88 Brake Master Cylinder rebuild kit available on eBay (Page 2/2) Vintage-Nut MAR 26, 04:57 PM I finally found the '88 brake master cylinder rebuild kit in the part and illustration catalog: Group 4.649 / Repair Kit 18010023 Thanks for the help! VN MikesFirstFiero MAR 26, 10:02 PM The difference between the S10 and fiero specs for bore diameter of 0.2mm is only .008" So the 18010083 kit may well work in the Fiero cylinder. Will .008" be a meaningful difference? The high pressure side (coming from the calipers) will force the ring to press on the bore and make the seal tighter. being flexible it probably will work ok. It's common to hone the MC bore or (old drum) wheel cylinder bores when rebuilding brakes. That removes metal and increases the bore diameter some but the brakes still work. I found this video that gives a good description. In our instance the brakes are a high pressure device so the o-ring expands and presses on the bore wall and actuator block that holds the ring and is pressed by the brake pedal. https://youtu.be/s5nJG0om8KY Vintage-Nut MAR 28, 10:37 AM quote I finally found the '88 brake master cylinder rebuild kit in the part and illustration catalog: Group 4.649 / Repair Kit 18010023 I'm Sorry - The Repair Kit is 18010083 (18010023 is the brake master cylinder) And never hone the master cylinder.... reinhart APR 25, 03:01 AM quote Originally posted by cam-a-lot: 88 owners, don't be typical cheap Fiero guys. It is a REAL pain in the ass trying to find an 88 brake master, especially when yours stops working and you really need one. Grab this kit and put it away for when you actuallly need it, since it may not be available a couple of years from now! For me, it's not being cheap. I've stocked up on a ton of spare parts. However, a brake master cylinder is one part I've never had an issue with in over 30 years and 5 Fieros of ownership. Doesn't seem like a high failure part and if it does fail, I've never seen one missing in the junkyards when I've gone part hunting. Seems like a non issue to me. ray b MAY 01, 06:10 PM they do not fail IF you do NOT full stroke bleed the brakes [let the petal full travel] that puts the piston&seal into the ruff unused part of the M/C and byby seals vac bleeds avoid that as will careful minor strokes when bleeding btw always bench bleed the New M/C or the air will not come out by wheel bleeding