

This thread was discussed between 02/12/2010 and 03/01/2011

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