difference between brake bleeding screw and grease fitting?

Hi,

I have to get my pistons out of the calipers. I tried squeezing grease into the brake bleeding screw... Well, (obviously?) It didn't work!

I do have a set of metric grease fittings which look remarkably similar in size and shape, but they appear to have a ball bearing in them to allow grease to enter...

Can I temporarily fit a grease fitting in there to remove my piston?

Anyway, what's the difference between these two fittings, im curious asto how the bleeding screw properly works as I must bleed my lines tomorrow with a mity vac... Something ivenever done before...

Thanks

 

Brake bleeding screw has a sharp ferrule for gripping the hose you put on for draining.

Grease nipple is designed to 'couple' and lock in with the grease gun nozzle.

 

This has been the subject of much discussion and there are a number of ways to approach the problem.

If your 750 is like mine it has two dual calipers on the front and one dual on the rear. What you don't want is to get one piston out and still have the other stuck in there because then you have no way of applying pressure to the other side ... get it?

This will give you some ideas ...

http://www.xjbikes.com/Forums/viewtopic ... moval.html

It doesn't really matter how you apply the pressure but a little help from some boiling water will make them almost fall out once the seals are softened.

 

I've always been able to "engage" my grease gun with a Yamaha bleed nipple. You might have an aftermarket bleeder valve.

The little spring-loaded ball in real grease nipples is to give them "one-way" functionality.

 

Re: difference between brake bleeding screw and grease fitti

Well, work got pushed off unexpectedly for a bit, so I have an hour to go out and play in my shop. I'll try the new grease fitting and gun first, I think air is my last resort, I don't think it's stuck that bad (I hope).

Tim

 

Great, my assorted metric grease gun fittings do not fit. Arrgh. My grease gun does not fit into the banjo bolt thread, either.

I have M8 and M6 grease fittings, but the thread is in between (M7?)

I'm stumped for now, maybe bring my caliper to the HW store and cobble together something that will adapt my grease gun...

 

UPDATE: So I went off to my local hardware store, and I verified the brake bleed screw is indeed an M7 size. The HW store had no M7 grease fittings, neither did two auto parts stores I visited. I'm so bummed today. I think I'm going to wrap a LOT of teflon tape around an M6 fitting out of frustration, no, that would get stuck in the caliper... arrgh!

 

I just went through the same issue. What I did:

Took off my bleed screw & cleaned cleaned cleaned. The tiny hole on the bleed screw was completely rusted closed. I used emery cloth on the screw (to knock the rust down to where I could see where the bleed hole was) and then used some of those tiny dental brushes (can get them at walmart, GREAT & cheap). Acting like a drill, turning them back & forth, with carb cleaner I was able to open the hole up. Put it back on, then stuck the grease gun on & viola (plugged the banjo bolt with a chunk of plastic).

Just be sure to open the bleed screw a bit when you pump in the grease. I kept wondering why no grease was pushing out the piston until I realized "Oh yeah, i have to open the bleed screw to allow it to get in." Duh!

hope that helps

 

My bleed hole is TINY...
Is that the way they are?

BTW, is this how the bleed process works? You back out the screw a little to expose the hole?

Cool, I'll try this tomorrow!
(or tonight)

 

Yes, I figured this out, here is how I removed one of my caliper pistons:

Added DOT-3 fluid to master cylinder (new sight glass, no leaks!! (24 hour curing period btw))

Put vacuum pump on a caliper bleed screw, pumped, cracked open screw, waited for fluid to come out, adding to MC as it dropped. Closed Bleed screw when air evacuated.

Redid for caliper 2.

When all air was evacuated, I pumped brake handle and watched my caliper piston (#1) slowly come out!

I'll clean/rebuild/reinstall the caliper and then repeat the whole process again for caliper #2

Tedious, but better than waiting for an M7 grease fitting!

And, I figured out HOW the bleeder screw works in the process!