Bleeding Aprilia brakes

[lancialulu]

As a newbie to this Aprilia (with its odd plunger and remote fluid reservoir) hydraulic system, can anyone guide me to the correct sequence to bleed this system (Sabif) having just rebuilt the master cylinder?

Many thanks

Tim

[ben]

Hi Tim
         I don't think there is any magic to bleeding the Aprilia brakes. I believe the general rule is to start with the wheel nearest the master cylinder and work outwards but I usually find it pays to go around all the wheels at least twice so the order then doesnt matter. The important thing is to have plenty of fluid to hand and keep the resevoir topped up.
                      Best of luck
                                       Ben

[Scarpia]

at the risk of starting a debate (here goes) I thought you should always start at the wheel "furthest" from the master cylinder and work "inwards".

The piston on the fluid reservoir (2nd series only?)is useful as it simulates a second person pressing the brake peddle making it a one man job (almost).
the fluid drops quickly so you need to top up regularly.Cleanliness very important.

Tim, are you certain about the state of the master cylinder, you need to be careful with rebuilding and be sure the inner walls are not (even a little) pitted with corrosion . This may not look more than a dark shadow inside in the metal but can lead to sudden failure which is undesirable especially on mountain passes......sleeving is also of doubtful reliability;exact replicas are available and not too expensive.

[lancialulu]

William

Am confident the master cylinder is OK but rear seal had gone in a big way (c 20 years old from what I can gather).

What is the purpose of the plunger on the reservoir??

Tim

[ColinMarr]

Tim,

I haven’t had any direct experience of Aprilia S2 brakes, so I may be wrong. The existence of a plunger on the top of the reservoir suggests it might be like the system used on the Aurelia. On an Aurelia the plunger is spring loaded so that you pull it up to pressurise the system. It should stay up and if it falls this suggests a leak in the system. With this arrangement it’s also possible to bleed the brakes single-handed although you do have to keep topping up the fluid and re-pressurising the system.

Oh how I envy you working on those in-board rear brakes! No swearing on a Sunday please.

Colin

[ben]

If you are right William that might explain why I always have to go around twice!!

[JohnMillham]

If you are right William that might explain why I always have to go around twice!!

I think William is correct, but even then I always have to go round twice!
Regards, John

[lancialulu]

Thanks for all this great input. Didnt try it today as great weather for other stuff so swearing is on hold!! Anyway, I am assuming inboard brakes are no problem if the car is up high enough or over a pit??

I assume the the spring loaded plunger on the reservoir goes down eventually??? or does it  stick up all the time if the system is working correctly.

With the massive loss of brake fluid I have some tidying and repainting of the chassis area around the master cylinder anyway..

Tim

PS I would go round maybe more than twice on a fulvia and still get a little bubble or two out every time I checked the nearside front....

[ColinMarr]

Tim,

The plunger should stay up and should feel hard if you try to push it down. If it goes down it is supposed to warn you that you have lost fluid and something is wrong!

Some of the D20 - D25 race cars had the plunger protruding through the scuttle to be visible to the driver – just to warn him when to get really worried! You should just be able to make it out in this photo of Castellotti – just in front of his right knee.

Colin

[Scarpia]

you can access the rear brake nipples through the cover in the boot. Not much space to balance a container (with anti return valve) but it is feasible. no pit necessary. Even without obvious faults the plunger on the reservoir will very gradually lower with time (weeks) but as colin says, you cannot push it down if it's ok.
The fulvia is much more difficult, i've never had great success in bleeding the brakes on mine.The master cylinder is a pig to get the air out. .

[lancialulu]

Re fulvia, I rigged up a positive pressure (c 2 psi) on the master cylinder which mad a great difference. On one master cylinder before I had this set up I couldnt get the air out and deduced the the small (c.7mm) feed hole was just too small for the viscous silicone brake fluid (in winter) to flow through so I opened it up to 1mm and problem solved.

Tim

[davidwheeler]

"Professionals" use system pressurisers.  The rest of us can get by very well with an Eezibleed from the likes of Halfords.  Saves having to borrow the wife's foot.

[fay66]

"Professionals" use system pressurisers.  The rest of us can get by very well with an Eezibleed from the likes of Halfords.  Saves having to borrow the wife's foot.

And they last, had mine for getting on 50 years, frightened the life out of me the first time I used it and the the plastic brake fluid resevoir puffed up, I had visions of the resevoir going bang! but it never did.


Brian

[Scarpia]

with a lot of fiddling I use one too but the supplied adaptors don't really fit properly on the (series 2 fulvia) reservoir.I rig up two clamps to hold it in place tightly enough.On the aprilia it's not necessary to use the eazybleed as the built in plunger does the job.

[davidwheeler]

It does say in the instructions not to exceed 10psi.  If you connect it up to the nearest wheel (as I did once) then it can be distinctly alarming.