The Ford Barn

Bassman/NZ · 11-08-2011, 02:01 AM

Is a dual master cylinder with a 1" bore and about 1 1/4" stroke going to work with my 39 front brakes and 47 pickup rears?
Thanks, Marty.

FlatheadTed · 11-08-2011, 02:17 PM

I would say it should .I used a MK 2 zepher on this set up once and it didnt because the bore size of the MC was 5/8 .So the displacment was not matched .You need at least the size of the stock 39 MC .

Richard (EV8G) · 11-08-2011, 07:46 PM

The bore of the original 39 MC is 1-1/16", or 1/16" larger than the dual MC. This will work, but will require slightly more pedal travel to push same amount of fluid, but pedal will be a little easier to push. You do need to confirm that the pushrod stroke (resulting from full available pedal travel, including about 3/8" for free travel at pedal and 1/16" at pushrod) is equal to or exceeds the full stroke of the MC. See my recent other post regarding dual MC's. Also, IF the new MC has no built-in residual pressure valves, will need to use external 10lb valves as near to the MC as possible. I am aware of ONE MC # that has built-in valves for 4-whl drum brakes, but there may be others; someone may know...

You don't say what year/model your vehicle is, but space above the dual MC
can be an issue/problem, as well as toward the rear of where the original MC
was located... Need access for the typically larger "lid" so have to cut a bigger
hole usually...

Bassman/NZ · 11-08-2011, 09:10 PM

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Thanks Richard. Its an AV8, space is not a problem. The m/c is Australian Holden, I will have to check whether it has the residual pressure valves. Here in NZ it's a legal requirement to have dual m/c on a new build.

11-08-2011, 02:01 AM	#1
Bassman/NZ Senior Member Join Date: May 2010 Location: Napier, New Zealand Posts: 2,001	Brake question... Is a dual master cylinder with a 1" bore and about 1 1/4" stroke going to work with my 39 front brakes and 47 pickup rears? Thanks, Marty.

11-08-2011, 02:17 PM	#2
FlatheadTed Senior Member Join Date: May 2010 Location: Auckland Posts: 4,755	Re: Brake question... I would say it should .I used a MK 2 zepher on this set up once and it didnt because the bore size of the MC was 5/8 .So the displacment was not matched .You need at least the size of the stock 39 MC . __________________ http://www.flatheadted.com Flathead Ted brake Floaters ,

11-08-2011, 07:46 PM	#3
Richard (EV8G) Senior Member Join Date: May 2010 Location: La Verne CA Posts: 432	Re: Brake question... The bore of the original 39 MC is 1-1/16", or 1/16" larger than the dual MC. This will work, but will require slightly more pedal travel to push same amount of fluid, but pedal will be a little easier to push. You do need to confirm that the pushrod stroke (resulting from full available pedal travel, including about 3/8" for free travel at pedal and 1/16" at pushrod) is equal to or exceeds the full stroke of the MC. See my recent other post regarding dual MC's. Also, IF the new MC has no built-in residual pressure valves, will need to use external 10lb valves as near to the MC as possible. I am aware of ONE MC # that has built-in valves for 4-whl drum brakes, but there may be others; someone may know... You don't say what year/model your vehicle is, but space above the dual MC can be an issue/problem, as well as toward the rear of where the original MC was located... Need access for the typically larger "lid" so have to cut a bigger hole usually... __________________ Early V8 Garage Pasadena Roadster Club

11-08-2011, 09:10 PM	#4
Bassman/NZ Senior Member Join Date: May 2010 Location: Napier, New Zealand Posts: 2,001	Re: Brake question... Sponsored Links (Register now to hide all advertisements) Thanks Richard. Its an AV8, space is not a problem. The m/c is Australian Holden, I will have to check whether it has the residual pressure valves. Here in NZ it's a legal requirement to have dual m/c on a new build.