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MGB How does on tell if an MGB has Overdrive

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Norton47

Jedi Warrior
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Hi
I was trying to figure out the dash layout and there is a push button switch in the upper left hand side, it has a small red lens by it. The car also has a straight shifting lever. I was reading an article in an old Classic Motorsports magazine it mentioned straight shift levers were used with overdrive transmissions. I looked under the car and there are several wires. Two of which go to a bulge in a case aft of the filler. The others go to at least one switch that is located on the shifting rod housing. I assume those are for the reverse switch for backup lights.
Are the wires going to the unit in the case for a solenoid? This all appears to be after the main gearbox case.
IF it is an overdrive are these fairly common, Triumphs don't seem to have them very often, is MGB's different?
Thanks
 
Best way is to get underneath and look. The OD sits at the stern end of the transmission. It'll be obvious. Some cars, like mine, have the switch but no OD. My car never had OD according to the BMHT certificate, but for reasons now lost to history, there is a switch on the dash for it. I have the angled shift lever by the way.
 
Straight shift levers are on 4-synchro boxes. "Angled" or "Bent" levers are on three synchro boxes. Has nothing to do with if it has overdrive or not. I'm guessing you have a 1968-1976 B, That would mean that switch, which is a momentary switch (only closes the circuit when you press it) is the test switch for the lamp beside it, which is the NHTSA mandated warning light for brake system hydraulic pressure.

Like the previous poster said, you have to get under the car to be sure.

Colin
 
Even levers can be swapped around with a bit of fiddling. I have an LH-type OD gearbox in a '67 GT with an early 3-sync shift lever. The only way to know what's going on there is to crawl underneath and see what the plate on the OD unit says!
 
Everyone has suggested that you crawl under the car and that is true, but once there you need to know what you are looking at. A NON-OD transmission has a long tail housing that looks, like a trumpet. If you have an OD down there the unit itself will look like a big silver cantaloupe with a short housing leading to the drive-shaft flange. There will be a flat plate on the bottom with either black or blue makings if it is an LH model OD.

The switch that you refer to is a check-it switch for brake failure. Rather useless actually IMHO, because if the light comes on you already will have noticed that you have little or no brake pedal feel and won't be looking for a litght, just someway to avoid that truck that stopped in front of you. The rocker part of the switch is just to test the viability of the little light itself.

If you have that switch you must have a '68 or later car. In that case the OD switch will be either a part of the right hand steering column stalk or if it is much later the OD switch will be part of the gear shift knob itself.

The column switch will move forward and back even if there is an OD unit present or not. They just used the same switch throughout that production period.

Jack
 
WA1KWA said:
Straight shift levers are on 4-synchro boxes. "Angled" or "Bent" levers are on three synchro boxes. Has nothing to do with if it has overdrive or not. Like the previous poster said, you have to get under the car to be sure.

Colin
Click to expand...

True, and on early 3 synchro cars, non-OD gearshift lever has two bends. OD gearshift lever has only one bend so that the top and the knob were inclined to the rear. -Clausager
 
Like Steve said, crawl under it, look at the tranny, if the OD is there, you'll know. If your not familiar with what they look like, check the numbers to see what model it is. Levers, trannies, engines etc, can and have quite frequently been changed over the years. So, you've gotta crawl around, get dirty and check the numbers.
evil_lol.gif
 
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