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Thread: '71 (series I) brake booster/master cylinder...

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    Default '71 (series I) brake booster/master cylinder...

    Hi All!

    I am realizing that my brakes have never been right in the two years of owning my Z. I have only put a few hundred miles on her as I go through the bits and pieces, so it has not been a big issue. Now, things are running good and solid and I MUST get the brakes right!

    Can anyone direct me as to the "correct" or "preferred" replacements? Not necessarily looking for originals, unless they are still avail. at a reasonable price. Do I just go to the local NAPA and buy what they have available?

    Thanks again, guys, for any help you may have for me!!!!

    Regards,

    Astrohog

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    Registered User JimmyZ's Avatar
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    It really depends on what you want for your car. Do you want it to have the "original" component setup that it came with. People swap brake boosters and MCs from different vehicles all the time. Check out HybridZ for such things. The jist of this site is more in the restoration end of the spectrum.

    If your Z was made before 8/71 the master cylinder and brake booster are different. You can still get rebuild kits for the early booster through Black Dragon. The usual culprit is the pushrod (and it's seal) which contacts the master cylinder. (Not the end which goes inside the cabin) Once the pushrod gets rusted or pitted the seal which acts on it wears and leaks vacuum. Simply rebuilding it will buy some time but on mine I fabricated a pushrod on a metal lathe. Surface finish is important on sealing surfaces such as this. Look up "Ra" finish for seals on google. Chicago Rawhide, a seal company has some good literature too.

    You can use a '72 master cylinder on an early 240 but need to switch the lines as front and rear circuits are reversed on the 72's. It is still possible to buy the early MC new but it's not cheap.

    Check for leaks on all four corners. If it pulls then you've probably got a stuck caliper. Rebuilding calipers is easy. Leaky calipers or cylinders will screw up the pad/shoes ability to do their job of course. Replace them after fixing any leaks.

    Use the search feature on the site as this sort of thing has been gone over quite a bit.

    2c

    Jim
    Last edited by JimmyZ; 08-09-2008 at 09:33 AM.
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    Thanks, Jim.

    I am trying to keep her as stock as possible, but when it makes sense to upgrade, I will for the most part as long as the upgrade is easily returned to stock if need be. Basically, I want to be able to drive in a spirited manner once in awhile and have the confidence that I have proper braking. I am sure that when working properly the stock brake setup is adequate, but If I have to give my firstborn for an original booster or master cylinder, I would rather just use something available off the shelf as long as it performs adequately. I really don't want to bastardize the Z with parts off other makes of cars as I would like to retain at least a semblence of "originality".

    I am not a machinist, so I doubt I will bother making a new rod, so, what are my options for a new booster if it turns out I need one?

    Regards,

    Jeff

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    You can get the '72 booster from Autozone etc. Might as well get a '72 master cylinder and swap the lines while you're at it. (Front and reverse circuit on the '72 MC are different. Keep your original MC and booster for historical preservation and a spare. Dont' give your '71 booster or master C as a core. The original (pre 8/71)MC "should" fit the '72 booster. I'd do a search on this site for it though.

    Getting a brand new master cylinder is a better idea than a rebuilt one. Be sure to ask when buying if it's new or rebuilt. Might as well replace it for safety.

    The stock brakes aren't the greatest compared to modern systems that you might be used to. The master vac has a small diameter so it doesn't help as much with braking. This results in more pressure needed at the pedal.

    You could just but a master vac from Black Dragon and let them keep the core charge of $35. (might be more expensive than your local parts dealer/might not.
    Last edited by JimmyZ; 08-10-2008 at 11:03 AM.
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    thanks all for your input! Upon closer inspection, I realized the pistons in the front calipers were stuck and I replaced with new and pads, and what a difference!!

    I guess I can hold off on the booster and master for a while now!

    Thanks again!!

    Regards,

    Jeff

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    Great!! That was a good stroke of luck with a relatively inexpensive fix!
    I will soon be facing the same job (and hopefully as simple as yours turned out to be). This reinforces the advice that some folks here put forth: start with the simple things.
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    Just FYI - - Our local Advanced Auto Parts (as well as others) sell a couple different after-market brands/types of Brake Master Cylinders for the pre 8/71 Z Cars.

    One type is $135.00 - but it comes WITHOUT the fluid reservoirs - so you have to remove the old one's from yours and put them on the replacement.

    Another type is $185.00 and comes with new reservoirs.

    NOTE - the rubber stoppers in the reservoir caps will dissolve in brake fluid over time. They turn into a thick black gooe.. So if you use your old reservoirs, be sure to order new caps. This is a very common problem with cars parked in the barn for 6+ years...

    FWIW,
    Carl B.

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    Carl,
    Are you sure they are the pre 8-71 types and not just the typical 1972>on types? What I found that was most places listed it but either couldn't get the part or were just offering a 72> model. I remember Central Auto Parts could get a brand new pre 8/71 MC for around $300 though.

    Curious

    Jim
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    Hi Jim:
    Advanced Auto - at least shows the correct part in their On-line inventory... They did not have one in Stock at the Store, nor in the Stores in this Area (nothing new), but said they could order it. I didn't order it, because I needed it now of course.

    Bumper To Bumper Auto Parts said they showed the number on "backorder" and did not have a "expected date" shown...

    I wound up over-hauling the one on the car.

    Searching on line, it looks like you are right. All the "new" one's show pictures of the 9/71 Forward, and the reman's show the correct master - but without the reservoirs.

    Interesting...

    FWIW,
    Carl B.

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    If you are not worried about originality, why not go with the larger 73-78 master vac? That's what I did. Requires drilling 4 holes in the firewall, but it provides more boost. Did that on my previous, (1971), Z and was happy with the result.
    Julio
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    I had a leak in my pre 8/71 brake booster last week, as a matter of fact. I used a '72 booster to replace it, but I had to exchange the adjustment screw-tipped MC rod between the booster and the MC (the pre- 8/71 was about 1/4", while the '72 was about 1"). I retained the original MC and reservoirs.

    I also had to use the brake pedal clevis pin from the '72, because while the '72's inboard rod is a larger diameter, it has a SMALLER diameter clevis pin, the holes on the adjusting "U" shaped bolt just weren't large enough to fit the original clevis pin. This gives a bit of "slack" because the brake pedal's clevis hole is larger than the new clevis.

    Also, instead of a round snapring (on the original clevis), the smaller '72's clevis drilled for a hairpin-type retainer.

    So, the 72 booster CAN indeed work with an early 71 MC.
    Last edited by Mat M; 08-27-2008 at 11:48 AM.
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    Quote Originally Posted by JimmyZ View Post
    Carl,
    Are you sure they are the pre 8-71 types and not just the typical 1972>on types? What I found that was most places listed it but either couldn't get the part or were just offering a 72> model. I remember Central Auto Parts could get a brand new pre 8/71 MC for around $300 though.
    It's been almost two years ago now, but in late 2006 I bought the correct early style master cylinder from my Nissan dealer for $175 (after club discount). Part number 46010-E4602.
    Arne - Former owner, HLS30-37705, 7/71, 905 Red
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