1978 master cylinder

how do you rebuild master cylinder for a 1978 corvette  

send it in to a power brake rebuilding company.. they can usually do the master cylinders in house...

they are not really hard to rebuild.. but if the bore has rusted pits in it...  and you really want to keep that one..   you can have it sleeved...   brass sleeves or stainless steel sleeves can be done..


there is one trick...     you can use clean brake fluid as a solvent...  if you use anything else...  you will really need to warm the master some way to evaporate the solvents..  like putting in in an oven..  before you put the parts in.. ..


lisle.. makes a 2 stone master cylinder hone..  with really fine stones...    course stones will leave deep honing marks and that will damage and wear out the soft rubber seals when you put it back together..

years ago..  master cylinder bores were bearingized..   they had a machine with roller bearings on the end of the spindle..   they could run that in and out as the spindle turned and expanded.. this rolling of steel on iron flattened out the bore.. left it smoother than most other finishes...   not a cheep machine...

the current crop of master cylinders are honed...  probably with a diamond hone.. but i feel it is actually still a bit on the course side..

i was looking at the autozone web site...  they sell reman masters that have been sleeved for 20 bucks...   but i have bought them .. most have new masters in them...  

if you plan on doing it your self...   you might invest in a 20 buck reman.. just to keep the car drivable..   and then spend the time if possible to clean and take apart your unit...    one warning.. i have had problems with the replacement lids that come on the masters.. many are slightly bent..     so taking the rubber gasket out.. laying it on the master and seeing if it rocks somehow.. and pretending its a transmission pan rail and straighten it slightly with a small hammer..    you might have to hold it upside down along one edge..  

az also has a great deal on 4 piston cast iron calipers  for your C3 also..

these are the size of the threaded holes in the side of the master..  some stores will have inverted flair plugs so you can block them off with something strong while cleaning the outside of the old one...  
Primary - Hole Size and Location: 9/16"-18 Fender Side
Secondary - Hole Size and Location: 1/2"-20 Fender Side  

thanks Wayne for the reply ..... some how my system got moisture in it and the fluid turned brown(rusty brown). I decided to overhaul the entire system starting with the calipers which a few were leaking. New lines wich are on order and the master looked in pretty good shape just dirty when I took it apart. I never knew that about using a different stone for the hone. The rebuild kit I got gives you a new primary piston assembly but just seals for the secondary. Here in Canada we don't have az stores but will check to see what Detroit has.