I'm upgrading from manual to power brakes on my '71. I'm curious on what the correct factory finish is for the master cylinder and booster. I would have expected yellow zinc, but I'm seeing a lot of variances on Google searches of 'original' engine bays. Black, grey, more of a silver. Maybe it was a lottery of whatever was in the bin that day for the guys to put on at the factory?!?

I was looking through a bunch of the other threads about this change to make sure I've got what I need. It sounded like just adding the booster to and reusing the existing master cylinder was ok?

Thx.

 

The booster was finished in zinc dichromate. This gives a rainbow look to the surface.

It's not a durable coating. If you have a fluid leak, the dichromate will not prevent rust.

What I found to work well is to plate first with nickel and then do dichromate for the final layer. That way the booster is protected from rust and the dichromate stays looking fresh.

 

The dichromate that Gary mentions above will be a gold or "yellow" color/tint. It'll probably be a lot brighter and "colorful" compared to the plating on an original booster but it will be considered "correct" IMO. Black or silver.....no. Black is indicative of possible auto parts store replacement booster (cheap finish to keep the price down) and silver isn't correct for your era. It wasn't a "that's what's in the parts bin" situation as you mentioned in your original posting.

As far as the master cylinder.....black or cast iron. I say black but others may argue bare (which would be a cast iron paint if rust is a concern). Cap should be dichromate (ie - yellow/gold).

Can you post a good pic of your current master cylinder??? Can you see if it has a two letter code stamped into a machined half-circle-or-so pad on the "nose" of the master?

 

I'd take a pict, but it's up at a shop getting some carb work done. Thanks for the confirmation.

 

New question related. I got the booster on. Had to replace the master cylinder too, it decided to give up the fight. Front lines replace, new valve. Felt like I still had manual brakes. Checked the vacuum off the manifold, 5-6" vs the 18" I need for the booster (big cam). Would a vacuum reservoir be the way to go to remedy this vs a vacuum pump?

 

Is your engine built with a lumpy cam? If not, I'd check for vacuum leaks.

 

A vacuum reservoir only recharges when the engine revs under light load (or is in coast mode).

I run a lumpy camshaft. I used a $20 junk-yard vacuum pump (from a Cimarron) with a vacuum reservoir and it's been working for me for 25 years. It always comes on when I initially turn the key and I appreciate having brakes even before the engine starts.

And it comes on infrequently at other times too, usually when I need to brake a few times in succession. That tells me the reservoir alone wouldn't be enough for my application.

 

Yes, lumpy cam. I'll look at the pumps. I got a tank off Jegs. Halfway there.