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Battery Cutoff Switch
- Thread starter J Eade
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tahoe healey
Yoda
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I opened my failed switch 3 years ago and cleaned the contacts closed it and bent back the original rivets and it has been fine ever since. But I carry a by-pass wire eith allegator clips just in case. Someone I talked to used one side of his battery jumper cable as an emergency over-ride.
Keoke
Great Pumpkin
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Hi JEade, The cut off switch is not made to be rebuilable, However, it seems to have two common failure modes that can be corrected by the DIY: 1} the spring inside burns and 2} the switched contact bar becomes pitted.The rivets can be drilled out and the unit opened which will allow you to turn the bar over gaining access to its remaining good side. The rivets can be replaced by 4-40 machine screws and the unit reinstalled. On the other hand if you get to E bay you can have one for less than $25.00 last time I looked-Yesterday.---fwiw---Keoke
AndrewMawson
Jedi Trainee
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[ QUOTE ]
I seem to recall that someone rebuilt this component, but I cannot find the thread providing the details....Is this switch something that can be rebulit or is it a matter of replacement?
[/ QUOTE ]
When mine failed, the two big copper contacts had worn down to just below the level of the insulation, and didn't always make contact (fun time stuck in multi-story carpark in Cantebury <g>). I considered re-assembling it with washers under the contact studs to raise them, but a decent quality replacement isn't that expensive and that's the route I went.
I seem to recall that someone rebuilt this component, but I cannot find the thread providing the details....Is this switch something that can be rebulit or is it a matter of replacement?
[/ QUOTE ]
When mine failed, the two big copper contacts had worn down to just below the level of the insulation, and didn't always make contact (fun time stuck in multi-story carpark in Cantebury <g>). I considered re-assembling it with washers under the contact studs to raise them, but a decent quality replacement isn't that expensive and that's the route I went.
The spring inside my switch was heated and rendered useless. I made a replacement from some wire I had, but I looked into why the spring had been overheated and checked - sure enough there was a possibility of grounding of the switch body through the bolts & rivets. I went to Home depot and secured some nylon washers and mounting bolts to isolate the switch - no problem since.
Regards, Bob
Regards, Bob
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The Lucas battery cut off switch is one of the most poorly designed parts on the car. The contacts are small & the "spring" that holds the contacts together is a joke. The first time the contacts develop a little resistance the spring gets very hot & loses what little tension it originally had. A conservative example: The starter draws 100 amps, 200 would be more likely. The switch contacts develop 1/4 ohm resistance, this causes the contacts to dissipate 2,500 watts. If the starter draws 200 amps the wattage in the contacts would be 10,000 watts. The contact bar & spring get hot, the spring anneals, & the switch fails. If that isn't enough, as Bob says, there is also a possibility of the switch contact grounding if the detent which holds switch positions gets weak. This detent relies on the same "spring" already mentioned.
I personally choose to do without the switch altogether. If I were going to keep a switch, I would get an aftermarket one which is readily available at rod shops or boat shops & much better constructed.
Aside: if you reverse the two large connections, the coil will be grounded when the switch is turned to the on position.
D
I personally choose to do without the switch altogether. If I were going to keep a switch, I would get an aftermarket one which is readily available at rod shops or boat shops & much better constructed.
Aside: if you reverse the two large connections, the coil will be grounded when the switch is turned to the on position.
D
SHG
Jedi Warrior
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I have spent hours trying to get the switch to work reliably, all to no avail. I had no idea why it was such a problem until now. They do appear on ocassion on eBay, but rarely go as low as $25. When a new old stock one appears, it commands a price around $75, with older used ones in the $50 range. New battery shut off switches can be bought there for under $10 shipped, but of course they are nothing like the original in appearance and go on the battery terminal. And I recall that they sell for over $100 from Moss. So it seems like this shut off is quite a problem piece.
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Here is an example of a good but "non-concours" switch. As mentioned, boat/marine supply shops have similar & cheaper switches.
https://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=37157&SortOrder=1
It would be hard to guess how many mysterious electrical problems have been created by the "Lucas switch"
D
https://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=37157&SortOrder=1
It would be hard to guess how many mysterious electrical problems have been created by the "Lucas switch"
D
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[ QUOTE ]
boat/marine supply shops have similar & cheaper switches.
Here's the one that I have in my 100 and my wife's 3000.
I like it because it has a surface-mounting flange and neatly fills the old hole. It's pretty reasonable:
https://store.summitracing.com/default.asp?target=partdetail.asp?part=HLA-87181
boat/marine supply shops have similar & cheaper switches.
Here's the one that I have in my 100 and my wife's 3000.
I like it because it has a surface-mounting flange and neatly fills the old hole. It's pretty reasonable:
https://store.summitracing.com/default.asp?target=partdetail.asp?part=HLA-87181
Keoke
Great Pumpkin
Offline
/ubbthreads/images/graemlins/savewave.gif
SHG, you must have been on the wrong E-Bay. So if you hurry there is one day left on Item # 4530494295 at $ 29.00 the seller is a well known big east coast restorer and guranties all the parts he sells.Better Hurry---Keoke /ubbthreads/images/graemlins/laugh.gif
SHG, you must have been on the wrong E-Bay. So if you hurry there is one day left on Item # 4530494295 at $ 29.00 the seller is a well known big east coast restorer and guranties all the parts he sells.Better Hurry---Keoke /ubbthreads/images/graemlins/laugh.gif
tahoe healey
Yoda
Offline
darn this thread! It cursed me! Took my healey to work today (sunny and a warm 45 degrees, streets dry). When I tried to start up for the trip home, guess what....At least I'm familiar with the thing. When I again opened it up this time, the spring had broken. Streached out what was left and good to go (home at least)in ten minutes. (I had left the by-pass on the work bench at home of course).
So my question is, where can I find a spring to replace the broken one? After reading the above posts I know this is only a temporary fix but I like the looks of the original. And, hey, it did last this long with a lot of use.
So my question is, where can I find a spring to replace the broken one? After reading the above posts I know this is only a temporary fix but I like the looks of the original. And, hey, it did last this long with a lot of use.
Keoke
Great Pumpkin
Offline
Hi TH , /ubbthreads/images/graemlins/shocked.gifWhat! no Snow!! Seriously, I do not know of a source for that spring. I happened to be cleaning up the work bench today and gave up but I ran across a spring from??? that may work. if you want him I will Mail him to you---Keoke /ubbthreads/images/graemlins/angel.gif---I just measured the little spring, it stands 1" tall,Has three coils,The bottom coil is 1" in diam and the top coil is 3/4" in diameter.When compressed he is quite strong. /ubbthreads/images/graemlins/laugh.gif---Also a grounding spring from a smallish flash light might do the trick-Just thinking out loud
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As you know, "the spring" is a coned spiral. Someone such as an experienced gunsmith could anneal a piece of real spring wire, wind & shape it, & hardest of all, temper & draw it to acceptable spring hardness. It sometimes takes several tries to get a good, long lasting spring out of the deal. More art than science. A simple cold wound spring usually won't last very long. Not really worth the trouble in my estimation. For a mega dollar antique rifle with no parts available - yes, for this stupid switch - no.
"---Also a grounding spring from a smallish flash light might do the trick--"
You know about how you sometimes have to shake or bang a flashlight to get it working? Often the result of a crappy spring.
D
"---Also a grounding spring from a smallish flash light might do the trick--"
You know about how you sometimes have to shake or bang a flashlight to get it working? Often the result of a crappy spring.
D
SHG
Jedi Warrior
Offline
[ QUOTE ]
/ubbthreads/images/graemlins/savewave.gif
SHG, you must have been on the wrong E-Bay. So if you hurry there is one day left on Item # 4530494295 at $ 29.00 the seller is a well known big east coast restorer and guranties all the parts he sells.Better Hurry---Keoke /ubbthreads/images/graemlins/laugh.gif
[/ QUOTE ]
I'm already keeping an eye on that one. But it hasn't ended yet. Watch what the final price is. Another one from England went off yesterday, ended around $79, plus shipping from England (which ain't cheap). But now that I know more about how the switches work, I figure why buy someone else's old, finnicky switch when I already am the proud owner of my own finnicky switch. By the way, the alternative switch I was thinking about, and it goes for under $10 shipped are the ones with the green knob that goes on the battery terminal. Simple, but does the job. Just take it off before you get to the show, because you're not going to win anything with one of these babies.
/ubbthreads/images/graemlins/savewave.gif
SHG, you must have been on the wrong E-Bay. So if you hurry there is one day left on Item # 4530494295 at $ 29.00 the seller is a well known big east coast restorer and guranties all the parts he sells.Better Hurry---Keoke /ubbthreads/images/graemlins/laugh.gif
[/ QUOTE ]
I'm already keeping an eye on that one. But it hasn't ended yet. Watch what the final price is. Another one from England went off yesterday, ended around $79, plus shipping from England (which ain't cheap). But now that I know more about how the switches work, I figure why buy someone else's old, finnicky switch when I already am the proud owner of my own finnicky switch. By the way, the alternative switch I was thinking about, and it goes for under $10 shipped are the ones with the green knob that goes on the battery terminal. Simple, but does the job. Just take it off before you get to the show, because you're not going to win anything with one of these babies.
Keoke
Great Pumpkin
Offline
/ubbthreads/images/graemlins/iagree.gif SHG, I told you to hurry /ubbthreads/images/graemlins/laugh.gif. I am willing to bet
though another one will show up by this same seller.---Keoke. "For Free"!! You not holding your breath are you. /ubbthreads/images/graemlins/laugh.gif
though another one will show up by this same seller.---Keoke. "For Free"!! You not holding your breath are you. /ubbthreads/images/graemlins/laugh.gif
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