Hey - did you know if you click on the title of a thread it will take you to the first unread post since you last visited that thread?
but were afraid to ask: 
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Pretty Please - add it to our Events forum(s) and add to the calendar! >> 
tony barnhill
Great Pumpkin - R.I.P
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Well, glad you guys caught that...now, I'm going back out in the garage to finish installing floorboards in a GT - the new & IMPROVED way using Fuzor 2-part glue instead of welding them in!
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OD question
- Thread starter jaybird
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Keoke
Great Pumpkin
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[ QUOTE ]
[ QUOTE ]
IFIN he is a "EE" he know what he is doing.---Keoke- /ubbthreads/images/graemlins/yesnod.gif
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Not the one's I work with. /ubbthreads/images/graemlins/frown.gif
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OH those fellas prolly Lucasites from across the pond.--Keoke- /ubbthreads/images/graemlins/laugh.gif
[ QUOTE ]
IFIN he is a "EE" he know what he is doing.---Keoke- /ubbthreads/images/graemlins/yesnod.gif
[/ QUOTE ]
Not the one's I work with. /ubbthreads/images/graemlins/frown.gif
[/ QUOTE ]
OH those fellas prolly Lucasites from across the pond.--Keoke- /ubbthreads/images/graemlins/laugh.gif
martx-5
Yoda
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I'm not familar with the OD on MGs, but I looked at a wiring diagram, the OD activation switch and interlock switch are simply wired in series. Shouldn't be a problem if one of them fail. When it comes to an electrical switch that can fail and cause extensive damage to a very expensive part, it seems to me that this is something that definetly can be improved upon.
From what I've been reading, when this switch fails, it allows the OD to be activated at all times, in any gear. This means that it is failing in a CLOSED position. What should have been done was to have a switch designed so that when it fails, then the OD CAN NOT be activated. It should fail in the open position. First off, you won't destroy the trans, and secondly, you will know right away that something is wrong...not have to ask "How do I know if the stinking switch is fakackta??"
Whether a switch fails mechanically or electrically, it should fail so the circuit is NOT ACTIVATED. Unless I'm missing something here, this is a poorly designed switch.
From what I've been reading, when this switch fails, it allows the OD to be activated at all times, in any gear. This means that it is failing in a CLOSED position. What should have been done was to have a switch designed so that when it fails, then the OD CAN NOT be activated. It should fail in the open position. First off, you won't destroy the trans, and secondly, you will know right away that something is wrong...not have to ask "How do I know if the stinking switch is fakackta??"
Whether a switch fails mechanically or electrically, it should fail so the circuit is NOT ACTIVATED. Unless I'm missing something here, this is a poorly designed switch.
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The OD interlock switch is spring loaded to the off/contact open position. To my knowledge, they don't fail in the contact closed position. I guess there could be rare exceptions.
If you try to back up & the OD IS engaged, the transmission will simply lock up & stall the engine. A good warning not to try & force things. If you persist & force things, yes, something would break. Nothing can be completely idiot proof.
D
If you try to back up & the OD IS engaged, the transmission will simply lock up & stall the engine. A good warning not to try & force things. If you persist & force things, yes, something would break. Nothing can be completely idiot proof.
D
Keoke
Great Pumpkin
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Well Matrix, Dave has already splained the switch's failure mode.However,based on the arguments presented here it seems if the switch has failed it is necessary that the engine and tranny be removed to replace a Ten Cent switch.Consequently, it would seem prudent to devise a work around rather than go through that extent at this time.At some future date when the clutch or other repair dictates the engine and tranny be removed then the ten cent switch can also be replaced.Further, adding a total OD Inhibit control when the tranny goes into reverse can be accomplished using a relay.---Fwiw---Keoke
A
aerog
Guest
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[ QUOTE ]
The OD interlock switch is spring loaded to the off/contact open position. To my knowledge, they don't fail in the contact closed position. I guess there could be rare exceptions.
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That blows my comment about broken/loose wires. I forgot that was causing the OD to not work - not the other way 'round.
The OD interlock switch is spring loaded to the off/contact open position. To my knowledge, they don't fail in the contact closed position. I guess there could be rare exceptions.
[/ QUOTE ]
That blows my comment about broken/loose wires. I forgot that was causing the OD to not work - not the other way 'round.
tony barnhill
Great Pumpkin - R.I.P
Offline
So, now its MOOT - gotta repair it...Janel - ask your mechanic who did Binabox if there's any way to reach the swirch from underneath.
I know you can take all the bolts out of the transmission, pull the shift tower & rotate the transmission 90-degrees either way - think you can even rotate it without removing the shift tower
But, I'm not recommending that, just a thought....&, without going outside to get under on of my cars, I can't remember if its possible to get to it from underneath.
I know you can take all the bolts out of the transmission, pull the shift tower & rotate the transmission 90-degrees either way - think you can even rotate it without removing the shift tower
But, I'm not recommending that, just a thought....&, without going outside to get under on of my cars, I can't remember if its possible to get to it from underneath.
tony barnhill
Great Pumpkin - R.I.P
Offline
Just remembered I've got a couple of OD's sitting in the garage...went & looked..if a guy gets the car high enough, he might be able to reach it from underneath....its on the side of the trans.
PaulHanley
Member
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Janel,
If the switch is not working, then your overdrive is not engaging??
The stuff about not switching off the overdrive before shifting into reverse is plain and simple--BUNK!! Urban MG myth that continues.
Here's the real story--if the overdrive fail to disengage AND you shift into reverse AND you then force the car much harder than you ever did before (like trying to back-up over chocks) then you will do serious damage to the overdrive unit. The switch on the gearbox that y'all have been refereing to "connects" the electric current to make the overdrive engage. As soon as you shift out of 3rd or 4th, the overdrive disengages.
I back out of my garage all the time with the o/d switch flicked to "on"--always because I forgot to turn it off from the prior excursion.
If your gearbox switch has failed, you're in for one heck of a job. Yes, you could pull the engine but that's a bit extreme. I believe you can remove the shifter and the large panel on top of the gearbox for some access. There may be archives here but the UK BBS has much on this topic.
If the switch is not working, then your overdrive is not engaging??
The stuff about not switching off the overdrive before shifting into reverse is plain and simple--BUNK!! Urban MG myth that continues.
Here's the real story--if the overdrive fail to disengage AND you shift into reverse AND you then force the car much harder than you ever did before (like trying to back-up over chocks) then you will do serious damage to the overdrive unit. The switch on the gearbox that y'all have been refereing to "connects" the electric current to make the overdrive engage. As soon as you shift out of 3rd or 4th, the overdrive disengages.
I back out of my garage all the time with the o/d switch flicked to "on"--always because I forgot to turn it off from the prior excursion.
If your gearbox switch has failed, you're in for one heck of a job. Yes, you could pull the engine but that's a bit extreme. I believe you can remove the shifter and the large panel on top of the gearbox for some access. There may be archives here but the UK BBS has much on this topic.
OP
jaybird
Yoda
Offline
[ QUOTE ]
So, now its MOOT - gotta repair it...Janel - ask your mechanic who did Binabox if there's any way to reach the swirch from underneath.
[/ QUOTE ]
My mechanic is my husband, remember?
/ubbthreads/images/graemlins/grin.gif
He put the engine AND transmission in the car.
So, now its MOOT - gotta repair it...Janel - ask your mechanic who did Binabox if there's any way to reach the swirch from underneath.
[/ QUOTE ]
My mechanic is my husband, remember?
/ubbthreads/images/graemlins/grin.gif
He put the engine AND transmission in the car.
