Is this 1" or 1 1/8" bore... my eyes suck!

[weever82]

Swapping out my master cylinder and putting in a disc/drum prop valve from a PO cluster bang and can't figure out the bore size of the MC. Where do you measure from? the lip, rubber surround... The sizes are so close I am getting nervous picking a size and ordering one. Any thoughts?

Appreciate the time!

Weev-

[geezer#99]

Measure the inside bore.

[DesertCat]

Hey Weev,

Get a vernier or digital caliper, one of my favorite tools.

[cdowns]

nuttin like havin the right tool for the right job

i second the caliper vote

[weever82]

Ya I gotta pick one of those up! Should check this weekend with Black Friday deals.

Thanks guys

Weev-
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[ulakovic22]

I'd guess a 1" bore. It looks like the lip is an 1/8" on either side so subtract a 1/4" off what you see.
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[kaycee]

I got my cheapy dial gauge from Harbor Freight for like $8

[Wrenchbender Ret]

It looks like 1 1/8 in. to me.

[SS Tim]

While having the proper tool to measure with is best, there are ways to use a tape accurately.
A tape measure is handy, but much better suited to building a house than a truck or an airplane. The biggest problem is the zero hook at the end. It slides in and out for an inside or outside measurement. Again great when a circular saw is used but not in this or similar cases.
To use a tape measure you need to remember the first inch is useless, period. Also the markings are not very uniform on less expensive tapes.
So the simple way take a measurement is to "burn" the first inch and start measuring at the 1" graduation as I did in the reworked picture. Now by laying the tape up and trying to line up with the true bore and not the relief bevel it looks close to 1 1/8" (1.125"). If the number needs to be really close try a second confirming measurement further up the tape say starting about the 4" mark.
Hope this helps and is a handy tip to remember at the used parts yard with a 10' pocket tape.

[weever82]

Originally Posted by SS Tim

While having the proper tool to measure with is best, there are ways to use a tape accurately.
A tape measure is handy, but much better suited to building a house than a truck or an airplane. The biggest problem is the zero hook at the end. It slides in and out for an inside or outside measurement. Again great when a circular saw is used but not in this or similar cases.
To use a tape measure you need to remember the first inch is useless, period. Also the markings are not very uniform on less expensive tapes.
So the simple way take a measurement is to "burn" the first inch and start measuring at the 1" graduation as I did in the reworked picture. Now by laying the tape up and trying to line up with the true bore and not the relief bevel it looks close to 1 1/8" (1.125"). If the number needs to be really close try a second confirming measurement further up the tape say starting about the 4" mark.
Hope this helps and is a handy tip to remember at the used parts yard with a 10' pocket tape.

That's a great idea! I was always struggling with the end piece slipping around and hard to read. Appreciate reworking the pic as well. Thanks again.

Weev-
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[gringoloco]

Are you running a booster or not? Generally speaking, the 1" is used for manual and 1.125" for power. Screwing this up can make a HUGE difference in pedal feel and braking ability.
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[weever82]

I have power brakes with a 9" booster.

Weev-
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