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Brake Master Cylinder Replacement


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Replacing my '71 brake MC with a Wilwood 1" MC due to an upgrade of the front brakes to the Toyota calipers.  The old Datsun MC has the front reservoir used for the rear brakes and the rear one for the front brakes.  There is also a "R" and "F" stamped under each reservoir.  The Wilwood MC has the "F" and "R" in reverse order so I assume the front reservoir is meant for the front and vise versa.  Due to the old brake lines entering the MC underneath being to short the stretch to the opposite inlets of the new MC can I still hook up the brake lines the way the old MC was connected?  Is there a difference between both?  Thanks for the help.    

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The difference between the front and rear master sections is the reservior size and the check valve. If you still have drum rear brakes you need to make sure the check valve is in the section used for the rear brakes. If you have disks in the rear make ure to remove the check valve. The reservoir size is larger for the front disk to allow for fluid level the drop as the pads wear. You should be able to move the check valve and reservoir as needed.

Edited by beermanpete
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I have drums in the rear.  So I assume that as long as the check valve is in the front section/reservoir then I can still position the rear brake lines to the front section and the front lines for the rear section (without the check valve)?  The check valve is what reduces the brake fluid volume for use in the rear drums?  Also, I understand the removal of the check valve but what is meant by removal of the "reservoir"?

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Miles,

 

Appreciate you pointing me to the other forum questions/answers but with reading it several times it still does not answer my question.  With my old MC the hard brake lines were positioned so that the rear line were placed under the rear reservoir and front brake line under the front.  The Datsun MC is labeled with a "F' under the front reservoir and a "R" under the rear.  The Wilwood F and R is just the opposite.  My hard lines will not stretch far enough to retain the same positioning as the old MC.  Can I run the rear lines to the rear of the new MC even though there is a "F" stamped under the rear reservoir?

 

Thanks, Tom 

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Tom, you do NOT want to skimp on your brakes for obvious reasons. dont mess around with brakes without a GOOD understanding of what you are doing! Your putting your car, yourself and others in harms way.  My suggestion is to get  new lines made to size with the appropriate fittings size's , the wilwood is a american standard size threads and the originl dastsun fiting sizes are metric. here is a great thread that explains it all! I don't mean to sound like a A___E but the few dollars and hours your trying to save is just not worth it. That's my 2 cents!

http://forums.hybridz.org/topic/102754-a-one-inch-diameter-brake-master-cylinder-for-the-s30-z-cars/

Edited by fastzcars
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If memory serves me, the 71 240Z MC has the front and rear lines reversed compared to 72 and newer. The tanks are also reversed on the 71. 

 

The Wilwood connects like the 72 and newer 240Zs.

 

Actually there are many posts here and over at ClassicZcar.com that deal with this issue. So keep researching.

 

 

Beermanpete gave you a solution to the line orientation and checkvalve issues.

 

 

Are you sure that the Wilwood is the reverse of the original?

 

Looking at the Wilwood site, it seems to follow convention (rear port/reservoir to front brakes, front port/reservoir to the rear brakes).

 

260-8794-lg.jpg

Edited by Miles
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If memory serves me, the 71 240Z MC has the front and rear lines reversed compared to 72 and newer. The tanks are also reversed on the 71. 

 

The Wilwood connects like the 72 and newer 240Zs.

 

Actually there are many posts here and over at ClassicZcar.com that deal with this issue. So keep researching.

 

 

Beermanpete gave you a solution to the line orientation and checkvalve issues.

 

In Sharkey's original post he said this:

 

 

 

 The old Datsun MC has the front reservoir used for the rear brakes and the rear one for the front brakes.

 

This sounds to me that it's the same as the Wilwood master cylinder as far as which port feeds which end of the car.

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Six Shooter, Miles

 

You are correct in that the '71 has the rear reservoir (smaller) servicing the rear brakes and the front (larger) servicing the front brakes.  That is the way my brake lines are situated. The newer Datsun MC reservoirs are reversed. 

 

As shown in your photo of the Wilwood MC the "F" is under the rear reservoir and the "R" is under the front reservoir.  Since my lines are not long enough to reverse position can I hook my rear brake lines to the Wilwood rear reservoir even though the is a "F" designation below the rear and the front lines to the front of the MC which has a "R"? 

 

My check valve is located only in the rear of the MC because I still run rear drums.

 

Fastzcars

 

Thanks for the advice.  I have made the correct Metric to American Standard fittings with a female 10x1.0mm convex seat to a 3AN male.  I had to shave off the convex seat to fit but it works. 

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Six Shooter, Miles

 

You are correct in that the '71 has the rear reservoir (smaller) servicing the rear brakes and the front (larger) servicing the front brakes.  That is the way my brake lines are situated. The newer Datsun MC reservoirs are reversed. 

 

As shown in your photo of the Wilwood MC the "F" is under the rear reservoir and the "R" is under the front reservoir.  Since my lines are not long enough to reverse position can I hook my rear brake lines to the Wilwood rear reservoir even though the is a "F" designation below the rear and the front lines to the front of the MC which has a "R"? 

 

My check valve is located only in the rear of the MC because I still run rear drums.

 

Fastzcars

 

Thanks for the advice.  I have made the correct Metric to American Standard fittings with a female 10x1.0mm convex seat to a 3AN male.  I had to shave off the convex seat to fit but it works. 

 

Yes, you can connect the rear brakes to the port marked "F" and the front brakes to the port marked "R". The piston size and other internal parts in the master are identical in each section. As long as you install the check valve in the port you connect to the rear brakes it will work fine. The Willwood master has the same size reservoirs so that is a non-issue. If you want to use the original Datsun reservoirs (and they fit on the Wilwood master) install the large one in the position on the master that is connected to the front brakes and the small one for the rear.

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  • 3 weeks later...

I'm running this 1" Wilwood setup now with a stock 240z booster.

I had to remove internal checkvalves in the Wilwood.

I have Toyota S12W front and 280ZX disks rear with a manual proportioning valve.

DTC60 front pads and DTC 70 rears with the adjuster about halfway (limiting rear brakes).

 

The pedal is amazing..  Very very strong brakes. 

Great pedal feel.

 

Done messing with brakes for a while, this setup should do me well.

Tj

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I'm running this 1" Wilwood setup now with a stock 240z booster.

I had to remove internal checkvalves in the Wilwood.

I have Toyota S12W front and 280ZX disks rear with a manual proportioning valve.

DTC60 front pads and DTC 70 rears with the adjuster about halfway (limiting rear brakes).

 

The pedal is amazing..  Very very strong brakes. 

Great pedal feel.

 

Done messing with brakes for a while, this setup should do me well.

Tj

 

Are you running those pads on the street or track only?

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