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Post by scottydugg on Feb 22, 2023 20:11:56 GMT
Thought I'd post here rather than the build thread, as this is starting to become a real battle. Removed the mk2 non-abs master cylinder and bench bled it. Happy days we now get fluid through when we pump the pedal, but it's still not forming up, I tried bleeding all 4 corners quickly: fluid did come out and some bubbles but the pedal will not firm up at all and still goes to the floor.
Something is not right and I'm not sure if it's my recipe of components. Everything I read suggest it all goes together just fine. As long as you're abs/non-abs and match up correctly.
I think it might be the servo isn't compliant,but the pedal is doing something and a quick search showed a deep mk2.5 servo which I definitely do not have, I belive its a mk2 unit, and would be the same for abs or non-abs, the difference being the master cylinders.
Might it just be I've not bled it enough and have air in the lines? The brakes aren't grabbing the discs yet.
Could use some help please, a weekend jobs now in week who the Canoe knows.
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Post by Zed. on Feb 22, 2023 21:19:08 GMT
you swapped servo & master-cylinder or just master-cylinder?
Rich.
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Post by scottydugg on Feb 22, 2023 22:01:49 GMT
Got what I think is a mk2.5 servo with the brakes, swapped the abs master cylinder to a mk2 non abs unit (from autotech), with three ports.
Opened the rear caliper and had the helper pump the brakes till fluid came out, I could still have air in the lines? Would that result in no brakes.
I've got a hand held vacuum bleeder I cm try, or try reverse bleed, maybe my bench bleeding hasn't worked.
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Post by dadbif on Feb 23, 2023 7:23:10 GMT
Sounds like you still have air in the system. If you have a vacuum/pressure bleeder, try that.
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Post by scottydugg on Feb 23, 2023 9:45:12 GMT
Thanks @dabif and Zed.. I've tried vacuum bleeding it and it's still the same result. I might have found a mechanical issue though: forum.miata.net/vb/showthread.php?t=363284 post #11
& forum.miata.net/vb/showthread.php?t=363284&page=12 post #277.Earlier master cylinder doesn't work with a later servo, due to push rod length. So I'm compressing my pedal fully but only getting minimal travel inside the master cylinder. Post #277 shows the difference in push rod length between the 2, it might be interchangeable, but I'm thinking for brakes, just swap a mk1/mk2 non-abs unit in - regardless everything needs to come back out which is a pain - again Autolink to the rescue. So mk1 and mk2 are interchangeable, but mk2.5 is not unless you start opening them up - I'll confirm when I pull everything out again, but hopefully this will save someone pain in the future. Moral of the story is, don't change the servo or master cylinder  , I changed my servo as it was rusty and looked prarrie canoe, mistake! |
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Post by Zed. on Feb 23, 2023 18:19:22 GMT
Thanks @dabif and Zed. . I've tried vacuum bleeding it and it's still the same result. I might have found a mechanical issue though: forum.miata.net/vb/showthread.php?t=363284 post #11
& forum.miata.net/vb/showthread.php?t=363284&page=12 post #277.Earlier master cylinder doesn't work with a later servo, due to push rod length. So I'm compressing my pedal fully but only getting minimal travel inside the master cylinder. Post #277 shows the difference in push rod length between the 2, it might be interchangeable, but I'm thinking for brakes, just swap a mk1/mk2 non-abs unit in - regardless everything needs to come back out which is a pain - again Autolink to the rescue. So mk1 and mk2 are interchangeable, but mk2.5 is not unless you start opening them up - I'll confirm when I pull everything out again, but hopefully this will save someone pain in the future. Moral of the story is, don't change the servo or master cylinder , I changed my servo as it was rusty and looked prarrie canoe, mistake! I'm lazy so didn't read.... there needs to be freeplay between pedal / servo & master-cylinder to allow the master-cylinder to return to it's 'open' (relaxed) position and obviously having full-stroke will help with building maximum pressure... sorta... hence my question re. whats been swapped as sometimes pushrods need adjusting - if they're adjustable or sometimes spacers added when playing Frankenstein  Rich. |
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Post by scottydugg on Feb 23, 2023 20:16:45 GMT
Thanks @dabif and Zed. . I've tried vacuum bleeding it and it's still the same result. I might have found a mechanical issue though: forum.miata.net/vb/showthread.php?t=363284 post #11
& forum.miata.net/vb/showthread.php?t=363284&page=12 post #277.Earlier master cylinder doesn't work with a later servo, due to push rod length. So I'm compressing my pedal fully but only getting minimal travel inside the master cylinder. Post #277 shows the difference in push rod length between the 2, it might be interchangeable, but I'm thinking for brakes, just swap a mk1/mk2 non-abs unit in - regardless everything needs to come back out which is a pain - again Autolink to the rescue. So mk1 and mk2 are interchangeable, but mk2.5 is not unless you start opening them up - I'll confirm when I pull everything out again, but hopefully this will save someone pain in the future. Moral of the story is, don't change the servo or master cylinder , I changed my servo as it was rusty and looked prarrie canoe, mistake! I'm lazy so didn't read.... there needs to be freeplay between pedal / servo & master-cylinder to allow the master-cylinder to return to it's 'open' (relaxed) position and obviously having full-stroke will help with building maximum pressure... sorta... hence my question re. whats been swapped as sometimes pushrods need adjusting - if they're adjustable or sometimes spacers added when playing Frankenstein Rich. Short version is mk2. 5 servo doesn't work with mk1/2 master cylinder, took it all out earlier and can confirm. Should have checked before installed it! That'll be why it didn't bleed, full pedal travel was only getting half travel at the cylinder. |
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Post by thruxton on Feb 24, 2023 6:55:38 GMT
That’s great information for all of us, thanks.
Regards.
Rich.
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Post by scottydugg on Feb 27, 2023 10:40:46 GMT
Swapped this all over Friday afternoon, can confirm now have brake pressure. Just need to bleed the brakes - have become very adept at pulling the servo and MC.
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, I changed my servo as it was rusty and looked prarrie canoe, mistake!
le sigh