1971 Master Cylinder question

[Brushz]

My 240Z has the early design master cylinder. I recently replaced the vacuum servo unit with the MSA one.

 

When everything was reassembled and brakes were bled, the brake pedal was very stiff. When I removed the master cylinder the piston only moves about 1/8 of an inch when I push on it.

 

My question is how much force does it take to move the MC piston? Is the MC shot?

[duffymahoney]

Not a lot of force, mine was bad, same early design.  Ended up going wilwood. 

[Brushz]

Did you have to reroute the front and rear brake lines?


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[duffymahoney]

I bent my own lines, it was a pain, but it ended up working.  They are switched, it's hard to see in the picture.  

[gira]

Make sure there is free play in the rod, since you changed the booster

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[duffymahoney]

2 hours ago, gira said:

Make sure there is free play in the rod, since you changed the booster

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Hard to tell, but I think there is, it's depth matches stock.  

[Brushz]

Make sure there is free play in the rod, since you changed the booster

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Which rod? The booster moves freely with the brake pedal without the MC installed. With the MC installed there is almost no movement.

Does anyone have any experience with the remanufactured master cylinder available from Napa? From the photo it looks just like the OEM with the name scratched off.



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[duffymahoney]

2 minutes ago, Brushz said:

Which rod? The booster moves freely with the brake pedal without the MC installed. With the MC installed there is almost no movement.

Does anyone have any experience with the remanufactured master cylinder available from Napa? From the photo it looks just like the OEM with the name scratched off.



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Have them bring it to the store, if it's a stock reman then you are good, most likely it will be a knock off.  

[Brushz]

Have them bring it to the store, if it's a stock reman then you are good, most likely it will be a knock off.  

Can the guts from the new one be used to rebuild my old one?


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[gira]

The length if the rod that comes out of the booster and contacts the cup at the rear of the master cylinder. This length is very important and many times when you change the brake booster it throws the adjustment off. It may be slightly push the master cylinder piston in which messes everything up.

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[duffymahoney]

5 minutes ago, Brushz said:

Can the guts from the new one be used to rebuild my old one?


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They make rebuild kits for them, depends on what is wrong with yours.  

[Brushz]

I think I may have it figured out. The rod coming out of the vac is longer than the original. I'll swap the end nut with the one from the original one and hopefully the will solve the problem.


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