MGB: MGB History

Can someone tell me if "all" 1977 B's overdrive only worked in 4th gear or did they make some early on in the year still working in 3rd and 4th?

I had a 77 about 20 years ago, it the O/D worked in 3rd or 4th gear.

Robert

I don't own a late MGB, but I *thought* that at some point they only enabled it in 4th - I think it was something to do with meeting emissions. Also, maybe California cars were different due to different emission specs.

I'm way out on a limb on this one - no idea if anything I've said is really true. :)

I *think* the change from OD active in 3rd and 4th to 4th gear only went along with the introduction of the transmission controlled vacuum switch. The vacuum advance needed to be allowed only in 4th for emissions reasons, and the OD uses the same enabling switches on the transmission. It would have required more engineering and cost to keep the OD active in 3rd and 4th. I don't think the OD being active in 3rd would have effected emissions directly.

According to Clausagers; The change occured at car "#428538 (feb77)". This was only for NA spec cars.

THANK YOU, THAT IS WHAT I NEEDED. WHAT IS Clausagers? WHERE CAN I FIND THIS?

As an aside, for those interested in trivia, the "factory" MGB GT V8 came standard with overdrive throughout its production life ('73 through '76 model years), but the V8's overdrive could only be engaged from 4th gear. This limitation was apparently based on durability concerns. Some troubleshooting info for the Laycock overdrive is included in this reprinted copy of Leyland's service training manual: http://www.britishv8.org/Articles/MGBGTV8-Technical-Notes.htm

The closest thing we have to a bible.

http://www.amazon.com/Original-MGB-C-V8-Compl-Complete/dp/1870979486

For what little it is worth, the O/D tranny in my GT came out of a 76 roadster and works in both 3rd and 4th. I suppose that they could have changed that for '77, but maybe mine points towards something, one way or the other. Sorry that is no more definitive than it is, but those with 77-80 cars with O/D should be able to weigh in and give you at least a consensus of their experience.

Good reading.

http://www.custompistols.com/cars/articles/ts_od_gearbox.htm

John Twist mentions the change in this video..


http://www.youtube.com/watch?v=JWlzTemci7M&feature=related

Just read Sotomayor's piece on OD transmissions, and I think its all there, and all correct. Nice to have the whole program explained in a concise and logical format.
Thanks for the link, it now lives in my little library.
Have fun