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MG MGB Technical - Cranky Misaligned Brake Pistons!

Hi all,

Checking the brakes the other day - both pistons were wrong way round with the recessed potion facing away from the center of the axle by differing degrees.

I extended all four pistons and lubed each with brake lube; was able to rotate and properly align the left hand piston (recessed area facing axle per the workshop manual) but not the right - extends and retracts okay, but will not turn in its bore allowing alignment the way the left one did. I did not pop the pistons from their bores; only extended them partially. I had drained a bit of brake fluid from the master cylinder, but left the cap on.

The pistons are not in perfect shape, but seem to be doing the job otherwise. No leaks, etc. Replaced both sets of calipers 2yrs and 5,000 miles ago.

And now (finally) the question: What happens when the pistons are not aligned in their bores (recessed area facing the axle) as per the workshop manual? Is a firey crash imminent? Should I videotape it for Youtube?

BTW - excellent video of an MGB running the "Tail of the Dragon" on Youtube. search "MGB"

Thanks in advance for your patience and help.

Greg Peek

I spose the rebate is there to clear the hub as the pads wear down, so if that's the case you will get an audible warning when its a problem
Stan Best

I believe the cut out is to help prevent brake noise.
regards johnwr
john wright

I posted a thread on this recently, the replacement pistons I had did not have any cut away.

I thought it was an anti-squeal measure, but opinion is that it is a way of equalising pressure across the pad to get even wear.

Personally, I would have another go at rotating the pistons, but I doubt if it will make much difference to the braking effort : presumably they have been like it for two years with no problems?
Martin Layton

Thanks much, will let you know if there are any consequences....
Greg Peek

This thread was discussed between 02/05/2007 and 03/05/2007

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