65\' brake question #2--dual master cylinder

I want to replace my stock jelly jar master cylinder on the GT to one with a dual master cylinder.

It has the factory standard DISC brakes on the FRONT, and the standard DRUMS on the REAR. Of course it has the factory proportional valve mounted for the rear drums.

I've considered using one from a 67' disc brake stang, but have heard that there may be an additional valve located near the rear axle. Don't know if it is equivalent to my GT front mounted proportional valve. The 67' disc type also has is power controlled, which is something else I wish to install (separate post.)

Anyways, what dual disk brake master cylinder should I use on a basically stock 65 GT with or without PB?
[addsig]

What you've got to watch is what the MC cyl bore and stroke are. Bore is the big difference in MCs - to keep it simple, I'd use a dual piston mc out of a similar weighted vehicle, maybe a mid 80s 4 door granada. It'll probably be around a 7/8" bore and will move the right amount of fluid to work your brakes with a decent feel. Too big results in you having to apply more pedal force to stop the car. Too small and you'll lock em up with very little pedal input on your part.

A large bore MC will move more fluid volume but at a lower pressure. Whereas a small bore MC moves less fluid but at a higher pressure.


[addsig]

Here is the mc I picke up. Appears to be solid unit. I have not installed it yet in my 65. I two have factory front disc and drum rear..i bought
the ssbc rear conversion and was recommended this mc to use w/
adjustable prop valve. i don't plan on having a power booster however. manual is find w/ me as i have a cable cluth set up and t5 to go in it and i've seen that there is a major inference issue on 65/66 if you plan to run a power mc w/ cable clutch

http://www.mustang-50.com/itemdy01.a...atKey=EMUSTANG

The master in that pic is from a linc mk VII for power brakes.
You can get it in manual too-standard euipment on 84-86 mustang SVOs.

Both are cheaper from a parts store than $110.

Im using a manual one on my 68...bolts right in, stops well. Pedal is noticibly stiffer than the stock 68 drum/drum manual, but this is a manly car.

Good excuse to keep the gf/wife/etc from driving it.

<font size=-1>[ This Message was edited by: ChicoB on 1/6/06 5:43am ]</font>

<font size=-1>[ This Message was edited by: ChicoB on 1/6/06 5:46am ]</font>

To my kowledge, there is not an additional valve near the rear axle, there is however, a distribution fitting mounted on the rear end housing that splits the rear brake line into two, one for each rear brake.

I paid about $63.00 for the same MC through Rockauto, including shipping, that is mentioned in ChicoB's post.

There is not additional valve after the prop valve. They might be thinking that the brass mounting block on the axle is one. It's not, just where the hose comes in and splits the line.

When I did swaps for a living for Global West, we'd use
the Granada/Versailles master cylinder for that app.
(1965 and up Mustang, disc front drum rear)
If it's still stock in the front and stock in the rear, that's
the master to use. The Granada with manual brakes,
disc front, drum rear is the model. I think I recall the
bore of that master being 15/16-inch. It has the check
valve in the rear port that is required for rear drum
brakes. You don't wanna go crazy with the bore dimensions
either. It's an inverse-square math equation.... just increasing
the dimension as little as 1/32-inch at the bore increases
the pedal pressure in a big way.

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
On 2006-01-05 18:30, gt289 wrote:
When I did swaps for a living for Global West, we'd use
the Granada/Versailles master cylinder for that app.
(1965 and up Mustang, disc front drum rear)
If it's still stock in the front and stock in the rear, that's
the master to use. The Granada with manual brakes,
disc front, drum rear is the model. I think I recall the
bore of that master being 15/16-inch. It has the check
valve in the rear port that is required for rear drum
brakes. You don't wanna go crazy with the bore dimensions
either. It's an inverse-square math equation.... just increasing
the dimension as little as 1/32-inch at the bore increases
the pedal pressure in a big way.
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR></TD></TR></TABLE>

Thanks for the info, gt289.

Yeah, the 75'-80' manual disc brake Granada master cylinder does sound like a good candidate. You are correct that it has a 15/16" bore.

The stock 65' disc jelly jar MC already has 2 outlets that can be rerouted to the new master. One goes to a normal T where it is split to run to both front brakes. The second goes into a remote proportioning valve which is specifically tied to the rear brakes.

My one remaining question concerning using this master cylinder is can I still use the stock 65' proportioning valve? Will it probably have the right adjustment as is or will I need to spring for one that is fully adjustable to complete the Granada MC swap?


[addsig]

I'd try the stock proportioning valve -if it has a residual pressure check valve in it you'll eat front pads due to excessive drag. Also make sure you can stop evenly = front or rear don't lockup excessively easily.
[addsig]