Hi All,
I believe my overdrive inhibitor switch on the gearbox is playing up. Question - where is it mounted and also I've read on an MGB forum that the position of the switch in relation to the contact pad inside the gearbox is controlled by some fibre washers between the switch and gearbox casing and as wear takes place the number of washers has to be reduced.
Does that make sense for the Dart?
Many thanks
Roger
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Always look at "ACTIVE TOPICS" to see all posts in date & time order as they are sometimes moved; or look at "Your Posts".
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Dart Overdrive Inhibitor Switch
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Re: Dart Overdrive Inhibitor Switch
The switch is located on the top cover of the gearbox, screwed into a boss directly above the 3rd/4th gear selector shaft (and sometimes another switch on the 2nd gear shaft as well).
The switch engages with an indent in the shaft and that is adjusted by thickness washers below the switch. I cannot see wear being a major factor there so regular adjustment should not normally be necessary.
The switch engages with an indent in the shaft and that is adjusted by thickness washers below the switch. I cannot see wear being a major factor there so regular adjustment should not normally be necessary.
Re: Dart Overdrive Inhibitor Switch
Hi
I have an o/d on my SP250 which jumps out regularly - mainly after a short period of use. The unit has been fitted for less than 10,000 miles - should I fit a new inhibitor switch to see if that helps. I have been told it is unlikely to be wear on the o'rings because of the relative low use. Any hints / tips gratefully received.
Cameron
I have an o/d on my SP250 which jumps out regularly - mainly after a short period of use. The unit has been fitted for less than 10,000 miles - should I fit a new inhibitor switch to see if that helps. I have been told it is unlikely to be wear on the o'rings because of the relative low use. Any hints / tips gratefully received.
Cameron
- RadfordJim
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Re: Dart Overdrive Inhibitor Switch
Silly question but have you checked the gearbox oil level? It should be 1/2" to 3/4" above max (as mentioned previously on the forum). Topping up the oil solved my sluggish/intermittent overdrive operation
Jim in Coventry - Home of the Daimler
Re: Dart Overdrive Inhibitor Switch
I agree with Jim's suggestion.
On my MGB, when the gearbox oil level drops below a certain level the overdrive drops out intermittently. I then know it's time to top up the leaking gearbox!
I don't know if it's the same electrohydraulic operation on the Dart o/d - but its a thought.
On my MGB, when the gearbox oil level drops below a certain level the overdrive drops out intermittently. I then know it's time to top up the leaking gearbox!
I don't know if it's the same electrohydraulic operation on the Dart o/d - but its a thought.
Cheers, Henry Curwen
Registrar for Conquest & Century Saloons (DJ250/1, DJ256/7, DJ260/1)
Conquest (Drop Head) Coupe DJ252
Registrar for Conquest & Century Saloons (DJ250/1, DJ256/7, DJ260/1)
Conquest (Drop Head) Coupe DJ252
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Re: Dart Overdrive Inhibitor Switch
Thanks guys - yes the oil is OK - if anything it worked fine after a recent oil change then this happened
Re: Dart Overdrive Inhibitor Switch
Hi Roger,
do you know whether you have a "J" or "A" type overdrive?
The J type solenoid acts directly, so the electrical connection to the solenoid is often the culprit for an intermittent overdrive, but the A type operation is more complicated, and as well as the electrical connection there's a mechanical setup that can also cause problems. Have you also checked your overdrive switch connections? (Mine is on the gearlever and occasionally decides to disconnect itself!)
HTH ,
John
do you know whether you have a "J" or "A" type overdrive?
The J type solenoid acts directly, so the electrical connection to the solenoid is often the culprit for an intermittent overdrive, but the A type operation is more complicated, and as well as the electrical connection there's a mechanical setup that can also cause problems. Have you also checked your overdrive switch connections? (Mine is on the gearlever and occasionally decides to disconnect itself!)
HTH ,
John
John M in Middlesex, NW London
1962 SP250 "B" Spec
DLOC Herts Region Sec
1962 SP250 "B" Spec
DLOC Herts Region Sec
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Re: Dart Overdrive Inhibitor Switch
Hi John,
It's an A type and, yes, I've actually fitted a new overdrive switch and checked electrics so all that's left, I think, is the inhibitor switch
Best
Roger
It's an A type and, yes, I've actually fitted a new overdrive switch and checked electrics so all that's left, I think, is the inhibitor switch
Best
Roger
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Re: Dart Overdrive Inhibitor Switch
Thanks for the advice all.
I ordered a new switch and was reconciled to the hassle of removing the tunnel to get it done but then had a brainwave! Maybe it's located right next to the dipstick and maybe I could get at it through the hole on the tunnel. I found I could - enough to get less than an eighth turn on the existing switch and....it's done the job! Don't know how long for but it was worth the try.
Best
Roger
I ordered a new switch and was reconciled to the hassle of removing the tunnel to get it done but then had a brainwave! Maybe it's located right next to the dipstick and maybe I could get at it through the hole on the tunnel. I found I could - enough to get less than an eighth turn on the existing switch and....it's done the job! Don't know how long for but it was worth the try.
Best
Roger
Re: Dart Overdrive Inhibitor Switch
Great stuff, Roger - well done!
John
John
John M in Middlesex, NW London
1962 SP250 "B" Spec
DLOC Herts Region Sec
1962 SP250 "B" Spec
DLOC Herts Region Sec