'77 disc brake booster on a '71

[DirtDonk]

We don't use anything. Which is why you, as the end user must do it.
I happen to like Rustoleum Rust-Converting Primer (standard spray can type) as a first step. Not because it's necessary when new to use a special paint, or it's even necessary to use a primer really. But it sprays on really nice and even, has a matte finish that I like for some things, and actually does really good as a primer.

I don't think most even scuff the surface on the tie-rod, but doing so would likely give you that little bit of extra adhesion to make it a perfect job.
So just clean, scuff and spray. Done.

Paul

 

[DirtDonk]

You could even use something more durable like under-coating or even powder-coating if you wanted to go all exotic on it. But in those cases you don't want to spray any of the threads.
Using the standard rattle-can stuff lets you spray on the threads to keep the rust at bay in the long-term, and not interfere with the function of the adjusting sleeves.

Paul

 

[75Denver]

Good question. I never committed the caliper piston size to memory, but it's printed around here somewhere. Been mentioned in threads many times as far as the caliper piston size, but not sure I remember seeing many references to the rear wheel cylinders.
Usually comes up when comparing the truck/small car calipers (what we use mostly) and the "T-bird" calipers which were for the larger size cars and had larger pistons.

For the rear wheel cylinders my book says the stock early rears were 13/16" for all rears and the later models were 15/16 inch.
I installed slightly larger rear wheel cylinders before I even knew the '77's had a larger size to (I assumed) bring back some semblance of balance to the system. Seemed to work for me, but it's been so long I don't remember what size cylinder I used. I want to say 13/16 to 7/8 but that's just a wild-assed guess.

For the master you can simply order a stock replacement for manual brakes for whatever year you want. I believe that they used the same piston size throughout the entire model run of Early Broncos, including power and manual brakes at 1" bore size.

Remember one more change though, which is that the ports on the power booster versions of the master come out on the driver's (fender) side, while the standard non-power assist master cylinder's ports are facing the passenger (engine) side.
This simply means that if you do go with the booster bracket later, you would need to swap masters or at least make some custom lines. I see a lot of custom lines when opening Bronco hoods, so it's quite common either way.

Paul

Okay Paul, I'm finally getting back to this project and after buying all the parts, was told that if I'm switching to a '77 DB setup, then I need to match the MC to that specified year.

Now, the MC I received has ports on the passenger side (engine) and has a larger front reservoir when compared to the non-power assist MC ('68-75?). Will this be a problem using a MC like this without the booster? Or were you recommending that style MC in the assumption that I'd be using stock MC brake lines? The books showed all the bore sizes the same throughout the years.

Second part of the question, since I'm replacing the rear 10" brakes and wheel cylinders, would it be best to upgrade those to the same size specified for '76/77 over the stock '71 WCs?

Finally, going back to the MC brake lines, is there anything in your catalog that will mount up to a non-power '76/77 MC and drop directly down into the proportioning valve WH sells? I bought that but never got lines to mate up to it...but that's probably a good things given all my confusion

 

[DirtDonk]

Hmm, thought I replied to this last night (late) but maybe I forgot to hit send before shutting down. Bummer.

I'm finally getting back to this project and after buying all the parts, was told that if I'm switching to a '77 DB setup, then I need to match the MC to that specified year.

Who told you that? Someone who obviously was just trying to be careful (as they should of course) with their customers and not wanting to think too much out of the box.
But you're already changing things so far from stock that some rules, while they may still apply, are not etched in stone.
And while they may have been technically correct in their "year" concept, the "model" was off. You could have used a '77 master, but from a manual brake model.

Now, the MC I received has ports on the passenger side (engine) and has a larger front reservoir when compared to the non-power assist MC ('68-75?).

They should at least have given you the manual brake version of the '76/'77 master. Yes, they were still offering power assist as an option, so there was such a thing as a manual master for those years with the correct port orientation.
The engine-facing ports are for use with the angled booster bracket.

Will this be a problem using a MC like this without the booster? Or were you recommending that style MC in the assumption that I'd be using stock MC brake lines?

Not a functional problem. Just more of a hassle with the lines. So yeah, I was thinking of keeping a stock manual style master so you did not have to mess with that.
You usually replace old lines after all these years anyway, so it's six of one, half a dozen of the other.

The books showed all the bore sizes the same throughout the years.

Correct. So no performance change that I'm aware of, using the different masters.

Second part of the question, since I'm replacing the rear 10" brakes and wheel cylinders, would it be best to upgrade those to the same size specified for '76/77 over the stock '71 WCs?

Yes and no.
Yes, because you get the biggest brakes offered for EB's at the time.
No, because you have to be sure to use a compatible backing plate AND axle shafts.
If you're changing to a big-bearing housing, and are going to upgrade your axles anyway, this is not a problem (other than maybe drilling some holes larger?). But if you were not budgeting for new axles (with the correct flange offset for proper brake drum spacing) then this can put a wrench in the works.

Finally, going back to the MC brake lines, is there anything in your catalog that will mount up to a non-power '76/77 MC and drop directly down into the proportioning valve WH sells?

Our #3199 could work, as they're flexible. But they're sized to fit the master that's angled more over by the bracket.
Probably the #3077 (my favorite anyway) because it's more flexible still, comes with multiple adapters (which may or may not fit all the ports, depending on which size the master has. But best of all is that you can request a special order size to your specifications.
If you put it all together than take some measurements and decide how you want the end fittings oriented, we can make you up just what you need.

Something else to think about though is that with your master's ports facing the engine, and the master coming straight out of the firewall, those hoses might be closer to the engine than would be best. Might be harder to route them cleanly, or they may even be closer to the exhaust than would be advisable.
Do you have headers? If not this may not be a problem.

I bought that but never got lines to mate up to it...but that's probably a good things given all my confusion

Here again, maybe you can exchange that, or go ahead and use it. I prefer the manually adjustable prop valves myself. You lose the dash mounted brake warning light, but you gain potentially a better balance.
You also get rid of the potential leak area that is the delay-valve in the other style of prop valve. That's the little rubber boot thingy covering the spring loaded other thingy.

Then again... All of that extra work is because someone thought you should use a power brake master in a manual configuration.
Not the best way to go in my opinion.

If it was one of our guys, sorry about the mis-information. They were correct in their basic thinking. But in the real world those things run into road blocks as often as not.
It's the same snowball effect as every other thing we do on these things. Might not cost as much as some, but you still jump through all the hoops.

Paul

 

[75Denver]

And while they may have been technically correct in their "year" concept, the "model" was off. You could have used a '77 master, but from a manual brake model.

They should at least have given you the manual brake version of the '76/'77 master. Yes, they were still offering power assist as an option, so there was such a thing as a manual master for those years with the correct port orientation.
The engine-facing ports are for use with the angled booster bracket.

Paul

Thank you again Paul! I should have mentioned that before, they did a full cross-reference to find a MC with the fender-side ports and proper bore size. After having them search a second time (I think I pissed them off), the search came up empty.

Does anyone have a '76/77 manual MC parts # or know which model to pull from? All of the reservoir sizes were different from the Bronco power version and the closest one we found had a different bore size.

The final option (and the one I went with but willing to cut my losses and start over) was to stick with the OE '71 master cylinder. When compared side by side, the manual '71 version is MUCH smaller than the power '76/77 version. What would be the worst case scenario of using the '71 version? I would assume that making sure the reservoirs are always full is crucial, but beyond that, would there be performance issues?

 

[DirtDonk]

No "worst case" as far as I'm concerned. Still knocking on wood (sarcastically speaking), but it worked fine on mine for probably 20 years. Can't claim the last few, since it's been sitting and now does not have brakes to roll around the driveway safely with, but it worked great for all those years I daily drove mine.

I used the Ford disc brakes, and on a whim, kept the stock master cylinder. I did not really want power brakes, so I gave it a shot. Never regretted the decision.
The only thing I had to do was remove the residual pressure check valve from the circuit feeding the front brakes.
That was 30 years ago or more now though, and from what I've seen most master cylinders don't even come with them installed anymore. It was a hold-over from the days when masters were mounted low on the frame and they felt it was a good thing to keep.
But as dollars and cents made the difference more and more, little things like that started getting left out of new and rebuilt models.

I think you can still find them now and then, so it's worth a quick check (literally a poke) to see if a master has one or not.

Let me see if I can find any pictures of my friend's original '76 with manual brakes. Maybe there is some sort of identifying characteristic we can use.
Since I never made a mental note of it, maybe it looks like an older unit and I didn't think anything of it.
The only thing Ford did for those years was add a spacer between the firewall and master. Roughly 1" thick maybe?
Not many of them out there so not surprised when someone has never seen one even though they've been around Broncos for a long time. But there are images here on classic showing some I think. Pretty sure I've seen them.
How's your search kung fu?;D

Paul