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Bleeding the mini brakes


Adrian
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Morning all. Attempted to bleed the brakes yesterday on the mini, did it in the order the Haynes said. First 3 fine but the final front offside has no flow. 

I think I’ve traced it down to the banjo union, if I slacken off the banjo bolt I get seepage of fluid.

new pipes, reused old joint. Any ideas?

thanks Adrian

 

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Yes it’s split front to back. Following your doubt about the banjo, I took the front calliper off and disconected. I got flow so the problem is actually the calliper, brand new. Should I be using a copper washer at the flexi hose connection? Does the connection depress something inside to allow flow?

just thought to loosen off the hose from the calliper and I got flow. This implies I need a thicker copper washer?

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I've put two washers on the offending connection and it now bleeds fine. I've ordered some more copper washers of a better size and will attempt to bleed the system fully next week when they arrive - I wonder what other issues I'll be faced with once complete - probably no pressure at the pedal for a start! Watch this space!

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cant visualise but if screwing the hose into the caliper causes an obstruction there has  to be a fundamental cock up in the caliper 

is the  fluid drilling off set to the threaded portion ???   two  washers is not advised on brake systems , theres a lot of pressure in these 

an eagle eye mot might even give it  a rejection 

Pete

 

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Adrian i have to agree with Pete, there must be something wrong somewhere. I think you might even end up with a brake inbalance between the two sides. You really do need the front brakes to work, as they do all the stopping on a mini. Like i say, swop the hoses around.... It will then tell which is at fault.... Caliper or Hose.

Tony.

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Well if it is a potential safety issue I’ll swap the calipers ( ironically easier than the cables in the first instant) but I know it’s just to test and not the right way round. I suppose i’ll Have to get a replacement if it’s defective

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I know what you mean Adrian, those hoses are an absolute pig to do. At least they wont be rusty. It will be interesting to find what the fault is though?  I have never come across it before, and i dont think Pete has either?

Tony.

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I actually think the depth of the thread in the caliper is a fraction too short (or the hose thread is too long) and when tightened up actually seals itself against the bottom face of the caliper thread.

i’ll have a look this morning. I’ve ordered some 1.5mm washers as the current ones are no more than 1mm. They may just be enough to get the clearance without using 2.

Adrian

 

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OK, found an old Mini caliper - it measures 0.75" deep to the bottom of the hose connection.

You're using braided hoses looking at the picture you posted; has it got the correct length end fitting?

I've pictured a goodridge hose which measures just shy of 1/2" long - so with the copper washer there should be plenty of clearance to the bottom of the caliper connection.

David.

 

 

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I do really enjoy this forum - knowing that problems and double checks can be resolved without pre judging my ignorance! But unless I'm mistaken my ignorance may be the cause of the problem.

So this morning I've looked at the clearance in the callipers, one measured 12.74mm and the problem one measured 12.33mm. Now the thread length is the same as Davids. I tapped the centre of the calliper with a smaller diameter bolt and the resultant measurement was 12.93mm so it moved. So from what I deduce is the hose feeds directly behind the piston and the problem piston was far enough back to make contact with the end of the hose. As I was using an eezibleed I guess the pressure was insufficient to move the piston forward. 

So the question of holes lining up doesn't seem to apply because there is no hole inside the calliper, just the back of the piston. Forgive the drawing - art was never my strong point.

Make sense?

Adrian

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If the hole that the hose screws into is just a parallel hole into the chamber, as you've drawn, then I can't see any problem with filing a mm off the tapered end of the hose. It's not doing anything as there's nothing for it to bottom onto except the piston, which you don't really want it to touch.

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