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throttle switch overdrive

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M

massimo

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I have changed the solenoid and the overdrive start to works again and it is perfect. After about 30 times the overdrive was burnt again and in the same time the throttle switch start to have a strange rumor after that i put out the throttle switch and opened the coffer to see if there was something wrong that didn't work. After the change of the solenoid i put on again the throttle switch but it made a more strong rumor and i have decided to put it out. i want ask to you if i can use regulary the overdrive without the throttle switch. also i've decided to put one fuse (10 amper) to protect the solenoid do you think it's correct?

P.S. Andrea i'm from Lucca. I have seen your restoration, congratulations, it is perfect!!
 
Hey Massimo,
My grandson is named Massimo too as his Dad is 3rd generation Italian and he wanted to honor a family member's name. To your Healey, I am not an electrical expert at all, but sounds like something is causing your overdrive solenoid to stick in one position or another and then it melts down. I had the same problem and never was sure what caused it but was able to keep it under control by putting in a 10 amp fuse as you are, to protect the solenoid. That is an excellent idea and a lot easier to change a fuse versus a solenoid - cheaper too. Imagine one of the folks who know Healey electrics better than me might be able to help you with what could be causing the solenoid to stick.
Good luck,
Mike
 
Hi Massimo
Throotle swtc is very simple object
https://picasaweb.google.com/lh/photo/MTaBPHgJEk7kkE5ZMpkhhdMTjNZETYmyPJy0liipFm0?feat=directlink
I argue that you have the swtc in yor hand
if you have a elect.tester you can see the contact resistance
or open again the swtc -you can apply at the contact one 10w lamp and with a 12volt power supply-move the arm of the swtc and see what is the rumor
probably your contact are only oxidized
you must control also the wiring from the OD swtc to the solenoid normally if the solenoid burn also the wires will be damaged , a 10 A fuse can be one good solution to save your money and wires

without the throttle switch you can experiment more brute
shifting - I know that this mod is applicable to racing AH
I think that can be used also for your car with one intelligent use of the clutch

Massimo
Mi fa' piacere di avere oltre a Daniele, un altro compagno di avventura in Italia-venivo spesso a Lucca negli anni 70 ora manco da parecchio tempo anche se ero in Toscana nell'autunno scorso- https://picasaweb.google.com/searunner44/TUSCANRAID2011?authuser=0&feat=directlink
or
https://picasaweb.google.com/112770819864514987162
spero che i miei Google album relativi all'Austin Healey ti possano essere stati utili- gradirei qualche foto della tua
e sapere di che modello e'
Cordiali saluti
Andrea
 
The overdrive solenoid has two positions. Initially it has a high amp draw (30 amps for a few miliseconds) to raise the plunger to move the lever to open the valve to allow high pressure oil to engage the OD clutch. When the plunger goes up inside the solenoid it hits a little button that changes to a low amp (about 1 amp) hold circuit. If the plunger is too short (mine was) it will not reach the switch to the low amp hold circuit and it will burn out. If you got a new solenoid but used the original plunger (which I did) this could happen. The new solenoid should have a new plunger with it. Use the new plunger with the new solenoid. I did install a 10 amp fuse before I had the problem and blew the fuse rather than the solenoid. But you need to fix the root cause or you'll keep blowing fuses. Check the amperage of the solenoid after the OD engages. It should be very low, if it is high the hold circuit is not being engaged. The throttle switch maintains current to the solenoid after you switch off the dash switch until you depress the throttle. If you are running the solenoid on the high amp circuit, you will be running that high amperage through the throttle switch causing an odor (smell) or burnout of the switch wiring, although the solenoid should burnout first.

Check out past threads that tell how to set the OD lever
correctly.
https://www.britishcarforum.com/bcforum/ubbthreads.php/topics/777012/Overdrive_issue#Post777012

The throttle switch prevents high loads being placed on the transmission when the OD down shifts. Without the switch, you must depress the throttle by about 1/3rd before switch off the OD or you will risk breaking the transmission.

It occurred to me that bad contacts in the throttle switch may cause a high load. You can take the switch apart and clean the contacts. I'm just guessing on this one.
 
Hello Andrea,

I have an Austin Healey 100/6 from 06/06/1957 with 4 disc brakes.


Vorrei mandarti una foto della mia macchina ma non riesco a farlo.
Puoi dirmi come fare?

Thank you

Massimo
 
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