spongy front brake

G

gassergrant

New member
Hi my 03 gg ec and developed a spongy front brake ive bled it twice, there is defo no air.
I am reckoning it the master cylinder, do they in the UK do cylinder rebuild kits

cheers grant
 
Before you get into that, lean the bike on the sidestand. Squeeze the brake lever and tie it in place. Let rest overnight eith the master cylinder being the high point on the bike. Try the brake the next day. Sometimes air gets trapped at the M/C and can't be bled out. Leaving the brake lever engaged overnight gives the air bubble some place to go...
Cheap fix if it works...
 
One time, and I am not proud of it. I had a spongy brake, and bled and bled and cussed and bled. Turns out the clip that spaces the brake pads was in upside down... That is an issue believe it or not. No idea if that will help you but something to note.
 
djroggen said:
One time, and I am not proud of it. I had a spongy brake, and bled and bled and cussed and bled. Turns out the clip that spaces the brake pads was in upside down... That is an issue believe it or not. No idea if that will help you but something to note.
Click to expand...

Admitting a problem is the first step to resolving it :D:D:D:D
 
Try the cheap fix... you can always return parts, or keep them in your tool box for when the cheap fixes don't work...
 
If your brake fluid is old, it could have picked up some moisture making the lever feel spongy. Bleeding with fresh fluid will help, but doesn't replace all the fluid. Best to pull the pistons and empty the caliper so you start with new fluid everywhere. With new parts in the master cyl and new fluid, you'll have it fixed right.
 
I had a very similar problem with my rear brake. I would get it working great. Then after not riding for a while the brake would not work very well. So bled again and went for a test ride. Well I looked back at caliper and saw some fluid on the swing arm.... Damnittt - there was a pin hole in at the crimped end of the brake line. New brake line and seems to be all good now.
 
Sorry if this is long-winded. Just want all the facts out there !

Front brake on my 2006 EC was spongy, and had poor performance since i first got the bike.

And today was my first real ride after having the front caliper professionally rebuilt with all new seals etc, and have my mechanic flush through the old fluid, re-bleed and fit new pads. Felt GREAT at the lever in the garage at rest, and ive had what is effectively a big elastic band on the lever - trying to squeeze out any air, for 4 weeks at least (Just incase there was any trapped in the line) as he did in his own words "Have a bit of a nightmare bleeding it"......

Ive ridden nearly 100 miles today and for the first 50 miles the brake wasnt astounding [I am pretty critical] - but was more than acceptable (Little spongy for my taste - but still able to lock the wheel pretty easily).

Then my riding buddy took a left turn into some woods, and i went to brake and at first i thought id 'lost the front brake' - the feel was soo mushy, and an instant and big change from what it had been ?
I rode on and at one point i thought it had hardened up again and felt a little better - but through the last 50 miles - brake felt very spongy again, with the lever nearly coming back to the bars. In saying that it will still lock the wheel i suspect with a good tug of the lever, and performance isnt that bad per-se.

I washed the bike, and oiled the chain when i got in - havnt actually done anything to the brake - but did look at the master cylinder and i dont appear to have lost any fluid ? I put the elastic band back on - 1. From habit and 2. To put some pressure on the system and see if i could force a leak.

Just been out and lever MAY feel a touch firmer again, and i cant see any fluid leaking anywhere.

Brakes are a closed system right: Anyone got a clue what might be happening at all ? Im lost.......
 
Possibly you have a small air bubble on the hose . The portion of the hose that routes in front of the handlebars is on a higher point than the master cylinder so you might have some trapped air on the hose.
 
Vindicator said:
Possibly you have a small air bubble on the hose . The portion of the hose that routes in front of the handlebars is on a higher point than the master cylinder so you might have some trapped air on the hose.
Click to expand...

Well, after 48 hours sitting in the garage with the lever pulled back, it now 'feels' completely normal as far as i can tell - with bike on stand in garage ?

I can only assume i did / do have some air in the line then.........

Is it a complete re-bleed thats needed, (Not sure if my mechanic removed master-cyclinder and raised to highest point or not to bleed) or could i hope that putting pressure on the lever [With resevoir cap removed perhaps] might expel the air ?
 
So: Last ride out....after 50 miles or so....brake started to go spongy / lose feel again :mad:

Last night i removed the master cylinder and raised it up so its the highest point of the system (Got rid of that 'loop' that goes over the intruments) and have got a band pulled tight around the lever putting pressure on the system to hopefully get rid of any remaining air trapped in the loop.

I also had some advice from a 'friend' (Who was head mechanic at a very large Honda dealership for 10+ years) who suggested i "Lube up the piston / seals". He said he had the problem of 'fading' brakes on a GSXR once after rebuilding the caliper and after trying everything he reaslised the piston wasnt sliding freely on the seals - and lubing it cured everything.

I had my caliper professionally rebuilt recently, and theres every chance it may have been fitted together slightly dry....

So what do i use to lube the pistons / seals to get a nice action going again ?
 
I rebuilt the hole of my front brake system Nd is crap on the lever but works fine stopping wise, strange no air think its the fluid
Any way what i found as i was trying to cure the problem was the brake hose had been rubbing on the fork gaurd and wore it down to the metal core
Air was getting and fluid was coming out but not enough to notice tho
 
Thanks for the info.

Took the caliper off again tonight (After using the bike just twice since being re-built; and having problems both times) and i find one of the pistons is sticking ?????

Got them fully out, lubed them up, got them in and out a few times to try to wet the seal; refitted back together and now i cant get any pressure in the system.....


Ive emailed the Motorcross centre to see if one of their 'kits' in stock will fit my 2006. For that price its not worth me messing around with it any longer, and suffering with bad brakes any more !

http://www.motocrosscenter.com/ecommerce/product_info.php?cPath=667_671_1614&products_id=18454
 
have you tried syringing by pushing the fluid through the bleed nipple to push air out.
I found when I pumped the brake lever and holding the caliper only one piston will come out. hold it half way in with a pair of grips and the other should come out or by pushing in the piston it should push the other piston out. if that make sense.
I don't think your caliper is at fault , have you reconed the master cylinder

:)
 
just reading your other messages. sounds like you have a air leek mate. try replacing the washer or check the banjo is not damaged and check the hose for damage.
trick with the washer is to get them cherry red hot under say a gas cooker and drop the in water it will soften them up again
 
Reckon with all the other bits done master cylinder refurb next step.
Just make sure it's sorted before I get back, don't want any excuses next time out! Guess who? Keeping my eye on progress.
 
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