I've stripped and rebuilt my front calipers on my 91 900ss. I've had the pistons out and cleaned everything up and put it back together. I've kept the original seals in due to lack of a service kit. I just can't get them to bleed properly. I've got a vacuum pump on there and it's sucking large amounts of fluid through, but it's always got air in the fluid coming out of the bleed nipples. If I shut the nipples off after bleeding as best as I can I just can't get the thing to pump up. There's no fluid coming out anywhere when I pull the lever. Is this fdue to reusing the old seals? There's a guy on eBay selling what he claims to be suitable seals for the brembos. Any ideas?
Proper seals will cost you around £60.....If you really need them give Jim Aim Motorcycles a call (KTM dealer). But first of all read this.......http://ducatiforum.co.uk/f4/bleeding-clutch-8022/ (Same principle) And also.....Get something like a big syringe or even a small squeezy bottle......push the pads right back and keep them back with a wedge. Fit the bottle to a rubber hose.......undo the bleed nipple and fit the other end of the hose onto the nipple......then upend the bottle. With the reservoir top open, squeeze the bottle with someone watching the reservoir..........FFS protect your paintwork though. Or.....Try filling the reservoir as much as possible, then put the cap back on and pull the lever several times right back, slowly each time, then leave it for a while.....You might find it starts to get some pressure, so you can then finish off.....I had to do this with another bike. AL
Get a small oil can the type with the thumb pump and the long thin spout flush it out with clean brake fluid then put the rubber hose on the spout then connect the other end to the bleed nipple open the nipple and pump it till it fills the master cylinder reservoir when you have done this then bleed the system the normal way
When you fill the reservoir with new fluid and start squeezing the lever, it aerates the fluid with lots of tiny lickle bubbles.......sometimes they collect quickly at a high point, sometimes slowly, hence overnight...........also it allows fluid to find its way down the hoses when there is too much air in the system to allow it to be pushed down. AL
Tying the lever back pressurises the system and stubborn air bubbles come out of the fluid,I've done it with good effect a number of times. Obviously you need to have most of the air out of the system before doing this.
i bought this.........its a fantastic seven quids worth..... Car Motorcycle Brake Bleeding Kit Tool With FLUID COLLECTOR | eBay
Pulling the lever back, isolates the circuit from the reservoir so that any air in the circuit will be trapped, furthermore air dissolves into a fluid better under pressure.
I've already got one of those, or at least something similar to it, but it just ain't working. That's why I've resorted to the vacuum pump.
It still rises to the highest point.....Besides, you do not want air (containing the atmosphere at the time, which has a percentage of water vapour in it) dissolving in a hygroscopic fluid. Besides, as Steve said, tying the lever back puts the system under pressure; so maybe you should have read it again. Notwithstanding the fact that my first post above contains numerous ways to deal with the issue.
Ok guys thanks or the advice. I'll give it a go tomorrow pumping fluid in from the bottom. It's weird though as there's obviously continuity between reservoir at mc and bleed nipple on caliper as I can draw fluid through the nipple, and have to keep topping it up at the reservoir, but there's just so much air coming through the nipple with the fluid. Tomorrow's another day, well see what that brings. I've done the tie the lever back trick previously and it does work, but that was with the system pretty much bled.
I pressure bleed with a rig I made up, puts 10psi on an external fluid reservoir, can flush/bleed in both directions, works a charm on rear brakes.
I just laid the rear caliper on the floor, jammed the pistons right back, opened the bleed nipple and filled up the reservoir..............when it ran out of the nipple, I tightened it up, left it for 10 mins, then cracked the top union slightly while I leaned on the brake pedal as I did it......tightened the union...Done. Front ones, jammed the pistons right back..........pulled the lever right back with cable tie........then opened one bleed nipple and then shut it. Did the same to the other one. (you should see the dirty fluid that comes out of the calipers when doing it that way. Topped up the reservoir, screwed the lid on, pumped the lever about six times......still a little bit in there, so I cracked the top union while putting a bit of pressure on the lever, then tightened it....Done.
I only an hour ago was bleeding the brakes on my project bike. Had the same issues as you by the sound of it. I ended up lifting each calliper up as high as possible and then bleeding with a pipe and container with pulling the lever. When I lifted the calliper s up the air bubbles came out and it bleed great. Just another option for you to try.
I've got one of those pump things to bleed brakes - load of old shit, just end up using loads of fluid and still having air in the system and no pressure. Best way, if refilling from scratch, is to use a big syringe and fill from the lowest point (caliper) upwards, that way you get pressure immediately and only have to bleed minimal air out of the system.
Aaargh, this is killing me. Another 2 hours and very little progress. I left the lever cable tied up overnight but that had done nothing. So first thing was to pump fluid in from the bleed nipple using a large syringe. Nobody told me to go slowly, particularly with an almost empty reservoir . Man that fluid can really travel. Once I figured out to go slowly a lot of bubbles came through in the fluid. So both lines primed, lid back on and pump. Nothing. No change. So, with fluid in the lines I then set at it again with the vacuum pump. More bubbles came out. When it ran clear I cracked up the nipples. The left hand caliper has seen some movement at the pads and a pull of the lever will apply the very gentlest of braking force. You can still spin the wheel by hand but there is some slight resistance. The right hand caliper has no movement, pads still pushed back. I've left the lever tied up again and I'll see what that does. she's doing her nut as she can see the bank holiday disappearing in a haze of brake fluid and bad language.
Al, I have been using the early version (the yellow box is now brown) on my cars for 30 years and swear by it. It is one of the oldest tools in my garage. I can do a complete system fluid change on the car(s) on my own in 5 minutes if it is on axle stands, it takes longer to take the wheels off to get to the bleed nipples. The things that are key for it to work properly. 1. Do not over pressure it (I use the spare wheel and let it down to around 15psi). 2. Tighten the reservoir cap properly before pressurizing it (I have had a blow out here due to too much pressure so always put a big rag around the fluid reservoir just in case) 3. Keep a close eye on the feed bottle fluid level 4. Always tighten the nipples against the pressurized fluid 5. Always use a clear bottle on the waste pipe 6. Make sure the nipple to waste pipe is clear and long enough so that you can see the fluid properly. However I have only used it on various cars and a couple of jap IL4 bikes, not the 748 so cannot say if it works very well (or at all) on Ducatis
