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Front Brake/ Anti-dive Spongey

  • Thread starter Thread starter LSCCOLT
  • Start date Start date
L

LSCCOLT

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.
 
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.
 
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.
 
LSCCOLT said:
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.
Click to expand...


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.
 
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.
 
LSCCOLT said:
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.
Click to expand...

Are you getting air bubbles when you bleed?
 
jwhelan65 said:
Are you getting air bubbles when you bleed?
Click to expand...


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.
 
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.
 
I have just ordered the syringes to try reverse bleeding. Hope this works.
 
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
 
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.
 
chef1366 said:
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.
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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)
 
New fork seals, new fork oil, leave the anti dive in place and remove the linkages from it so the callipers are just connected to themselves instead of the anti dive.

If you are getting or have gotten any air at all from your brakes you need to continue bleeding them. Several reservoirs per side works for me. It is also possible you need to rebuild the master cylinder.

All this is basic maintenance., at least on bikes as old as these, anyway.

- boingk

Edit: Just a though, the brake pads aren't down to the limit are they? That may compound any issues you're having.
 
Last edited:
LSCCOLT said:
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?
Click to expand...

Green fluid?! That sounds like fork oil... I don't know how the anti-dives are engineered, and I'm not saying this is your problem, but it's possible that something's blown out in your fork. I have to leave further advice to the experts of these systems. Maybe someone nearby can lend you a hand...

Last thing I'll mention is that some people have argued that the anti-dive stuff is more trouble than its worth. I have seen threads where people have deactivated the anti-dives by machining aluminum plates to cover the ports.
 
Well I have brakes, somewhat, they are not as firm as before I started but I will see how it stops before I get too happy.

I used the single banjo bolts from the anti-dive units on the calipers and blocked off the anti-dives with solid bolts.

I now need to put new fork oil in. should I use what the Suzuki manual suggests or something thicker to compensate for the extra dive now?

Thanks
 
LSCCOLT said:
Well I have brakes, somewhat, they are not as firm as before I started but I will see how it stops before I get too happy.

I used the single banjo bolts from the anti-dive units on the calipers and blocked off the anti-dives with solid bolts.

I now need to put new fork oil in. should I use what the Suzuki manual suggests or something thicker to compensate for the extra dive now?

Thanks
Click to expand...

I would go thicker, typically when blocking off anti-dives and adding emulators it call for 30wt. Even without the emulators I would go heavier.
 
Can I just pull out the top bolt of the forks to refill the forks after I drain them all the way?
Thanks
 
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