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LH Overdrive
Posted: Tue Oct 30, 2018 6:38 pm
by David Ramsbotham
Hello All, can anyone tell me the differences between a “black” and a “blue” cover plate overdrive unit and if they are interchangeable?
Many thanks, David.
Re: LH Overdrive
Posted: Tue Oct 30, 2018 8:14 pm
by David Ramsbotham
Think I ‘ve just answered my own question! Black goes with 1280 tpm speedo whereas blue goes with 1000 tpm speedo as drive gears in overdrive units are different.
Anything else? David
Re: LH Overdrive
Posted: Sun Jan 13, 2019 11:15 pm
by steve00136
Found this link that explains the difference as well at
https://mymgbinfo.wordpress.com/2019/01 ... ox-mgb-gt/ just taken my gearbox out.
Re: LH Overdrive
Posted: Mon Jan 14, 2019 12:04 am
by Peter Cresswell
Although you can use a blue Overdrive in car that had a Black overdrive originally the speedo will be wildly inaccurate. In theory a Blue LH Overdrive can be rebuilt as a Black LH Overdrive and vv. The speedo drive gear needs changing, but the only way you can do this is to use a overdrive specialist as you need a lot of specialist tools to dismantle and reassemble the unit. There are not many specialists in the UK (3 I think) that deal with Laycock Overdrives, but I have used ODSpares in Rugby who I have found to be very good.