Master cylinder
 

What master cylinder is commonly used with a juice brake conversion? My 37 has 40 hubs and I think a ford (mustang?) dual reservoir master cylinder.. I have blead and adjusted them twice now and still have a low pedal.. It has residual valves on both lines..Thinking maybe the bore is to small.. I sure would appreciate some advice..
Thanks in advance..

Re: Master cylinder
 

67 mustang is commonly used. There are two types, disc/drum and drum/drum. The disc/drum has different size resvoir, the durm/drum are equal. Make sure the shoes are adjusted properly and bleed them starting with the furthest wheel cylinder. Sometimes it takes a couple of tries to get all the air out.

Re: Master cylinder
 

Thanks.. Mine is a disc/drum type. Any idea if there is a difference in the bore size? I would think the disc brake cylinder would have a larger bore?? I have blead probably a quart of fluid through it and adjusted them twice... Still... Low pedal..

Re: Master cylinder
 

The link on mine was short. pedal up and just touching piston with good return spring.
Gravity beed MC high point.
I did get a MC from speedway NG got another from NAPA.

Re: Master cylinder
 

In my opinion the mustang master cylinder is to small a bore, it's a good chunk smaller than a stock 40 type master cylinder.
I use the stock 40, single circuit I know but it works good.
Martin.

Re: Master cylinder
 

The mustang cylinders commonly used are a 1" bore. The stock cylinder is 1-1/16" bore. I reworked my roadster from a 1" to a 1-1/16" and improved the brakes. Counter intuitive you might think, but it got the brakes on quicker and the braking is done at the sweet spot in the pedal.

My 33 has great brakes with a stock 39 type cylinder, and 39 pedal box.

The 1-1/16" dual cylinder I used was for a mid 70s E250 van. It's massive compared to the mustang unit, which is a downside.

Mart.

Re: Master cylinder
 

Are you using 1/4" or 3/16" brake line? The disc/drum master cylinder was intended for power brakes and the drum/drum master cylinder for manual brakes. The disc/drum master cylinder should be 1" bore. In general as you increase bore size you increase the effort you have to apply to the brakes and decrease line pressure. The advantage is increased volume of fluid in the lines. Ford used the larger diameter brake lines and a larger bore size. In modern cars most larger bore master cylinders are used with power boosters because of the increased pedal pressure required. I would think that a "low pedal" would indicate some other problem in the brake system. Increasing the bore size of the master cylinder will decrease pedal travel, but it will also require increased force (leg effort).