master cylinder bore size

jlat

Greasemonkey
Jan 25, 2013
195
28
hell people: Any of youz know how to do it? I did a quick search and it talks about volume and bla bla. There has to be a hard measurement you can take but you'll probably have to take it apart?
IBBY
 

Hurricane77

Not-quite-so-new-guy
Nov 11, 2020
48
33
Ottawa, Canada
Not exactly clear what you're asking? Stock master cylinder bore size? Or you want to upgrade to a larger master cylinder? Putting in a larger master cylinder should be done with caution, it might make your brakes feel better, but you can actually reduce your stopping power.
 
  • Love
Reactions: 1 user

jlat

Greasemonkey
Thread starter
Jan 25, 2013
195
28
hello: I bought a hydro boost kit for my 86T and the guy who sold it to me don't know what size it is so I want to measure it. He won't give me P/N as he's afraid of people copying the kit. He say's it's made for the kit. It's been a PITA.
IBBY
 

malibudave

Greasemonkey
Supporting Member
Mar 12, 2010
187
43
Houston, TX
Get some cheap ID/OD calipers from HomeDepot and measure the bore. Just place the caliper on the top of the c-clip to get a accurate measurement. You can eyeball it with a tape measure.

Let us know what you find.
 

John Wm. Zick

Not-quite-so-new-guy
Jun 10, 2021
35
18
Winter Haven, Florida
Not exactly clear what you're asking? Stock master cylinder bore size? Or you want to upgrade to a larger master cylinder? Putting in a larger master cylinder should be done with caution, it might make your brakes feel better, but you can actually reduce your stopping power.
THE SMALLER THE BORE SIZE, THE MORE STOPPING POWER WITH DISC BRAKES..............
 
  • Like
Reactions: 1 user

oldsmobile joe

Royal Smart Person
Nov 12, 2015
1,755
113
mpls
THE SMALLER THE BORE SIZE, THE MORE STOPPING POWER WITH DISC BRAKES..............
this is a vague statement and should not be repeated with out specifics.
 
  • Like
  • Agree
Reactions: 3 users

JAMCAR223

Royal Smart Person
Jun 6, 2014
1,728
113
Houston, TX.
I'm not an expert, but this is my opinion. The correct size master cylinder is the one that provides 1,000 - 1,200 PSI at the caliper. This can only be confirmed with a pressure gauge at the caliper inlet. Although a smaller bore will usually provide more pressure, it's still a very vague statement to say >> THE SMALLER THE BORE SIZE, THE MORE STOPPING POWER WITH DISC BRAKES..............

Overall stopping power is comprised of several variables - bore size, pedal ratio, hose/line composition, rotor size, pad composition, tire compound, etc, etc.

Malibudave , in a previous post has supplied us with some great information on bore size for our cars for various disc/drum & disc/disc combinations. I would trust his knowledge as a great starting point for anybody doing brake upgrades, but in the end if braking performance is not up to par, adjustments will need to be made.
 
  • Like
  • Winner
Reactions: 3 users

jlat

Greasemonkey
Thread starter
Jan 25, 2013
195
28
hello people: My MC is for a hydro boost and I've heard you need a 1.125 bore to make it work right. I took it apart today and that clip was the only pain. It is 1.00 bore and I will be making a call to the seller and hear what he has to say..
IBBY
 
G-Body Performance Upgrades

GBodyForum is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of Amazon.com, Inc. or its affiliates.

Please support GBodyForum Sponsors

Classic Truck ConsolesDixie Restoration DepotMike's MontesP-S-TSouthside Machine PerformanceUMI Performance

ContactAdmin@GBodyForum.comfor info on becoming a sponsor