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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGA - Starter Switch

It looks like my original starter switch is on the way out - sometimes takes a few pulls to make a contact. Sods law that I have 2 good quality part used items sitting in long term storage. So it looks like a new purchase is required. There has been mention in the past that some new switches are a bit sub-standard. Who supplies a satisfactory item that will last me up to a year before I can get at my original items?

Steve
Steve Gyles

Maybe it is work opening the switch and cleaning out the contact as per Barney's site before buying a new one. The mechanics of the switch are simple and the copper contacts inside look thick enough.
Seem easiest and the cheaper option to start with!
Gonzalo Ramos

Steve,
Bad luck having them in store. I put one on recently, bought on ebay from lotsofclassicbits (duncan.lloyd@lineone.net). c.£22 with postage. Worked well for the last couple of months (with car undergoing work) but not sure for how long it will continue. Welcome back to the South.
Shane
Shanerj

Steve, I mentioned in an earlier post about the premature failure of an after market starter switch. That unit was of the type with a white nylon terminal base, and the second one of that type to fail on me, so I would suggest avoiding them. I replaced it with one from these people http://www.vintagecarparts.co.uk/en/list+electrical~switch~start/ at the beginning of April, about 1500 miles ago. Not much of a test yet, but it works nicely and looks exactly like the original starter switch; not like the ones offered on eBay.
Lindsay Sampford

Sorry Steve, that link doesn't seem to want to work properly. Go to the main vintage car parts web site, then select "Classic car parts", "electrical", "switch", "start", then part No. ET6-11450-B.

Lindsay Sampford

Gonzalo. Right with you there. Unfortunately the majority of my workshop and the means of opening up things like this are also in storage. I need to buy my double garage with attached house sooner rather than later!

Lindsay, Thanks. Will investigate.

Cheers

Steve
Steve Gyles

Hi Steve - mine did the same a couple of years ago - I just bought a cheap repro one from ebay for around £15 - seems OK so far - cheers Cam
Cam Cunningham

Here is your link in a working manner Lindsay
http://is.gd/dCu1H

Steve go down the scrap yard and get an electrical solenoid of a Metro or something and install a little starter switch circuit with a push button to energise the solenoid. :) But don't tell anyone here otherwise you will have oodles of grief. :)

Then in a couple of years when you get into your storage you can then sell your other items as you will be sold on progressive motoring equipment.
Robert (Bob) Midget Turbo

Ah-ha Bob! the short link trick. I'd forgotten about that, and it was on here just a couple of weeks ago. Must be getting old.
And what's all this stuff about electrical solenoids, sounds like the work of the Devil!
Lindsay Sampford

This problem was addressed (at some length) some time ago. New (repro?) switches don't seem to last before the problem arises. I often pull them apart (both "factory" and later) and clean the contacts but crimping them back together looks a "bodge". If your MGA has a heater (as mine do) the trunking hides the switch and the "cobble-up" is not really seen! I think that "gentle annies" (like me) who pull the starter knob relatively gently (causing excessive arcing) have more trouble than more brutal owners!
Barry Bahnisch

Steve, Switch is in the mail -
Cheers, Barry
Barry Gannon

Thanks Barry. I think I have a spanner to fit it! I brought a selection of spares and tools to see me through for 6 months or so, but a starter switch was not one of them. Always difficult to know where to draw the line.

Cheers

Steve
Steve Gyles

I have removed the suspect switch. It had been opened up before. knowing that Barry has kindly put one in the post to me I took a hammer and chisel to this one.

It was certainly corroded inside with just one small point of contact (see photo).

Would this small area of contact have reduced the power going to the starter, reducing rotation speed?

Steve

Steve Gyles

Steve, That has not been my experience, in my case (or cases!) it has been either normal starter operation or nothing (leading to repeated pulls which ultimately don't work!). In some cases modern components are designed to send a few amps to a solenoid or somesuch but these switches have to transmit a lot of current, no wonder the contacts burn and give trouble! This may be another reason that the original switches seem to last much longer than "after- market" ones, even though the latter look alike (both inside and out!).
Barry Bahnisch

small contact area = high resistance

V = I X R, or I = V/R

Resistance and voltage are inversely proportional, so as resistance increases (for a given temperature), voltage drops

As voltage drops to the starter it will try to draw more current to produce a given amount of power, or the power output will drop.

It may be here that there was enough contact area to allow a sufficient amount of current to flow, but I'll bet your starter motor was getting hot. Fortunately, it's duty cycle is rather low. (It's off far more than it's on, so it has time to cool off between uses...)

It's too bad that these switches cannot be more readily disassembled as it would be possible to clean the contacts periodically - though the switch is inexpensive enough that you can just replace the whole thing, so the designers probably didn't see the need...

JIM in NH
AJ Mail

I do believe my 53 year old MGA with 383,000 miles has the original starter switch, and it still works fine. For sure the key to long life here is regular use, as the contacts will burn the corrosion off with each use, and there will be multiple and redundant contact points.

If you think your switch is failing due to contact corrosion, try operating the switch a couple hundred times under load, and it might clean up its own act.

Several years ago I disassembled an aftermarket switch that had failed due to multiple points of bad construction, but the contacts were in good condition. See picture.

Barney Gaylord

With the unit apart I noticed that rotating the shaft holding the disc in contact cleaned up the contact points quite a bit. When assembled there is a spring that holds the disc away from contact. I guess that as a temporary measure you could always uncouple the shaft from the start pull and manually twist the disc against the spring pressure to clean the surface a bit. Also, this would bring a different part of the disc into contact when coupled up again.

Steve
Steve Gyles

I meant to add that M-types have similar system in that the cable from the battery runs up to the dashboard switch and then back to the starter motor. I bought a new solenoid and mounted it down near the battery (ie under the floor where it is not seen) and use the switch just to send a few amps down to turn the solenoid on. Regrettably the MGA layout does not lend itself to "mods" like that!
Barry Bahnisch

Barry G

Starter switch just arrived in the post. Very many thanks. It's almost correct for my car, being dated 1 59. My car is August 1958.

Cheers

Steve

Steve Gyles

Wow. What a difference. I have not had my starter spinning so strongly for a very long time. You tend not to notice a gradual drop off in performance as something like this slowly deteriorates. It is only when you fit a replacement that you realise what you have been putting up with. All sorts of things had been going through my mind from bad earths/connections to a worn out starter. I had never considered the inside of the switch. I had always assumed that it would either work, or not.

Steve
Steve Gyles

Steve, my switch didn't fail completely, the starter motor just got more and more sluggish, and, like yours, the new switch made a world of difference.
Lindsay Sampford

I will have to fit one of my old spares to my car! It has been rather sluggish of late and I thought it was just the cooler weather. Cheers, Steve.
Barry
Barry Gannon

This thread was discussed between 22/07/2010 and 03/08/2010

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