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MG Midget and Sprite Technical - Centering the PDWA

Hi, all.

This question actually concerns a friend's '79 Spitfire, but since the system's very similar I'll ask here. The left front brake hose has split, and the PDWA has worked as advertised and shut off that braking circuit. I'm going to install new hoses tomorrow - will I need to manually recenter the PDWA valve, or will it center itself when the faulty circuit is sealed and bled, and with pressure applied to the pedal? If it needs to be centered, can I simply reach in through the switch hole with a small tool and push it?


Gryf Ketcherside

This is from haynes Gryf. I tried to to upload a scan but there seems to be a gremlin in the electronics, so I just took a photo instead.

I hope it helps.

The implication seems to be that the shuttle centralises itself hydraulically once the system is sealed during the normal bleed process. If you see what I mean.

By the way if you're doing this with the ignition on for the sake of the warning light you should temporarily disconnect the LT supply to the coil to avoid cooking it.

Good luck, let us know who wins!



From what I remember, you repair the fault then bled the brakes.

In order to get the shuttle back to centre, you open a bleed nipple on the other circuit and push the pedal 'til the light goes off.

Although it was 20+ years ago, so careful reading of the manual is advised.
Dave O'Neill 2

Hi Gryf, where ya bin?
Bernie Higginson

>>> Hi Gryf, where ya bin? <<<

Nowhere. :-) Nothing's changed really; except that it's been a while since I've had the Midget out regularly. Still runs flawlessly, I just don't mess with it as much as I used to. Hopefully that will change when I retire in a few months.


Gryf Ketcherside

@ Rod -

Thanks for the info from Haynes! I've read that before, and am familiar with the procedure. Unfortunately, it's hard to bleed both sides of the system simultaneously when you're working solo - plus, the brake warning light in this particular Spitfire doesn't seem to work. S'pose I should look into that too.

When working alone I usually bleed hydraulics with a MityVac, which seems to work okay. I'll let you know how it goes. Hope it cooperates... I don't want to make an all-day project out of this. Besides, it's not my car, and I'm donating my time.

Gryf Ketcherside


As others, I've been wondering where you went. Always good input from you.

As far as retirement goes you have to prepare yourself for the hard task ahead. Getting up when you want, doing what you want, if you want, when you want. It's a tough job but somebody's got to do it. I retired almost 2 years ago and it took me almost 20 minutes to get used to that schedule.

Good luck with Spitfire and drive the Midget more.
Martin Washington


Sorry Gryf. I'd assumed the Spittie's owner would be assisting, maybe moving the pedal on demand for you. If you're on yer ownio it's going to be tricky.

Still - the shuttle "should" centre up itself. Hopefully. In'sh Allah!

Nice of you to do it for him btw.

This thread was discussed between 28/08/2015 and 29/08/2015

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