gs750es brake problems

[hardley davidson]

this is driving me nuts!!!!! I recently purchased a non running long sitting 83 gs750es ive been redoing everything and just have the front brakes left. i can build up pressure with several pumps of the brake but if i lay off for a second while it dosent lose ALL pressure theres a noticable loss and while test riding the brakes are weak and inneficient.

Ive rebuilt the master cylinder
dissassembled and cleaned out both calipers twice
checked all the lines and connections for leaks and havent found any
bled the system going on seven times in the correct sequence including alternating bleeding the master cylinder itself.
what am I missing!?!?!?!?!?!?!?!

[mrbill5491]

this is driving me nuts!!!!! I recently purchased a non running long sitting 83 gs750es ive been redoing everything and just have the front brakes left. i can build up pressure with several pumps of the brake but if i lay off for a second while it dosent lose ALL pressure theres a noticable loss and while test riding the brakes are weak and inneficient.

Ive rebuilt the master cylinder
dissassembled and cleaned out both calipers twice
checked all the lines and connections for leaks and havent found any
bled the system going on seven times in the correct sequence including alternating bleeding the master cylinder itself.
what am I missing!?!?!?!?!?!?!?!

Does that bike have the anti dives units on it ? I don'[t recall.

[hardley davidson]

Does that bike have the anti dives units on it ? I don'[t recall.

yes it does

[GateKeeper]

are you using the original 30 year old lines ? or did you get new ones, are you bleeding them in the right sequence ? I found when I bled and finished with mine they still felt soft, so I pumped the lever 5-10 times, held and opened the bleeder valve, once that was all done the last thing I did was pump the lever and held it and strapped it pulled back towards the handlebar over night.

In the morning I released it and it was working properly no need to pump to builld up pressure, and no loss of pressure and brakes felt good.

.

[mrbill5491]

yes it does

Okay, someone in the forum should be able to help you since you still have the anti dives on. I have not a clue if there is a specific way to bleed those.

[Agemax]

Okay, someone in the forum should be able to help you since you still have the anti dives on. I have not a clue if there is a specific way to bleed those.

they are bled the same sequence as normal brakes. furthest from M/C first.
so it would be left A/D,left caliper,right A/D,right caliper

[hardley davidson]

still using old lines, following manual bleeding sequence, 1. L anti dive, 2. L caliper, 3. R a/d 4. R caliper. just tried putting a known good master cylinder from a different bike and got the same results. pump the brake a couple times and its good and stiff, let go count to 5 and i can pull the lever in almost all the way to the handle bar.

[GateKeeper]

you sure all the air is out....

try as I mentioned, pump the lever, tie it back overnight, and see how it is in the morning

.

[hardley davidson]

you sure all the air is out....

try as I mentioned, pump the lever, tie it back overnight, and see how it is in the morning

.

im as sure as i can be with it still not working? if that makes sense. ive bled them twice more at this point with the swapping of the new master cylinder. pump, hold lever, crack bleed, tighten, repeat until theres no more air bubbles in the stream, move to the next...ill try tieing it back tonight when i finally give up.

[GateKeeper]

it was the only way I was able to stop it from being spongy, pump the lever until it get hard/stiff and hold, tie it back and leave it overnight.

it's worth a shot

[Agemax]

it has to be M/C seals. we had the same problem on here a while back and replacement seal kit cured it.
i had the same problem on my bike as well on the rear. new seals in caliper,new brake line,swapped M/C's same symptoms as yours. replaced my M/C with OEM seal kit and hey presto, bled up and rock solid brake.

[hardley davidson]

it has to be M/C seals. we had the same problem on here a while back and replacement seal kit cured it.

thats what I kept thinking in the begainning so i rebuilt it with the k&l m/c rebuild kit after I cleaned out the calipers so it already has new seals. got the brake lever tied back now...

[Agemax]

thats what I kept thinking in the begainning so i rebuilt it with the k&l m/c rebuild kit after I cleaned out the calipers so it already has new seals. got the brake lever tied back now...

if that doesn't work, go for OEM Suzuki parts.....

[chuck hahn]

Soon as i read "K&L" I thought the same thing. Also I go back and forth a few times on each front caliper and rebleed them even after I have ised the mighty vac. I use a clear tubing and hand bleed them each again to be 1000% certain there isnt any residual air anywhere.

[mrbill5491]

Since you STILL have the old brake lines on, this would be a good time to upgrade to the SS lines.