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Using A Brake Mc For The Clutch?

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Best Answer Spider , 06 November 2017 - 03:00 AM

There's a couple of problems here with using a Brake M/C for the clutch.

 

The flange orientation isn't right, as you've found out, but that's the least of it.

 

Brake Master Cylinders have a residual pressure valve in them that retains around 4 - 10 psi in the system, and it also slows the flow back rate, once the pressure gets below about 30 - 50 psi. This won't do your thrust bearing much good.

 

Also, the Bore Size of most Mini Brake M/C's is only 0.70" and the Clutch ones are 0.75". While this will give a slightly lighter feel on the pedal, it also won't give enough travel at the clutch to allow for proper disengagement. You might - just - get away with it when everything is new and in perfect order, but as soon as you get any wear in it, you'll struggle shifting gears.

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#1 Kombi

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Posted 06 November 2017 - 01:30 AM

Dumb question time folks.

 

So a while back I bought a single reservoir master cylinder. So I replaced it with the one that looked the same and I now learn this was my clutch MC because I actually have a dual reservoir brake master cylinder.

 

So my question is, how big of a problem will this cause? The immediate thing I noticed was that the clearance between the brake lines and the new reservoir is non-existent.

 

I do have the original part that I can put back in place if necessary.

 

I hang my head in shame with a touch of disgust.  :shy:


Edited by Kombi, 06 November 2017 - 01:31 AM.


#2 Spider

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Posted 06 November 2017 - 03:00 AM   Best Answer

There's a couple of problems here with using a Brake M/C for the clutch.

 

The flange orientation isn't right, as you've found out, but that's the least of it.

 

Brake Master Cylinders have a residual pressure valve in them that retains around 4 - 10 psi in the system, and it also slows the flow back rate, once the pressure gets below about 30 - 50 psi. This won't do your thrust bearing much good.

 

Also, the Bore Size of most Mini Brake M/C's is only 0.70" and the Clutch ones are 0.75". While this will give a slightly lighter feel on the pedal, it also won't give enough travel at the clutch to allow for proper disengagement. You might - just - get away with it when everything is new and in perfect order, but as soon as you get any wear in it, you'll struggle shifting gears.


Edited by Moke Spider, 06 November 2017 - 03:01 AM.


#3 Kombi

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Posted 06 November 2017 - 07:05 AM

Blast. I wish I had thought to question this before I installed it.

I guess I'm glad I asked before putting it on the road and thankfully the old part is still around to replace it. But dang, what a waste of time and money.

Thanks for letting me know, I really appreciate the thorough answer.

#4 MIGLIACARS

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Posted 06 November 2017 - 09:53 AM

There's a couple of problems here with using a Brake M/C for the clutch.

 

The flange orientation isn't right, as you've found out, but that's the least of it.

 

Brake Master Cylinders have a residual pressure valve in them that retains around 4 - 10 psi in the system, and it also slows the flow back rate, once the pressure gets below about 30 - 50 psi. This won't do your thrust bearing much good.

 

Also, the Bore Size of most Mini Brake M/C's is only 0.70" and the Clutch ones are 0.75". While this will give a slightly lighter feel on the pedal, it also won't give enough travel at the clutch to allow for proper disengagement. You might - just - get away with it when everything is new and in perfect order, but as soon as you get any wear in it, you'll struggle shifting gears.

Some people just seem to know everything!







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