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Mystery hole in brake booster

jerry

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There is a large hole next to the one for the pushrod to go through the firewall. Can anybody tell me what this is for?

Thank you, Jerry
 

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catfan

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There's a rubber plug in that spot that sticks out of the firewall.
 
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jerry

jerry

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What an interesting spot for there to be such a large hole.

Is there a plug specifically sized for that (a link would be great), or should I just fab up something to stick over it?
 

catfan

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It's like the other two large holes in the bracket so you can mount the bracket without taking a bolt or rubber plug out.
 
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jerry

jerry

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It's like the other two large holes in the bracket so you can mount the bracket without taking a bolt or rubber plug out.

Makes sense. I'm just trying to plug everything because I'm finding that the older I get, the more I appreciate actually being able to get warm. :) So as I put things back together I am patching holes, installing new weatherstrip, and have rebuilt my heater box.

If nobody has a link to a the correct body plug, I'll hunt around (I think I remember those help! packages having body plugs) or just stick something like a cork in it.

Jerry
 

jckkys

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I recalled a thread on the Bronco chat forum with photos of a '77 without the power brake booster here;https://bringatrailer.com/listing/1977-ford-bronco-37/. Scroll down to the 6th photo. There appears to be a stiff looking cable, wire, or vacuum tube using that hole. The lack of a booster in an otherwise original '77 engine bay, is the only thing I see that's odd. The butchered air cleaner is a common knucklehead mod.
 

Slowleak

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I recalled a thread on the Bronco chat forum with photos of a '77 without the power brake booster here;https://bringatrailer.com/listing/1977-ford-bronco-37/. Scroll down to the 6th photo. There appears to be a stiff looking cable, wire, or vacuum tube using that hole. The lack of a booster in an otherwise original '77 engine bay, is the only thing I see that's odd. The butchered air cleaner is a common knucklehead mod.


That’s probably the original setup. Power brakes were not standard even on ‘76 and ‘77 models. I had a base model ‘77 with power steering and manual disc brakes.
 

904Bronco

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;)

The hole (in the brake booster bracket) is there so that the rubber plug(s) that holds the factory firewall insulation in place will remain unmolested and continue to do its job.
 
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jerry

jerry

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;)



The hole (in the brake booster bracket) is there so that the rubber plug(s) that holds the factory firewall insulation in place will remain unmolested and continue to do its job.
It just seemed to be a little larger than I expected.

I should spend a little more time looking next time. Thanks!

Sent from my Pixel 4a using Tapatalk
 

DirtDonk

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That cable on the BAT Bronco looks like they converted to a manual choke (common for people that spent much time at higher altitudes).

Looks like a stock manual brake setup too, based on the fact that it has the factory 1" spacer between the master and the firewall.
Kind of rare to see one any time, but with all the other stuff on the Bronco I'm not surprised that the owner would have wanted manual brakes. Other than the speed-control, looks like they were the typical old-school backwoods explorer. No power anything.

Get a kick out of those two variable resistor thingies on the firewall and fender. My first thought was trailer brake controller, but I'm not sure that's correct. Part of the cruise?

Paul
 

DirtDonk

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The butchered air cleaner is a common knucklehead mod.

Window screen super desert "pre-filter" don't you know. All the cool racers do it...%)
I wonder what would have happened to the original snorkel that it needed to be removed? Or maybe they didn't want all that dirty nasty cool air coming into his engine. At least the cold-air duct is still in place. Too bad the hose is gone, but I see lots of them fall apart over the years.

Did you note the position of the windshield hinge seal too? Reverse of yours, with the rib at the back towards the passenger compartment.
Guess they could have put them in either way at the factory (I think you recently said yours was forward?) but most I've seen were like this one.

It went for a good price for both parties it seems. But I bet the seller could have gotten even more for it if they'd bothered to clean it!
Made an effort at least.

Paul
 

jckkys

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In my restoration, I researched the windshield hinge seal and everyone said the bead goes closer to the hinge pin. That agrees with 3 of my factory assembled Broncos.
2 of my EBs had standard steering and brakes. I would never have intentionally order a '77 that way. No coincidence I've seen very few of them. Without power high speed stops were just plain scary, and tight maneuvers with big tires were a PITA.
 

Slowleak

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Get a kick out of those two variable resistor thingies on the firewall and fender. My first thought was trailer brake controller, but I'm not sure that's correct. Part of the cruise?

It’s a brake controller. You loosen a wingnut and slide the metal piece to change the resistance. I rotated the picture and you and see it has arrows labels light and heavy trailer.... Not something you adjust while you are rolling.

e8e83bb3bb84ada5fc40d85a029fd7fe.jpg
 

DirtDonk

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Thanks. I figured that's what it was (especially since there is a controller under the dash), and have seen them before but never used one of that type. Was wondering how the variable bit worked. Is it personal preference, or a special setup procedure with guidelines during initial setup?
Something you can change the sensitivity on when towing different trailers maybe?

Thanks

Paul
 

DirtDonk

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Oh, and is having multiple resistor modules normal? Seems like I've only see one at a time before. Or maybe I just never saw the second one.

Paul
 

Slowleak

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Oh, and is having multiple resistor modules normal? Seems like I've only see one at a time before. Or maybe I just never saw the second one.

Paul


I’ve never see duals. Maybe there was a way to switch between the two while driving? One could be set for light or flat driving, the other for hills or heavy loads. Or, being the crafty kind of guy he appears to be, he had two harnesses, one for his heavy trailer, and one for the light one so he did not have to adjust.

I don’t see anything here about needing two resistors..
http://67-72chevytrucks.com/vboard/showthread.php?t=782914
 
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jckkys

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I got curious and looked at my '77 firewall/booster adapter. My original firewall has no hole there. Neither does the adapter backing plate. The adapter that is after market to raise the master cylinder off the ignition module does have the hole. Go figure.
Paul. I did install a manual choke cable for my high altitude carb equipped with a manual choke. The Knob sits between the headlight and wiper switches and the cable runs through the same hole as the heater valve cable. A choke cable just wouldn't work well if run through the hole in question. Choke levers are almost always on the pass. side of carbs.
 

DirtDonk

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Yeah, lots of possible curves when trying to run a cable into the engine compartment.
In my case I ran it in the original spot (as I'd seen it on '69 Broncos) over on the left side above the fuel gauge selector switch and throttle knob. Had to run it straight out the firewall I think, due to it's location way over there.
But now I'm curious and am going to have to go out tomorrow and make sure I'm remembering correctly how it's routed. Makes sense where you have it for a better angle to the carb.
It was a factory cable bought from the dealer in about '77 or so, and seemed to have plenty of length.

Paul
 

jckkys

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My effort in routing cable controls is all about minimal turns. The straighter they are the smoother they operate. The manual choke especially, because tiny movements make a big difference. I've worked in a bunch of manually choked trucks and learned how to avoid flooding and no starts far better than the best automatic chokes. They never seem to open fast enough.
 
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