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Technical Area => Transmission Related Discussion => Topic started by: december2008 on November 02, 2008, 09:43:29 AM

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Title: Bad first gear
Post by: december2008 on November 02, 2008, 09:43:29 AM
I have a tech question that you mybe able to answer.
I have a 1965 B with a bad first gear. First gear assembly is $350. Victoria British.
I can get a full synchro transmission for a local salvage yard for $200 out of a 1971B
will it fit?
Marc Satterfield
New Member AMGBA
Title: Re: Bad first gear
Post by: Art on November 02, 2008, 09:46:27 AM
Hi Marc,

I would like to do a bit of research to confirm, but, with some differences, the later gearbox will definitely fit. 

The differences I do know are the rear transmission mounts (which if you are getting the used box from a wrecking yard, you might want to get the complete later crossmember assembly from the donor car), starter, speedometer drive and cable.  The speedometer may have to be recalibrated and you need to make sure you also get the shifter mechanism and clutch activation arm complete as well.   Those are not intercahangeable.

The catalogs show different flywheels for the 3- and 5-main bearing engines, but I do not believe they make a difference if the trans is changed (the clutch is the same for all years 62-80).

Same for the engine back (adapter) plate, but I will check all this as well.  There's a minor difference in the body clearance at the starter that may take a few hits with a hammer to provide some additional room, but that is not major.

Also, by the time you recalibrate the speedo, replace all the mounts, clutch and other components (remember, the engine has to be removed to replace the trans), the conversion will be more costly than just the $200 for the used gearbox and then that box may be no better than your original after a short time.  Keep in mind that even the newest original gearbox is over 28 years old now and the one you are considreing is 37 years old and though a 4-speed synchro, still won't have overdrive. 

For all your effort and money, though much more costly, a better direction might be to consider a shop-rebuilt trans or converting to an OD trans in the deal.  Cost will be around $1500-$2,000, depending on the OD gearbox price, but it adds to the usability of the car and it's overall value.  With MGB's auctioning still at near $20,000 and trading on the streets for $10,000+ for a good example, a better trans is a good investment.

Let me check this out further and see how much work really need be done to convert this over and get back to you.

Best regards,

Art Isaacs
Title: Re: Bad first gear
Post by: december2008 on November 02, 2008, 09:47:36 AM
Hi Art
Thanks for your response to my transmission question. I think I'm leaning towards
your suggestion of staying with the original transmission installation in view of the added
modification to the car and additional part needed to install the later model trans.
I went ahead an disassembled the trans. using the shop manual. Assessment of the damage
is a lay-gear, lay shaft, first gear, reverse gear and an overhaul kit all for around $700.There an  outfit in Atlanta Ga. that has rebuilds for $1100. butt shipping is $175 each way. I'm aircraft mechanic by trade, butt I've never tackled a transmission. I'm confident I can reassemble this one with the parts mentioned. That will keep the car all original and of greater value. Like you mentioned the best investment. Once again thank you for your advice and I welcome any further advice on this endeavor.
Cheers Marc
Title: Re: Bad first gear
Post by: Art on November 02, 2008, 09:48:53 AM
Hi Marc,

The MGB transmission is not particularly special, which is not to say it is easy to work on, but that most competent shops that do off-road or other performance vehicles should be able to do.  In other words, you don't necessarily need a specialist MG shop to do this.

I am not sure where you are, but check locally and you might find a shop or someone capable.  Check with your local clubs, including those owners of other LBC's (Triumph, A-H, etc.) and even American cars and trucks and you may find someone locl that can do it for a similar price, with the cost and time for shipment.

Also, you might find all or some of the parts as NOS sitting on a parts shelf somewhere or on EBay for less than the catalogs.  Same for a conversion to a 4-spd.  It's worth doing a google search.

Also, Victoria British offers your original type trans (62-64) factory rebuilt and sold outright for about $1,400.  Shipping is only one-way (and may be free from them with a sale offer at that price) and you still have your old box to sell for as "rebuildable" or use to experiment with fixing yourself.  This will end-up costing about the same as the Atlanta rebuild and the warranty might be better.  Just some thoughts.

Hope that helps you.  I will still look at the actual adaptation, if just to clarify for my own reference. 

Let me know what you do and how you make out.

Best regards,


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