I started to hijack a thread started yesterday by FoxSpeed, but decided that since this may help others - and not wanting to have his thread get too far off topic - I'd start a new thread. In his thread, it was suggested to use a '67-'76 Corvette master cylinder for 4 wheel disc brakes - something I've been trying to determine. I've been looking at the MC for '78 corvettes 'cause the remanufactured units are CHEAP at Autozone (see below) - price undoubtedly due to volume / availability of the later units. 1967 - 1976 New Part # NM1372 $45.99 Reman #M1372 $36.99 w/o core 1977 - 198? New Part # NM1749 $64.99 Reman #M1749 $23.99 w/o core So...the question for the brake gurus - what is the difference between the '67-76 and the '77-? master cylinders? It was also stated that the '67-'76 didn't require a booster. Some feedback would be great along these lines - pedal hardness, etc. Booster delete is appealing - one less item to deal with! I do have a 7" booster that I was planning on using - what is your experience? Also, while picking your brains: Is there a cheap remote fill option to use with these units? What have you found or done? I'm running a under dash set-up, and I'd love to be able to fill without standing on my head!! I've seen some alterations - but I'd love to get real feedback. Thanks Flamed34
the difference in the masters is bore diameter. it depends on a few factors, caliper piston diameter for one. give ralph a call at eci brakes, use google for ph. number, he will ask you some questions, and tell you what to run.
rd martin, I might follow up on your suggestion...I'd like to see what Hambers come up with first of course. I did hit the website...some good info. Both versions of the MC are actually 1 1/8" bore per specs. Perhaps variance on the stroke or snout configurations. There certainly has to be a reason why the '67-'76 is preferred, that's what I'm trying to figure out primarily. It's the old give a man a fish / teach a man to fish argument - I want to know why, not just what to use. FWIW: I'm using 1974 Jag 3 piston front calipers with a '86 12 bolt WS6 TA disc rear. The '86 MC has a 36 mm bore (@ 1 27/64") - but it's one of the plastic snap on cover styles which I do not want to run.
I believe the early model has the deep hole in the piston for the pushrod. This would be important if you plan to run manual brakes.
I have manual four wheel disc brakes. I went to NAPA and picked up a 67 427 Vette Big Block manual disc brake master cylinder. I figured if it worked on the manual brake option for that year vette, then it would work for me. I decided to run manual brakes, because I have a pretty big Lunati jet boat cam in my pickup, I have very low vac/hg at idle.
I have very good pedal feel. My master cyl is located under the floor, connected to the original 47 Ford brake pedal. I have my check valves fwd and aft of the cylinder, because the cylinder is equal or below the caliper level. I'm running early GM front calipers ( nova/chevelle) and a 1980 Lincoln Versailles rear,disc brake. I have an access panel right on the floor where I can just pull the carpet back and service the master cylinder. Simple/safe and stops as good as my Lincoln Aviator.
Jamn47... We used a similar set up on our '51 Ford. Used a later '70's MC with an 8" booster, appropriate residual valves, proportioning valve to set the rear. Used jag rear discs and '68 vette calipers on the front with modified bracketry to mount on the jag front end. While the brakes are "good", they've never been stop-on-a-dime like I'd like. I don't believe we saw the advantage we thought we would with the 'vette front calipers - hence staying with the factory jag units on this build. Because the MC will mount under the dash, access isn't great...part of the reason why I'm thinking I'd like to go with non-power ***ist brakes - one less thing to deal with while standing on my head. I was just looking at the call out for the '68 manual brake MC - reman at $35.99 part # M1371 used on both the 327 and the 427. I notice is shows only a 1" bore...there is no manual brake option on the '76 - ? vettes. So...I can see the reasoning for the 67-76 MANUAL MC...but what would the difference be in the power MC?
I have several old Bendix application books, and found, according to them, that '67-'77 Corvettes had both manual and power brakes, and used a 1" master for manual and an 1 1/8" for power. Starting in '78, all were power with a 1 1/8" master, at least up to 1990, the latest info I have. Thought this info might help this thread. From a Ford guy yet!
So...***umably the 1" MC would be desired: less bore diameter = less displacement = less pedal effort. I'm really leaning towards manual brakes, just less to go wrong and deal with. If power, probably really no "real" difference in earlier vs later units. So, back to one of the original questions: Options for plumbing remote fill? I'm really trying to stay budget minded, so a complete Wilwood (o equivalent) set up really isn't in the plans.
Can you drill and tap the side of the new master cyl. ? Then run a line from the side to an old single pot master cyl as a reservior ??
I've thought of that too. I can't think of a drawback. Perhaps plug the original snout end to avoid ever having a leak? Could always use an aftermarket holding canister and just feed into the side of the MC. Can anyone come up with a reason why NOT to drill and tap the side of the MC?
You need two reservoirs and two lines taped into the master, one in each fluid chamber. The master cylinder is divided, and forget drilling a hole through the divider as that would defeat the dual chamber concept. Plus you would never know which system is low or needs fluid. The big question is where in the heck are you going to place the remote reservoir with an under-dash master? Keep in mind, once the system is bled and carefully leak checked, you rarely need to check the fluid. Simply pop the cap and use a mirror. You may be making this more complicated than it has to be. Let me add you always want a new master vs a reman, if there is a choice. The price difference isn't worth the possible problems. JMO
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