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Discussion Starter · #1 ·
I am renewing my oem clutch master cylinder due to old age and would like to upgrade the clutch master cylinder with a Tilton branded one. From what I have read is that Tilton are a good quality brand.

Is anybody currently using the Tilton 75 series?

I have a clutch with 1350 kg clamping force (not yet installed), would a Tilton 3/4" bore clutch master cylinder be suitable with a the single port slave cylinder conversion?

Your thoughts and opinions please.
 

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Discussion Starter · #2 ·
Just to add, to quote the clutch manufacturer ATS & Across "Pedal effort is 30 % to 50 % heavier than the stock ".
 

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What are you trying to accomplish here? The stock master cylinder works fine with the Camry single port slave. Are you looking to get a shorter pedal distance? I think you need to contact Tilton to see what they say, it may only be for use with their slave and not meant as an upgrade for use with a stock slave cylinder.
 

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An extended clutch slave cylinder push rod (1/4” longer than OEM) is another additional option for making a shorter clutch pedal release disengagement. I used this mod on a rebuild and it works great with no issues. This is one source for this upgrade:
 

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Discussion Starter · #5 ·
I'm thinking that I might need a larger bore to compensate for the extra pedal effort. I read on this site that some people were considering the Tilton cmc, but they didn't report back. I will contact Tilton and see what they have to say.

If I end up buying a oem clutch master cylinder I will consider the extended pushrod.
 

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A smaller bore increases line pressure, but makes the throw longer. Too much smaller and you won't be able to displace enough fluid to disengage the clutch.
 

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Discussion Starter · #7 ·
So going smaller with a longer pushrod may help, but going larger will actually require more effort and less travel, correct?
 

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Longer pushrod doesn’t change travel relationship between pedal and slave cylinder.
Honestly, it’s always a red flag that you’re likely to cause thrust bearing issues when getting to a point where you need to change clutch hydraulics to release the clutch. It won’t happen immediately, but run this for a long time and it can cause way more bearing wear.
 

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The clutch hydraulics are a bit tricky. Trickier than brakes anyway. With the brakes it's all pressure based, there is very little fluid movement. So you can change the size of the master pretty much at will and it will change the feel of the pedal and not much else.

With the clutch it's the volume displaced that matters, since you are actually creating significant motion at the slave cylinder. A larger master cylinder will move more fluid and increase the distance traveled at the slave. That might be beneficial if you are having trouble getting the clutch to release, but you could also very easily get into a situation where you over extend the slave and damage the clutch, and you wouldn't know it until it's too late.
 

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Discussion Starter · #10 · (Edited)
I have been looking at other websites and it's made me think that I have been asking the wrong question. There is some math needed to answer this question and I don't have the numbers or experience for the equation.

I have a ATS & Across twin plate clutch with 1350 kg clamping force.
Single port Aisin slave cylinder conversion 13/16" (20.64mm).
Braided hose line.

Am I trying to over-engineer the clutch master cylinder or maybe I need a different size slave cylinder?

So in Layman's terms, what do I need to do (if possible) to make my pedal feel standard when the clutch requires 30%-50% more effort?
 

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So in Layman's terms, what do I need to do (if possible) to make my pedal feel standard when the clutch requires 30%-50% more effort?
I'm not sure that's possible, unless the new clutch requires significantly less travel, allowing you to run a smaller diameter master cylinder. That should require less effort, but will also move less fluid and therefore generate less motion on the other end. Also could get the same effect with a larger slave cylinder.

If you need the same motion at the other end, you would need to increase the motion at the pedal end in order to reduce the effort.

Twin disk clutches are definitely outside of my area of expertise.
 

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Discussion Starter · #12 ·
I think that the Supra uses the same size clutch master cylinder which lead me to this . . .
🤔
"upgrade to a race-grade Tilton master for the 1993-1998 Toyota Supra. The Tilton master cylinder kit is designed with racing clutches in mind and offers a larger bore size than the factory 5/8” unit which gives the driver a more consistent pedal feel through the entire range of travel.

This kit is offered with your choice of 2 compatible Tilton Master cylinder kits in either ¾” or 7/10” bore size. We typically recommend the ¾” for Tilton clutch kits or factory style single disk clutches without a heavy pressure plate. The 7/10” bore size is a great option for those with multi-disc or clutches with a heavier pressure plate."

Which has got me thinking that maybe a 7/10" bore size is maybe what I should use.
 

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Given the stock bore is 16mm (~5/8"), a 3/4" bore will increase your pedal force about 42%, while a 7/10" will increase it about 24%.
You're really unlikely to get stock clutch pedal force with a significantly uprated pressure plate and still be able to swing enough fluid around to actually disengage the clutch.
 
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