American MGB Association

North America's oldest, largest and best club for all year MGBs, MGB-GTs and Midgets!!  Established in 1975.


American MGB Association

Club Blog

Subscribe Blog

Message Board

 Subscribe Message Board   

Photo Gallery

 Subscribe Photo Gallery

What We Offer

Join the AMGBA! 

for all year MGBs, MGB-GTs and Midgets
Established in 1975

Phone/Text: 773-769-7084

American MGB Association on Facebook American MGB Association on Twitter American MGB Assoczaiation on Instagram





Member Benefits

Join the Club!

 History of the AMGBA

Meet Info

  Credit Card/PayPal Form

 Secured Order Form


Membership Benefits

 Classified Ads


Tech Tips   Club Store

Submit Classified Ad

Events Calendar

 Member Stories/Articles

 Member Car Photos

Past Shows/Photos



Social Networks


Ad Rates    Officers

Members Login    Membership Updates

  Submit Classified Ad     Parts Exchange

 Renewal of Membership  Tech Services   Parts Suppliers   Tech Staff

 Online Octagon Magazines    Repair and Body Shop Recommendations  Local Chapters



Transmission Not Engaging
this is an excerpt from the articles appearing in the OCTAGON

also see upkeep and performance hints on our message board at
and on our Facebook group at

Transmission Not Engaging

Q:     I have been having trouble with my stock original overdrive (OD) for some time. It will not stay engaged and occasionally when the solenoid is activated and I shift to reverse the car just shudders and goes nowhere.

In my research this isn’t good and the OD may be ruined. The transmission man at my local shop installed a new solenoid as the old one was hanging up. He found that apparently the internal spring that moves the fork back when the solenoid is switched off must be broken as the fork doesn’t retract. The transmission works fine with the OD disengaged.

My current plan is to leave the solenoid disconnected and drive it as a four speed for the time being. My questions are: how much of this is correct? Is my o.d. toast? Is there a different rear end ratio in o.d. cars vs, non OD? Suggestions for what I should do next? Thanks.

Jim Kraft
Morehead City, North Carolina

A:     Well, let's start that the OD shouldn't engage in reverse other than 3rd or 4th gear in forward. I'm sure that did some damage beyond the broken spring found by the mechanic. How much, hard to say without getting into the box.

Answering your questions, there's not a difference between the differential of the OD versus non-OD cars. There is also no difference in the length of the driveshaft. The OD and non-OD units are the same length, the tailshaft making up the difference on non-OD trans.

In terms of running the car with the OD disengaged, as long as it is not making audible, ominous noises, chances are it is fully disengaged and should operate fine as a 4-speed. Just as a note, my OD was added, my car being a 4-speed from the factory. It quit last year (an electrical issue, but I just don't have time to look into it) and I drive it as a 4-speed with no issues.

What you do next is up to your driving choices and your budget. The OD cannot come out without removing the engine and trans, so a fairly involved job. Then there's what you'll find when you open it up. Finding a decently qualified shop to work on it is another challenge. Fortunately, the OD unit is the same for MG, Jaguar, Austin-Healy and others from the era, so while still a small cross-section of transmission shops, it's expanded a bit by the added marques.

If you have time and are familiar with the OD unit or have a cooperative shop, take it out and open it up.

If it's too far gone, go for a rebuilt from Moss or Victoria British. Victoria British offers the type D OD you have as an outright sale for about $1,000 (part no. 2-1043-R), so the condition of yours doesn't matter.

From Moss, you'd have to upgrade to the later LH type from the 68-up cars. Cost is about $1050 for the OD unit, but that includes a $300 core charge for your old one (which has to be in rebuildable condition), so a net of about $750. You will probably need the later trans mount for this as well.

Check with your local shop on what they would charge to rebuild it. You may find the V-B or Moss prices comparable.

Also, depending on your budget, how you use the car or how original you want to keep it, the alternative to go to an American 5-speed is available as a kit. Moss offers it (part no. 440-075), as do others. The new trans is the same as used in a Mustang, so parts and service are easy and readily available. It also offers the added feature of being able to be removed without taking out the engine, as it is set, like an American car, with the trans bolting to the new bellhouse from the back. This makes for much easier clutch changes down the road as well. Cost is prohibitive at about $4,200 from Moss, but includes trans, bellhouse, shifter & linkage, driveshaft and trans crossmember & mount.

I hope that helps you. Let me know how you make out.

Safety Fast!
Art Isaacs

More tech items at, at
and and on our message board at


   HOME      Contact Us

  AMGBA Privacy Policy | AMGBA Website Terms of Use

1997-2021 All Rights Reserved - American MGB Association.