Master Cylinder Mounting Holes

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Surveyor
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Master Cylinder Mounting Holes

Unread post by Surveyor » February 9th, 2019, 6:54 pm

This may have been covered before but I don't remember seeing it explained. Awhile back I read about a few of us having problems with the mounting holes for the master cylinder being too small. At the time I believe it was blamed on being a poorly made reproduction. Well I started reassembling the pedal assembly this morning and grabbed the recently purchased NOS master cylinder. I had remembered about the differences so I looked for one labeled Wagner Lockheed made in the USA like the one I had removed. I do not think it is a reproduction (old packaging, labeling, etc.) and purchased from a respected member here. Unfortunately, it too has the same problem. After review of the -20p it appears there are two sizes of through bolts called for the master cylinder. The m151 and a1 required 3/8ths bolts while the a2 requires 5/16ths. This is also supported by the fact that there were two different numbers right hand brackets (nuts attached) that the through bolts are supposed to thread into. All models however call for the same part number for the master cylinder. One other thing I noticed was the old MC had one through hole threaded while the replacement does not. I think it entirely possible that there were two styles of MC's.
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"There is one nut on a M151 that is very difficult to remove....." - K8icu
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Hambone
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Re: Master Cylinder Mounting Holes

Unread post by Hambone » February 9th, 2019, 7:35 pm

I think you are correct, A2's had 5/16 bolts and A1's 3/8, I had to drill the master cylinder out, I remember Ken posting something several yrs. ago about it.
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rickf
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Re: Master Cylinder Mounting Holes

Unread post by rickf » February 9th, 2019, 10:42 pm

I don't think the holes were threaded unless someone tapped them out to put bolts directly into the master. More likely the threads on the bolt imprinted on the master cylinder, it may not have been installed tight enough.
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Barlow L
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Re: Master Cylinder Mounting Holes

Unread post by Barlow L » February 10th, 2019, 10:00 am

What I know about the matter is M151 and M151A1's used two 3/8 through bolts with captive nuts on one side.

The Ford M151A2 used two 5/16 through bolts with captive nuts on one side.

I do not know if other manufactures of the A2 possibly used short bolts threading in from both sides or not.

Regardless the case, if you have 3/8 bolts, drill the holes to such.

Lee

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