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Post by tony2stroke on Jun 2, 2020 20:30:42 GMT 1
An easy but messy way to remove trapped air is to start at the master cylinder, remove brake line, pull on lever put your finger over the bango hole and release lever slowly, do this until fluid starts to flow, you will feel it suck your finger if all is good with master cylinder, then put brake line back on the cylinder, move down to caliper do the same there, put line back on and the bleed caliper as normal, as said above it helps to push pistons home first, this is the best way I have found to bleed brakes that give trouble, sometimes if the master cylinder has been dry they are a PITA to bleed back up, same with new ones, as said messy but your best hope of getting them bleed ASAP, make sure you cover any paint though and clean all the lines master cylinder and caliper of all fluid after, this has never failed me trying to get rid of trapped air.
I haven't read all this thread so if twin set up, then only work on 1 caliper at a time, once the fluid is flowing everywhere it will be fine.
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Post by chrisg on Jun 2, 2020 21:41:18 GMT 1
To force air out of the caliper force the pads apart. Driving the piston back into the caliper is the best way to push air out Basically if you have to fk about and they don't bleed up in 5 to 10 mins there is something wrong. I would never spend more than 10 mins bleeding brakes, I'd start looking for what was wrong if I didn't get a firm lever in that time. I certainly wouldn't be hitting things or hanging the bike upside down overnight hoping it cured the problem Totally agree
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Post by shergar on Jun 3, 2020 11:57:35 GMT 1
Are you sure everything's built back up correctly. As mentioned I had an issue with a rear MC. The little brass disc was out of place (after the seal) I managed to find this pic and rebuilt back up with no issues. Just a thought. just took master cyl apart again for the hell of it and noticed theres no brass shim , this was another (2 fitted so far) new one as the first pissed and no shim in the set can this be the problem dose it need this if so why not in the set i wonder ?
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Post by shergar on Jun 3, 2020 12:14:37 GMT 1
what is the best cleaner to wipe brake fluid of when on caliper paint ect in your opinion ?
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Post by veg on Jun 3, 2020 12:20:13 GMT 1
I use spray on brake cleaner it moves it then evaporates
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Post by Deleted on Jun 3, 2020 12:26:21 GMT 1
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Post by shergar on Jun 3, 2020 15:17:11 GMT 1
Couple of reasons brakes don't bleed or the lever is too soft If the master cylinder isn't pumping properly, seals knackered or the piston is seized, then you won't get the air out Fluid isn't flowing out of the master cylinder, passage way blocked Not enough fluid in the reservoir, and it's sucking air Connecting pipe (reservoir to master cylinder) is sucking air. Unlikely as it's only a gravity feed. Air is trapped at Banjo bolts. These need bleeding as well as at the bleed nipples If the master cylinder is a mis match with the calipers, e.g a single 1/4" with twin disks, it will feel soft The master cylinder is a bit rubbish, like the 350LC master cylinder or it's in need of new seals (see the 1st point) Copper washers are leaking air (unlikely but crushed copper stays crushed so use new ones) or the banjo bolt is loose. They don't have to be wound in with a scaffold pole !!! I recently had a rear master cylinder that just wouldn't pump. The lever seem to be working fine but nothing. Closer inspection and the piston was stuck. A little heat and it freed off. A rub down with scotch bright and worked perfectly (even on the original seals). Bleed up no problem in 5 mins, using old brake lines and new washers. have to say this made me giggle ( They don't have to be wound in with a scaffold pole !!! ) lol
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Post by shergar on Jun 3, 2020 21:25:59 GMT 1
Are you sure everything's built back up correctly. As mentioned I had an issue with a rear MC. The little brass disc was out of place (after the seal) I managed to find this pic and rebuilt back up with no issues. Just a thought. just took master cyl apart again for the hell of it and noticed theres no brass shim , this was another (2 fitted so far) new one as the first pissed and no shim in the set can this be the problem dose it need this if so why not in the set i wonder ? any answer on the shim ?
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Post by LC_BOTT on Jun 4, 2020 7:26:52 GMT 1
I've not seen a shim in any of the ones I've done (what make/bike was the pic from) Normally the spring end, sits tightly in a small tin metal cup, I would think it's there to stop the spring working it's way into the alloy piston.
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Post by chrisg on Jun 4, 2020 11:34:49 GMT 1
Its from a 400D rear master cylinder. The shim sits on a plunger with little holes in and acts as a non return valve.
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Post by shergar on Jun 4, 2020 13:46:57 GMT 1
Trying to bleed up the front brakes on my F1, its got the 4 pot triumph calipers, fazer M/C. bled them through and no lever at all, so replaced the M/C seals, swapped out the lines for a spare set, new washers etc, still nothing No leaks on the system i can see, not stripped the calipers but they look like new. Getting pissed off now, i must have bled hundreds of brakes over the years and not had this problem, only thing i can think of is replace all the caliper seals OR sack the whole thing off and go back to standard set up, problem is, i've only got a right hand caliper and no M/C Rant over Anyone else had issues with trumpet calipers ? did YOU ever get the brakes sorted mak ?
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Post by shergar on Jun 4, 2020 15:38:02 GMT 1
i have tried every forum tip , youtube video that iv seen and heard and i still cannot get a brake im loosing all reason at this stage .
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Post by tony2stroke on Jun 4, 2020 18:41:56 GMT 1
i have tried every forum tip , youtube video that iv seen and heard and i still cannot get a brake im loosing all reason at this stage . If you have tried my way, can you tell me at what point if any you didn't get fluid please, did you get fluid at the master cylinder, then at the bottom bango bolt hole on brake line, then out of 1 caliper and then the other.
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Post by shergar on Jun 4, 2020 20:49:23 GMT 1
An easy but messy way to remove trapped air is to start at the master cylinder, remove brake line, pull on lever put your finger over the bango hole and release lever slowly, do this until fluid starts to flow, you will feel it suck your finger if all is good with master cylinder, then put brake line back on the cylinder, move down to caliper do the same there, put line back on and the bleed caliper as normal, as said above it helps to push pistons home first, this is the best way I have found to bleed brakes that give trouble, sometimes if the master cylinder has been dry they are a PITA to bleed back up, same with new ones, as said messy but your best hope of getting them bleed ASAP, make sure you cover any paint though and clean all the lines master cylinder and caliper of all fluid after, this has never failed me trying to get rid of trapped air. I haven't read all this thread so if twin set up, then only work on 1 caliper at a time, once the fluid is flowing everywhere it will be fine. ok i havent done this to be honest sorry and the reason being i have fluid flowing perfect at both nipples and absolutely no air when bleeding at calipers .so your saying to have the master filled with fluid and then remove banjo for finger to cover yes ? some mess id ok .
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Post by tony2stroke on Jun 4, 2020 21:02:19 GMT 1
An easy but messy way to remove trapped air is to start at the master cylinder, remove brake line, pull on lever put your finger over the bango hole and release lever slowly, do this until fluid starts to flow, you will feel it suck your finger if all is good with master cylinder, then put brake line back on the cylinder, move down to caliper do the same there, put line back on and the bleed caliper as normal, as said above it helps to push pistons home first, this is the best way I have found to bleed brakes that give trouble, sometimes if the master cylinder has been dry they are a PITA to bleed back up, same with new ones, as said messy but your best hope of getting them bleed ASAP, make sure you cover any paint though and clean all the lines master cylinder and caliper of all fluid after, this has never failed me trying to get rid of trapped air. I haven't read all this thread so if twin set up, then only work on 1 caliper at a time, once the fluid is flowing everywhere it will be fine. ok i havent done this to be honest sorry and the reason being i have fluid flowing perfect at both nipples and absolutely no air when bleeding at calipers .so your saying to have the master filled with fluid and then remove banjo for finger to cover yes ? some mess id ok . Yes, messy, but it will ensure no air trapped in the system, it works for me on difficult to bleed brakes, never failed me, yes fill master cylinder first, to get fluid flowing there, pull lever put finger over bango outlet hole, release lever slowly, finger off pull lever then finger over hole release lever slowly until fluid flowing, attach the brake line, pull lever then finger and thumb over bottom bango hole on brake line, release lever, finger and thumb off bango hole, you get the picture until fluid flows, then attach line to caliper and bleed caliper, 1 at a time, first 1 then over to the other.
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Post by shergar on Jun 4, 2020 21:18:27 GMT 1
when you disconnect the master banjo will the fluid not just piss out as normal anyway ?
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Post by tony2stroke on Jun 4, 2020 22:24:23 GMT 1
To an extent, but sometimes there can be a air lock behind first seal between plunger, also your tinny little hole can be blocked or partially blocked, there are 2 holes in master cylinder, you will find out when doing this way, if your finger skin is sucked in and stays sucked in with the same feeling of suction and only a little fluid comes out, master cylinder hole is most likely the cause, or seals.
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Post by shergar on Jun 4, 2020 23:24:17 GMT 1
i had master of yesterday new kit fitted both holes are clean and pumping up fluid and air into master.
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Post by tony2stroke on Jun 4, 2020 23:49:11 GMT 1
Just try it my way mate, you have nothing to loose.
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Post by darboots on Jun 5, 2020 11:19:42 GMT 1
I managed to get a 'good' lever after tying the lever back with an old 'O' ring. I also wrangled the master cylinder around to try to get any trapped air out from the m/c banjo before tying the lever back. Left it for two days, and a firmer level. Job done. Or so I thought.
Came back to it after a week (SWMBO kept me busy with household chores), and I found that brake fluid had been dripping out of the rubber m/c reservoir diaphragm, which has stripped the freshly painted m/c. FFS!!!
So, the plan is now to repaint with VHT Caliper Paint, after disassembling the effin' thing again. The m/c sight glass guy on eBay is doing a royal trade from me - five sight glasses so far!
- Ordered one sight glass. First one went in off square, f**king up the metal ring. - Ordered two more sight glasses - just in case. Second one went in fine but pushed out the rubber gasket ring. Destroyed that one by taking ot back out to fix the gasket. Third one went in fine using the old gasket (new ones are double the thickness). Have to now remove this one in order to repaint and bake. - Ordered two more sight glasses - just in case....
Wish me luck with my ham-fistedness.
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Post by mak595 on Jun 5, 2020 11:51:05 GMT 1
Trying to bleed up the front brakes on my F1, its got the 4 pot triumph calipers, fazer M/C. bled them through and no lever at all, so replaced the M/C seals, swapped out the lines for a spare set, new washers etc, still nothing No leaks on the system i can see, not stripped the calipers but they look like new. Getting pissed off now, i must have bled hundreds of brakes over the years and not had this problem, only thing i can think of is replace all the caliper seals OR sack the whole thing off and go back to standard set up, problem is, i've only got a right hand caliper and no M/C Rant over Anyone else had issues with trumpet calipers ? did YOU ever get the brakes sorted mak ? Yep, i found that one of the disks was warped, so it was pushing the piston back hence i was always getting a spongy lever. I would bleed it, it was ok but if i rolled the bike around or rode it, back to a spongy lever as it had to push the piston back onto the disk before it would squeeze the disk. Strange thing was, there was no pulsing while braking, which you usually get with a warped disk, only sussed it out when i got the front wheel off the ground and spun it... Fitted a spare disk i had and the lever is rock solid now, still not Brembo monoblock braking but reasonable with a good tug
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Post by shergar on Jun 5, 2020 12:15:18 GMT 1
I managed to get a 'good' lever after tying the lever back with an old 'O' ring. I also wrangled the master cylinder around to try to get any trapped air out from the m/c banjo before tying the lever back. Left it for two days, and a firmer level. Job done. Or so I thought. Came back to it after a week (SWMBO kept me busy with household chores), and I found that brake fluid had been dripping out of the rubber m/c reservoir diaphragm, which has stripped the freshly painted m/c. FFS!!! So, the plan is now to repaint with VHT Caliper Paint, after disassembling the effin' thing again. The m/c sight glass guy on eBay is doing a royal trade from me - five sight glasses so far! - Ordered one sight glass. First one went in off square, f**king up the metal ring. - Ordered two more sight glasses - just in case. Second one went in fine but pushed out the rubber gasket ring. Destroyed that one by taking ot back out to fix the gasket. Third one went in fine using the old gasket (new ones are double the thickness). Have to now remove this one in order to repaint and bake. - Ordered two more sight glasses - just in case.... Wish me luck with my ham-fistedness. i know im no one to talk with the problems im having but i too used the vht caliper paint and just to let you know it will still come off with the brake fluid but yes it is still much better than std paint but if you leave fluid on for a time its ruined . i normally just mask the glass with tape and bake be for a short time and no issues never changed glass as a possibility of more leaking , jmo
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Post by shergar on Jun 7, 2020 13:24:04 GMT 1
Just try it my way mate, you have nothing to loose. tony you are THE MAN its worked . first time iv had lever since i started , messy is correct but worth it just to get done fair play and thanks for all advice iv received from all on the forum great gang of lads , p
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Post by tony2stroke on Jun 7, 2020 13:29:49 GMT 1
Just try it my way mate, you have nothing to loose. tony you are THE MAN its worked . first time iv had lever since i started , messy is correct but worth it just to get done fair play and thanks for all advice iv received from all on the forum great gang of lads , p Brilliant!! glad its worked for you too, never failed me, sometimes they are a PITA, specially when dry to start with or new master cylinders can be the same, just some trapped air, glad you tried it.
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Post by mannanan on Jun 17, 2020 21:05:01 GMT 1
I guess I put myself in the spanner man category as I’m no master bike builder, but I did think bleeding my brakes would be a simple affair. I have to say it all made me feel pretty inadequate after the first two days! Bought a set of Trumpet calipers for my F2, £70.00 + new seal kit for £48.00 and overhaul all went swimming well ..... until it came to bleed time. Yes, air bubbles through M/C sorted reasonably quickly, air in calipers didn’t want to move. Pull through with syringe, reverse bleed, undo banjos, tighten banjos, lever held on overnight and bleed again. Finally on day three, a little air through the nipple followed by some more air, same on other caliper and lever starts to firm up. I reckon one more go tomorrow will see the job done. One benefit of the pandemic, I did at least have the time. Glad to see it’s not just me who had problems looking back through this thread. Three pages of good tips certainly helped and got me through so thanks to all.
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Post by flames on Jun 17, 2020 22:55:36 GMT 1
I had a gpx600 years ago that I changed pads on and decided to change fluid while I was at it.i got them bled ok but always had a spongy lever unless I tied it up overnight. I tried countless times to bleed it to get some meat in the lever. In the end I bit the bullet and asked my mechanic mate to come round and help / advise what I was missing........didn't take long before I got shouted at. I wheeled the bike out of the garage and while my mate was checking for any sign of leaks etc I went of to get my tools and fluid. He soon started barking at me as I waltzed out of the garage 'stop shaking that brake fluid like a f**king can of deodorant you tw4t'!!! Didn't I feel like an idiot. Never shook any kind of fluid for car or bike since then. I even mix my anti freeze with a light swirling action . That was probably 23 - 24 years ago now. Funny how things stick with you.
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