Master cylinder replacement suggestions?

[77 Spyder]

Hi Guys, I brought the Monza out of storage for a local show last weekend. Everything was fine until I discovered
a drip coming from an area I knew too well. When I originaly put the car together in 2008, I bought a master cylinder from
my local NAPA parts dealer. I media blasted it, epoxy primed & painted it in cast color. Upon bleeding out the brake lines I
found it had a leak. I pulled it out of the car & took it apart to find that when it was "rebuilt" one of the seals was flipped over
& pinched causing the leak. Parts store ordered another unit & because of the work already done to the unit I had I remove the piston
from the replacement to simply swap them. To my surprise the replacement cylinder had the same seal damaged
I was able to swap out the next seal inward & get mine back together with good seals. Low quality assembly no doubt.

So, fast forward to this past weekend & I find it leaking again. Its been 8 years, so good possibility its from sitting, but with my earlier findings,
I am sure the quality comes into play as well. I want to replace it with something better to minimize the risk of it happening again. I see there are quite a few options from AC delco, Bendix, raybestos, etc. I know sometimes these are rebuilt by the same company & private labeled. Can anyone make a recommendation?

The widest selection I found is on Rock Auto. However I am more than happy to buy locally too.

http://www.rockauto.com/en/catalog/chev ... om+URL+%2F

[cjbiagi]

Carl, you may want to consider sending your old MC to a place that does QUALITY rebuilding. Check this out http://www.whitepost.com/brake.html

[OldsStarfire]

I've had this happen to me several times on my 442. Rebuild quality is crap!

[Monza Harry]

With the amount of detailing in your master, I would think you would want to re-build it yourself, it would be cheaper [maybe?] and you would have control over your finished Master, Build a plate that you clamp in your vise that has the mounting pattern and centre hole in so you don't have to clamp o the outer finished surface. Then it will be ready for bench bleeding. Just an idea, I am sure you will be able to find the seals, you could also consider having the bore "Hard Chromed" [also known as "Flash chromed] this finish is available as thin as 0.0002" thick, or some other non-rusting finish applied. Perhaps the un submerged part of the bore had some flash rust and wasted your seals. Harry

[77 Spyder]

Thanks for all the ideas. I was thinking of putting new seals in the master I have, but am suspect of it just being a poor quality item that
possibly has a sub-par bore within.

Anybody know what is meant by: "with Cast Iron Cylinder; with Stamped Steel Cylinder " I see this on some of them.
Is the cylinder bore within main body steel? Pretty sure they all have aluminum pistons.

[cjbiagi]

Carl, that is the nice thing about sending to WHITE POST to have it rebuilt. They drill the bore oversize and then press in a new brass sleeve. So, if you bore is messed up it doesn't matter, you end up with a new brass insert which supposedly won't pit or rust.

[cosvega76]

Anybody know what is meant by: "with Cast Iron Cylinder; with Stamped Steel Cylinder " I see this on some of them.
Is the cylinder bore within main body steel? Pretty sure they all have aluminum pistons.

Many '76s (I don't know if it extended into '77) had a master cylinder with a stamped steel reservoir instead of being all cast iron. It had a more rectangular cover held down with two bails. The Cosworth I owned had one.

Stamped steel master cylinder.JPG

Edit: There is one on eBay right now with good photos: http://www.ebay.com/itm/1976-Cosworth-V ... ZA&vxp=mtr

Chuck

[77 Spyder]

Thanks for that info Chuck! I just learned something, I had never knew there was a master like that. Now the stamped steel part makes perfect sense.

I will call White Post as Clyde recommended to see what the cost is. But, I am guessing their rebuild process would strip the repainting process I like to do.
If they just use cast spray over a blasted body its going to rust at some point IMO. I really like coating everything with epoxy primer before paint.

[77 Spyder]

Oh, One other thing. Does the manual brake master differ from the power version? I didn't see a listing between the power brakes & non
when looking up the parts I would think they are different, but they are not listed separately if they are.

[cosvega76]

For the Monza, they are the same. The difference between the two in the Vega is that the manual brake Vega has the pushrod attached.


Chuck

[77 Spyder]

Did the manual brake Monza have a pushrod? Never looked at one. I was just surprised looking up masters they are not listed
differently between manual & power brakes. Thanks!

[cjbiagi]

Carl, not sure about their painting process or if it would ruin what you already have. Maybe they powder coat it? Anyway, mine is just painted with the cast gray paint and I have no issue with rust through....I haven't touched it in years so I wouldn't be too concerned. I have not use White Post for mine but I was going to use them when I thought I had a leak but it just turned out to be the top gasket. You might want to try and replace that gasket first. It will run down the back of the MC and down the front of the booster if it leaks.

[cosvega76]

Did the manual brake Monza have a pushrod? Never looked at one. I was just surprised looking up masters they are not listed
differently between manual & power brakes. Thanks!

The Monza manual master did use a pushrod, but it wasn't attached to the master. The piston had just a dimple in the end, just like the power master, so the pushrod was held in place by a cup that fit through the firewall.


Chuck

[MonzaRacer]

Actually many will do this if stroked wrong as well. When the I did try doing rebuilds started using seals with .ore flexible makeup you can even flip seals long stroking it. Many now even say plug the ports and only move piston 1/8-1/4 in
The new seals are not as stiff as long time ago.
I prefer using my Phoenix Injector to reverse bleed before moving piston.