ok so i will in the not so distant future perhaps tonight even I will be converting my brakes on my 90 1.6 over to the 1.8 pads and rotors. My question is if the master cylinders are different from the two? Is the balance of how much power applied to each axle the same? I am just wondering if it would be better if I swapped out the master cylinder as well or if it is pointless to do so. I really don't want to swap it out but if it is a better choice then I will. Thanks Jared

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1990 1.6

ok so i think i just answered my own question
the part numbers on autozone.com are the same for both years. 90 and 95 that is

is it gonna be ok to run the old pads from the 1.8 car? im sure they are the original pads since that drivetrain only had 18k on it. so im sure they got life on them but do pads get bad with age?

I don't thinkk so. Should be fine for street use. Anything else and you would be better off with a higher temp rated pad anyway.

I have jsut changed mine over but with a new kit.

well i got it done now.
It doesn't seem to be anymore responsive, if anything less responsive. Then again when I pulled the miata out of the garage after it had been setting all winter the brakes seemed to be more responsive after I had slammed them real hard several times. I didn't have the chance to do that today and probably wont til tomorrow or monday night.

The master may not be any different, but the brake boosters could be. Search using Google. I ran across a thread on m.net I think, where BBundy and some others were discussing this subject.
Along with this look into a proportioning valve and Hawk HPS.
Just my 2 cents.

Master cylinders from 90-00 are 7/8" bore. 01-05 are 15/16" bore. This size does not affect brake balance.

The proportioning valve affects brake balance. Refer to this for factory prop valve specs: http://www.flyinmiata.com/tech/stock_bpv.php

The 01-05 non-abs prop valve gives the most rearward bias of all factory valves, besides the ABS ones which are just straight through.

AFAIK, brake boosters on all NAs are the same, 99-00 might be larger, and 01-05 non-sport is definitely larger.

I have installed in my car the 02 non-abs prop valve, master cylinder, and brake booster. Some would say the NB2 sport booster is ideal for optimum pedal feel, claiming the non-sport boosters provide too much assist. I just used what I had on hand.

Swapping in the 01-05 master cylinder was pretty easy and only required bending lines by hand. BUT, you would have to swap the booster in with it too, otherwise the pushrod would require lengthening or something. I can't remember.

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I wouldn't expect an inch for rotor diameter to feel much different if it's paired with 17 year old pads and rotors, 18,000 or not. Put some new rotors and hawk HPS in, then you'll start seeing the difference.

What does the bore size affect then?

My master appears to be leaking between it and the booster and would be a good time to upgrade...

Well at least I saved a buck by not going out and buying new pads since I had this stuff lying around. If I am not particularly fond of these brakes within a few weeks then I will start considering opening up my wallet.

Planetmiata used to have $99($89?)/axel deals on rotor/pad combos. Not sure if they still exist.

Larger master bore will cause more pedal effort and less pedal travel. With the matching brake booster it becomes easier to regulate braking by pedal pressure instead of pedal travel.