Spongy brakes after swapping the line | GTAMotorcycle.com

Spongy brakes after swapping the line

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tricky

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Hey, I am at my wits end here

I changed the front brake line on my GS500. I drained the system, pulled the old line, put the new one on, and filled it up while getting the air out of the lines. I got to the point where I wasn't seeing any air bubbles come out of the bleed line, the lever felt good, so I closed it all up, and it was fine, went for a ride and everything.

The next day I saw some brake fluid out around the reservoir cap, so I pulled the cap off and cleaned it up, made sure everything was in order, put it back on. I also noticed the brakes were a little spongy. I zip-tied the front brake lever to the throttle overnight, which has helped in the past to remove the sponginess when I bled the lines

Few days later, some fluid around the top of the reservoir again, brakes still spongy. So I cleaned it up and zip-tied again. Over and over, probably 3-4 cycles now. There is no fluid leaking from the brake line connections at the reservoir or caliper, and the reservoir is still at the same level pretty much.

Any suggestions? The sponginess means there is air in the system, right? It seems to be getting worse with use or time, I am not sure which one.

Is it just all **** because I started from an empty line and don't have a vacuum pump? Do I just need to bleed it more?

To make matters worse, my bleed nipple is in bad shape, the 8mm wrench rounds it out and the 7mm is too small. This is why I haven't tried to re-bleed it, because the parts websites are saying it will be 3-4 weeks and $50 in shipping to send a new $7 bleed nipple

I am so confused at everything
 
does it have a little vent in the cap and is that plugged?
 
sounds like air
minor leakage around the reservoir cap would not cause spongy brakes

try a socket over the bleeder?
more contact points then a wrench
1/4 drive set is good for this

5/16 socket is tiny bit smaller than 8mm

needle nose vise grips would be a last resort
 
The reservoir cap should have three parts - the metal lid, a rubber expandable seal, and a little plastic spacer that holds the rubber seal correctly in place while you fasten the lid back on. Are any of those missing?

Vacuum bleeders can be helpful for speeding up the job, but they are absolutely not necessary. I have yet to personally use one for brake service.

Don't pay $57 for a bleeder screw. You should be able to get one for a reasonable price at an auto parts store. Or a motorcycle dealer - bleeder screws are DEFINITELY a stocked item
 
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tricky said:
To make matters worse, my bleed nipple is in bad shape, the 8mm wrench rounds it out and the 7mm is too small. This is why I haven't tried to re-bleed it, because the parts websites are saying it will be 3-4 weeks and $50 in shipping to send a new $7 bleed nipple
Click to expand...

Just go to a dealer and buy a new one - why is it so hard ?
 
Based on snowcity parts finder, the bleeder should cost you $5.17 + tax. There is a big chance that they have it in stock or they can get it in 1-2 weeks. Btw, you can pick up it from them and it would be free.

I chose snowcity just because they are close to me but you can choose any Suzuki dealer which is close to you. Prices should be similar. Just call them and ask (don't forget the part number for the bleeder).
 
J_F said:
sounds like air
minor leakage around the reservoir cap would not cause spongy brakes

try a socket over the bleeder?
more contact points then a wrench
1/4 drive set is good for this

5/16 socket is tiny bit smaller than 8mm

needle nose vise grips would be a last resort
Click to expand...

also if you can make-sure it’s a six point wrench or socket
 
It's likely a M7 X 1.0 bleed screw. Take it to any auto parts store, they should be able to match it up. Failing that, any caliper shop should be able to match it up (I use Midland Calipers at 1720 Midland Ave #12, Scarborough, ON M1P 3C2 - they have helped me with misc bleed screws in the past. )

As for the reservoir leak at the cap -- that's a simple one. You are either over filled or you have a seal problem at the cap. Maybe silly so say but sometimes small goof ups happen.... there should be 3 parts to the reservoir top: 1) a rubber diaphragm that sits above the fluid chamber, 2) a plastic plate and 3) hard cover. Make sure you have them in the right order and the correct sides facing up.

As for sponginess, that's air in the system. If the bleed screw is really messed up, change it first, be sure to have a peek at the seat too. When bleeding some older bike brakes, the front wheel might need to be straight and the bike on the center stand (or at least standing straight up) in order to keep the bleeder at the highest point AND allow air to move up and out of the caliper - if you bleed on the side stand, the tilt might create an air trap inside the caliper. Rebleed.
 
Bleeding brakes on a bike can be a tricky thing. Just the way they are built adds mechanical challenges; the master cylinder volume is quite small but bikes use automotive size hoses, the calipers are well below the master making it difficult to get air "down" to the bleeder.

Tying the lever to the bar overnight is an old trick that seems to work when you try it the next morning, but what you're really doing is causing the air to be absorbed into the fluid. This just contaminates the fluid and as you've seen, it comes back.

Air bubbles can get caught in any little high spot; humps in the line, cavities in banjo fittings and calipers where the bleeder isn't perfectly aligned to the top. There are situations where the caliper must be removed and repositioned for bleeding.

There are a few procedures you can use to get around these issues.
Try rapping on the calipers and lines with the handle of a screwdriver the knock loose any bubbles held in place by surface tension.
Remove the caliper and raise it as far as possible so that the line runs "up hill" from the master. Place a block of wood between the pads to simulate the rotor. Hold the caliper with the bleeder to the top.
Bleed the system backwards. This can be messy. With the system with as little air as possible, lower the level in the master cylinder reservoir. Push fluid backwards through the system by pressing in a cylinder in the caliper. This has the advantage of running up hill and more volume. It might be very slow depending on the orifice in the master, in this case cracking open the banjo at the master is an option.

Cover everything. This job can be messy and brake fluid is a particularly good paint remover. Use old brake pads, save your new pads till after the bleeding is complete. Get a friend to help, this job often requires three or four hands.
 
You have air somewhere. You can try a reverse bleed (using a syringe to force new clean fluid INTO the caliper and back up into the master cylinder instead of the traditional way the other way around. Always seems to work better/faster/easier on motorcycles.

bitzz said:
Canadian Tire and most auto parts stores stock a decent selection of bleeder screws
Click to expand...

Assuming you get a kid at the parts counter who actually knows what a bleeder screw is and knows where to go find them instead of insisting on punching all your info into their computer system only to have it tell them they don't carry that...when in reality, they probably have something that will work.
Oreilly.jpg
 
Easy there. The days where a CT counter job pays enough for a kid to have a car to work on and learn these things are in the distant past
 
Everyone - thanks a lot for your input, its been really helpful

It did not even occur to me that the bleed screw would be a universal part. It does appear to be M7x1. The CT didn't have one even close to the overall length of mine (not sure if it matters much). I'll look at a more specialized shop next time - thanks to those who pointed this out

The diaphram and everything is put together right - I think I did overfill it causing the seepage

We managed to bleed it again, trying different steering angles on full lock, it helped - some air was bled out, quite a few bubbles, so that was a learning experience. The lever felt much improved after the bleeding, but hours later was back to spongy

We rebled again - and again, saw a bubble or two. we moved the brake line around as much as possible to try to shake loose any bubbles. the lever felt better, but then a few hours later, back to dog ****

All this time I was bleeding with a 6 point box wrench that I got on to the bleed screw, but I think I damaged it too much on that first pass and now I can't get much purchase on it, so its rounded out a bit too much to keep going. I could use vice grips in the meantime but it hurts the soul

We'll try to find a new bleed screw, and try bleeding with the reservoir off the bars and lower down than the caliper (may be easier than the other way around?) if possible to try to shift whatever bubbles are in the line to the bleed screw

Thanks to everyone here for offering advice, I'll keep you posted
 
Are you using a piece of silicone hose on the bleeder dipped into a bottle of brake fluid during bleeding? This ensures that you don't accidentally draw air back into the system during bleeding.

I'm left wondering (if you're not) if you're not getting the technique quite right and are actually introducing air back into the calliper every time you open the bleeder.

As for Vice Grips on the bleeder, do what ya gotta do... it's an easily replaceable part.
 
You can use a longer M7 bleeder, just not a shorter one. Make sure the dump hose on your bleed screw is underwater (not water, under brakefluid) in the catch jar.

1595891920667.png
 
Have you tried bleeding it directly from the master cylinder? I just swapped my old lines for new stainless braided ones and was having trouble bleeding, with no lever feel at all. And bleeding from the calipers did nothing, until I bled it from the master and everything went smooth after that. There was just way too much air in the system after swapping the lines.
 
tricky said:
Hey, I am at my wits end here

I changed the front brake line on my GS500. I drained the system, pulled the old line, put the new one on, and filled it up while getting the air out of the lines. I got to the point where I wasn't seeing any air bubbles come out of the bleed line, the lever felt good, so I closed it all up, and it was fine, went for a ride and everything.

The next day I saw some brake fluid out around the reservoir cap, so I pulled the cap off and cleaned it up, made sure everything was in order, put it back on. I also noticed the brakes were a little spongy. I zip-tied the front brake lever to the throttle overnight, which has helped in the past to remove the sponginess when I bled the lines

Few days later, some fluid around the top of the reservoir again, brakes still spongy. So I cleaned it up and zip-tied again. Over and over, probably 3-4 cycles now. There is no fluid leaking from the brake line connections at the reservoir or caliper, and the reservoir is still at the same level pretty much.

Any suggestions? The sponginess means there is air in the system, right? It seems to be getting worse with use or time, I am not sure which one.

Is it just all **** because I started from an empty line and don't have a vacuum pump? Do I just need to bleed it more?

To make matters worse, my bleed nipple is in bad shape, the 8mm wrench rounds it out and the 7mm is too small. This is why I haven't tried to re-bleed it, because the parts websites are saying it will be 3-4 weeks and $50 in shipping to send a new $7 bleed nipple

I am so confused at everything
Click to expand...
Does the master cylinder have a diaphragm? did you pump the fluid out with the master cylinder cap on it and now the diaphragm is pulled out or is it flat? If the diaphragm is pulled out to fill an empty reservoir when you refill the reservoir and reinstall the diaphragm it’s going to overflow out of the reservoir unless you flatten the diaphragm.

If you have air in the line and no bubbles coming out of the bottom, bleed the banjo bolt at the master cylinder end. Same procedure pump pump crack the bolt, repeat
 
Yes, I have been putting the end of the bleed hose under some brake fluid in the bottle I'm draining in, so I don't pull air up

PP - I have certainly been wondering if I have been doing something wrong!!

I started bleeding with the directions from some online tutorial (crack the bleed screw, press the lever, close the bleed screw, release the lever). Then I switched to one I found on a motorcycle garage youtube video (press lever, crack the bleed screw, close, and release lever). This second one makes more sense to me, building the pressure before cracking the screw. I turn the bleed screw 1/8-1/4 turn only, and I can visually see the brake fluid build-up in the line at the bleed screw, which is solid brake fluid with no air bubbles, I do not think I am drawing any air in through that

mistersouthpaw - I have done all of the bleeding with the cap and diaphragm off of the reservoir, so the diaphragm hasn't changed shape at all as far as I know

Bleeding from the master cylinder end sounds terrifying - but I might have to try, or use VFR.CBR's technique

I will keep this thread updated when I take another stab at it. Once again, thanks to all of you for your help and advice
 
The second method you found is the one you want to use. Have someone hold the lever hard (this really is a 2 person job) and then crack the bleeder and ensure whoever is holding the lever keeps constant pressure - tell them to expect it to move - they MUST keep pressure on it. Before the lever bottoms out, close the bleeder again. If the lever bottoms out or the pressure is released it'll draw in air.

Anyhow, strongly consider the reverse bleeding method - get a big syringe and some neoprene/latex hose, slip it over the bleeder nipple and then forcefully push out all the air. Remove about 75% of the fluid from the master cylinder to make room for the fluid you're forcing up, then crack the bleeder while holding some pressure on the syringe plunger and close it again before the plunger bottoms out. Check the lever and see if it's firming or firmed up. If not, repeat again. Just be sure the syringe and line is 100000% purged of all air the bleeder before opening the bleeder otherwise you're just forcing more air into the system.
 
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