26 replies to this topic

[josh.evans]

Hi Im having a nightmare trying to bleed minisport 4 pot calipers I havr tried everything still soft spongy pedal its a split yellow tag cylinder bleed nipples at top any ideas...

[RedRuby]

Never done it but have heard of people turning the calliper upside down for bleeding so the nipple is at the bottom.

[cradley-heathen]

when i saw the title i immediately thought "nipples at the bottom" but i can see your already on the ball there!

 

are you sure you have bled the system through sufficiently?

 

try wedging the pedal down over night with a block of wood or something, then trying bleeding again tomorrow

[cradley-heathen]

Never done it but have heard of people turning the calliper upside down for bleeding so the nipple is at the bottom.

that really wouldnt help, bubbles float and you would never get them out like that

[Gr4h4m]

I used a power bleed kit like ezibleed. I then left it for a day and then I got a little more out. Leaving it over night let the air rise.

This was on my kad setup.

[josh.evans]

Used the ezibleed kit I have chocked the brake pedal and will re bleed tomorrow... gone through 3 liters of fluid already

[Alex_B]

What about gravity bleeding, takes a lot longer but connect up a large pot to the reservoir so you dont run out of fluid and then crack off the nipples, I would be inclined to so a split portion of the system at a time and gravity should let the system fill 

[j.cooper]

If you have someone to help you, get someone to press and hold down on the brake pedal, crack off one of the nipples, air or fluid should come out, tighten the nipple, let the foot brake off, keep doing this until or you get is fluid coming out, then do the same on the remaining nipples, always works, hope it helps
Cheers jim

[tiger99]

Gravity bleeding has no logical or physical basis, and doesn't work in most cases, in fact it doesn't work at all on most Minis because there is a loop of pipe above the master cylinder port, where air will collect. However j.cooper has a point, indeed he has well covered the common problem, which happens when using stupid bits of tube, sometimes with non-return valves, and jam jars, which used to be widely sold. Those methods ALMOST ALWAYS fail because on the up-stroke of the pedal, air creeps in around the screw thread of the nipple. (Yes, I know someone on this forum has refuted that in the past, but it is proven fact.). But as stated, by closing the nipple with the pedal down, that is completely avoided, and j.cooper.s method is proven to work, almost always. When it doesn't, which isn't very often, I have good reason to believe that the air is trapped above the master cylinder, a problem which could be circumvented by fitting a banjo and downward sloping run of pipe, and a bleed nipple.

 

In difficult cases a suction bleeder almost always works. It is immune to air drawn in around the nipple thread, as it is just sucked out immediately. However, it might not achieve sufficient flow rate to flush the air from above the master cylinder. To do that, you need to quickly push a fair volume of fluid down through the pipework, as far as the nearest bleed nipple, relying on the surface tension of the fluid to keep the air pocket travelling with it. An Eezibleed at full rated pressure, and a few vigourous kicks of the pedal, returning fully up each time, "may" do the trick, starting at the nearest nipple (drivers side caliper), but the system really needs a local nipple.

[Alex_B]

Ahh ignore my suggestion of the gravity method! I can't say I have ever tried it as I have always had success with my eezibleed, but it certainly seems logical enough why it wouldn't work :)

[Captain Mainwaring]

If you have someone to help you, get someone to press and hold down on the brake pedal, crack off one of the nipples, air or fluid should come out, tighten the nipple, let the foot brake off, keep doing this until or you get is fluid coming out, then do the same on the remaining nipples, always works, hope it helps
Cheers jim

 

I like to shut the nipple while it is still under pressure - for what it's worth.

[The Principal]

Last time i fitted MS 4 Pots I had a few issues mainly getting the flexi hoses to seal tight but that was overcome, when it comes to bleeding the old fashioned method works all the time. As above start at the furthest cylinder and work back to the closest. Find a willing volunteer to sit in the car and push the brake pedal on command then go to the passenger rear wheel cylinder loosen the nipple a tad then connect the plastic transparent tube (other end of the tube in a suitable jar). Open the bleed nipple and ask the helper to press the pedal to the floor, once the fluid has stopped comming out tighten the nipple enough to seal it and the release the pedal repeat until the brake fluid runs clear without any air bubbles this may take several cycles of pressing the pedal, repeat working your way back to the front drivers side caliper. Make sure the rear brakes are adjusted properly as any free play will cause excess travel in the brake pedal. Important to note never let the fluid level drop too low in the master cylinder or you will draw in air so top up often as you bleed the car. Its a slow process but works.

 

Check your flexible hoses all round for signs of 'Ballooning' old persihed hoses can expand causing spongy pedals and obviously dangerous.

 

And one last point of you use a power bleeding kit make sure all four corners are fullty assembled with pads and shoes as the pressure will move the pistons outwards causing problems.

Edited by The Principal, 04 April 2014 - 05:34 AM.

[Captain Mainwaring]

Having reread that..Hmm...it's easier said than done.

[screech]

Nobody has suggested going round checking for leaks where air can be getting in as quick as you're pushing it out...?

Agree with the method above though. I've grew up helping my dad and brother bleed brakes with them shouting 'up' 'down' as they open and close the nipple whilst watching the air come through a clear bit of pipe that's catching the fluid in a bottle.

I used this method (and have MS 4pots) with no issues, except for a couple of leaks to start with.

[maccers]

I have fitted a few new calipers before, and use small blocks of ply wood to allow the pistons to come out further than they usually would with a brake pad. I dont know what happens exactly by doing this, maybe flooding the whole caliper inside with fluid vs air, then bleed as normal using ezi bleed at 20 psi or so.

 

The ply wood needs to be thinner than the brake pad to allow the psitons to come out, but not too thin that they will fall all the way out. You'll need to wind them back in after to allow the pad to go in, and probably remove some fluid from the reservoir so when the pistons go back in the fluid wont spill out the top.

 

This has worked for me every time, on single and split systems with 4 pots and cooper s single pots. May be worth a try.