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Overdrive conversion LH type

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Overdrive conversion LH type
#1
  This topic is about my 1977 MG MGB
buzzda Buzz Davies
Erwin, TN Tennessee, USA   USA
Where can I find out details about the shifter lever and shifter knob? Is the knob just hollowed out to allow the switch to fit in it?
Do the wires run down thru the gaiter to the transmission connections or are they routed out thru the firewall and down from the front of the transmission?
My Haynes Manual makes reference to only having the OD Switch work in 4th gear --- Yet my OD Switch works in both 3rd & 4th. Is there another isolation switch missing from my transmission?

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bawest47232 Avatar
bawest47232 bruce west
houston, tx, USA   USA
1980 MG MGB "Maggie"
This is from my 80mgb



1980 MGB on blocks in the garage.
Emission free engine with Weber Carburetor
One ticked of wife who hates my new girlfriend Maggie... Sometimes, I wish I'd never seen her face either.


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bawest47232 Avatar
bawest47232 bruce west
houston, tx, USA   USA
1980 MG MGB "Maggie"
My camera on the phone jacked up but there are 2 wires that feed through to the transmission. But it depends on the year. Some had overdrive switches in different places

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Noble66 Avatar
Noble66 Gold Member Noble Bradford
Orlando, FL, USA   USA
1964 MG MGB "Black Betty"
1969 MG MGC GT
1974 MG MGB "Whitey"
The knob and gear shift lever are different. There is a channel in the lever for the wires. I’m not sure where the wires go on the Mk. 3 & 4 cars.

The black label LH transmission worked in both 3rd and 4th. The blue label only worked in 4th. Your car may not have originally had OD and one of the PO’s added a black label. I’ve also heard there’s a way to switch a blue label to work in 3rd but I don’t know anyone that’s done it.

Other than the blue or black label on the OD the other way to tell which OD you have is if it has a dipstick it’s a black label. If it has a plug on the right side it’s a blue label.

In reply to # 3680900 by buzzda Where can I find out details about the shifter lever and shifter knob? Is the knob just hollowed out to allow the switch to fit in it?
Do the wires run down thru the gaiter to the transmission connections or are they routed out thru the firewall and down from the front of the transmission?
My Haynes Manual makes reference to only having the OD Switch work in 4th gear --- Yet my OD Switch works in both 3rd & 4th. Is there another isolation switch missing from my transmission?

ohlord Avatar
ohlord Gold Member Rob C
North of Seattle, N.W., USA   USA
1957 Land Rover Series I "EYEYIYI"
1971 MG MGB
1971 MG MGB "Bedouin 2"
Early 77 (june 76 to feb 77) was blue lable still overdrive in both 3rd and 4th gears.
After feb 77 dropped 3rd gear overdive operation.



"I'm a long way gone down this wild road I'm on
It's gonna take me where I'm bound
It's a long way around"



"These are the days that must happen to you"

RD2 Radar/ Electronic Warfare Technician
Vietnam 1969-1972

Donthuis Avatar
Donthuis Don van Riet
Rijswijk, ZH, Netherlands   NLD
Not having OD in 3d is not a great loss, I almost never use this feature. It is really only relevant for long stretches on winding country roads, where 4th gear is just too high and 3d rather low eye rolling smiley
Over the years there were times I forgot having it available at all, maybe now that France reduced its max speed on country roads from 90 to 80kmh (the same value we have here) I will use it even less.

PS There is one disadvantage with how BL arranged OD activation and blocking: if left on after downshifting automatic OD upswitch will follow after leaving the next traffic light stop
Astley contains a circuit diagram for preventing this from happening automatically, but I find it rather complicates the basic circuitry of the simple solenoid activation



Edited 1 time(s). Last edit at 2018-02-14 03:38 AM by Donthuis.

ohlord Avatar
ohlord Gold Member Rob C
North of Seattle, N.W., USA   USA
1957 Land Rover Series I "EYEYIYI"
1971 MG MGB
1971 MG MGB "Bedouin 2"
I drive on plenty of winding country roads, comes in very handy.

Takes but a few times to learn switching off and back on after upshift.
It one needs a modification to switch it off than they arent paying attention.



"I'm a long way gone down this wild road I'm on
It's gonna take me where I'm bound
It's a long way around"



"These are the days that must happen to you"

RD2 Radar/ Electronic Warfare Technician
Vietnam 1969-1972

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dickmoritz Avatar
dickmoritz Platinum Member Dick Moritz
Philly 'burbs, PA, USA   USA
I’ve also heard there’s a way to switch a blue label to work in 3rd but I don’t know anyone that’s done it.

You do now... cool smiley

Dick



In reply to # 3680925 by Noble66 The knob and gear shift lever are different. There is a channel in the lever for the wires. I’m not sure where the wires go on the Mk. 3 & 4 cars.

The black label LH transmission worked in both 3rd and 4th. The blue label only worked in 4th. Your car may not have originally had OD and one of the PO’s added a black label. I’ve also heard there’s a way to switch a blue label to work in 3rd but I don’t know anyone that’s done it.

Other than the blue or black label on the OD the other way to tell which OD you have is if it has a dipstick it’s a black label. If it has a plug on the right side it’s a blue label.

In reply to # 3680900 by buzzda Where can I find out details about the shifter lever and shifter knob? Is the knob just hollowed out to allow the switch to fit in it?
Do the wires run down thru the gaiter to the transmission connections or are they routed out thru the firewall and down from the front of the transmission?
My Haynes Manual makes reference to only having the OD Switch work in 4th gear --- Yet my OD Switch works in both 3rd & 4th. Is there another isolation switch missing from my transmission?



Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

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