Stuck on how to convert to manual brakes on Mirada

[72Dodge]

I'm converting the '83 Mirada to manual brakes.

I'm picking up the A-1 CARDONE Part # 10-1821 manual brake master cylinder (unless someone else has a better idea), an adjustable pushrod (unless someone has a factory one), so I think the only other thing I'll need (other than adjustable prop valve) is the power to manual adapter plate for the firewall.

But, I'm confused on what will actually work.

First, here is a pic of my firewall that had the power booster attached to it:

Next, here is what I believe to be a factory adapter, probably from an F-body (I found this here on an old wanted post):

Last, here is the Mopar Performance P5249315 master cylinder adapter plate:

The problem is, I don't see how either of those two would work unless I'm missing something.

The general area on my firewall where the power booster mounted (the raised/clean area in the picture ) is 5"x5.5".

The Mopar Performance adapter is something like 7x4.5 (I can't remember, but it's taller and narrower than what I think I need), and I don't see how that older factory one would work, because it looks like it would put the master cylinder hole much lower than what I have.

Do I just need to make a custom one out of sheet metal? I'd rather have a factory or aftermarket already-done solution if not too expensive than to have to fab something, truth be told.

What do I need to do? Or do I just get the factory one shown above (the green one) then just cut new holes in the firewall for the lower master cylinder hole and mounting holes? It looks like it might work if I do that....? But even then, how does the master mount? Seems like there should be 2 more holes (like on the Mopar Performance adapter).

Thanks!

 

[72Dodge]

Then there is this other one (I think from Aspen/Volare), that is different than the green one above. Note how the two mounting holes for the master cylinder are in line with the large master pass-through hole? That looks like it would fit on my car and would work, if I made another master cylinder hole in the firewall where that hole is. On the green plate above, there are no mounting holes for the master to mount to.

My guess is this is the one I need, and the dimple on my firewall is probably the center of the new hole I need to drill.

If so, anyone have one of these to sell me?

 

[High Speed Pursuit]

Just curious....why convert to manual at all? The smaller power brake booster from an Omni/Horizon will work if you are installing a BB or if you are running a huge cam and are worried about vacuum.

 

[72Dodge]

Good info, thanks, but I like manual brakes and steering, and this car won't see much street use if any. Anyone know the answer to my question? If not, I'll just have to fabricate one, I guess it really shouldn't be too hard, but I'd still rather hear from someone who has done this or has knowledge of it.

 

[High Speed Pursuit]

You wouldn't happen to dislike consoles, Tuff Wheels, and 10 spokes would you? Seriously there is a lot of good information on this website and I'm sure somebody will have the correct answer...my guess is a mounting plate off an F Body will work with a little fab...good luck.

 

[slant6billy]

Ok. I pulled a clutch pedal assembly off a manual brake car. What I can tell you is that the non power master cylindar came off in my hand when I removed all the hardware from the pedal assembly as well the brake rod from the pedal. Now that was 2 years ago. I think the car met the crusher. Your last picture is what you need. Sadly, that means you can't use the other part, but I think you know- sorry to state the obvious. On a good note, someone here went the other way: manual to power. Perhaps they still have the parts. I also remember an ebay basketcase volare that pops up every few months with a parts car that is a manual brake car. Good luck. If I get out junk yard diving, I'll keep an eye out.

 

[72Dodge]

Nope, I love consoles and 10 spokes (this car will have neither though), but it might get a Tuff Wheel or I'm looking at a Grant also.

This car is just going to be very stripped down, all-business, straight-line.

 

[72Dodge]

Ok. I pulled a clutch pedal assembly off a manual brake car. What I can tell you is that the non power master cylindar came off in my hand when I removed all the hardware from the pedal assembly as well the brake rod from the pedal. Now that was 2 years ago. I think the car met the crusher. Your last picture is what you need. Sadly, that means you can't use the other part, but I think you know- sorry to state the obvious. On a good note, someone here went the other way: manual to power. Perhaps they still have the parts. I also remember an ebay basketcase volare that pops up every few months with a parts car that is a manual brake car. Good luck. If I get out junk yard diving, I'll keep an eye out.

Yeah, I sort of half figured it out even as I was typing, it was starting to make more sense that it was the one in the last picture that could be made to work. Without having it in my hand, it seems like it would drop the master down a little along with the brake pushrod, putting it at a little bit of a downward (toward the master) angle, which seems funny to me, and not right. That's my only concern, but my fear may be unfounded once I try it in real life. EDIT: I think the hole may be in the same place, just the mounting holes are not. Don't know. I think I just need to get one, then it will make sense!

Anyway, thanks for the info!

 

[NoCar340]

The top two studs on the adapter go through the original upper mounting holes. Use the bracket itself as a template to clearance the lower master cylinder hole and the other bolt holes. The aluminum manual cylinder has studs pressed into it that go through the firewall have the nuts on the interior side of the firewall. Those hold the bottom of the reinforcement/adapter plate in place. The manual cylinder sits lower because there's no linkage other than the pushrod on the inside of the car. It bolts right to the pedal, and the other end is retained in the master cylinder by a rubber "clip" that just looks like a small chunk of vacuum line.

The green plate is for older cars with iron 4-bolt masters, the MP-style unit shown is to adapt that to the manual 2-bolt cylinder. The bottom one is the manual two-stud adapter plate used on the later cars. I can't remember the year spread, but I think the '76-'77 cars had the iron four-bolt cylinders while the '78-'83 (including all J/Y bodies) used the two-bolt aluminum setup. My manual setup came out of a '78 Volare Premier 4-door with a Super Six and a 4-speed.

 

[72Dodge]

THANK YOU! Yes, that makes so much sense now. Of course it would sit lower without the booster linkage in there.

So it looks like, if I'm understanding correctly, I need a factory plate from something like a '78-'83 (or so, I understand) car, OR it seems like I could use the earlier plate, then just get the MP adapter and drill the 2 extra holes... that seems a roundabout way of doing it of course. Alternatively, since I now understand how it works, I could just make one myself. If I can find the ~'73-'83 plate, great... if not, I will make one.

Thanks so much again!

 

[DCAspen]

That master cyl plate photo is mine.I am converting to man. brakes on my 80' Aspen.I'll look in my parts book and see if the J-body uses the same adapter.The green one is for 76-78 4 bolt master cyl.79-80 F-body uses the 2 bolt master cyl.that attaches with 2 nuts inside the car,4 bolt master cyl. have the nuts in the engine compartment.

 

[72Dodge]

That master cyl plate photo is mine.I am converting to man. brakes on my 80' Aspen.I'll look in my parts book and see if the J-body uses the same adapter.The green one is for 76-78 4 bolt master cyl.79-80 F-body uses the 2 bolt master cyl.that attaches with 2 nuts inside the car,4 bolt master cyl. have the nuts in the engine compartment.

Thank you!

 

[NoCar340]

Manual brakes went dodo at the end of '80 and were never available on J-cars, so you're looking under the hoods of F and early M-cars only for the 2-bolt plate. The drawback with using the 4-bolt plate and the adapter is that you're starting to get into an awfully long pushrod... flex might be an issue.

On the subject of pushrods, there are two different ones. There's a thick one with two flats near the bolt hole, and a thin one that's just round in that area. The round one will work with the original pedal bolt; the thick one used a special bolt with a longer shoulder on it. It's steel, though, so it can be safely ground to fit if it's the only one you can find. Just make sure it moves freely on the bolt before you install it. Binding is bad, especially in a panic situation!

 

[72Dodge]

Thanks again! If I don't find an original one, i was going to use this adjustable one from Mancini. Will this one work for this application?

http://chucker54.stores.yahoo.net/manadbrakrod.html

 

[DCAspen]

Checked my parts books,3766120 bracket for man. disc HNFG.The firewall is different,You would have to open the hole the pushrod goes thru on the bottom.The bolt pattern for the 4 bolts is the same and the F-Body plate lowers the master cyl.I don't see why it wouldn't work with a little firewall trimming.The pushrod end in the picture looks just like my manual one.

 

[NoCar340]

Yep, that's the right pushrod on both ends. The one with the flats is much thicker than that.

 

[72Dodge]

Sweet. Thank you all for your help. The search is on for a manual bracket to complete the conversion! I ordered the last of what I need to convert to manual steering too <gasp!>.

 

[NoCar340]

I think the manual-disc upgrade is one of the best mods one can make to any Mopar. My first FMJ car was a full-manual Nightwatch Blue '80 Aspen, Super Six/4-speed. I loved the way that car drove, and have done several manual-disc conversions since that one.

 

[72Dodge]

I agree. Plus, in this case, it's a bonus that it's costing me quite a bit less to just go all manual than to replace all the missing power items on my car. I also think the guy before me didn't have a fully baked plan because he put his custom big block mounts right in the way of where the power steering pressure hose needed to mount... on the brand new power steering gear he installed - doh! So I was going to have to either cut out the mount he made (I'm leaving it in, in case I want to go big block later), or go manual steering anyway.

 

[72Dodge]

OK, enough already with this.... after some more soul searching, and more frustration with trying to find the right parts to convert to manual brakes, I decided to take High Speed Pursuit's suggestion and use an '83 Omni booster and master. I don't like the overboosted feeling, but I'd guess this smaller booster will reduce that, and should still work more happily with my big cam. It'll be fine.

Thanks again ALL for your help, I learn so much from these explorations of things I don't know about, now I know a lot lot more about Mopar brakes.

EDIT: It's still going manual steering though, have everything I need for that except the Firm Feel adapter that I'll get in the spring.