Whats going on!

Schurminater

Schurminater

Hero member
Location
Surrey Hills
Okay, so I noticed that one piston on the left front caliper on my Jota was sticking on and slow to return,so i decided to strip and overhaul both calipers with new pistons and seals.
Superb service from Ducati Paddy had parts delivered and fitted the very same day,Super and so far so good.
Just the bleeding to do and that has so far taken me 2 days and i am getting nowhere fast!........well theoretically i could as i can't slow down  :D

So what is going on and why are my brakes not working now?..........i have fluid at the pistons but there doesn't seem to be any power behind them,pumping the lever which feels notchy i get a reasonable flow of small bubbles in the master cylinder with every stroke.

the notchyness i am putting down to air in the system but i am wondering now if my master cylinder has gone down on me too?....though it was working okay before.

Any tips graciously welcomed as this is doing my head in!

 
I would think if you had faulty brake line connections you would see leaking fluid, so next question would be why the air bubbles are there--sometimes it  takes quite a few goes to purge all the air out. That master cylinder has to be forced in fully on assembly.
(A suction device at the bleed nipple is my choice for filling the fluid.)

But, if you went to the trouble and expense of completly refurbishing the pistons, I suggest you also renew the master cylinder and see if that corrects the problem.
 
Hello Schurminater,
The notchiness in the master cylinder would indicate a new piston /seals kit is advisable.
Quite often a small amount of air get trapped in the mastercylinder where the hose connects. A vacuum or pressure bleeding kit eliminates this but a simple Bleed Nipple Banjo Bolt installed at this position is more economical.
https://damclassicracing.com.au/30490121-3-banjo-bolt-domed-single-10x1-0-with-bleed/
 
A brake system that refuses to be bled is usually because of the little port between the MC reservoir and cylinder being blocked. Can either be a bit of crud in the wee little hole, or the MC piston not retracting far enough when the lever is released, and not uncovering the port. Take the MC apart and give it a good clean. Poke a fine wire through the MC ports.
 
Dellortoman said:
A brake system that refuses to be bled is usually because of the little port between the MC reservoir and cylinder being blocked. Can either be a bit of crud in the wee little hole, or the MC piston not retracting far enough when the lever is released, and not uncovering the port. Take the MC apart and give it a good clean. Poke a fine wire through the MC ports.
Click to expand...
Yes, a good point often overlooked. A jet drill 0.65 or 0.7mm for the small hole works well. This should be done each time when replacing the piston/seal kit.
 
This  has to be one of the most discussed topics on this forum over the years. Provided all your seals and connections are tight and the master cylinder is good, fluid clean so no blockage at the little hole  in the M/C piston then your onto  bleading. The system can be very hard to bleed . The banjo fitting at the master cylinder is the highest point so,it traps air. Make sure you start by pushing the caliper pistons all the way in. Either remove the master cylinder  I  attach mine to an old handlebar and point the banjo fitting slightly down as I bleed it. Or if you leave it on the bikes handlebar then tap the banjo with a wrench etc to break the bubbles free as you bleed it. This should accelerate the bleeding . Once you have  most of the air out but it is  still mushy.....tie wrap the lever to the handlebar as tight as it will go ( as if you were squeezing the lever ) and leave it over  night with the cap loose. In the morning it should  be all good as the last of thei air works it way out overnight all by itself. You  might  need one more bleed just to be sure.

If this does not work then you have air getting in or leak at m/c piston seal.

 
If you don't have one of Greg's nice banjo bolts with a bleed screw, you can still bleed it easily enough.

Firstly, stuff a bit of absorbent rag or paper towel under it to mop up any escaping fluid. Then, while holding pressure in the system with the hand lever, loosen the banjo bolt enough to allow a quick bleed, and nip it up again. Usually gets rid of any air trapped in the banjo fitting. If there's air in there, you'll hear and/or see bubbles escaping past the banjo washers. You may need to repeat the process a couple of times to be sure all the air is out.

 
Okay Guys, thanks for all your reply's all very much appreciated.

Having removed both calipers again last night to take stock and start a fresh,with the system now practically empty,the master cylinder lever still feels notchy and not smooth as you would expect,so that is going to be stripped and overhauled first before moving on.
Hasn't given me any problems in the past but these things happen especially when disturbed which is how i was feeling about the whole bleeding situation at 1.00am this morning!  :-X

I am also going to try and seal the bleed nipples threads a little better due to leakage around these when trying to bleed the calipers which obviously doesn't help.

I did manage to back flow fluid and air into the master cylinder from one caliper last night using a syringe but gave up with the other one.

I will start afresh after coffee and once I have the spares,.....will update later.

Cheers for the much needed support.....it really shouldn't be this hard. :LOL:

Schurmy


 
I had an issue once where the lever end had rubbed a step in the end of the piston or maybe the opposite. It made for a step that had a click produced. It made for a horrible braking action. Easy fix with a bit of smoothing with a file.
 
Are you sure your not drawing air into the system from one of the calipers in particular the join. Syringers, bleeders on the bango and all the other mumbo jumbo shouldnt be required if the system is OK.
 
Vince said:
I had an issue once where the lever end had rubbed a step in the end of the piston or maybe the opposite. It made for a step that had a click produced. It made for a horrible braking action. Easy fix with a bit of smoothing with a file.
Click to expand...

Checked and noted,with a small mark at the end of the piston.....thanks for the tip.
 
Brett said:
Are you sure your not drawing air into the system from one of the calipers in particular the join. Syringers, bleeders on the bango and all the other mumbo jumbo shouldnt be required if the system is OK.
Click to expand...

Calipers have been resealed but will check before reassembly just in case,I now have the master cylinder apart and will inspect the seals
but will replace the assembly anyway.

One thing i will say is the Brembo parts are quite nice to work with and service........many thanks to whoever posted the repair guide for the master cylinder on Laverdamania.....life saver (bigthumb)
 
Little update.......We are back in business  (Lavflag).......Big thanks again to Ducati Paddy for not only supplying the spares but also for having in mind the tool needed for securing the new piston kit for the master cylinder,very much appreciated your help and it made all the difference to me (bigthumb) so thanks again.

So for some strange reason the master cylinder had decided enough was enough,after a thorough strip down and clean the new piston assembly was fitted and she started pumping fluid again.
With the help of a syringe attached to the bleed nipple i was able to aid and draw fluid through the calipers until they were all bled.
I also taped the threads of the bleed nipples to make a better seal and this worked well and stopped the air drawing around the threads.....as a belt and braces i also used the syringe to back fill the master cylinder and push any air upwards.

Couple of other tips learnt was to loosen the splitter from the bottom yoke and move it around to allow any trapped air there to be dislodged and I was very surprised how much more air came out once the steering was turned fully left.......helpful tips to know for the future.

Eager to get her out on the road again for a test ride,many thanks for all your inputs.

Steve

 
If you have fluid leaking from the nipple threads, doesn't that mean your bleed nipple seat is not doing it's job? Normally fluid never reaches the threads except when bleeding. But well done on getting it sorted.

Can be very frustrating working on hydro brakes - the new trend in bicycle brakes is hydro discs, so I have to work on them in ever-increasing numbers. Amazing how often owners have a crack only to have to give up and bring the resulting mess to us in the shop!
 
I had similar on the rear of my Pantah years ago, new pads and 2 full days bleeding using every trick I could think of and nothing. So I finally gave up and took it took a Ducati specialist. Next day I get a call, all fixed and all for the eye-watering price of $400, that's no parts just successful bleeding. I was happy to have it fixed so I went and got it. Halfway home the brake stopped working, I was pissed off so stopped only to find the calliper danging below the bike attached only by the brake hose. Seems the bloody mechanic had forgotten to tighten the calliper mounting bolts, just lucky it hadn't dropped into the spinning wheel and locked it.
So I rang to tell the boss of the shop that one of his idiots had nearly killed me. The reason why it would bleed was it had an extra washer in the system stopping the piston from clearing THAT LITTLE HOLE.
 
How did the extra washer get there between fitting new pads and the Ducati extortionists sorting it out??? That's a lot of hours with gallons of brake fluid, Vince! If it worked before you put ads in ...??? :-\ :-\ :-\

I had a similar experience trying to get to the bottom of a sinking clutch pedal in the Skoda. Over a thousand buck in labour to some idiot for nil result. First visit to bleed the system - yes, there was air in the sys - but WHY???!!! Another - when the prob came back almost immediately - to fit a new master cyl, because it was a simple fitment and would eliminate that as a possible cause.

In the end I fitted a new clutch because the prob can only have been the slave cyl, which is very cleverly attached to the pressure plate inside the bell housing. Didn't make sense to remove the gearbox and 4wd ancillaries and not do it all (180,000km). That job was done my my regular GOOD mechanic - who'd unfortunately recommended the other joint because he was booked out for two weeks.

Sorry Clem - no short, direct posts from me  :D
 
It's a TL Pantah that was moded to look like a TT2 with homemade rear sets jacked to the sky, the TT2 tank died with the new fuel and its now much more SL Pantah. The washer was there but went where it didnt help when the pads went in, part of the rear set arrangements. The rearsets are now 30mm lower and the bars 40mm higher and it's still only good for 400ks before it starts the hurt a lot. It's much better than when the original builder rode it to Darwin as a TT2, the solo seat had 5mm neoprene as padding and the as that long thread said very harsh Maz suspension. It must have been narsty on the body
 
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