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MG MGA - Starter switch problems

On my third switch. Maybe a poorly made batch. Anyone with tips on installing a pre-engaged starter motor as in the later MGBs ? The idea of an electrical starter switch in place of the manual/mechanical OE pull arrangement looks quite attractive. (But the devil may be in the detail).
Grateful for your thoughts
Roger
Roger Walker

If you're not having any issues with the starter motor itself, maybe an early MGB style electrically operated solenoid -then you'd still have a button on the solenoid under the bonnet for doing things like valve clearances etc---You'd need a starter button inside or a different ign. switch with a crank position (MGB)-
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https://www.mgsales.com.au/products/546-020
William Revit

I have a hi-torque pre-engaged starter. Apart from it avoiding all the gnashing of teeth with an inertia starter it also engages on the front side teeth (unworn) of the flywheel starter ring. The other big bonus is that the battery and starter lead are joined together on the 'output' side of the pull switch so no heavy loads through the switch. All that goes through it is the light load from the ignition circuit wired to the other post on the switch to the starter motor integrated integrated solenoid wire that shares the terminal with the battery and starter cable. Not given me any issues in 10+ years.

Steve
Steve Gyles

Sorry. Ignore my wiring. All wrong. Will look at it shortly

Steve
Steve Gyles

Roger. Just had a look at mine. Serves me right for writing from memory at my age! On one post of my starter switch I have the battery cable, starter cable, brown ignition wire and the yellow wire to my alternator. On the other post all I have is the wire to the starter solenoid.

Steve
Steve Gyles

Barney has it covered in his ET-251A. I bought the starter from MGOC around 2016 and put it on the 18V in my car. All the switches are original MGA. It cost about £65 in the day and works fine.
Bolney Coupe

All comment much appreciated. Willi - the starter motor seemed to be trouble free but its age is unknown which makes me a little nervous. The solenoid idea is where I started.
Bolney- have also checked out Barney's advice - allied to Steve's experience - seals the fate of the motor.
Steve- Anno domini can't be ignored - for me it means this will be a winter job.
Thanks alround
Roger Walker

Hi Roger,
I have always had a starter solenoid on my MGA, it just came that way and it operates the standard MGA inertia starter motor.
I have a push-button starter switch on the dashboard in the usual pull starter position, this triggers a solenoid that is fixed in the same position as the original starter switch.
It is a Motocraft solenoid and it seems to work really well, I have attached a picture of it.

It works really well and I think that this is because it it provides a much more positive high-current switch than the repro MGA pull-switch does.

I did try a "High-Torque" starter but I had a nightmare trying to use it.

My MGA is a bit of a hybrid with a 1950cc 5-bearing MGB engine, it has an High-Gear early MGB bell-housing and a Ford T9 5-speed box.

The "early-MGB" bell-housing caused an alignment issue which meant that the "High-Torque" starter would easily start the engine, but then would not disengage from the starter ring once the engine fired up! So the engine was still driving the starter motor around!

So I had to go back to the standard inertia starter motor.

After this, I did try a total of three different High-Torque starter motors which were supposedly suitable for an MGB motor like mine. Two of them would not engage the starter ring and so were no use, but the third one almost caused the car to be a total loss!

As soon as I pushed the starter button, the motor caused a dead-short through the battery, I quickly flipped the battery isolator switch but in the 5 or 6 seconds before I did this, the entire battery cable was beginning to melt, all the way to the battery. It also melted the battery isolator switch!

So, after I replaced the entire melted battery cable system and the isolator switch, I decided to abandon the idea of the "High-torque" starter motor and went back to using a std inertia starter motor.

So far, this has worked really well and I think this is because I decided to install a thicker starter cable and also, make sure that the earth connections were sound.

I donated the High-torque starter to my friend Roger Martin who has apparently used it quite successfully on his MG ZB Magnette (with MHB engine) project.

Cheers
Colyn



Colyn Firth

Colyn- really interesting thank you - where have you put the solenoid ?
Roger Walker

Hi Roger
I was about to say that it is mounted on the inner wing close to where the original pull switch brackets, but I have just been out to the garage and taken a picture which shows how it is mounted.o
The solenoid is bolted to the side of the oval air-vent. See pic.
As you can see, I use the input terminal from the battery as a convenient power take-off for my extra electrical equipment, for example, the twin-electric fans and the electric power steering.
Cheers
Colyn


Colyn Firth

Roger
If you're going electric push button start-
If you use an early MGB style solenoid you get a rubber press button on it that you can use in the engine bay, handy for doing valve clearances etc.

https://www.mgsales.com.au/products/546-020

willy
William Revit

Colyn - thank you. I guess that's easy to get to.
Willy - good point - much easier to use the push start than the turning handle plus I have always used mg parts when adapting our cars.
Grateful for your advice - thanks to everyone
Roger
Roger Walker

Willi - I now have the early MGB solenoid and the original MGA ignition switch - I guess the solenoid takes a reasonable current from the starter switch - perhaps a starter relay is needed ?
Roger Walker

Roger
Been a while since I measured one, but I think it's around 5-6amps to operate the solenoid so doesn't really need a relay
What are you going to use as a starter button---or do you have an ignition switch with a crank(start) position
Cheers
willy
William Revit

Willy - that's not more than the push-button can handle. I shall put it on the dash in place of the OE handle but I am a little nervous about adding it to the starter load from the ignition switch. Perhaps it would be best to take it direct from the battery through an inline fuse ?
Roger

PS Don't suppose there are many As in Tasmania ?
Roger Walker

Roger

With my hi-torque starter I just have the solenoid load going through my standard Chinese copy rubbish starter switch - the one we all complain about. It has been there for some 15 years without issue - very light load.

Steve
Steve Gyles

Steve - I guess that is a dash-mounted combination of the ignition and starter switches ?
Roger Walker

Roger
The push button should handle it ok, but yeah it will put extra draw on the ign switch if that's where you're powering it from.
As a safety concern, probably best to not go direct to the battery though, the starter button would be operable at any time hooked direct like that so maybe a relay would be best choice.

Relay operating power from the ign.switch through the button to the relay coil to earth, then run a power wire from the battery powered side of the solenoid through the relay switching contacts and back to the exciter post on the solenoid

As far as MGA's go here--there's heaps, There'd be probably around 10 within 10klm's of me here and I have some friends in Launceston (about 100klm away) that have 5 Twincams between them--Did an engine for one of them last year which was interesting getting pistons made and getting my head around the camshafts spinning anti-clock doing the timing etc. A mate in Launceston has a mint condition A he restored with a 3500 Rover in it, a real eyepopper.
cheers
willy
William Revit

Roger. No exactly standard. Just altered the wiring through the pull switch. My hi-torque starter has the inbuilt solenoid. The only current across the switch is low power to the solenoid. The main motor is connected directly to the battery.

Steve
Steve Gyles

Willi - exactly as I thought - there was a reason for the ignition relay in the B !
As for Tasmania - I wish I was still up for the long haul - would particularly like to see the V8 in the A. There is not much room in the engine bay of my B.
Is this the car originally widened over here for a Japanese enthusiast ?
Steve - thanks. You have been ahead of the game.
Roger
Roger Walker

Roger
The MGA V8 here was built here by a longtime friend at his MG workshop. I've got pictures, I'll ask if it's ok to put them on here.
Do I understand from what you've said that you have a V8 B. I've built a few over the years, and have a bit of a soft spot for them--In Aust. we had a car called a Leyland P76 and it ran a 4.4 litre version of the Rover engine and a close ratio 4spd. box. The combo works really well in a B--strong as an ox.
cheers
William Revit

local twin cam





William Revit

the v8





William Revit

Willi - would love to see the pics. Yes my GT is a 3.9 - added the fuel injection and RV8 bonnet myself. I share the A with my son - he has an 1800 roadster which the grandchildren are learning to drive.
The A doesn't get used in the salty season but the other two are on the road year round.
As ever R
Roger Walker

Very good--I have a question --does the 3.9 injection fit under The RV8 bonnet without having to reduce the height of the plenum etc.----The car I did last year was the first 3.9 injected one I've done and there was a bit of cutting/machining to get it to fit under a std bonnet, it fits and is ok but the RV8 bonnet sounds like a good option
willy
William Revit

Willy - yes it does fit but is very tight. I have inadvertantly made it tighter than necessary by putting two additional spacers on the starboard engine mount. (That was because the engine was touching the steering shaft under load and there is no room for Clive Wheatley's steady bracket)
The plenum chamber also comes from the RV8 and I suspect it may be a couple of mm lower than the standard RR 3.9. The original did fit even with the extra spacers.







Roger Walker

Does look a little lower than a std 3.9 plenum
I struggled on for ages with steering clearance and finally bit the bullet and went for through the fender headers on the last few i've done.
Haven't got a pic of that at the moment and the guy with the last one is away for a couple of weeks--I'll get a pic. then.
Here's a pic of my B getting one of the 4.4 motors a year or two ago, as you can see they're a fair bit wider and taller, but they fit under a flat bonnet--just
Cheers
willy


William Revit

I think I still have a manifold with the original 3.9 plenum - will get the tape measure to it.
I guess you have the RV8 exhausts on the 4.4. I don't recognize the fuelling arrangement and what have you done with the radiator ?
The Twincam pics brought back memories - mine was nothing but trouble - swopped it for a P1800 - the V8 MGA is very smart - bet you can wag the tail on that !
Roger Walker

Willy - the top part of the RV8 plenum is 23cm high - so far as I can see -within a mm or two of the standard 3.9. I suspect the additional clearance has come with the effect of age on the engine mountings.
[
Roger Walker

The RV bonnet must make a fair difference, You have to machine about 20mm off the 3.9 plenum and shorten the ram tubes to get under a std bonnet.
With the 4.4 I had to fab. up some exh.manifolds, RV8's weren't about back then(longer ago than i remembered for this car around 1982-3) The carby is/was a competition Carter 4bbl -magic in a straight line but terrible fuel surge on the track, ended up with a 780 Holley on it.
The angle of the photo's a bit tricky, there was plenty of room down the front there for a radiator
Twin cams do/did have their issues but with all the info and aftermarket parts available now they can be made good---there are some dodgey parts about still though, you have to be carefull--We have a bloke here that makes forged pistons for them, you can order whatever comp.ratio you want--9.5 seems to suit them for road cars, it's half way between the two original specs
William Revit

I was aware of the mods needed to get the plenum under the standard bonnet and chose the RV8 option when the RV8 bonnet came along. No regrets now as the bonnet has received a lot of critical attention.
The twincam was a casualty of neglect - the factory should have sorted it but was more interested in the 1800 going in the B.
Roger Walker

Roger- found this pic of the A exposing itself--The car was built with the running gear from a dead factory v8B

How's progress with the starter--


William Revit

That's amazing. It must be interesting to drive.

Gear all lined up for A's starter - son still has the car on the road in London
Roger Walker

This thread was discussed between 31/08/2023 and 08/10/2023

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