Front Brake/ Anti-dive Spongey

[Guest]

I have bought my first bike a week and a half ago. It is a 1983 GS750ES. It rode great but my uncle who said that my stem bearings were bad. A friend and I replaced them yesterday but now the brakes are no where near as firm as they were before we messed with the bearings.

I bled the system many times already, have tried tying the lever back overnight and it helped a bit. I also bled the M/C and individually bled all the banjo bolts from the M/C to the caliper.

Any help would be greatly appreciated, I need to get it fixed by Monday so I can go to work.

Thanks in advance.

[jwhelan65]

The bearings have nothing to do with the braking system. Are you leaking fluid anywhere? Check the splitter above the front fender for starters, if it were me I would pull both calipers and inspect them along with the master cylinder and start from scratch. Drain all the fluid and check the piston seals also. New lines? if so you need to keep bleeding, new lines always take awhile to bleed.

[LSCCOLT]

The M/C and calipers were rebuilt before I bought it. To do the bearings we had to remove the forks from the bike, therefore we took off the line from the master.

[jwhelan65]

The M/C and calipers were rebuilt before I bought it. To do the bearings we had to remove the forks from the bike, therefore we took off the line from the master.

You need to keep bleeding, if you unhooked at the M/C you probably took in a huge air bubble at the farthest point from the bleeder valve.

[LSCCOLT]

So, I have been messing with these brakes for three days now, have gone through more brake fluid through bleeding than I care to mention. Where do I go from here.

[jwhelan65]

So, I have been messing with these brakes for three days now, have gone through more brake fluid through bleeding than I care to mention. Where do I go from here.

Are you getting air bubbles when you bleed?

[slayer61]

Reverse bleeding is the way to go. I'm telling you!

[jwhelan65]

Reverse bleeding is the way to go. I'm telling you!

It sounds like it would make sense but what is your process?

[LSCCOLT]

Are you getting air bubbles when you bleed?

No, I am not getting any air bubbles, which is what has left me so confused. This is my first bike so working on it is a whole new game, but I am competent with mechanics on cars and am still not understanding why there are no brakes.

[subid]

Reverse bleeding is the way to go. I'm telling you!

Reverse bleeding also solved my squishy brake problem after a full caliper rebuild with new lines. Plus, it's the easy method IMHO.

[eil]

I did vacuum bleeding on both my front and rear brakes. Took around 1 minute per caliper and I had firm levers right away. And it was my first time bleeding brakes on anything.

Do you have a vacuum bleeder or other kind of vacuum pump? If not, go to Amazon.com and buy a set of five 60cc syringes for around $5 shipped. You'll only use one, but you'll have four left over for future use.

You have anti-dive stuff so I don't know how this affects your bleeding procedure, but this is the general idea:

1. Connect the syringe to the bleeder with a clear piece of fuel line. One or two feet in length. Fill brake reservoir to the top with fluid. Crack bleeder valve (just barely and no more), pull on syringe to create suction. Hold the syringe upright to let air bubble to the top. You might get a steady stream of small bubbles from air coming in through the bleeder valve threads. This is okay if they're small. If they're big, you need to seal the bleeder valve threads with teflon tape. Keep an eye on your brake reservoir and make sure it doesn't run dry.

2. Once there are no more bubbles, close the bleeder screw while still applying some vacuum. Squeeze the brake lever several times, and tap the handle until no more bubbles come up from the reservoir.

Repeat #1 for the other caplier or anti-dive mechanisms.

[LSCCOLT]

I have just ordered the syringes to try reverse bleeding. Hope this works.

[LSCCOLT]

Well, I tried the syringes to bleed the brakes, I still have a very weak lever.

I pulled of the left side anti-dive unit and a sickly green fluid came out that smelled like oil. Is this normal? Is it a problem with the forks?

Also, depending on if there is a solution here, I was thinking of swapping to a newer GSXR forks if it will eliminate the anti-dive bs.

Thanks

[chef1366]

Take off the brake lever and push the master cylinder piston in with a screwdriver. The lever does not push the piston all the way in and air bubbles love to hide in that small area.

[LSCCOLT]

Take off the brake lever and push the master cylinder piston in with a screwdriver. The lever does not push the piston all the way in and air bubbles love to hide in that small area.

I have also tried this, and did get some bubbles out. Now I am concerned about an internal fork seal or something because of the fluid that came out when I removed the antidive unit. I am not sure this is normal
(first time working on a bike and first bike)