Replacing MC on a 66 with a dual bowl

[maw]

Didn't want to hijack John K's post but after seeing RB64"s pic of his dual bowl I was wondering if you would give us some details on your setup.
What is that off of and where did you get that? Part #'s??? What booster did you use? Does it all work well together? I like the idea of having the PV in a place where it is easy to adjust. Do you have discs on the rear also? I want to put a dual on mine, I have discs on the front and drums on the rear and don't want to change that. Any replies greatly appreciated

Thanks Mike

[RedBird64]

Hi Mike!
I installed brakes off a 65/66 so I have the same brake setup as you now.

To answer your questions:
The Master cylinder is for a 1969 Mustang V8 with Disc/Drum brakes. It's Raybestos P/N MC 36251 ($33.79) from Rock Auto. It is an appropriate piston dia and has the same stroke as what you have now.

My booster is stock for a 64 and works great. Your booster is even better so there's no need at all to change it or do anything to it.

As far as the adjustable PV, you wound't really need to use it. You can keep your original in place unless you have reason to do otherwise. The way I mounted it makes for a very close/tight fit. If you use the new adj PV, you'll want to remove your old PV because you don't want to double-regulate.

I do not have disc's on the rear. This MC is for Disc/drum only.

To use this MC, all you would have to do is install it. No other modifications would be required other than a brass adapter to go from your lines 3/8-24 IFM to the MC's 1/2-20 IFF to get your brake line fittings connected. I got them from Speedwaymotors.com. Link:https://www.speedwaymotors.com/Earls-00 ... 90740.html
Assuming your present setup works fine, nothing would feel or work much differently with this new dual MC.

If you go this route, let me know how it goes!

Scott

PS; If anyone has a dual 9" booster off a 65~66 T-bird, working or not, and want to get rid of it cheap or free, I'd sure like to have it (I'd happily pay shipping). I need it to make sure I have enough clearance next to my aftermarket VC's for a larger booster before diving in and buying an expensive rebuilt part. If it works, I'd use it as a core.
Thanks in advance,
S

[paulr]

Scott,

If the OP is running a stock 65/66 booster it will involve considerably more length from firewall to brace. Aside from the valve cover issue, when you bolt on the 69 'stang disc/drum master will there be room inside the curved brace for all that? Just asking.

[RedBird64]

Good question Paul.
Looking at mine, the MC can move 3/4 to 1" towards the front of the car before you'd run out of room for the front-most line to connect. However, If the MC moves foward at all there wont be any room for the adj. PV to mount like I have it. It could be mounted elsewhere though.
I know you've had a dual booster (65/66) in your hands, any idea how much thicker it is?

S

[paulr]

I shoulda measured when I had a 65 booster here recently (May have another chance coming up). It’s big. A guess: it’s around 3” deeper front to back than a ‘64. I think that’s conservative.

Every time I bang my head up against this calculus I start thinking about hydroboost for fitment reasons. Then, I look at the budget and cry. but, I’m not willing to chop or remove that brace. (Currently using a curved 65 brace).

[RedBird64]

I have been looking at pictures of 65 and 66 Tbird engine compartments and the large round MC doesn't seem to sit that far forward. In fact, it takes up the same space mine did. The dual MC takes up the about same distance (maybe 1/2~3/4" more) as the big single does so I suspect Mike will be OK. It could be that the years later than my 64 have different linkage, firewall or something else that makes up for the bigger booster.

1966 eng bay:
https://cdnstatic.specialtysales.com/up ... 874aa6.jpg
I'm not sure I started out with even that much room!

Scott

[wallyblackburn]

Have to admit to being a bit confused... So, it seems like we still aren't sure if this MC will fit on a 65-66 with the original booster and stock braces, right?

I really want a dual MC on my '65. I found this same unit on Amazon:

https://www.amazon.com/Raybestos-MC3625 ... B000C71JX8

and ordered one. I currently have MC off of mine trying to put some lipstick on this pig of an engine bay. I'll try and fit this baby up and see how it goes. I'll report back with status and pics.

Thanks guys,
Wally

[RedBird64]

I believe it will fit because it sits in the same location as the large round MC you have now. The dual MC has smaller resevoirs and isn't much bigger overall - probably just slightly longer.
I think it will fit fine.

You will want to check your pushrod length to make sure it works as well as possible.

[wallyblackburn]

Not gonna fit without some mods to the guide plate and dash panel brace.

Dual bowl is a bit longer.

Guide plate goes on - could just be ground away a touch.

But dash panel brace is another story. Afraid if you cut that part away, you're gonna lose too much strength in the stamped steel part.

Maybe fabricate a tubular steel one or weld on something to strengthen after cutting some away?

Tight, but a 90 adapter should fit.

[wallyblackburn]

Shaped the brace for clearance and welded in a piece of 1/8" steel for strength.

Still need to clean up a little more and paint it.

[stubbie]

Nice Wally. As my old man used to say " Where there's a will, there's a way"

[RedBird64]

Yes, that is really nice work! Looks like it might be a challenge to get the front fitting in though. It was close, but not that close for me.
Sometimes it just takes trying a few different things and pressing on even if it costs something or takes lots of time. Sure was worth it in this case. It's guys like you that have the patience to put tons of effort into the little details who end up with the best product and the most admiration at shows.


S

[wallyblackburn]

You guys are very kind! I really don't live up to it...

Anyway, now I have a dumb question about the lines to this new MC:

I think I need to run one line from the circuit closest to the booster to the proportioning valve for the back brakes. And then I need to run the line from the front circuit into a Y-fitting to send to both sides of the front.

Is that right?

Thanks,
Wally

[stubbie]

Do you still have the brass block from the front of the single pot? You could use that and I think you would use the bigger chamber for front brakes. Although I have said before I'm not a brake expert.

[RedBird64]

Stubbie's got it.
The larger resevoir is for the disc brakes and the smaller one is for the drums. So the prop valve needs to connect to the forward, smaller res.
I used the old brass block for the front brake lines and tapped the end hole for the brake light switch.

Scott