 Brake bleeding, Nothing but air from rear brakes |
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| Medtner3 |
 Oct 4 2020, 07:49 AM
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#1
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Member  Group: Members Posts: 187 Joined: 7-July 20 From: Cedar Park Member No.: 24,467 Region Association: None  |
Just rebuilt my rear calipers with seals from PMB Performance. Using a vacuum brake bleeder I started with the right rear caliper lower bleeder screw ( I have two screws) and initially pulled about an inch of brake fluid with lots of bubbles and then zip. I get zero brake fluid now.
What could cause this? I have no signs of any leaks and the brakes were not bad before I rebuilt the calipers. I read somewhere that I might need to bleed the proportioning valve or even pump into the caliper some brake fluid through the top bleeder ? I ordered a Motive pressure bleeder which arrives in a few days Attached image(s)   
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Replies
| davep |
Oct 8 2020, 08:09 PM
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#2
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914 Historian Group: Benefactors Posts: 5,300 Joined: 13-October 03 From: Burford, ON, N0E 1A0 Member No.: 1,244 Region Association: Canada  |
Have you correctly set the venting clearance on the rear calipers? IIRC, the correct value is half of the value printed in the books.
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| Medtner3 |
Oct 9 2020, 07:27 AM
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#3
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Member Group: Members Posts: 187 Joined: 7-July 20 From: Cedar Park Member No.: 24,467 Region Association: None |
QUOTE(davep @ Oct 8 2020, 09:09 PM)  Have you correctly set the venting clearance on the rear calipers? IIRC, the correct value is half of the value printed in the books. I set them at .008” there is a slight drag |
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| Gint |
Oct 10 2020, 09:55 AM
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#4
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Mike Ginter Group: Admin Posts: 16,098 Joined: 26-December 02 From: Denver CO. Member No.: 20 Region Association: Rocky Mountains |
QUOTE(Medtner3 @ Oct 9 2020, 06:27 AM) QUOTE(davep @ Oct 8 2020, 09:09 PM) Have you correctly set the venting clearance on the rear calipers? IIRC, the correct value is half of the value printed in the books. I set them at .008” there is a slight dragThis last time I did this, I followed that advice and set them to .004 instead of .008. Worked much better that way. I intend to do the same with my current 914 as it needs the restored PMB calipers venting clearance set. One of these days... Drive it for a while. Give the pedal an extra pump first when stopping. Sounds like you have an air pocket somewhere. And try tightening up the rear venting clearance. |
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| Medtner3 |
Oct 11 2020, 08:30 PM
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#5
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Member Group: Members Posts: 187 Joined: 7-July 20 From: Cedar Park Member No.: 24,467 Region Association: None |
QUOTE(Gint @ Oct 10 2020, 10:55 AM) QUOTE(Medtner3 @ Oct 9 2020, 06:27 AM) QUOTE(davep @ Oct 8 2020, 09:09 PM) Have you correctly set the venting clearance on the rear calipers? IIRC, the correct value is half of the value printed in the books. I set them at .008” there is a slight dragThis last time I did this, I followed that advice and set them to .004 instead of .008. Worked much better that way. I intend to do the same with my current 914 as it needs the restored PMB calipers venting clearance set. One of these days... Drive it for a while. Give the pedal an extra pump first when stopping. Sounds like you have an air pocket somewhere. And try tightening up the rear venting clearance. Okay . I am thinking possible the proportioning valve but if I drive for a while and careful I should be good to bleed again. I can also try the .004 " clearance if the .008" does not seem good enough |
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Posts in this topic
Medtner3 Brake bleeding Oct 4 2020, 07:49 AM
mlindner Chances are the brake fluid drained out of the mas... Oct 4 2020, 08:06 AM
Medtner3
Chances are the brake fluid drained out of the ma... Oct 4 2020, 08:25 AM mlindner Yes I would try the fronts first...I know that is ... Oct 4 2020, 08:36 AM Medtner3
Yes I would try the fronts first...I know that is... Oct 4 2020, 08:42 AM davep On a caliper with two bleed nipples, the top is th... Oct 4 2020, 08:55 AM Medtner3
On a caliper with two bleed nipples, the top is t... Oct 4 2020, 11:51 AM iankarr
On a caliper with two bleed nipples, the top is ... Oct 4 2020, 12:08 PM Medtner3
[quote name='Medtner3' post='2856582' date='Oct 4... Oct 4 2020, 01:42 PM Medtner3
[quote name='Medtner3' post='2856582' date='Oct 4... Oct 6 2020, 04:28 PM Olympic 914
It only pressurizes to 5-6 psi I wonder if tha... Oct 6 2020, 06:42 PM Medtner3
It only pressurizes to 5-6 psi I wonder if th... Oct 6 2020, 06:47 PM iankarr
[quote name='Olympic 914' post='2857140' date='Oc... Oct 6 2020, 07:59 PM Tdskip The other thing that I would add is that for whate... Oct 4 2020, 10:55 AM iankarr I like to use pressure (motive @ 5-10 psi) followe... Oct 4 2020, 11:12 AM rhodyguy Get some speed bleeders. One for each caliper. Ins... Oct 4 2020, 12:05 PM Gint Get some speed bleeders. One for each caliper. Ins... Oct 6 2020, 04:45 PM Amphicar770 I had no luck vacuum bleeding the 914, couldn... Oct 6 2020, 05:19 PM Medtner3
I had no luck vacuum bleeding the 914, couldn... Oct 6 2020, 06:49 PM rjames I could never get the brakes bled properly until I... Oct 7 2020, 11:07 AM Medtner3
I could never get the brakes bled properly until ... Oct 9 2020, 05:17 PM draganc Assuming you are not in a rush to drive the car I ... Oct 8 2020, 05:38 PM Medtner3 Damaged master cylinder or impatient? I put on spe... Oct 8 2020, 07:13 PM Medtner3 UPDATE: Pedal bled four times have a pedal now it... Oct 9 2020, 05:19 PM Frankvw I understans it is very frustrating yes. Keep up t... Oct 10 2020, 06:44 AM davep http://www.914world.com/bbs2/index.php?showtopic=3... Oct 10 2020, 09:27 PM mb911 Kind of have the same issue.. The entire brake sys... Oct 11 2020, 06:36 AM iankarr
Kind of have the same issue.. The entire brake sy... Oct 11 2020, 07:08 AM mb911
Kind of have the same issue.. The entire brake s... Oct 11 2020, 07:10 AM Medtner3
[quote name='iankarr' post='2858075' date='Oct 11... Oct 11 2020, 08:31 PM Medtner3
[quote name='iankarr' post='2858075' date='Oct 1... Oct 11 2020, 08:33 PM |
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