Hi All. I need help to find a 7/8" disk/drum master cylinder, please. Manual - left hand connections - preferably with a boot - 3 1/4" mounting holes. I'm in New Zealand so can't pop down to the local brake store unless I have a japanese car and know exactly what it fits. I've emailed a bunch of online stores and never get a reply. Also looking online, non of the sites provide specific details other than the bore and car they fit. My car is a 1931 pickup on a TCI chassis from the late 80's. Front brakes are the Magnum Axle Co. 4000 series discs with GM metric calipers and 68 mustang drums on the rear. Magnum axle sell a 7/8" master for $120 but not sure about the mount etc. really hoping to find something more reasonably priced. Even at $60, with shipping and the exchange rate it's going to hit NZ$200. Ouch. Current system is a rock hard 1" single master. Cheers Kon.
I bought a 7/8" from ECI, I'm running 4 wheel discs, and works great. Around $80.00 if I remember right.
Just looked at the one I got from Speedway, 91031420 but it has a 1" bore. But this is something close to what you want. Look at Rock Auto to get a better idea. 1969-1973 Mustang or Fairlane masters probably come in a 7/8" bore.
My take on your post is wanting to reduce the pedal effort, but down sizing the master bore to a small 7/8"may not be the best approach, as this can lead to excessive pedal travel and marginal fluid displacement. I would first check the pedal for a minimum 6:1 ratio, and modify if necessary before changing the master bore from the 1". Most '60s/'70s Fords (as well as many other brands) used a 1" master, with a 15/16" on Pintos and Mustang 11s.
Hi Guys Thank you, but I really need someone with an exact model number, the brake places just won't reply. V8 Bob, Thanks, to the best of my knowledge I have a 4.5 to 1 ratio. It's really hard to measure, but the long pedal arm is 9" and the short piston arm is 2". Seems odd. But there is no room to modify as it's all welded in pace, plus in NZ you can't mod your brake pedal without going through a REALLY long and REALLY expensive certification process through the government. And I figure it to be about right, under a hard push the pedal moves 42mm (just over 1 5/8") and the master cylinder rod moves 9mm (~3/8") which is about 1:4.5 so yes a crappy ratio. I might be wrong as it's all hard to do in-place. I could play safe and go 15/16", but 1" is pretty hard, but works. Anyway using a volume calculation 7/8" diameter will give me 30% more travel for the same volume as a 1". so my pedal travel would go up from 1 5/8" to 2" travel - I think that is OK, my 66 Mustang moves a little more than that. bobss396 - Thanks. Re Mustang, mine is a 1" boosted, but non of the brake sellers ever reply to questions. Including Rock Auto :-(
I did a quick look at RA for a '72 Mustang, anything that did specify a size was 1". The rest had nothing.
Here is an on line guide to the paper catalog http://www.pageturnpro.com/CARDONE-Industries/56617-Master-Cylinder-Id-Guide/index.html#1 It has listings by bore size in it.
Hi Wayne thanks for the link. I can hopefully find a few possibilities and put google to work with the part number to find the rest of the info. Hole spacing, manual, disc/drum etc.
Great link indeed, everyone should download & save it. Didn't see the spacing thing either, but most Fords are 3.200 or 3.250 for the two mounting holes.
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