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Post by dusty350 on Jan 13, 2018 15:37:07 GMT 1
Hi Fast losing the will to live trying to bleed the brakes on my white Lc (last job then MOT) This bike came with a dry system - Nissin master, 2 new Goodridge lines and some lovely 6 pot Beringer calipers. First problem is the bleed nipples on the calipers are very close to the banjo bolt and I struggled to get purchase with a spanner to get onto the nipple. After struggling for too long I decided to get the 4 pot Rgv Tokicos off the other bike and start again. I've borrowed Yamarks vacuum bleeder which pulls the fluid through at a fair old rate but I've still got a spongy brake lever. I've had the calipers off the bike, tapped them and the lines etc and all te other things you do when bleeding brakes. I did leave the lever tied back to the bars overnight and it was better this morning but bleeding them again has gone backwards rather than forwards. Traditional bleeding reveals no air - I've put half a litre of fluid through the system now ! Never had these 4 pot Tokicos before. Are they known to be difficult to bleed ? Anything I'm missing ??
Dusty
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dbgr
Drag-strip hero
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Post by dbgr on Jan 13, 2018 15:41:27 GMT 1
Hi dusty, I once had a terrible time with the 6-pots on my YZF750 and an old trick I was told was to try pushing the fluid in through the nipple into the reservoir and it could force the trapped air back into the reservoir,.... it worked for me, Dean
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Post by jackjabba on Jan 13, 2018 15:48:59 GMT 1
Are all the pistons moving freely, if one is tight it can give a spongy brake feel.
I had the same thing a few years ago and it turned out to be the new master cylinder.
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Post by earthman on Jan 13, 2018 15:57:34 GMT 1
Just a thought, is the brake fluid nice and fresh, not from an half empty bottle that's been stored on a shelf for a few years?
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Post by dusty350 on Jan 13, 2018 16:07:53 GMT 1
Brand new fluid opened yesterday. Pretty sure all pistons are good too. The vacuum pump really draws the fluid through well but also entrains air where the clear pipe sits on the nipple so can give a false reading if you get my drift. Doing it the old skool way shows no bubbles. Tied the lever back to the bar about an hour ago and it's better - cant get the lever to touch the bars now. As I have no experience of these brakes I'm not sure what sort of lever travel to expect from them. Spose I'll only know by doing a road test. I thought the lever would start getting tight sooner than it does ??
Dusty
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Post by steeley on Jan 13, 2018 16:22:09 GMT 1
Hmmm , yes I have had trouble of late with brakes . Had a problem with my Lockheed caliper's on my lc . I had rebuilt them with new seals and when they were bled up the lever nearly went to the bar when applied and would pump up solid . Then when applied again later same thing. So I used a large syringe to pull fluid ,still the same . I took the caliper's off one at a time and put a 3mm piece of steel between the pads and pumped the lever then refitted caliper . When they were both done the brake was fine .It was as if the pistons were going back in to far and the pads were to far from the disc.
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Post by gazsellars on Jan 13, 2018 16:22:47 GMT 1
Dusty.,
Try tapping the master cylinder with a screw driver handle, I had this with mine I'm using a fazer master cylinder, couldn't get a good feel on the lever, when I tapped the master cyl air bubbles came up through the master cylinder, did it for about ten minutes then the lever started to have a good feel. Could be worth a try
Gaz
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Post by stusco on Jan 13, 2018 16:37:45 GMT 1
I refurbed my 6 pots on my zx9 years ago had a nightmare bleeding took about three days still never felt like I thought it should I had fitted braided hoses all new pistons and seals so I thought it would be rock hard and stop on a dime but it still felt spongy
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Deleted
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Post by Deleted on Jan 13, 2018 16:47:00 GMT 1
Try a larger output master cylinder. If you have a 18mm master cylinder it will only ever feel spongy regardless of how well it's bled. How do i know ......
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Post by dusty350 on Jan 13, 2018 17:06:47 GMT 1
Hi It's a 14mm Nissin master cylinder, correct for the Rgv calipers. It's the set up that came on my blue (now orange) hybrid originally and they worked fine back then so I don't think it's a mismatch there. It must be air trapped somewhere. I've tried tapping the calipers, lines and master cylinder with a rubber mallet.. Both calipers have been off and moved around to try and dislodge air. There is no splitter in the system so it's not hiding in there. When the calipers were off the bike I had a spanner between the pads and the calipers gripped it pretty tight but the lever was a few centimetres off the grip by that point. I feel it should be gripping long before that point. Just as well I didn't make a YouTube video of my progress - I'm already 4.5 hours in !! Dusty
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kevm
Drag-strip hero
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Post by kevm on Jan 13, 2018 17:53:17 GMT 1
Had this problem on rally cars and bikes, check the master cylinder nipple is level, bleed caliper furthest away then the other caliper then lastley the master cylinder. Even if the cylinder is at a few degrees it can leave air trapped giving a soft feel.
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Post by pistanbroke on Jan 13, 2018 18:20:40 GMT 1
Hi It's a 14mm Nissin master cylinder, correct for the Rgv calipers. It's the set up that came on my blue (now orange) hybrid originally and they worked fine back then so I don't think it's a mismatch there. It must be air trapped somewhere. I've tried tapping the calipers, lines and master cylinder with a rubber mallet.. Both calipers have been off and moved around to try and dislodge air. There is no splitter in the system so it's not hiding in there. When the calipers were off the bike I had a spanner between the pads and the calipers gripped it pretty tight but the lever was a few centimetres off the grip by that point. I feel it should be gripping long before that point. Just as well I didn't make a YouTube video of my progress - I'm already 4.5 hours in !! Dusty Had a nightmare also with the Hybrid with 4 pot Tokico calipers , I just left the brake tied back for 3 days in end , is better but never been happy really , but Iโd exhausted every trick in the book like you , actually after about 509 odd miles the brakes are no bad now , get it as good as you can then do some miles would be my advice , mine passed the mot ๐, take a half bottle for the tester lol ๐๐
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Post by mattybeckett on Jan 13, 2018 19:17:21 GMT 1
Have you tried one piece of pipe across both bleed nipples with a T piece central and draw fluid through. Had the same problem a while ago and that worked in the end. Also obviously you will know if new pads were fitted the lever can sometimes be spongy until the pads are bedded in. Bleedin frustrating I Know. Good luck.
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Post by midlifecrisisrd on Jan 13, 2018 19:37:46 GMT 1
Had this a few times
As mentioned before operate the lever just and no more rapidly
Usually air trapped in the master
You can see it bubbling into the res.
Steve
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Post by davey on Jan 13, 2018 19:52:26 GMT 1
As steve says , i had probs with mine and by pulling the lever about 1/4 in slowly then releasing slowly and repeating , i also saw small bubbles apearing in the master.
Worked for me and worth a try
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Post by stusco on Jan 13, 2018 19:56:06 GMT 1
Rings a bell with me
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Deleted
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Post by Deleted on Jan 13, 2018 20:00:40 GMT 1
IMO 14mm Nissin on twin tokico's will be pants. 16mm is designed for the single disk Wolf VJ21. I have a 20mm AP racing radial (4 pot tokio) on one of mine and it's stops like hitting a brick wall. The 5/8th (16mm) it came with felt dangerous. The 19mm (gsxr radial) on one of my VJ21's feels a bit soft but it does have 6 pot tokicos. Tockicos need lots of pressure. I even put a Brembo from my Aprilia on and again it felt pants. Same master cylinder on brembo calipers gave a solid lever. Best cheap replacement master cylinder that works is from the pre radial braked fireblade
If you can get the RF900 Nissin calipers (same spacing as an RGV caliper) they are a million times better.
I presume you have bled the top banjo joint
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Post by doohanno1 on Jan 13, 2018 20:11:45 GMT 1
Had this a few times As mentioned before operate the lever just and no more rapidly Usually air trapped in the master You can see it bubbling into the res. Steve +1 I posted about the same problem a few months ago and got some great advice.. In the mean time a friend of mine ( proper bike mechanic ) called over and said I had the hard work done as I was getting fluid through the system. he proceeded to tap the lever in and out for a minute or so and voila , hard brakes..
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Post by gazzatt2 on Jan 13, 2018 21:20:08 GMT 1
you are leaving the cap loose when tying lever back ?
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Post by bazzer5115 on Jan 13, 2018 21:48:13 GMT 1
Never had any real problem bleeding brakes but recently had the same problem as your having,on a totally new system. Even bought a vacuum bleeder,still no good. Asked people,googled it etc etc. Apparently you need to "bench bleed "the master cylinder first before connecting to rest of brake system. So I undid the banjo at master cylinder and with a load of rags to catch fluid I simply bleed master cylinder buy loosening bolt a couple of turns,pulled lever in,tightened bolt,released lever(same normal bleeding process-but your only bleeding master cylinder and not whole system) Did it about 20 times until just fluid came out,had a little air to start with.Then fully tightened banjo and re-bled system. Bingo- best lever I ever had!!!๐๐ Good luck
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Post by donkeychomp on Jan 13, 2018 22:37:52 GMT 1
I know that bike doesn't have a centre stand and that won't help if you are bleeding the brakes on the side stand. And if the brake levers are adjustable have them on the most open setting. If you need a hand I can pop over.
Alex
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Post by JonW on Jan 13, 2018 22:50:16 GMT 1
The 4 pots are usually ok to bleed, its the Tokico 6 pots that are usually the problem child. So... with the 6 pots I take one caliper off, pull the lever and then when the pistons are out a bit i push them back in to see the fluid go back up to the master, this also gets all 6 pots working together on those calipers, which isnt always easy.
Ive really struggled with some setups over the years so feel your pain mate. shame youre not using the Berringers, id love a set of those...
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Post by dusty350 on Jan 14, 2018 12:34:16 GMT 1
Cheers for the advice so far fellas Bike is level on a paddock stand and I've left the bars on each lock to try and dislodge any air. Still not any better after leaving the lever tied back to the bars overnight. I may try loosening the banjos at the master to see if I can release any air that way. Had a chat with Yamark on the phone yesterday who recommended the slight tap of the lever but no bubbles as yet. Cap is off the reservoir too. The Beringer Aerotecs are a lovely caliper. The previous owner bought them as low mileage Gsxr13 items I believe and had the original red anodising pro polished off. He paid a stupid amount of money for them. They are very "bling" but I think I will flog them on and fit some other 4 pots to the other bike. Interesting about the Rf9 calipers - I will look into that, cheers Dusty
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Post by philmill on Jan 14, 2018 12:40:02 GMT 1
One trick Iearned was to just move the lever enough to slightly move the master cylinder piston, this lets the air come back up the line, in fact you can actually bleed the whole system this way without even undoing a bleed nipple. I was shown this as a spotty young lad on a dealer trip to Honda in Chiswick back in the good old days, the other way on really tough one, but it needs a lot of care is to blow air back up the line from the bleed nipple, Honda brakes were bad for bleeding, I remember spending hours trying to get 400 Dream (not Superdream!) to bleed, this trip saved a lot of grief over the years.
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Post by rich on Jan 14, 2018 12:59:16 GMT 1
As above, I have used a similar method in the past. Once you have some pressure at the lever, do several short strokes against the pressure without loosening the bleed nipple. Then do some short, slow strokes without letting the lever fully return. You will often get a stream of fine bubbles coming up though the hole in the base of the reservoir. Keep trying and eventually the lever should firm up. Not easy to explain but hopefully you get what I'm on about!
Good luck and watch for the jet of fluid you may get in the reservoir. Rich
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Post by dusty350 on Jan 14, 2018 21:46:02 GMT 1
Cheers guys Yamark recommended the very light tapping of the lever but I'm getting no bubbles whatsoever. Been busy today so no chance to mess with it but I did find the lever comes back to the bars again tonight Dusty
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Post by bazzer5115 on Jan 14, 2018 22:18:42 GMT 1
I tried all that tapping etc etc. Only thing that worked for me was "bench bleeding" the master cylinder. Google it,some good info there. Bleeding brakes can be a nightmare at times,sometimes easy, sometimes driving you mad. I have used tokico 4 pots and 6 pots on my hybrids. Once bled well(and lever tied in for the night)both gave good brakes with good feel using the standard RGV cylinder. Good luck for tomorrow ๐
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Post by bazzer5115 on Jan 14, 2018 22:29:28 GMT 1
Dusty, If you google"bench bleeding motorcycle master cylinder" and read the post in The Cbr forum you will will see what your up against and the way around it. I know how frustrating it can be,but read this and other posts and your be taking the for its mot tomorrow afternoon๐
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Post by dusty350 on Jan 14, 2018 22:32:34 GMT 1
Cheers Bazzer I will have a look and give it a go tomorrow Dusty
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Post by donkeychomp on Jan 15, 2018 1:08:36 GMT 1
Perhaps someone with a bit more knowledge of bleeding bleedin' brakes might pop over in the not so distant future? Alex
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