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MG Midget and Sprite Technical - 1500 brake pressure warning swith leak

Heroes,

I am trying to wake my midget after about three years of storage. Got everything cleaned and running. However brake pedal went to the floor. After trying to bleed the system I noticed a significant leak out of the brake pressure warning switch. Fluid is coming out of the nylon? plug. Do I just crank it down with a wrench, remove in place, take out the entire switch?? Do I just need to replace it? Looks like a bear to get to so hoping for a simple solution. Thanks in advance.
-Trig
Trig Lennard

Well, the plastic switch broke when I tried to remove it. Ended up having to remove the entire thing. No fun. I guess I need to take this apart to free the plunger? It doesn't seem to move when i stuck a small screwdriver down there.

Lots of archived posts said folks replaced the plastic switch with a bolt. thoughts?


Trig Lennard

Difficult one.

UK cars only had dual-circuit brakes for the last two years of production, so it’s not something we’re that familiar with.
Dave O'Neill 2

Still available, but pricey.

This one is specified for MGB and Mini, but should work. As Dave rightly says our cars only had the dual circuit brakes for a little while, but I don't believe we had the pressure warning light. Certainly my '78 doesn't.

https://www.scparts.co.uk/sc_en/warning-switch-1-86821.html

The thread will be 3/8" x 24 UNF, if you prefer the bolt-and-copper-washer approach, which is what I would do. After all, you'll probably figure out for yourself if you have no brake pressure, light or no light.
By the way the hydraulic brake light switch is a common failure too. Still available, but modern quality not inspiring, so probably better abandoned in favour of a traditional mechanical switch.
Good luck - let us know how you get on.
Greybeard

Grey

Does your car have a handbrake warning light? I believe that doubles as the pressure warning switch.

You might not notice that you had lost pressure in the rear circuit, but the warning light should alert you.
Dave O'Neill 2

Ah. Good point Dave. I'll consult me trusty wiring map when I get home.
It seems to me though that the plastic switch is a bit of a weak point and as likely to cause a brake problem as to warn of one!

Or maybe I've been listening to Nigel to long and got cynical haha.
Greybeard

You could be right about that switch, but it was all down to federal legislation, I believe.
Dave O'Neill 2

Great advice. I ended up going the bolt method. With a fresh bolt and washer I think I can swap it out for a warning switch later. Seems accessible. I didn't want to spend the money at Moss for now.

Bled the brakes and all seems to functions as it should. Took it for a short drive last night. First time in 3 or 4 years(see image). Hand brake needs adjustment and I have some idling/timing work but not too bad.

My car does have a handbrake warning light but I disconnect that years ago when I was putting in new carpet. No idea why I did that and I regret it.

Now if I can just find the bolts I misplaced to reattach the hood :)

-Trig



Trig Lennard

Well done and good luck with the hood. Post here if you can't find the screws and I'll measure them for you if need be.
Greybeard

Greybeard, thank you for your offer. If you can tell me the size and length of the screws to attach the hood to the supports, I would greatly appreciate it.

If it is not an easy process for you, don't worry about it. I am sure I can figure it out with some trial and error.

Not sure what happened to my bolts. Too many home projects to keep track of I imagine.

Thank you.

Trig Lennard

I just thought - do you mean the hood or, er, the other hood?
(Roof or bonnet)?
Greybeard

If I remember correctly, the bolts for the bonnet (hood this side of the pond) are 1/4" - 28 or 1/4" unf about I/2" long but I'm not too sure about the later style hinges. But you've got a starting point.
Martin

Right enough Martian. Or very near.
I measured one of mine this morning.
1/4" x 28 UNF X 5/8" long plain setscrew.
Easy! 😁
Greybeard

I’m fairly sure that the screws for the later US-style hinges are the same as the early ones (as posted by Martin & Grey) although there are only four of them, rather than eight.
Dave O'Neill 2

You guys are awesome. Yes, I think there are just four. Not sure the difference between hood and bonnet but the lid over the motor :)

I'll pick the bolts up and my way home from work then hit the road for a proper test drive.

Thanks to all!!
Trig Lennard

This thread was discussed between 13/06/2019 and 18/06/2019

MG Midget and Sprite Technical index

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