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PopUpProject
Joined: 06 Aug 2025
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Location: NE Ohio
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 Posted: Sun Dec 21, 2025 8:25 am Post subject: |
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| 924RACR wrote: | | And make sure, for that final squirt, that you close the bleeder off while the pedal's still dropping/caliper is under pressure... |
Good to know, thank you!!! I'm obviously very new to all of this, but we're slowly getting it all figured out 
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Poppy the '82 924 Resurrection in Progress |
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PopUpProject
Joined: 06 Aug 2025
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| Posted: Sun Dec 28, 2025 12:56 pm Post subject: |
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| Raize wrote: | Just when you're pushing on it.
Keep hard pressure on it for a minute or two. If there's a nick on the master cyclinder bore, or a slightly torn seal, the fluid will slowly get pushed past that and you'll eventually push the pedal right down to the carpet.
But if it's just some air you're compressing, it'll not move any further. |
Alrighty, I held full pressure on the brakes for 5 minutes and the pedal did not fall to the floor or fall beyond the what I think is the normal stopping point. Our buddies lift is currently occupied so we weren't able to throw her in air jail tonight.
When we get around to having her in air jail, if I crack the lines off and I'm not getting good streams off the mc, what could be going wrong? Or on the flip side, if we do get good streams off the mc, would that point to the hose lines being gunked up?
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Poppy the '82 924 Resurrection in Progress |
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924RACR
Joined: 29 Jul 2001
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Location: Royal Oak, MI, USA
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| Posted: Sun Dec 28, 2025 10:36 pm Post subject: |
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If you're not getting good streams from the ports of the master - then yeah, time to investigate/rebuild/replace the master. But I'll be surprised at this point if that is the outcome.
Yes, if you are getting good streams directly from the master ports, there must be an obstruction in the hoses or lines. Next step would be to take the hoses and lines apart (starting at the wheel end, with the hose) until you've gotten the blocked component off and can get a good stream again...
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Vaughan Scott
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'79 924 #77 SCCA H Prod racecar
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chuck21401
Joined: 20 Feb 2005
Posts: 606
Location: Annapolis, MD
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| Posted: Sun Jan 04, 2026 4:00 am Post subject: |
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The brakes in my car didn't feel quite right after a hard stop. I checked the brake fluid reservoir and it was low...but couldn't find any signs of leaking brake fluid from the brakes or the hydraulic clutch system.
Added fluid and went for a quick drive...same symptoms. I figured the brake MC was going bad but the missing fluid was a mystery. Ran some searches here...sometimes when the seals go the brake fluid ends up pooled in the brake booster. Pulled everything apart...sure enough...that's where it went. What a mass. Cleaned everything up, installed a new/re-manufactured brake master cylinder, bled the brakes...and was back on the road.
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1981 Porsche 931 w/S1 engine & euro g31 transaxle. Water-cooled intercooler |
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PopUpProject
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| Posted: Sun Mar 08, 2026 11:54 pm Post subject: |
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Alrighty I am back with some more findings, we haven't pulled the lines or hoses yet, but there is a slow seep between the mc and the brake booster, which leads me to believe at a minimum that seal is bad between the two but could that be a sign of a bigger problem with the mc or brake booster?
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Poppy the '82 924 Resurrection in Progress |
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PopUpProject
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| Posted: Sat Mar 28, 2026 12:23 pm Post subject: |
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I have gone dumpster diving in the depths on here for more info on the mc, and along the way I managed to find a PDF of the Porsche Workshop manual, and the absolute rage of all there being on the mc was "replace mc". I was hoping there would be some tips on rebuild or further troubleshooting -.-
We have determined it is almost 95% certainly the mc. Yippee. not.
Although we mostly determined its a large risk trying the rebuild kit from pelican, I am still tempted to try it. However at that point, am I better off attempting to find a shop that could do a rebuild, sacrificing a matching one that I find on fbmp for dirt cheap to a shop, piecing together a kit from Pelican and where ever else I can find, or attempting to use a more modern MC and booster?
An oem from porsche is out of the question budget wise and online/ebay has not been much cheaper unless I want to risk it for the biscuit overseas.
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Poppy the '82 924 Resurrection in Progress |
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924RACR
Joined: 29 Jul 2001
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Location: Royal Oak, MI, USA
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| Posted: Sat Mar 28, 2026 9:43 pm Post subject: |
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Well, I mean all a rebuild encompasses is replacing seals, cleaning, and hopefully no corrosion to deal with (which would require at a minimum re-honing the bore, possibly replacing the piston if damaged)... if you got the kit and found it had correct replacements for the seals in yours, then you should be in business.
In my mind, it's really just a question of if you're willing to gamble the cost of the kit...
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Vaughan Scott
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PopUpProject
Joined: 06 Aug 2025
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| Posted: Thu Apr 02, 2026 11:39 am Post subject: |
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| 924RACR wrote: | Well, I mean all a rebuild encompasses is replacing seals, cleaning, and hopefully no corrosion to deal with (which would require at a minimum re-honing the bore, possibly replacing the piston if damaged)... if you got the kit and found it had correct replacements for the seals in yours, then you should be in business.
In my mind, it's really just a question of if you're willing to gamble the cost of the kit... |
Yeah and the fun would be finding a shop that would be able to rehone everything if it needed it (which with my luck, it probably does) I do have plans of one day swapping to a 5 lug to have more modern brakes. Would it make sense to maybe go to a 944 mc and booster even though I am staying 4 lug for the foreseeable future, as I'm assuming they have more availability (and hopefully maybe cheaper)?
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Poppy the '82 924 Resurrection in Progress |
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924RACR
Joined: 29 Jul 2001
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Location: Royal Oak, MI, USA
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| Posted: Thu Apr 02, 2026 8:40 pm Post subject: |
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You can get a brake hone for your drill at a decent auto parts store! Easy-peasy...
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MikeJinCO
Joined: 08 Jun 2010
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Location: Maysville, Colorado
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| Posted: Thu Apr 02, 2026 10:32 pm Post subject: |
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The differing rod lengths between the 944 and 924 master cylinder and booster make it a swap requiring fabricated spacers. If you try to use the 944 booster it interferes with the throttle cable location coming thru the firewall.
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Mike
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PopUpProject
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| Posted: Fri Apr 03, 2026 7:35 am Post subject: |
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| 924RACR wrote: | | You can get a brake hone for your drill at a decent auto parts store! Easy-peasy... |
I can barely draw a straight line, I'm not sure how successful I would be at honing everything out properly XD But it is worth a shot. I might try and build my own rebuild kit from Pelican and see what the individual items vs the 928 kit on there would cost, if I can get all of the little bits.
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Poppy the '82 924 Resurrection in Progress |
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PopUpProject
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| Posted: Fri Apr 03, 2026 7:36 am Post subject: |
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| MikeJinCO wrote: | | The differing rod lengths between the 944 and 924 master cylinder and booster make it a swap requiring fabricated spacers. If you try to use the 944 booster it interferes with the throttle cable location coming thru the firewall. |
Good to know!!! Thank you, I hadn't fully explored that rabbit hole yet, it was more of just a thought as I've been going through the rolladex of options
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924RACR
Joined: 29 Jul 2001
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Location: Royal Oak, MI, USA
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| Posted: Fri Apr 03, 2026 9:21 pm Post subject: |
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| PopUpProject wrote: |
I can barely draw a straight line, I'm not sure how successful I would be at honing everything out properly XD But it is worth a shot. I might try and build my own rebuild kit from Pelican and see what the individual items vs the 928 kit on there would cost, if I can get all of the little bits. |
I guess it's a good thing the hone is flexible and self-aligning, then... 
https://www.autozone.com/p/duralast-brake-cylinder-hone-82-002/1266662
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#25 Hidari Firefly P2 sports prototype |
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