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MG MGB Technical - O/D Transmission

Will a 1970MGB OD transmission fit in a 1976 MGB?

I have a person locally selling one and neither of us are sure if it is compatible
Kevin

Hello Kevin,

Yes it will fit without any problem. But driveshaft lenght are different for those 2 gearbox.

JG
Jean Guy Catford

Hi Kevin:

Yes the o/d gearbox will fit, and all drive shafts will fit from 1968 to 80, but not from 62-67 non o/d cars.

The only concern, is your 76B may not have a hole in the gearbox tunnel to check for oil/dip stick, which is the method for 68-74 gearboxes. The 75-80 MGB's
have only a side fill plug on both non o/d and o/d gearboxes.

Good luck: Rich Boris
Rich Boris

Thanks for the advice. I have been doing some looking around on the web and have another question.
I have not been happy with the high revving engine noise with my 4-speed transmission and when I saw an OD transmission for $150 I thought it would be a good opportunity to upgrade. As I researched the web I also found an adaptor plate that I could put in a GM T5 5 speed transmission.
I am a novice at working on MGB’s and would solicit the help of friends who are more mechanically inclined to help out with the switch. So I guess I would get to the question
What route would be the best way to go O/D MG transmission or adaptor and a 5 speed GM transmission? Would sticking with the MG and drilling a hole in the transmission channel be the easiest? I am getting in over my head for a novice?
Thanks in advance for any advice you can give me.
Kevin
Kevin

Can't tell you what work it takes to mount the GM in your B, but the OD is very nice. I would also qualify this based on if the OD is usable or needs to be rebuilt. Your looking at $750 and up for a thorough rebuild.
Bruce-C

Kevin, Bruce-C

A T5 trans. is cheap and easy to find, according you do not need to rebuild it. An OD in good order is usually $2000( have a look at quantum mechanic) or $1600 for a T9 ford 5 sp. There are many also kits available mainly from NZ or Australia using Toyota supra trans or Nissan 300 Z trans.

No matter the route you select, if it is a kit everything is almost there, but expensive.

if you do it by yourself you are facing:

- clutch fitment to match GM clutch with B flywheel & pressure plate
- starter fitment
-pilot bushing to adapt to GM shaft
- adaptor for speed-o cable + speed-o gear selection
- make a custom crossmember
- have driveshaft shortened + U-joint compatibility
- shifter positioning to modify

Here are the more frequent topics to solve...

Not a piece of cake for a novice...

Cheers,

Jean G.


Jean Guy Catford

I converted my '77 MGB to OD over the winter. I bought the correct (side fill) transmission locally for $750. I then sent the OD unit to John Twist for a rebuild/check up as the unit had been off the road for along time, another $340 (plus $65 to ship). Of course, while I had the engine out I spent money on maintenanace items (seals, etc) plus a new Borg/Beck clutch. I also bought new OD related electrical items (solenoid, isolation switch, gear shift switch), another $100.

So now I have a nicely working OD, but spent more money than I expected. At the end of the day, I think I'd have been just as happy to have kept my standard 4-speed.

For what's it's worth~David
David Steverson

Hello,

Well David approach was the cheapest and the best to my advice.Driving a B on highway at 4000RPM, with a standard gearbox, is a bit annoying after a moment...

Cheers,

Jean G.
Jean Guy Catford

The od trans is one of the best options one can fit to an MGB. It adds that British flavor which allows you to use od in 3rd or 4th gear. The 5 speed transmissions mentioned here are all excellent units, but you loose the fun of flipping a switch to access two different gear ratios. It was one of the best upgrades I did to my car. RAY
RAY

Kevin: Are you sure you saw an adapter to put a T-5 behind a 4 cylinder MGB? I've seen a lot of MGBs with V6 or V8 engines using the T-5, but never a 4 cylinder. Please share the URL if you have it.
John Perkins

"but you loose the fun of flipping a switch to access two different gear ratios"

Couldn't agree more. Why would you do away with an additional ratio, especially one that fits between 3rd and 4th? Superb for spirited twisty bits and hill-climbing. Remember the electric overdrive anticipated the high-kudos paddle change!

I can also confirm that 4-synch gearboxes use the same length prop-shaft regardless of whether they have an OD or not. It is 3-synch gearboxes that need a different propshaft for OD and non-OD, and that is regardless of whether the axle is a banjo or a Salisbury. FWIW the 3-synch OD banjo prop-shaft is the same as for the 3-synch non-OD Salisbury, which is the same as for both 4-synch gearboxes. 3-synch non-OD banjo is shorter, 3-synch OD Salisbury is longer.
Paul Hunt

John,
I tried to find the link for the T5 plate and did not find it, if I find it I will send it along. You can also be right as I did not get into much detail on the spec's.

Thanks to everyone's input , I think I will opt for the MGB overdrive as the T5 may not be for the 4 cylindar, and there would be a lot of adapting to do.

The overdrive I had an eye on is gone, so I will now start my search for another one.
Kevin

Kevin: I just installed a 3-Main 1800 in my ZA Magnette with a Ford T-9 5 speed using the kit from High-Gear. I highly recommend Hi-Gear for the quality of their kit. The conversion in an MGB is a straight forward bolt-in. I've been really pleased with how well my Magnette drives, the Ford T-9 is a sweet piece.
John Perkins

Depends what you want from the car. For me for a fun car for use at MG events then o/d is the way to go. O/Ds are complicated things and can give trouble so for a daily driver I would go 5 speed.
Stan Best

Kevin,

If you run into another OD box for $150, do not hesitate. Get the money out of your jeans ASAP. If you don't use it, you could double your money in a heartbeat, and triple it in two heartbeats.

Charley
C R Huff

Complicated compared to an extra gear maybe, but hardly problematic. They are very reliable.
Paul Hunt

This thread was discussed between 15/05/2009 and 22/05/2009

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