We knew we needed a reverse gear and a new layshaft but needed to find out what else had been damaged during the previous owner’s lack of finesse at shifting.Īfter about an hour we had transformed the gearbox into a table full of parts. We disassembled the gearbox and overdrive unit and examined all the parts. With my trepidation about disassembling the gearbox and overdrive, I am grateful that my friend Mac was there to help and tell me the job is not as hard as I thought it was going to be. Mac pleased with looks of planetary gears
When activated, the overdrive engages and lowers the engine speed relative to the driveshaft, making for better fuel economy.
Mg laycock overdrive manual#
The overdrive is basically an electromagnetic, solenoid-activated planetary gear set that sits between the normal manual transmission and the driveshaft.Īt the flip of a switch, the overdrive unit gives a reduction in gear ratio, basically adding a gear. In the 1940s he adapted this idea of epicyclic gears for an overdrive unit. His initial gearbox invention was an epicyclic 4-speed gearbox for Humbler in the 1930s. He wrote for Motor Magazine, The Daily Express and Chronicle newspapers, and also wrote a number of automotive books. Normanville is an interesting character, an automotive journalist as well as an inventor. The Laycock de Normanville overdrive was invented by an Englishman named Edgar de Normanville and was manufactured by automotive supplier Laycock Products. Gearbox out of the car and ready for disassembly It is possible that you know as little about these overdrive units as I did, so I thought I would give you a little history on the development of these technological marvels and describe how they work. If the gearbox is magic, the overdrive seemed to me to be like high sorcery, something that only a graduate of Hogwarts could master. That goes doubly for the Laycock de Normanville type-D overdrive in my MGB GT’s gearbox. I always think of them as some magic device. They have always scared me a bit as I really do not know how they work. Mac from The Paddock and I did a light cleanup on the gearbox before we started the job of disassembly.Ī point of information is that while over the years I have rebuilt many engines, everything from Alfa Twin Cams, to Porsche 356 and 911s, to name a few, I have never before attempted to disassemble, let alone to rebuild a manual gearbox.
Mg laycock overdrive how to#
I know how to shift a non-syncro gearbox so I knew that something was not right. However, I noticed while driving the car before I decided to disassemble it that first and reverse were very difficult to engage. The gearbox was rebuilt about 10,000 miles ago by John Twist, founder of University Motors and the expert on such cars, and should have been fine. The latest project has been tackling the gearbox.įor a bit of history: The 3-syncro overdrive-equipped gearbox in this car is the one in it when the car was delivered. During this time spent indoors during shelter in place, I have been able to continue work on the MGB GT restoration.
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