Technical Need smaller bore clutch M/C that looks period correct?

Does anybody know of a Brake or Clutch M/C that is smaller than 1.0625? My M/C is up on the firewall so it needs to be an old design for looks. I am running both master and slave cylinder that are 1.0625 and my clutch is a bear to depress on the flathead 3 speed. My current master is a '57 ford truck clutch master and I am using a 62 chevy truck slave. Or does anyone know were I can send my master cylinder to get a sleeve put into it to reduce the area of the piston? I cant increase the length of the arm on the clutch fork input shaft, because it is right under the floor now. ??

 

You may check the bore on a '55 Chevy master. Those look about the same and maybe the chebby is smaller bore.

 

Why not use the 1962 Chevy master cylinder that goes with the slave, it is side by side style. Brake on one side, clutch on the other.

 

Check out White Post Restorations.....(One Old Car Dr.,White Post , VA, 22663).
www.whitepost.com
They offer sleeving services, & have advertised in Hemmings for years.

 

Because the bore on that combo is 1.125 each or larger. Apple Hydraulics is another that will sleeve..Stainless Steel brakes used to..

 

Used this one on my coupe.

 

My limited research has shown that usually the mast cyl & the slave cyl have the same bore diameter. Increasing the slave cyl bore diameter or decreasing the mast cyl bore diam will decrease the effort needed at the pedal. Either method will also reduce the travel of the slave cyl piston. Greg

 

What is your pedal ratio. Needs to be about 6 to 1

 

My pedal ratio is 6 to 1. My Master and slave are a both about 1". The 62 chevy truck salve is about 1" dia. as is the 55 chevy master. The problem is that my flathead tranny's input shaft arm is the same length as the arm that pushes on the throw out bearing. They are both 3.5" So I have no mechanical advantage after the force comes out of the slave cylinder. Most slave cylinders push on an arm that has some mechanical advantage on the throw out bearing. Thanks for the names of the shops that can sleeve a cylinder. I am going to try an MGB salve cylinder 1st, because they are cheap. It is a 1-1/4" bore slave and should help a lot if I can manage to adapt the hydraulic line to attach to it and if it will move far enough at the slave end. I will post the results. If that does not work I will be contacting one of those shops to reduce the bore on my Master. Thanks to all who responded. I appreciate the help. Here is a picture of what the setup looks like to illustrate the heart of the problem having to mechanical advantage on the throw out bearing.

 

I used the MGB slave on my 327/4 spd powered MGB and it worked ok. It just barely had enough stroke so I had to stay on top of the adjustment. But I was moving a Chevy fork. I seem to remember it had about 3/4-7/8” of stroke.


Sent from my iPhone using The H.A.M.B. mobile app

 

A 40 to 48 Lincoln clutch arm is longer than that if that would help decrease the effort, but being longer you would need more throw on the slave cylinder. I have one at home and will try to measure it tonight.

 

To add to Jason's post, is it possible to move the slave mount upward if you were able to lengthen the clutch arm?

 

That's good to see it worked for you. Do you remember if you had a hard time making a line to go from the MGB slave to the Master you used? I hope it does not have some weird thread. ?

 

My current arm is right under the floorboard. I cant use a longer arm unless I want my clutch slave were my gas pedal should be. Thanks for the effort!

 

No. I cant move it up, the are is right at the bottom of the floorboard now.

 

MGB thread is 3/8"-24 UNF

 

The resleeve shops are now charging BIG bucks for their work, I called them all! Instead I took a '62 Chevy truck dual brake & clutch master cylinder and re sleeved it myself, pretty easy, the hard part was finding the internal guts (rubber, Etc.) for the downsizing. The Bronze sleeves can be bought off the net, than honed with brake master cylinder hone. The downsizing was a noticeable difference in pedal (to the good) but I would like to go another 1/8" but can't find compatible internals...………………..

 

The MGB save cylinder I got in the mail yesterday has 7/16-20 straight threads for the line going into it. That is the same as the input threads on a 1939-1948 ford wheel cylinder. Both seal using the brass washer. Last night I verified an early ford front flex brake line will plug right into the MGB slave cylinder. I verified it with an old flex line that is not usable, so I have ordered a new early ford front flex brake line, and will be reporting out how it all works (or not) I believe that flex line will work as an adapter to get me from the MGB slave to the 1/4" line that goes into an early ford Master Cylinder. ? We will see. Not claiming victory yet, but it is looking pretty good. The MGA slave has existed since 1955. Someone has figured this one out a long time ago if it works.

here is the clutch slave I am talking about at Moss Motors
Clutch Slave Cylinder by Classic Gold, 1-1/4" bore
$15.99
PART # APPLICATION
180-715 1955-80 MGA, MGB

https://mossmotors.com/clutch-slave...MI_8-3ttyh6AIVQb7ACh1fYQpXEAQYASABEgLeVvD_BwE

 

Just musing here, what clutch are you using and are there lighter clutches available? Truck vs car, performance vs standard, custom sprung vs stock?
Too light a spring pressure could allow slippage but maybe yours is excessively heavy?

 

I am using what ever was bolted to the back of the truck engine I bought. It was not a hotrod. Just an old truck. I have no reason to think it is stiffer than OEM. But thanks for helping.

 

Hmm haven’t ever seen this brought up. Following along to see what you end up doing to make it work.

 

How much did you downsize the master?

 

The heavy pedal is with you in the driver seat using normal leg pressure correct?
I know dumb question but this is not just pushing the pedal with your hand right?

 

Doug, Very hard pedal with no travel or stopping power, downsized from 1 1/8" to 1". Was a step in the rite direction but would like to go to 7/8" but haven't found the internal "guts" yet. A side note here I was using the '62 GM truck master for brakes only, the one marked brakes for the front, the one marked clutch for the rear brakes. The principle should be the same no matter what's at the other end of the hydraulic line...………………………...

 

Right. Setting in the seat I can push it with my foot. But it is very heavy. I have a high performance clutch in my 67 mustang and understand what you meant before about them being a little heavier than normal. After studying it a bit I have learned that if you have a master and a slave that are the same bore, then usually there is some mechanical advantage gained by the slave pushing on a clutch fork. Of course flathead three speeds dont have a fork. They have an input arm. I cant go any longer on my input arm or it will hit my floorboard. thanks for your help

 

That's good info. Based on that, going from a 1" master & 1" slave ratio to a 1" master & 1-1/4 slave ratio might be pretty good. Fingers crossed.

 

Here is what the MGA slave looks like.

 

If you want to find some smaller guts for you master, you might try looking at MGA/MGB master internal. I think the master is 5/8 bore. They used really small master bore with really large slave bore.

 

Brigrat. Here are two master cylinders that use a 7/8" bore if you want to use their internals. Cardone 13-49221 & 3-55642. If you want 3/4" bore look at Cardone 13-36469. The 13 in the p/n means new, if it has 10 that means it is rebuilt. Here is the link to the Cardone catalog that was given to me by a friend.

http://pageturnpro2.com.s3-website-us-east-1.amazonaws.com/Publications/201407/3154/56617/PDF/130487993789071126_CARDONE%20Automotive%20Master%20Cylinder%20ID%20Guide_MCID14.pdf

 

1.062 is a large bore for a clutch master, okay for where it belongs but tough for what you are doing and the limited space. I run a .750" master and .875" slave and it works well.