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| Spongy brake dilemma... https://www.ausmini.com/forums/viewtopic.php?f=2&t=83020 |
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| Author: | Sean1098 [ Mon Oct 07, 2013 1:52 pm ] |
| Post subject: | Spongy brake dilemma... |
Hey Guys, In need of advice with my braking system as I'm struggling to get a decent pedal. I've recently replaced all wheel cylinders, linings, and master cylinder on my all drum, non boosted set up but am still coming up with a garbage brake pedal. I've adjusted all the shoes, and bled the set up with a pressure bleeding kit but to no avail. Brake pedal pushes right to the floor although will become firm once pumped up a couple of times. Having bled them is the usual way, from furthest away to nearest a couple of times and not getting any more air out I'm starting to think that there must be some air stuck in the system that is being pushed about when I'm trying to bleed? I've also tried jacking the rear up and gravity bleeding with no success. Would the pressure regulating valve that splits the line on the rear having anything to do with it? Any advice would be much appreciated. |
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| Author: | Irish Yobbo [ Mon Oct 07, 2013 2:48 pm ] |
| Post subject: | Re: Spongy brake dilemma... |
First thing's first - what type of brake system do you have? From what you've said, I'd presume it's all drums with twin-leading shoes at the front? What type of master cylinder do you have? A good thing to check is to put some vise grips on the hoses, and check the pedal. Is it still spongy? If it is, it's master cylinder/bias valve side, if not, it's wheel side. I had an issue with the brake pedal dropping right to the floor, and it turned out to be my PDWA valve, found on later aussie cars. Your bias valve can be the issue. It can also be an issue with old hoses expanding. |
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| Author: | Morris 1100 [ Mon Oct 07, 2013 2:52 pm ] |
| Post subject: | Re: Spongy brake dilemma... |
With 2 leading shoe fronts, you need to back the adjusters right off before bleeding. I know it sounds wrong but that is the way you need to do it. |
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| Author: | MiniVLT [ Mon Oct 07, 2013 3:10 pm ] |
| Post subject: | Re: Spongy brake dilemma... |
The pressure regulation valve sounds like the culprit to me. I've heard this way, but haven't put it into practice : When bleeding the rears, pump a few times to get the pedal firm, then when the bleed nipple is cracked and you feel the pedal start to drop, lift your foot slightly, to relieve pressure from the valve & reset it, then back on the pedal again quickly. With no pressure built up the valve should not "limit" and the fluid should flow. Cheers Shane |
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| Author: | Sean1098 [ Mon Oct 07, 2013 3:30 pm ] |
| Post subject: | Re: Spongy brake dilemma... |
[quote="Irish Yobbo"]First thing's first - what type of brake system do you have? From what you've said, I'd presume it's all drums with twin-leading shoes at the front? What type of master cylinder do you have? A good thing to check is to put some vise grips on the hoses, and check the pedal. Is it still spongy? If it is, it's master cylinder/bias valve side, if not, it's wheel side. I had an issue with the brake pedal dropping right to the floor, and it turned out to be my PDWA valve, found on later aussie cars. Your bias valve can be the issue. It can also be an issue with old hoses expanding.[/quote] As mentioned, all wheel drum. Twin leading shoe front end. I replaced the brake master cylinder with the plastic previous type available from mini parts suppliers. I've no PDWA valve? only the brake bias valve found on earlier cars... |
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| Author: | Sean1098 [ Mon Oct 07, 2013 3:31 pm ] |
| Post subject: | Re: Spongy brake dilemma... |
[quote="Morris 1100"]With 2 leading shoe fronts, you need to back the adjusters right off before bleeding. I know it sounds wrong but that is the way you need to do it.[/quote] Ah, okay. I've not tried this method. I'll have a go and see if it makes a difference. Is this required on the rears as well? |
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| Author: | Sean1098 [ Mon Oct 07, 2013 3:36 pm ] |
| Post subject: | Re: Spongy brake dilemma... |
[quote="MiniVLT"]The pressure regulation valve sounds like the culprit to me. I've heard this way, but haven't put it into practice : When bleeding the rears, pump a few times to get the pedal firm, then when the bleed nipple is cracked and you feel the pedal start to drop, lift your foot slightly, to relieve pressure from the valve & reset it, then back on the pedal again quickly. With no pressure built up the valve should not "limit" and the fluid should flow. Cheers Shane[/quote] I'm using one of those pressure bleeding setups that connects to the reseviour on the master cylinder and not using the pump at the peddle method. Getting plenty of fluid through the rears, just no sign of air... thanks mate. |
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