Preload on Masster Cylinder?

[siggyfreud]

Hey all,

Installing a Baer Master onto a GM hydroboost unit. I have about .100" of preload when the two come together. Baer says there should be no preload, Hydro vendor says all GM MC's have preload and it's normal.

Not sure who to believe lol.

Anyone have thoughts on this?

[Bigdav160]

I would say "no" to the preload.

[Chris_oz]

I think the 0.100" may be enough to give you issues.

The piston must be able to fully retract so the bypass hole is uncover. otherwise the brakes will lock

[siggyfreud]

That's my thinking. Not sure what to do since the hydro unit isn't adjustable, and neither is the master. Baer makes a spacer that is .17", but that would likely be too much gap. So my only option would be to get it, and mill it down. Just sucks since this should all be plug and play!

[siggyfreud]

Got the Baer measurement tool and checked it out. Looks like I need about .100" of space or so. I have a spacer that is .17" coming, but I might just try shaving the bullet that goes inside the MC first.

[68Gold/white]

NO WAY on ANY preload!!!

[Madkidd007]

Well being as it’s hydroboost it’s a little different story then you would normally think. The hydroboost will take some of the preload, no saying all of what you have. Your brakes won’t lock up because of this either, not like it’s fully depressed. Now when I did my hydroboost I just kept removing my pushrood, grind it, reinstall. I wouldn’t put a spacer in there when you can just grind the pushrod down. I can’t tell you how much preload mine has but I would say it’s about 1/2 the thickness of a standard 3/8 flat washer. Drive my truck everyday for the past year with no warped rotors or worn out pads, can also push the truck by hand.

[siggyfreud]

How do you remove the pushrod? I was just going to mill the master cylinder bullet down.

[Madkidd007]

Originally Posted by siggyfreud

How do you remove the pushrod? I was just going to mill the master cylinder bullet down.

The pushrod between the two should just pull out. Also keep in mind I would never machine a wear item. Say your master goes bad and your out of town or just not where you Can machine your new one. I always modify brackets or non wear items to fit parts that can wear or brake.

[Madkidd007]

A couple google images to show the two styles that I’ve seen before. Mine is like the one circled in red with no retainer

[siggyfreud]

Thanks. You'd mill the pushrod over the mc bullet? This is what in talking about taking about .07" off the back of. https://baer.com/Bullet-1-1-8.html

[Madkidd007]

Originally Posted by siggyfreud

Thanks. You'd mill the pushrod over the mc bullet? This is what in talking about taking about .07" off the back of. https://baer.com/Bullet-1-1-8.html

Yes I took metal from my pushrod, I’m unfamiliar with the aftermarket setup so is that piece you put the link, go between the master and hydroboost? If it’s not a part that is specific to either but acts just like the pushrod on a stock setup then Drill then end and refit till you’re just a tiny gap and bolt it down.