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Overdrive solenoid problem GT6


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So my o/d conversion continues part time.  First attempt, when fitted, the lay shaft needle bearings gave up (another story) but once that was fixed the od wouldn’t engage.  Traced to the Solenoid.  Basically there’s a bad connection in the solenoid unit.  The solenoid works if I squeeze the plastic end in towards the metal casing.   Question, does the plastic bit on the end come off?  The 2 little screws in the unit don’t seem to release anything.

Also, anyone know the thread size of the screws/bolts that hold the solenoid to the od? One of the Philips heads is shot so I plan to fit hex headed bolts.

many thanks

Rich

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mostly the switch under the plastic cover is solid sate and sealed up you will probably only access and mend to destruction

gully did a mod using a long stud and locknuts  to aid access from behind the unit 

some use a socket cap screw so you can get on it with a long key 

pete

 

 

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Trouble is how good are they Colin? Seem to be plenty of complaints about these pattern replacements including recomendations to try to find NOS and sure enough Rich's doesnt look very old☹️

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To be fair, I wouldn’t be surprised if it got damaged during gearbox fitting.  The amount of abuse the box as a whole takes to get it fitted, little wonder something like the plastic section can get damaged if prefitted.  It’s in a very vulnerable position!

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This was my piece on removing and replacing the solenoid - was in The Courier back in 2017. There's a picture of what my solenoid looked like when the rubber cap was removed - it was supposed to have been a new solenoid with the rebuilt gearbox / overdrive and looked great until I dug beneath the surface... I did find a NOS replacement.

Gully

Overdrive Solenoid Replacement.pdf

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3 hours ago, Gully said:

This was my piece on removing and replacing the solenoid - was in The Courier back in 2017. There's a picture of what my solenoid looked like when the rubber cap was removed - it was supposed to have been a new solenoid with the rebuilt gearbox / overdrive and looked great until I dug beneath the surface... I did find a NOS replacement.

Gully

Overdrive Solenoid Replacement.pdf 609.5 kB · 10 downloads

Thanks Gully, that’s very interesting.  I’ll probably follow your lead.  Mine came out ok once  I’d disconnected the prop and raised the back of the box above chassis height.  For me it’s refitting the rear gearbox mount that’s the biggest challenge!  I couldn’t remove the mount from the chassis so had to remove the gearbox from the rubber extension.  I know from experience that lining up those 2 bolts again with the bell housing bolted to the engine is VERY challenging.

Anyone - The lower bolt holding my solenoid was not very tight. Out of interest have I read that only one of the bolts is acting as earth?

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  • 2 weeks later...

Ok, new solenoid installed, even made a ‘Gully’ type screw for the inaccessible lower screw 😁

However, I included a new plunger and adjusting the nut on the end was a right pig.  The lock nut off the old one which I reused was also too wide to engage to locking part….  Anyway, my new query is….

i aligned the lever using a 3/16 bar.   The solenoid is working but surprised the throw is so slight? (Yes the holes align).

Also, I  connected an ammeter in the circuit expecting to see a 20amp spike then a drop to 2amp but in fact, it’s consistently sitting a 1amp when switched.  As I say, the solenoid is definitely firing although I haven’t tested that the overdrive is engaging yet.

Does this sound like an issue?

Thanks for all advice.

Rich

 

 

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I suppose its too late to try it now but it would have been good to have measured the solenoid resistance to earth (lower) and then manually operate the plunger to see if it changes to a higher resistance...

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1 hour ago, johny said:

I suppose its too late to try it now but it would have been good to have measured the solenoid resistance to earth (lower) and then manually operate the plunger to see if it changes to a higher resistance...

Can I do that on the car?

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So took the car on a test run.  Switching in and off as it should, no change to the current draw.  Maybe modern solenoid doesn’t have the spike?

what I do notice is the disengaging in both gears felt like changing down gear with no clutch control.  Quite jolty like if you let a manual clutch out to quickly?

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its quite normal to feather the clutch or throttle same as changing gear to make smooth progress

you can or not is purely down to your  driving style some like a kick under power some like to smooth it out  with a 

short dip of clutch or a change of throttle 

do what you like 

Pete

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