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fiddlebrakes and upside down calipers


v8bobber
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Hi all,

Long explanation for a relatively simple problem.........

I am in the process of trying to fit fiddle brakes to the back of my trialler. It had fiddle brakes before and have re-used the calipers which were on there, i think they are 110 ones (ie 4 pot ones with 3 bleed nipples on). The idea is that each pair of pistons in the caliper is independent, one for the fiddles, and one for the foot brake.

Anyway, i know they worked previously and the last trial i ran without fiddles as I didnt have time to fit them, and the brakes were fine, and the pedal solid.

However, in order to fit the fiddles I have turned the calipers upside down (although they look "right" for the back) with the hoses pointing out of the top. The two bleed nipples are on with one each side and the third one is now at the bottom.

However I am now finding it impossible to bleed the brakes. I have a Gunsons easybleed and I have done the entrie system twice, starting from the the wheel furthest away from the master cylinder and I am not getting any air out.

I notice that on the front calipers, the third nipple (should nick name the machine Scaramanga! lol) is at the top. My understanding is that the two inlet pipes relate to each of the circuits in a dual circuit system and should be completely independant.

my question then really is would the fact that the bleed nipple at the back make it impossible or at least very difficult to bleed? I need to get this resolved today I have at least another day of reassembly to get the rest of the trialler back together and the trial is on Sunday, so i'm very pushed for time

Hope someone can help!

Regards,

Dave

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If I understand you correctly then this may help:

Consider the calipers the right way up. Then each pipe will feed a separate pair of (opposed) pistons. The top pair can be bled using a single top nipple, however the bottom pair need to be bled separately hence the two nipples. Now - in their correct orientation, all of these nupples are connected to the top of the cylinder - where the air will settle. With the caliper upside down, none of the bleed nipples will work effectively.

So - in summary (IMHO):

The bleed npples won't ever work with the caliper upside down.

You need to bleed all three nipples to get peddle.

The only way I can see of doing it is to use flexi pipe right to the caliper and then lift it off, orientate is correctly, place a bit of wood between the pads and bleed it that way.

HTH

Roger

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Thanks guys,

Sorted it now, you must have been typing while I was getting it to work.

I (wrongly) assumed that with easybleed, the pressure would overcome any problems like this. I was considering taking the calipers off and putting them around the wrong (right?) way but as I am pushed for time I unbolted them and swung them up throught 180 degrees and then bled them. The way it is plumbed up at the moment, i simply bled the top/bottom one and got a solid pedal.

Bizarre thing is even though the other two are in the middle I had a go with those and it brought the fiddle brakes online aswell! Must be something to do with the way the innards of the calipers are. I might well get to the church on time after all!

Cheers,

Dave

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they don't have to be mounted when you're bleeding. so unbolt them, bleed them up then turn them back upside down and bolt them back on ;)

g

But remember to chock between the pads - especially when using eazibleed!

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