There was a recent bench bleeding thread and I am starting this one instead of highjacking his. I always have this argument with my buddy:

We both agree that bench bleeding a used MC or doing any kind of on-car bleeding of a used or in-use MC requires a short stroke or wood block under the pedal. The reasoning is that when a brake system is properly bled and in use the piston stroke rarely goes past a certain point and corrosion and whatever can build up past that point and rip or damage the o-ring if it is made to sweep past the rough part.

My argument that he doesn't agree with is that if it's a NEW or REMAN MC the whole bore should be clean and even and ready to seal to the piston's o-ring. Therefore you shouldn't have to worry about giving the piston a full stroke- it won't be damaged and you will bleed faster.

Kinda funny- I use a mity-vac now for all bleeding. It saves a bunch of time and my wife used to groan whenever I would call her out to the garage for brake pedal duty.

What's your take? Any pros wanna chime in?

Short stroke bleed even new MCs? single choice
	Go for it! New MC will have a smooth bore
	Yes no full strokes, it will rip the oring
Votes accepted starting: 03/27/12 10:51 AM You must vote before you can view the results of this poll.

I installed dozens of new master cylinders over the years and bench bleed every one and full stroked every one......They all worked.

Same as above!

I've always used full strokes,never hurt one yet!

heck I've bolted mine in to the car then bled it with the pedal

I never bench bleed, just bolt them on and bleed on the car. Since I do almost everything by my self I use a vacuum pump and a mason jar, just have to remember to keep an eye on the fluid level in the mc.

bench bleed it, put some fluid in it and let it drain thru till it drips out the ports, then start stroking it to bleed - havn't had one fail yet that was my fault

All depends on the master cyl in question. Some dont have the ability to go full stroke alot. The piston can bottom out in the bore and cause damage. That typically doesnt happen in a car though.