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Identify master cylinder bore


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 A previous owner upgraded this 510 with 280z front brakes and there seems to be a lot of pedal travel.  That can be corrected with a larger bore master cylinder but I am not sure what the car currently has.  Is there any way to identify the bore from the outside?


This master cylinder has a 2 x 2 1/2 inch rectangular front brake reservoir and a 1 1/2 inch round rear brake reservoir.  The lines attach to the bottom of the unit. The only external markings are: AB-02.

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Normally the size is marked on the cylinder. 280Z normally came with a 13/16" or 7/8". Not entirely sure. 



Pedal pushrod length being incorrect will also cause the same condition. Or air in the circuit. Or a leak somewhere. 

Fucking brakes. 




EDIT: After poking around the web, the 280Z came equipped with the 7/8" size MC. 

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The larger calipers will require more fluid to work them and so more pedal travel. Going up in cylinder size will move more fluid but you will have to push harder. Basically you have traded more travel for more work just like using a shorter lever to move a rock. As long as the brakes work you should be fine. Within reason, more travel makes it easier to modulate your brakes near lock up. If you do go to a larger master look into a brake booster to help reduce the effort.


I think the 510 had a 3/4" master. A 13/16" would firm the pedal slightly and reduce the pedal travel. Just remember you can't get something for nothing. (well you can with a booster)


The A10 ('78-'81 HL510) used a 13/16" master and it also had a booster. It might fit your early PL510 but if not the B-210 master will.

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I understand all that about bore size, pedal travel and pedal pressure.  What I want to know is what size master

cylinder bore do I have in the car right now.  The only markings on the unit is 'AB-02' which is probably a part number; no bore size and no manufactures name.  I want to go up at least 1/16 of an inch, maybe 2/16.  I strongly prefer to find a replacement part before disassembling the working car. I do not wish to remove the existing master cylinder to measure the bore then have the car sit around 3 months while I try to find the desired master cylinder.


So once again, can anyone identify the marking 'AB-02'?

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If the master is not marked with a bore size it is not a Nissan MC. There will be little hope in knowing with very little info to go on. 




If it is, in fact, a master cylinder from a 280Z it is 7/8". 


I think he said just front brakes.


Stock 510 master is 3/4". As Keith said, if not marked it may not be a Nissan master. They also usually have an F and an R cast on them for front and rear.  The 510 masters have a rectangular front and a round rear reservoir and the fluid lines exit from the bottom.


Nissan part numbers are expressed like this... 46010-23101 (early 510 master)



Post a picture of it.

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