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Originally posted by AdrianH
Hi David.

From viewing your archive you are using the same pedal arrangement as me, the same sierra MC, you mention drums on the back may I ask what size they are, 8 or 9".
Are you on the vented front disks?

Reason for my questions are I am on vented fronts and 9 inch drums at the rear and know with the same pedal set-up I have enough travel.
I've got vented fronts and 9" rear drums. My rear cylinders were actually leaking so I bought some new smaller sized ones based on the sizes in your build diary.

From some of my past problems with brakes, I would look initially at the brake pedal movement itself.

With your foot off the pedal, do you have a small amount of free play between the push rod and the cup in the MC, allowing the MC to come back fully to the end and at what position does the brake pedal rest.
Currently, I've got about 3-5mm of slack between the push rod and the master cylinder. When I first press the pedal, the first 20mm or so of pedal travel (at the footplate) is just taking up the'slack'


There is a stop underneath the pedal through the floor (Bolt and nut), drop the stop down and allow the pedal to move further away from the bulkhead at rest and use a slightly longer or adjust the push rod to just give some allowance and try again. I quick check of a MC here and the maximum travel is 30mm, just wondering if you are getting near that travel on the push rod.
I haven't checked exactly how much m/c movement I am getting,will check tonight, but my pedal does hit the bulkhead rather than reach the end of the travel. With the bleed nipples open, the pedal moves freely in the master cylinder with no sign of the pushrod binding or similar.


I did change my rear cylinders down in size for the 9 inch drums to get brake balance to meet IVA , that would therefore take less fluid to fill them and less movement on the MC.

Adrian

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Originally posted by Ivan
Maybe the clue is in the amount you say the caliper is moving - you should barely see any movement of the pads never mind the caliper.

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Originally posted by davidimurray

Currently, I've got about 3-5mm of slack between the push rod and the master cylinder. When I first press the pedal, the first 20mm or so of pedal travel (at the footplate) is just taking up the'slack'
I would try to reduce this down to 1-2mm if at all possible

There is a stop underneath the pedal through the floor (Bolt and nut), drop the stop down and allow the pedal to move further away from the bulkhead at rest and use a slightly longer or adjust the push rod to just give some allowance and try again. I quick check of a MC here and the maximum travel is 30mm, just wondering if you are getting near that travel on the push rod.
I haven't checked exactly how much m/c movement I am getting,will check tonight, but my pedal does hit the bulkhead rather than reach the end of the travel. With the bleed nipples open, the pedal moves freely in the master cylinder with no sign of the pushrod binding or similar.
In theory you want it to hit the end of travel before hitting bulkhead, but I can honestly say I have never measured the amount of travel that is possible on the hayes pedal/push-rod

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