MGB & GT Forum

Your efforts may be best directed to finding a good 2nd hand OD gearbox that can be shipped to you. What year is your MGB as there were different OD transmissions used over the years ? This article explains; https://mg-stuff.stlbrits.com/kb/overdrive-options/



Edited 2 time(s). Last edit at 2024-04-10 07:18 AM by Not-Anumber.

He has a 3sync because it's a '66 (unless it's already been changed to a 4sync - I didn't go back to check).

OP you are unlikely to find an OD box where you live - you have a compatriot on MGE going by the moniker Windmill who might wise you up.

IDK where you want to shop for an OD box but you've got Dick already replying and he's one good NA source and really the goto builder on MGE. You've also got Philip Waterman (mgb281) who has been supplying OD boxes to NA ex UK but not only is he in AU at present ( he may be on a flight home) but he also reports that supply is dwindling and shipping getting very expensive.

IMO you should advise if your chasing a 3syncOD or 4sync OD. Once that's established those with the requisite knowledge can lead you to a possible outcome.

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Mk1: CKD 11/66 first registered 8/5/67; owned since 3/77. 18GB +40 balanced. Peter Burgess BVFR head. Piper 285. 123. FidanzaFW. 4synch c/r box. Superpro. Nut and bolt rebuild 2010 - 2015. Tartan Red.

GT: 12/78. VW Golf guards, flush fit front and rear valances, frenched indicators, Mk1 rear lights - LED lights. 'Worked' Rover V8, Monsoon ECU for EFI. Commodore VSV8 GM4L60E, Lokar tiptronic shifter & Quick4 controller. Vintage Air A/C. FC IFS. CCE 4 link rear. Salisbury with Quaife. Jaguar Storm.



Edited 1 time(s). Last edit at 2024-04-10 07:41 AM by MGB567.

Roland
I admire you enthusiasm and you would be best to follow the advice provided and swap out your gear box wholesale.
These early gearbox with overdrive are not so common.
I link to one available;

https://www.kijiji.ca/v-transmission-drive-train/bedford/early-mgb-overdrive-gearbox/1682882467

I have no asssociation with the vendor, the item is located in Eastern canada, so not exactly next door to you.

Best of luck going forward..

B

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Life's most persistent and urgent question is, "What are you doing for others?"

Quit worrying and wasting time, Buy an OD from Dick Moritz. Be done with it. I did!

Thank you for all your messages.
As I live in Malaysia it is indeed not so easy not find and ship parts...

Believe it or not it is nearly £100 cheaper to ship to Kuala Lumpur than to the USA! However it takes a few days longer. Barrie is correct about prices in the U.K. they have been rising steadily ( ie almost trebled for a known good one) and 3 synchro ones are also quite rare.

Sorry, I missed your location.

For the record,

Dick M does not offer a service for these early geraboxes.

In my post I linked to a clean one but it is in Canada. Not eactly easy for the OP, and would ultimately be a logistical challenge, unless the vendor is a helpful chap.

In any event 500$ CDN is a fair deal for you south of the 49th paralell

B

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Life's most persistent and urgent question is, "What are you doing for others?"

Yep...Thank Bruce

To respond to Barry's message ( #17) my 4 speed gearbox is 3 synchro.
Therefore I need a 3 synchro gearbox with OD (typeD) or and OD to adapt to my existing gearbox if possible.

Can I buy a separate OD + Shaft + Accessories and fit it to my existing gearbox ?

I saw from MOSS that they sell separate OD + shaft + accessories as detailled below :

OVERDRIVE & SOLENOID 3 synchro 'D' type overdrive Ref MOSS : 22H210EX Price £ 630

PROPSHAFT, (A = 31 1/8 inches, 78.9cm) Notes: Banjo & Tube rear axle 3 Synchro overdrive and 4 Synchro Ref : AHH7487 Price : £121.10
Note : The PROPSHAFT without OD is A = 30 inches, 76.2cm. I dont understand why without OD the shaft is shorter ?

Accessories :
1 RELAY, overdrive 3 synchro Ref MOSS 142169A Price £28.80
2 SWITCH, overdrive vacuum 3 synchro Ref MOSS BHA4282 Price NCA
3 HOSE, vacuum 3 synch ro Ref MOSS : AHH6747 price £6.70
4 CLIP 3 synchro Ref MOSS : GGT1113X price : £2.69
5 ADAPTOR, manifold 3 synchro Ref MOSS : AHH6962 price NCA
7 SWITCH, overdrive, (angled) 3 synchro Ref MOSS BHA4513 price : £18.89
or
8 SWITCH, overdrive, (gear knob) 4 synchro from (c) GHN5 410001 Ref MOSS : 520999A price £13.79

Can I install the switch 8 on the gear knob for a 3 synchro gear box as it is mentioned only for 4 synchro ?

Cheers.
Roland

Can I buy a separate OD + Shaft + Accessories and fit it to my existing gearbox ?

See post 15. It will prove all but impossible to find a third motion shaft/mainshaft available for sale anywhere. Note that the shaft I reference is the main shaft in the gearbox which carries first, second, and third gears and the synchronizer assemblies, not the drive shaft.

Bruce is correct, I no longer rebuild the 3-synchro gearboxes, these days restricting my work to only rebuilding 4 synchro MGB overdrives and supplying rebuilt such gearboxes to folks who want to upgrade their MGB from non-overdrive to overdrive. I do have rebuilt 4-synchro overdrive gearboxes available for sale...

You might want to check with John Esposito at www.quantumechanics.com He may be able to ship a rebuilt 3-synchro gearbox with D-type overdrive internationally...

Dick

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Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

Thanks Dick for the clarification.

I believe that I cannot install a 4 synchro + OD gearbox in my 1966 MGB as my transmission tunnel is smaller isn't it ?

It is quite common to install a 4sync where a 3sync was - as you can read in my signature block I'm one of many who has done it and I did mine using 3sync parts from the backplate back. Others do it by changing the backplate to the 4sync. There are several discussions on MGE about this transplant. For me there were no mods necessary to the tunnel but mine is a CR box not OD. Your only mod would be to the hole for the gear stick. Fortunately Clarke and Clarke make a cover for this.

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Mk1: CKD 11/66 first registered 8/5/67; owned since 3/77. 18GB +40 balanced. Peter Burgess BVFR head. Piper 285. 123. FidanzaFW. 4synch c/r box. Superpro. Nut and bolt rebuild 2010 - 2015. Tartan Red.

GT: 12/78. VW Golf guards, flush fit front and rear valances, frenched indicators, Mk1 rear lights - LED lights. 'Worked' Rover V8, Monsoon ECU for EFI. Commodore VSV8 GM4L60E, Lokar tiptronic shifter & Quick4 controller. Vintage Air A/C. FC IFS. CCE 4 link rear. Salisbury with Quaife. Jaguar Storm.

You can install a 4-synchro overdrive gearbox in your 1966 MGB, a conversion that is done often, since many folks face your situation and are put off by the lack of synchronized first gear in the 3 synchro boxes, and their relative fragility compared to the more robust 4-synchro overdrive box.

You just need to use the engine back plate, clutch fork, and flywheel from any 1968-80 MGB, overdrive or not, and a gearstick from the same years cars, overdrive or not. These parts should be plentiful and readily available.

The only modification needed is to modify the tunnel, since the 4 synchro gearstick comes up through the tunnel several inches rearward of that of the original 3 synchro box. There is a very nice tunnel replacement piece available for this task at modest cost. See here: https://clarkandclarkinc.com/catalog/detail/mgb-transmission-cover

Rarely there is a little area of interference at the right angle of the firewall just above the starter motor area, but this is easily addressed with a couple of taps from a BFH. You may also have to use a driveshaft of a different length, but this is not a big deal.

A nice benefit of this conversion is the fact that your car no longer needs the firewall-mounted overdrive vacuum switch and electrical relay, since the original 3-synchro overdrive solenoid had a large current draw of 17 amps on pull-in and 3 amps on hold-in. The redesigned solenoid in the 4-synchro Type LH overdrive draws less than one amp, only about 800 milliamps, so no relay or vacuum switch are needed...

A blue label/side fill 4-synchro overdrive gearbox from a 1976-80 MGB will afford a more accurate speedometer/odometer reading in your 66 than you would get from an earlier black label/top fill unit, but the function of the gearbox and overdrive is identical either way...

Dick

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Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

Beat you Dick but you typed more.

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Mk1: CKD 11/66 first registered 8/5/67; owned since 3/77. 18GB +40 balanced. Peter Burgess BVFR head. Piper 285. 123. FidanzaFW. 4synch c/r box. Superpro. Nut and bolt rebuild 2010 - 2015. Tartan Red.

GT: 12/78. VW Golf guards, flush fit front and rear valances, frenched indicators, Mk1 rear lights - LED lights. 'Worked' Rover V8, Monsoon ECU for EFI. Commodore VSV8 GM4L60E, Lokar tiptronic shifter & Quick4 controller. Vintage Air A/C. FC IFS. CCE 4 link rear. Salisbury with Quaife. Jaguar Storm.