Bleeding marina discs from dry

Post by **morrisman1** » Thu Sep 11, 2008 5:49 am

hi

the brake system on the ute is having trouble bleeding, theres still a heap of air in the front calipers. ive looked at a dismantled one i have here and i can see the design flaw! the bleed nipple is located halfway along the brake line (in the casting) that links each piston chamber together. i cant see how the brake fluid is going to get through to the second chamber with this setup, as the fluid will just go out the bleed nipple before it reaches the second chamber.

does anyone know of any tricks to bleed these discs effectively? its costing me money when the mechanic spends time on it and i want to be able to speed up the process.

cheers,
Cameron

Post by **Stig** » Thu Sep 11, 2008 8:04 am

I don't remember having such a problem when I originally fitted them to my Minor. All I can suggest is to press each of the pistons in while the bleed nipple is open to push the air out -using thin (worn out) brake pads should help with this.

Are you 100% sure the air is in the front? Only the rear brakes on a Minor are notorious for this sort of problem as the bleed nipple is before the cylinder.

There must be a Marina forum you could try asking.

Post by **MarkyB** » Thu Sep 11, 2008 9:58 am

A trick that is used on motor bikes to overcome this is to remove the calliper leaving the flexible connected and turn around to the optimum position for air to come out and the bleed it.
You need to slide something between the pistons to stop them popping out.
A bit of tapping can help dislodge air bubbles too.
Hope this helps.

Post by **morrisman1** » Thu Sep 11, 2008 10:29 am

yes 100% sure its the front. when they crimp off the front flexi hoses, the brakes are perfect (so only driving the back). the back is a toyota starlet/corolla diff anyway with new slave cylinders.

is there any sort of compressable piece between the pistons and the pads on these calipers? im still sure that theres air in the sytem. the pedal goes quite a long way down but it starts resistance right from the top.

Post by **MarkyB** » Thu Sep 11, 2008 10:55 am

Have a look at what is happening when the brakes are applied.
It may be that you have a stuck piston and the working one is trying to bend the disc

Also check the condition of the flexible hoses, they can balloon under pressure.
If this is a new installation make sure the calliper is parallel with the disc in both planes.
If it is the sliding calliper type and its not sliding properly you get the same symptoms as a stuck piston.

Post by **bmcecosse** » Thu Sep 11, 2008 10:58 am

Make sure the calipers are mounted right way up - with bleed nipples at the top. Amazing the number of Mini lads who fit calipers upside down - and then can't get them to bleed!

Post by **morrisman1** » Thu Sep 11, 2008 11:07 am

yes they are up the right way.

the calipers are rebuilt with new pistons and a new kit by one of local brake specialists.

the brake flexi hoses are all brand new

everything in the system is new or rebuilt.

i had the mounting faces of the calipers machined by 1mm so that the caliper itself wasnt touching the discs, this was performed by a local precision machine shop so i trust their work fully.

they are twin pot calipers so arent the sliding type

Post by **Stig** » Thu Sep 11, 2008 4:11 pm

morrisman1 wrote: is there any sort of compressable piece between the pistons and the pads on these calipers? im still sure that theres air in the sytem. the pedal goes quite a long way down but it starts resistance right from the top.

There shouldn't be anything compressible there, just a thin steel anti-squeal shim.

If there's resistance when you first press the pedal it doesn't sound like air. Does the pedal get firmer after you've pumped it a few times? That's the symptom of air in the system, maybe you have a different problem. As MaykyB said, have a close look at what's happening when the pedal is pressed.

Post by **bmcecosse** » Thu Sep 11, 2008 4:16 pm

To bleed - just pump up the pedal and then have worthy assistant open and close the bleed nipple - in a short 'blast'. That will clear any air!

Post by **morrisman1** » Thu Sep 11, 2008 8:56 pm

Stig28 wrote:
morrisman1 wrote: If there's resistance when you first press the pedal it doesn't sound like air.

the resistance is like normal brake pedal resistance.

Post by **MarkyB** » Thu Sep 11, 2008 9:06 pm

Is there a servo fitted?

Post by **morrisman1** » Fri Sep 12, 2008 7:15 am

got the ute back today. while over at the workshop we bled then fronts again and tried a different method: taking the outter pad out, an pumping till that piston was almost full extended, then we clamped off the flexi hose and opened the bleed nipple, then levered the piston back in. no air came out this way at all so it means that both pistons are full of fluid

to answer that, yes there is a servo fitted. i think that the servo may be contributing to some of the spongeyness because it has no vaccuum to it, its like that on all our other modern cars when there is no vaccuum in the servo.

im happy with the brakes now, i think it does need some bedding in but they seem to be alright at the moment. ill have to get the ute on the road to really test them out

Post by **rvwp** » Wed Sep 17, 2008 8:08 am

morrisman1 wrote:yes they are up the right way.

the calipers are rebuilt with new pistons and a new kit by one of local brake specialists.

the brake flexi hoses are all brand new

everything in the system is new or rebuilt.

i had the mounting faces of the calipers machined by 1mm so that the caliper itself wasnt touching the discs, this was performed by a local precision machine shop so i trust their work fully.

they are twin pot calipers so arent the sliding type

Hi, I have just fitted Marina Calipers to my Minor and could not get them to bleed giving me a spongy pedal. The calipers were new old stock so I took apart an old Marina Caliper to see the oil ways and eventually realised that as the pistons were right back in the bores, the piston on the bleed side seemed to be blocking the oil way in the bottom of the bore not allowing the fluid to pass to the other piston. By prising the piston out slightly with a couple of screwdrivers and rebleeding, problem solved. Rich

Post by **Kevin** » Wed Sep 17, 2008 3:55 pm

Hi Rich that's a rather useful tip

, post it up the useful tips section.

Post by **bmcecosse** » Wed Sep 17, 2008 8:28 pm

Seems strange they would be like this - any caliper I have opened up had some sort of channel arrangement to let the oil in behind the piston even when fully 'home'. However -I haven't opened a Marina caliper !