|The MGA With An Attitude
BRAKES LOCK UP, OR CLUTCH SLIPS - HT-102
On 8/4/03, Craig Reese wrote:
>>.... I have a '61 Bugeye .... As the brake pedal gets worked a number of times the travel in the pedal gets less and less until the brakes are totally synched up, none of the wheels will turn at all. ....
I haven't heard this one recently, but it was a very common problem 10-15 years ago (late 80's) with the MGA, which uses the same master cylinder. For a while there were some master cylinder rebuild kits with rubber cups a bit too long, and they wouldn't clear the little hole in the cylinder wall to return fluid to the reservoir. This can make the brakes lock up or drag after several applications. On the clutch side of the master cylinder it can cause the clutch to not fully engage, and the release bearing to drag and wear rapidly. It was an easy fix though.
Remove the end plate from the master cylinder. Install two paper gaskets. Cut out holes in the gaskets to clear the working bore(s). Reinstall the end plate, and bleed the system if necessary. This small amount of extra return travel allowed for the piston should be enough to make it work properly.
There is another possible cause for these same symptoms. If the master cylinder pushrod is misadjusted so that it is a bit too long with no free play, then the piston may not be able to return all the way to the resting end of the stroke. Then the same thing happens when the rubber cup inside will not clear the return port to the reservoir. The cure for this case is a proper adjustment of the pushrod length to leave a touch of free play in the pushrod and at the pedal.