andyfreelandy
Well-Known Member
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Having fitted a new clutch, new slave and attached this to a known working master cylinder I was not at all surprised to find the clutch bite was in the carpet. It has happened before but never really found not why it happens and how to fix it. Sort of got a solution by trial and error and not really studied it.
Here are my tips on the matter:
1. The clutch fluid in the master goes green and milky. Best to remove the master and tip it out otherwise the gungy fluid goes down into the clutch. I took the master off anyway, see 3 below.
2. Opening the bleed valve just 1/2 a turn I could hear air sucking in when the pedal was brought up. One reason why it seems to take all day to get the air out I guess. Open 1/2 turn to clean the fluid through, then tighten and open max 1/4 turn to prevent air going in faster than you get it out!!
3. The master cylinder piston has a skirt on the push rod which makes it impossible to compress the piston fully and thereby appears to always leave air and dirty fluid in the master cylinder. I popped the master out by releasing the clip off the pedal and then 1/4 twist out of the bulkhead. Used a junior hacksaw and removed the plastic ring preventing complete compression. Then bled by compressing master by hand before refitting.
Result was a clutch with sensible bite point and firm pedal.
I think the manky fluid probably compresses and contains moisture from many years under the bulkhead. Bleeding allows this duff fluid into a part of the piston in the master cylinder where it appears to get stuck until fully compressed and moved out as in 3 above.
Not the best designed hydraulics I have seen
Here are my tips on the matter:
1. The clutch fluid in the master goes green and milky. Best to remove the master and tip it out otherwise the gungy fluid goes down into the clutch. I took the master off anyway, see 3 below.
2. Opening the bleed valve just 1/2 a turn I could hear air sucking in when the pedal was brought up. One reason why it seems to take all day to get the air out I guess. Open 1/2 turn to clean the fluid through, then tighten and open max 1/4 turn to prevent air going in faster than you get it out!!
3. The master cylinder piston has a skirt on the push rod which makes it impossible to compress the piston fully and thereby appears to always leave air and dirty fluid in the master cylinder. I popped the master out by releasing the clip off the pedal and then 1/4 twist out of the bulkhead. Used a junior hacksaw and removed the plastic ring preventing complete compression. Then bled by compressing master by hand before refitting.
Result was a clutch with sensible bite point and firm pedal.
I think the manky fluid probably compresses and contains moisture from many years under the bulkhead. Bleeding allows this duff fluid into a part of the piston in the master cylinder where it appears to get stuck until fully compressed and moved out as in 3 above.
Not the best designed hydraulics I have seen
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