What is included in MC Rebuild Kit

[vesnyder]

Been considering rebuilding a spare master cylinder I have and was wondering what all is included in the rebuild kit? Having disassembled my spare it appears that for $70 you must be getting more than new rubber bushings?

Thanks

[john walker's workshop]

hard to fix the pitting in the bore without a sleeve job. buy a new one.

[wholberg]

If you rebuild a MC, you need to hone the bore to take out the pitting. The problem with this is that you enlarge the bore each time you hone it. If the pitting was very light and only a slight hone was required, then it's probably OK, but you cannot hone a MC very many times before the enlarged bore will cause the seals to fail under high pressure, such as, a panic stop.

I used to rebuild my old american MC's when a rebuild kit was $5 and a new MC was $40. Two or three rebuilds at most before I would replace the MC, and if the pitting was real bad I would just replace it.

As the Porsche kit is 1/2 the price of a new MC, you are better off just buying a new one.

[vash]

buy a new one.

[Zeke]

I have purchased 2 M/Cs from Pelican (the 19mm dual circuit variety for the early cars) and the price was so close to the cost of a rebuild kit that it was a no brainer. That is no longer the case. At $100 difference, I now would consider the rebuild kit as we used to do with all things brakes. But, good points have been made here. You need to inspect the bore after a light honing to see how bad the pitting is. Then, choose which way to go. If you don't already have a BC hone (or small bore hone), the choice is already made. A good one will set you back enough that the new M/C is the way to go.

[Early_S_Man]

There is very little information in print regarding inspection, and making the decision as to whether a master cylinder is rebuildable or not. I have an old manual from Raybestos circa 1972 that I have used many times as a guide when attempting to instruct friends in some of the details of disk brake servicing ... it is not readily at hand right now, but if memory serves me ...

Most of the so-called brake cylinder hones sold to individuals are NOT actual hones, but rather, should be properly called glaze breakers!

After cleaning and running a glaze breaker up and down in the master cylinder, followed by cleaning again ... test the bore by locating the crescent-shaped area of the bore where moisture-laden brake fluid would have accumulated by gravity, then use your little finger to probe the area for pitting. If you can feel any roughness compared to other smooth 'upper' locations not subjected to moisture, then that master cylinder is NOT a candidate for rebuilding ... unless it can be re-sleeved by a machine shop.

I have rebuilt many master cylinders using the above procedure and criteria without ever having experiencd a failure of the rebuilt part, but I have also rejected many MCs when new or rebuilt replacements were readily available! I always recommend keeping the pitted part around as a backup part that can be resleeved if availabilty of a replacement is questionable or has a lengthy delay.