John.Taylor
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| posted on 5/8/07 at 05:59 PM |
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Help with brakes beore I organise a garage fire
I've installed by braking system and it should work but it doesn't.
The calipers are off my Sierra donor, the fronts have been rebuilt by Biggred and the rears (disks) are as they came off the Sierra.
The master cylinder is from a scrap yard Sierra as my donor had abs, but it is untested.
Having connected everything up and checked the lines to 30psi for leaks I got my father round to use the tried and tested method of pedal down, nipple
locked, pedal up, nipple open and we got them working to an extent (they stop the car when it's pushed) but the pedal still hits the stop.
I bought a Gunson Eezibleed, pushed all the fluid out and started again (longest first) running two litres of fluid through them but the pedal is
exactly the same as was the original way.
With the force of the Eezibleed (20psi) and the amount of fluid running through without bubble we're sure that there is no trapped air.
Could it be the master cylinder letting in air? If you have the master cap off and press the pedal a few times in quick sucession, the fluid races
back into the pot from from below and a few small (0.5mm dia) bubble come back. Could the master cylinder be letting air in when the plunger is
pushed into it - no fluid comes out through the plunger barrel or on any of the brake connections?
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jollygreengiant
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| posted on 5/8/07 at 06:08 PM |
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Personally, brakes are very important and I for one would not trust a second hand master cylinder.
My own personal opinion that is.
Beware of the Goldfish in the tulip mines. The ONLY defence against them is smoking peanut butter sandwiches.
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caber
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| posted on 5/8/07 at 06:09 PM |
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Sounds like duff master cylinder. I presume you have got calipers on the correct sides so the bleed nipple is at the top. also how about your flexi
hoses are these new?
I would fill the system and clamp off all the flexis if you get a pedal then you MC should be OK. release flexis one at a time until you lose pedal
that will be the one where the trouble lies .
Best of luck
Caber
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John.Taylor
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| posted on 5/8/07 at 06:15 PM |
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Flexis are new from MK.
I wasn't looking for a second hand M/C but whilst stripping the steering column off the scrapped car (mine had power steering) I couldn't
help myself in the hope that I'd save a few quid.
Looks like I'll be phoning around for a new M/C tomorrow.
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t.j.
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| posted on 5/8/07 at 06:17 PM |
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Having connected everything up and .......method of pedal down, nipple locked, pedal up, nipple open .........
Sorry that's not the way!
It is pedal down, nipple open, let air out, nipple lock, than push pedal up/down/up/down till pressure, pedal down, nipple open, etc.
Or: let gravity do the work, everything untouched: enough fluid in Mc, then open nipple and let it flow( works slowly)
Or: push fluid downwards into MC. By using a ordinary oil-can, push fluid into nipple side.
Air can be nasty, avoid higher mounted brake lines than MC.
Make sure that the MC is completed loose off the pedal at rest, this makes the compensation hole free to breath and let the fluid in.
Grts
[Edited on 5/8/07 by t.j.]
Please feel free to correct my bad English, i'm still learning. Your Dutch is awfull! :-)
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britishtrident
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| posted on 5/8/07 at 06:18 PM |
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New VW Golf Mk1/2 or Polo master cylinders can be bought for well under 20 pounds, they come withour resevoir so a trip to the scrappies is called
for.
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rusty nuts
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| posted on 5/8/07 at 07:11 PM |
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Disconnect the handbrake cable and undo rear caliper mounting bolts, adjust piston to pad clearance on O/S and N/S to approx 0.004" refit
caliper, pump pedal , reconnect and adjust handbrake
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Dangle_kt
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| posted on 5/8/07 at 08:26 PM |
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could be air trapped in the caliper, try taking them off the mounts and lying them on their side over night, might release bibbles trapped there.
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RazMan
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| posted on 5/8/07 at 08:28 PM |
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I have NEVER had any luck using the Eezibleed - 3 times I tried it and it lrft trapped air in the system every time.
I found swmbo's foot and a jam jar to be the best method, and tell her to pump firmly  while you are on each caliper - the strong surges
should expel any trapped air. Also make sure that the rears have the nipples facing up when you bleed them - take them off and use a piece of wood to
substitute for the disc if this is not the case.
[Edited on 5-8-07 by RazMan]
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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bob
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| posted on 5/8/07 at 08:50 PM |
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Apart from re setting the piston on the rears as rusty nuts suggested and leaving handbrake lever down, remember the sierra rear calipers are normally
on the top of the hub ie 12 o clock.
On the MK they are in a different position so will airlock, i unbolted my calipers and slid them up round the disc to bleed with the the bleed nipple
at the highest point.
Unfortunatly gravity wont work as the master cylinder is below the calipers, i found moving the caliper up the only way to disperse the unwanted
air.
I hope this helps
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owelly
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| posted on 5/8/07 at 09:51 PM |
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Try pumping up the pedal and leaving it overnight with the pedal pressed. Use a piece of wood or similar wedged against something to hold it down. Not
sure why it works on awkward systems but it does!
http://www.ppcmag.co.uk
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02GF74
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| posted on 6/8/07 at 08:42 AM |
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quote:
Originally posted by t.j.
Having connected everything up and .......method of pedal down, nipple locked, pedal up, nipple open .........
Sorry that's not the way!
It is pedal down, nipple open, let air out, nipple lock, than push pedal up/down/up/down till pressure, pedal down, nipple open, etc.
Although I'd haveto check, I'm pretty sure the way of haynes manual is to get assistantto push pedal and then you open the nipple. you
allow time for the pada lto reach bottom, then you close the nipple andthe assitnat lift fott of pedal.
the way you describe is similar but not the quite same. I have used both and the latter method of opening the nipple when the assistatn is pushing
down seem to push out the fluid much a much bigger force.
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