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MG MGB Technical - O.D. Vs 5-Speed??

I'm sure that this has most lilkely come up before and is somewhere in the archives. I'm equally sure that this is one of those questions where if you ask ten people you are most likely to get eleven answers, but here goes: Considering an upgrade to either an O.D. trans or 5-speed, as my wife and I use our '65-B mostly on the "Blue Roads" thru the foothills in Northern California on weekend outings with fellow club members. We do however, often use some freeways and cursing speeds. Would like to hear opinions of one vs the other. TIA

Cheers - Dennis - Sacramento
Dennis Rainey

Dennis,

I think it depends on how "original" you want to keep the car. The OD would seem to be more original, but finding a 3-synchro OD is difficult and expensive. Just my opinion, but I would think going to a 4-synchro OD would be the way to go, and easier to convert back if a future owner wanted it completely original. Also keeps it "all-MG", which may or may not be important to you.
Paul K

If you want to stay original then I can help with a 3 synchro OD conversion kit.....
Chris Betson

Well then here is the first of your eleven answers.
Overdrive is a sheer delight. The ease of changing down to overtake on fast roads or to change down at the last moment before accelerating around serious bends on country roads is wonderful and I don't see any any special benefit in using a 5 speed box instead. In many years of having owned about a dozen MGBs I had to change an overdrive box only once and the added benefit is that you willo be keeping a very old example of the marque in its origial spec. The one piece of sophistication in the whole car. Don't get rid of it.
Marc

Dennis-
A five-speed conversion will give you a used transmission sourced from a junkyard that has supposedly been "rebulit". However, when you allow for transatlanic shipping ($$$$$, far from cheap for something like that) and markup ($$$), you have to wonder just exactly what's really been "rebuilt". New gaskets and seals do not a new transmission make. I can engage overdrive in both fourth gear And in third gear. Try that on a five-speed! Better yet, the overdrive gives the car a character that more "modern" cars lack, and nobody can question whether or not my car is a "real MG".
Steve S.

>change down at the last moment before accelerating around serious bends on country roads is wonderful

Marc, the question was asked by someone in the US, where serious bends don't exist. ;)

I too like the O/D on the B. I concur with Paul K - the 4 synchro with O/D is the best route.

Ralph
Ralph

I would go for a 5 speed if you were looking for brisk acceleration but if you dont care about that then I would stick a 4 synchro with OD in your car
Ross

Dennis,
I gotta second Marc, the OD is a shear delight when downshifting...a simple flick of the finger and your off. The added advantage of OD in both 3rd & 4th (MK II) is something that comes in very handy on the curvy blue roads, 3 high to cruise, down to 3 low for the turn, all at the flick of a switch! Not sure if the MKI OD is 3rd & 4th.
Good Luck!
Robert Dougherty

Ralph, In the the right places in the US there are lots of serious bends. If you are ever in the US in the western North Carolina area you may want to try NC hiway 28 and US 129 in the Deals Gap area for one of the best drives you will see anywhere. Or you may want to join the Piedmont British Motor Club on their annual drive from Statesville, NC to Pipestem, WV for lots of seroius bends and fantastic scenery. Bob Thompson knows where the good MG roads are in that area. Be warned it will take your arms a while to unwind after making the trip. Just wanted to let you know the US roads and hiways are not all boring Interstates. Regards, Clifton
Clifton Gordon

Curves? You want curves? How about 318 curves in eleven miles? Try Deals Gap, as Clifton suggested. In motorcycle circles, it's refered to as "The Dragon." Take a look at http://www.tailofthedragon.com Motorcyclists come from all over the world just to drive this piece of road.
Dan Masters

slightly off topic but,....

Each written source i have consulted has different advice regarding engaging and disengaging the OD....do you depress the clutch or just engage with your foot off the gas?

rn
RN Lipow

A little off subject but just couldn't pass up the opportunity to comment. In the most recent issue of R & T there is an article written by a fellow who drove the "Oakville Grade" several yaers ago in his mgtf-1500 and the article was well written about that experience. This past weekend I drove the Oakville Grade from the Napa Valley to the Sonoma Valley. It deserves everything ever said about it. A good ride.

Cheers - Dennis
Dennis Rainey

I put a Merkur fivespeed in my 72B and a O/D fourspeed in my 71BGT. Love them both, but they are different cars. The factory O/D is a dream to cruise with, laid-back and smooth, and the fivespeed is a blast to drive hard. I would not change either one to the other because they both fir the personality of the cars that they were installed in.
gerry masterman

Neither, under the circumstances you describe. I used an A-H Sprite, then an MGA for many years of "blue highway driving" and ocassional "cursing speeds" and highway driving. I have also used MGBs, without overdrive, for similar runs. While the OD feature is excellent for fast highway cruising, I have driven for many hours in direct fourth, at speeds of up to 80 mph, with no problems. Cruising at 5K rpm does not overtax an MG engine, in my experience. So, I would not worry about it myself. If you decide you need an overdrive tranny, I would recommend a three syncro OD if you desire originality (requires a new prop shaft), a four syncro if you do not require originality (may require a new prop shaft and does require some modification of the tranny tunnel) or a five speed, in that order. Any one of these should have been "rebuilt" to guarantee that it is in good working order and will provide good, long lasting service. The quality of any "rebuild" is only as good as the person doing the work. As Steve S. notes, a "rebuild" is more than just a "reseal". I would trust Chris Betson to rebuild a transmission going into my car. There are few others whom I would. Les
Les Bengtson

Dennis, do want to fit the original 6 speed transmisson ( 4 speed + OD on 3rd and 4th) or do you want to make do with an after market 5 speed. The advantage of the origianl OD is that you get OD on 3rd gear. This is wonderful if you flying around country lanes and want to upshift and downshift at a moments notice. I think it would be very similar to the paddle shifters of the latest technology (2002). It works almost ivisibly with just the flick of a switch, and just think it's all original and designed over 30 years ago. If you want a Datsun there are lots of good ones around. If you want to convert to a Sierra buy a Ford.

Keep it origianl and maintain the marque.

Totally original Andy
Andy Preston

RN, Lipow

You don't use the clutch at all with overdrive (- in fact I seem to remember that there is some safety device which disengages it when the clutch is depressed). You simply switch in and out when you need. Disengaging occurs immediately. Engaging may require a very slight delay. You don't worry about throttle either - especially engaging overdrive. You can be accelerating strongly and the switch into OD. If there is too much difference bewteen engine speed and road speed when disengaging then you may well get a loud lurching but you will soon learn when that happens and how to avoid it.
The only serious rule is DON'T engage overdrive whilst in reverse. Once again there is a safety override to prevent this happening but I have heard that if this fails then the damage to the gearbox is catastrophic.
Marc

I stand corrected. I've only driven in Florida, in the US. Boy, was it difficult to keep to the speed limits (and keep awake!). I'm used to driving at over 70mph on British roads (but don't tell the plod).

If you're interested, it was a GEO Storm that I rented whilst I was out there - the only thing that I could find that even barely resembled a UK sports car.

Ralph
Ralph

Ralph-
Next time you come to the USA, come to the Shenandoah Valley of Virginia. We have the Blue Ridge mountains to the East and the Alleghenny mountains to the west. If you like to drive on twisty roads, you'll think that you died and went to heaven!
Steve S.

Ron,

I have not driven a 5-speed "B", but I do have OD in my B/GT. For local driving I agree with Les, and enjoy the normal 4-speed and rarely use the OD. Reading the owners manual MG stated not to use the clutch when engaging the OD, and I never have. I will say for the open road it is nice to have the OD.

Ralph,

Sorry to hear about your Florida experience. All I can say is if that was your impression of the roads here in American you need to come back for another visit. I have also driven the Dragon, and think you might enjoy any travels along the blue ridge parkway. Plenty of club support here as well for your next visit.

Regards,

L.C.
Larry C.

Keys to the correct choice are how/where car to be driven and power plant.
Where I do most driving if one goes under 55 then in must be in a school zone. DFW area mostly covered by hiways 70-80 mph common. There are nice driving roads around, just not many and mostly not real close.
The 5 spd works for me. When I do find the better roads its 2nd and 3rd for the most part.
I'll stick with the 5 spd until the V6 gives me problems. I intend to go back to the B engine. With the B.. 4sp OD.

chuck
n tx
Chuck Roche:65 MGB/V6:-71 Midget-86 944-03 Matrix

Flipping it out of OD top to overtake is much easier than changing down, and OD 3rd is very useful on long climbs or twisties.
Paul Hunt

Marc,
Plz check out the web site for favorite roads. MG drivers all over the US are emailing great roads to drive on...next time your here, try some of them.
http://www.theautoist.com/favoriteroads.htm
Robert Dougherty

I am very pleased with my Sierra 5-speed conversion but would happily have installed an OD transmission if I could have assured myself of finding a good unit. I would not advocate one solution over the other and did not go the 5-speed route due to any known or perceived bias. All my club colleagues with OD's are more than happy with their cars.

Regards,

BarryQ
73B
B.J. Quartermaine

Dennis:

Go with the later 4 sync trany if you are staying with MG parts. The 3 sync will always have the first gear growl, be harder to find and repair, cost more to purchase and it will not be as strong as the 4 sync. As a bonus, it shifts better.

If you get a 5 speed conversion, you will benefit from modern design and materials. Also the internal parts will not have as many years behind them.

Pete
Pete

I just went finished with this decission and after much thought went with the overdrive. Ideally it would have been nice to drive both but that wasen't possible so it came down to staying original and cost.
After spending 4 hours yesterday just droping the engine back in and hooking up that %$#$%^##** rear crosmember and transmission mount I think maybe I should have gone with the 5-speed. (tip) mark all mount & crossmember pieces as to left, right, front, back, top, bottom when you take them out.

Bob Radenbaugh

I went to Euro 2002 at the BMW factory and Butch White at www.mgfivespeed.com had a vendor space showing the MG 5 speed conversions. He uses the Ford Sierra 5 speed for the conversion. It seems to be complete and doesn't require any extensiver modifying. The components including the transmission look new. The cross member should be very easy to install. I didn't ask the price, I have OD trannys on both my MGB's. I think I saw a price of around $1700 in an ad he placed ijn the MG classifieds. Anyone contemplating a conversion may want to give Butch a call. I don't know him but Gordon Strickland at the B Hive highly recommends him. Regards , Clifton
Clifton Gordon

Noone else seems to have mentioned this but i think im right in saying, the most likely 5-spd gearbox you would get for a B if you were to source in the UK would come from a ford sierra...

I believe although someone will correct me if im wrong, that the ratios are very very similar to the B ratios with the exception of 2nd gear, 2nd on the 5-spd is much closer to third. The similar ratios is one of the reasons why it was chosen, that and its of a similar mating pattern, which requires less work to get it in the car.

Personally on the BGT i have always found the jump from 2nd - 3rd on the 4-spd(OD) box i currently have a little large if you're draggin someone out of a tight hairpin curve or off a roundabout. Once in third with sneaky use of OD third before standard 4th usually reinstates your authority on the road however.

For this one reason i would not consider a change to 5-spd however, one of the joys is the flick of the switch - it is an outrageously useful bit of kit and speed at which it engages and disengages can be extremely useful, especially as mentioned earlier if a corner has caught you out and you nede a quick change done for more power....

One mod if you do go to the OD route is to consider having the switch on the gearstick - mine is on the dash, which looks sooo cool, but it is a thousand times more practical to have the switch on the gearstick (i believe some models had this option anyway). I had a ride in a race prepped B and the ease at which the driver could use the OD on the track whilst braking into - and accelerating out of - bends was outrageous. It certainly beat me trying to juggle stick, wheel, switch, brake and throttle all at once!!! ;->

~PHIL
Phil

Phil & others

Following is the information (taken from the Hi-Gear Engineering web site)on the relative gear ratios for the Sierra and MGB boxes:

MGB/Standard Ford/Modified Ford/Closer Ratio
First 3.44/3.65/2.98/3.36
Second 2.167/1.97/1.97/1.81
Third 1.382/1.37/1.37/1.26
Fourth 1.0/1.0/1.0/1.0
O'Drive/
Fifth 0.82/0.82/0.82/0.825

This indicates that the standard Ford gives about a 10% higher second gear and all versions have the same fifth ratio as the MGB OD. I have the standard box and enjoy holding onto second a bit longer.

BarryQ
B.J. Quartermaine

There's nothing wrong with a five speed, but the MGB O/D gearbox is one of the things they got right from the factory. On a list of the top ten favorite features of a B, I bet the O/D's on a lot of drivers' lists. I wouldn't mind tweaking the ratios a little, but would rather source the expensive close ratio gear sets than sourse the expensive conversion. Dean
Dean Lake

OK, there's an idea for a new thread - top, say, 5 things most loved about the MGB. Also Top 5 things most hated.
Marc

Has anybody disconnected the O/D vacuum relay on a '65B? I find it a bit disconcerting, when I flick out of over drive, and it doesn't disengage until I hit the gas again.

Dan
Dan Johnson

Didnt see it mentioned so:

Reason the 2nd in a B is so low is beause the gearbox is based on the 3 syncho unit which had a low 2nd so you didnt have to go into 1st so often
Paul

I would consider Chris Betson's 3 syncro conversion kit. I just converted my 67 GT to a 4 syncro O/D and while I agree with everything that has been written here about the beauty of the O/D, I really miss the shorter throw of the 3 syncro trans. In addition, I bought a used O/D and wound up spending quite a bit to rebuild the 4 syncro-trans and the O/D. Not quite as much as a 5 speed conversion but close. If you keep the transmission you have, rebuild the lower end along the main shaft and O/D conversion from Chris, you wouldn't have to make major modifications or cut holes to make it work.

Jon
Jon

I have a 5-speed in my present car for reasons that aren't relevant but I will say that O/D is one of my fondest memories. My first car was a slightly disheveled '71 BGT with O/D and it just seemed so cool and so right. It's one of the Truly Right MG things, like alloy bonnets and those beautiful instrument panels. Whatever gearing is produced by overdrive-3rd, the mathematics are divine!
David

Thanks to all who chimed in on this one. I believe that I've made my decision on which way to jump. The biggest part is still ahead of me and that would be selling the whole idea to my wife.

This BBS is great. Cheers - Dennis - Sacramento
Dennis Rainey

This thread was discussed between 18/10/2002 and 25/10/2002

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.