New calipers... how much fluid to bleed?

[pupp]

Hmmmm... just fitted some 4-pots and am having a battle to get a nice firm pedal. About 2 litres of nice new Dot 5.1 gone through and although the air finally stopped (took ages), still feels a little softer than I would like (with more travel too) Any tips and tricks to crisp it up (I'm thinking of the bike racers' trick of cable tying the brake lever back towards the bars to allow any air to rise trough the system... are there any car equivalents?)

Interestingly, the caliper makers suggest letting the fluid bleed through under gravity alone??

Guess it might firm up with bedding in etc? Certainly has plenty power and feel now.

[cln1]

Could try using an Ezibleed, it's always sorted probs like that for me.

They're under £20 from Halfords

Colin.

[shpub]

The more travel is due to the change in the calliper piston sizes and thus the master cylinder can't move enough fluid. The pedal has to be pushed further and this gives the longer travel.

[scoule]

What is the diameter of the pistons on the new and old calipers?

If the total cross sectional area of the pistons on the four pots is more than double the piston area of the original sliding caliper, the pedal travel will be longer. If it's not, then you probably still have some air in the system.

[brummiewedge]

Just done the same, my calipers bled in seconds, my pistons are 34.7mm x4 pedal is good, if your pistons are larger, more pedal travel will result, but more power. Have you roadtested them?

[that daddy]

hang on if your looking for a short hard pedal,if you have fiited new pads as well dont forget the pads have not bedded in hence,longer pedal softer feel they may just need bedding in,you may find the travel and firmness will improve once the pads have bedded in.failing that refer to previous posts.