The elusive 7/8 bore master

[Ramcharger90]

So I was reading some dead threads about 7/8 bore masters and the lack of accessibility. I want to go with the Tilton internal slave but I would need a 7/8 master for the 10.5 clutch in the T5. I know many of these master are advertised as 7/8 but fall short. So besides making an adapter plate and push rod for a wildwood or similar priced master, What is a bolt on solution anymore. I was thinking about the modern driveline external slave since the Nissan slaves are such poor quality anymore and wiped out my mcloed clutch this time when it leaked around the bore.

 

[RonD]

Dorman lists them: https://www.dormanproducts.com/p-16962-cm39896.aspx

 

[Ramcharger90]

But are they actually 7/8?

 

[RonD]

That's what the specs say, I guess you would have to measure one
0.875 in = 7/8"

Math here: https://decimal.info/decimal-to-fraction/8/what-is-0.875-as-a-fraction.html

 

[Shran]

So if my research is correct... 83-87 should have a 3/4" bore, 88-91 is 7/8", 92-? is 5/8", does that sound right?

I have what I think is a 3/4 bore (1986) master and a Speedway push type 7/8 bore (but mine is on a NP435 four speed manual not a T5.) The clutch pedal is pretty stiff. Previously I had a '75 Land Cruiser slave that had a 3/4 bore and the pedal was much stiffer.

What exactly is your goal? Seemed to me that a smaller master and a bigger slave resulted in less pedal effort. I would like to try a 92+ master at some point and see if I can make it softer yet but I am afraid that I'll have to build a custom length push rod and modify some other things.

 

[Ramcharger90]

Im not sure if they are actually measuring the same size as they are advertised. I have found a few threads on here that claim the 7/8 bores are actually measuring 3/4 or there about. That Tilton internal slave requires a 7/8 master for proper function with the clutch I would be using. I guess I have to order a few and measure them but I'd figure if I could skip that step then I wouldn't have to return 2 other masters

 

[Rager351]

I HAVE AN 88 RANGER WITH A 3/4 BORE MASTER AND I'M USING THE TILTON INTERNAL SLAVE. RAM HD CLUTCH AND A TKO 600. WORKS GREAT WITH PLENTY OF CLUTCH DISENGAGEMENT. 3/4 BORE MASTER WILL PROVIDE LESS PEDAL EFFORT THAN THE 7/8 BORE MASTER. 7/8 BORE MASTER WILL MOST LIKELY REQUIRE A PEDAL STOP TO KEEP FROM OVER EXTENDING THE SLAVE PISTON.

 

[NakedDucks]

Why does the bore size matter?

 

[Shran]

Why does the bore size matter?

Increases or decreases the pedal effort depending on the slave cylinder you use...does not really matter for stock applications, mostly applies to engine/trans swaps

 

[Ramcharger90]

Why does the bore size matter?

Tilton called for a 7/8 master for their slave.

Also the m5odr2 slave needed a 7/8 master

Which I could never get it right.... bench bled a million times and tried different lenght rods. Still was never even 75% right.

 

[Rager351]

RC90, YOUR PROBLEM MAY BE THAT YOU DIDN'T GET ALL OF THE AIR OUT OF THE MASTER WHILE BENCH BLEEDING. I AGREE THAT THE 7/8 MASTER SHOULD WORK FINE. THE RANGER MASTER CYLINDERS CAN BE A CHALLENGE TO REMOVE ALL THE AIR FROM WHEN BLEEDING AS YOU PROBABLY ALREADY KNOW. I REMOVED MY MASTER AND RESERVOIR ALONG WITH THE LINE TO THE SLAVE CYLINDER STILL ATTACHED. I THEN HUNG ALL THESE COMPONENTS FROM A 6 FOOT LADDER AND BLED INTO A FULL CONTAINER OF BRAKE FLUID. TIP THE MASTER CYLINDER UP AND DOWN WHILE ACTIVATING THE PUSH ROD. TAPPING ON IT AS WELL WILL MOVE AIR THAT GETS TRAPPED IN THE LOWER PORTION OF THE MASTER. WATCH FOR AIR BUBBLES IN THE RESERVOIR AND KEEP BLEEDING UNTIL ALL AIR BUBBLES CEASE. CAP OFF YOUR LINE TO THE SLAVE WITH A RUBBER CAP. REINSTALL EVERYTHING AND ATTACH LINE TO THE SLAVE. BLEED THE SLAVE AND TEST. HOPE THIS WORKS FOR YOU.

 

[PetroleumJunkie412]

Why does the bore size matter?

Ask your wife.

 

[fastpakr]

RC90, YOUR PROBLEM MAY BE THAT YOU DIDN'T GET ALL OF THE AIR OUT OF THE MASTER WHILE BENCH BLEEDING. I AGREE THAT THE 7/8 MASTER SHOULD WORK FINE. THE RANGER MASTER CYLINDERS CAN BE A CHALLENGE TO REMOVE ALL THE AIR FROM WHEN BLEEDING AS YOU PROBABLY ALREADY KNOW. I REMOVED MY MASTER AND RESERVOIR ALONG WITH THE LINE TO THE SLAVE CYLINDER STILL ATTACHED. I THEN HUNG ALL THESE COMPONENTS FROM A 6 FOOT LADDER AND BLED INTO A FULL CONTAINER OF BRAKE FLUID. TIP THE MASTER CYLINDER UP AND DOWN WHILE ACTIVATING THE PUSH ROD. TAPPING ON IT AS WELL WILL MOVE AIR THAT GETS TRAPPED IN THE LOWER PORTION OF THE MASTER. WATCH FOR AIR BUBBLES IN THE RESERVOIR AND KEEP BLEEDING UNTIL ALL AIR BUBBLES CEASE. CAP OFF YOUR LINE TO THE SLAVE WITH A RUBBER CAP. REINSTALL EVERYTHING AND ATTACH LINE TO THE SLAVE. BLEED THE SLAVE AND TEST. HOPE THIS WORKS FOR YOU.

Check your Caps Lock button please.

 

[PetroleumJunkie412]

Check your Caps Lock button please.

He wanted to make sure we could hear him.

I turned my hearing aid up, but I still couldn't make it out.

 

[Roert42]

He wanted to make sure we could hear him.

I turned my hearing aid up, but I still couldn't make it out.

He’s all the way out in Michigan, it’s only reasonable to have trouble making out what he is saying.