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OD question

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jaybird

jaybird

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Not sure exactly what I'm talking about or asking, so bear with me.

Is there a 'button' or something on the gearbox that disengages the OD when you shift into a gear lower than 3rd? I've been told there is, I've looked in both manuals and at exploded pictures on Moss, but I can't find what I'm talking about. Maybe because I don't know what I'm talking about?

If anyone knows what I'm talking about, HELP! If anyone has a 'picture' of what I'm talking about, that would be even better!!!
 
On late model MGB'a, the OD switch was built into the gearshift knob.

On earlier MGBs, one could flick the stalk on the right side of the steering column.

On very early MGBs, I believe there was a toggle switch.
 
Sure is Jaybird, it is same as reverse light switch, and is mounted on gearlever housing. Real pain to change in situ.
Cheers Ric
 
What she's talking about is the electrical circuit that only allows an OD to work in 3rd & 4th (except for '77's up which will only work in 4th)...don't think there's a photo of the electrical circuit, Janel.
 
Rick Ingram, not the OD switch to turn the OD on or off. On the gearbox itself.

Ric. I'm confused. Same as reverse light switch???

It's on the gearlever housing. Ahh, I think I saw that in an exploded picture on Moss's website. A real pain to change with the OD in hey? I don't think mine is functioning. I know I'm being a PITA, but can you explain more?
/ubbthreads/images/graemlins/angel.gif
 
Tony, is this controlled by a switch or button or something, that when your gear lever is to the right in the 3rd & 4th position, OD is on, but when you shift over to the left (1st and 2nd) it 'knocks' the button/switch off?

Are you guys confused yet? I am and I know what I'm talking about. Sort of.
 
On the gearlever is the switch used to turn the OD on & off - not the OD isolation switch that keeps it from operating in 2nd or reverse

What makes you think your OD isn't kicking off correctly, Janel?
 
Its item #123, page 38 of Moss catalog...if it isn't working, you gotta pull the engine & trans to replace!
 
Janel - you have a switch that turns the OD on & off - manually...there's also an OD isolation switch that automatically kicks the OD off if you shift into any gear other than 3rd & 4th or if your speed drops below 45mph....now, which do you think isn't working? & why?
 
That's IT, that's what I'm fumbling around asking about, an OD isolation switch!

Actually, how can I know if it IS functioning? Chuck's driving me nuts about this freaking OD, constantly on me to remember to turn it on, turn it off, switch it off when I downshift to 2nd or first, making me crazy about being sure it is NOT on when I go into reverse. If he mentions it one more time to me, he's going to be sitting on an OD transmission.

So, where exactly is the switch, what does it look like? He's been in the manuals today, and the Moss catalog trying to find out.

I KNEW I didn't want that bloody OD in Binabox. I can't turn the key on without him reminding me about that OD.
 
I know about the switch on the dash to turn the OD on and off, I've been driving her for 2 months. It's the isolation switch I need to know about.
 
Found it in the Moss catalog. Now, theoretically, if it IS working, when I downshift, it would kick out of OD, my RPMs would increase, right? Now - would the OD lever on my dash, flick out of OD and back up into NON-OD also?
 
OD lever in dash stays just like it was so that when you shift back into 3rd at proper speed, you go back into OD...you can't downshift to 2nd to check because your RPM's automatically rise when you downshift.....try this...got into 3rd at about 55mph & flip your OD switch on....then, let your car drift down to about 35 or 40...somewhere along the way from 55 to 35, your RPM's should rise & you should be able to feel it shift out of OD....give her gas again & get back up above 45 & you should feel her automatically go into OD...if that doesn't happen - pay attention to what he says or you'll eat an OD!
 
I don't have a speedo, remember? Waiting until this winter to send it to Nisonger.

I "KNOW" about the overdrive and its workings. I posted a question about ODs and their operation, how to use them, before Binabox was even on the road. I just need to know if the isolation switch is working or not.

So, I can still get the car up to speed in 3rd (not 4th?) - flip on the OD, then let it coast down UNTIL I feel it pop out of OD. IF it doesn't shift out, then my isolation switch isn't functioning, correct? Then back up to speed, should shift back into OD.

It's not worth my aggravation to even use the bloody thing..

So,
 
Yes.
 
Try this Jaybird, drive along in 2nd gear, select/engage the o/d switch. You should not feel the o/d engage, no drop in rpm's. The main thing of concern is should reverse be selected/used with the o/d engaged, you will mess up the o/d unit, to the cost of many $$ Usually the sprag/clutch is wiped out instantly.
Cheers Ric
 
That's what Chuck keeps harping about. I'll take the car out in a bit, after Chuck goes to bed. Check it out.

Thanks you guys. IF the isolation switch isn't working, we can replace it this winter when we pull (UGH!) the engine.
 
Jaybird, please remember. If the inhibitor switch is not working, double or triple check that the o/d is not switched on before reversing. (Don't want to read that thread)
Be safe
Cheers Ric
 
Yes Sir Ric, I'll remember. Because Chuck pounds it into my head continually.

A guy in our club has a relay or switch or something, not quite sure, he 'made' (an electrical engineer) that shuts the OD down when you try to go into reverse or something if you have it on. I'm going to talk to him a bit more about that at our meeting Monday.
 
[ QUOTE ]
A guy in our club has a relay or switch or something, not quite sure, he 'made' (an electrical engineer) that shuts the OD down when you try to go into reverse or something if you have it on. I'm going to talk to him a bit more about that at our meeting Monday.

[/ QUOTE ]

Its called an OD Isolation Switch & Moss sells them quite reasonably! $13.00 if I recall correctly...a DPO or DCO can't make one for that (without causing more problems when he whacks into the wiring)! & I wouldn't let him near one of my cars!
 
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