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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: 3dachshunds on May 10, 2025, 01:24:04 PM

Title: Rebuilding K75 rear master cylinder - plasting fitting with 45 degree angle
Post by: 3dachshunds on May 10, 2025, 01:24:04 PM
Happy Saturday! I am working to new to me 1992 K75S. I destroyed plastic fitting that connects brake fluid reservoir to MC while removing it. There was as blockage in incoming fluid port from dried up brake fluid crud. Piston was seized as well. I honed cylinder wall with 600 grit paper and blockage is cleared as well, ordered rebuild kit, but I am unable to find replacement inlet fitting (or whatever the part is called online). Do I need to buy entire master cylinder? Thank you!
Title: Re: Rebuilding K75 rear master cylinder - plasting fitting with 45 degree angle
Post by: The Mighty Gryphon on May 11, 2025, 01:19:12 AM
If you're talking about the rear master cylinder, don't bother with it, just get a $15 Chicom part on eBay and modify it per the thread here from 2017.  It's a long thread, but a good read if you have some time.

The part with my version of the adaptation starts at post #17.  I've done it on all five of the Bricks I've owned and it's worked great, better than the original Magura master cylinder.

https://www.motobrick.com/index.php?topic=9364.0
Title: Re: Rebuilding K75 rear master cylinder - plasting fitting with 45 degree angle
Post by: Laitch on May 11, 2025, 01:35:43 AM
For those with no time to lose, here's (https://www.motobrick.com/index.php?topic=9364.msg77325#msg77325) where The Mighty Gryphon's unboxing and installation analysis begins.
Title: Re: Rebuilding K75 rear master cylinder - plasting fitting with 45 degree angle
Post by: Laitch on May 12, 2025, 07:16:43 PM
I am working to new to me 1992 K75S. I destroyed plastic fitting that connects brake fluid reservoir to MC while removing it.
Post a photo to show what is meant by "destroyed plastic fitting". In the meantime, at such an inexpensive price this item might have possibilities.
Title: Re: Rebuilding K75 rear master cylinder - plasting fitting with 45 degree angle
Post by: 3dachshunds on May 12, 2025, 08:43:46 PM
I meant I couldn’t detach incoming fluid port (circled) and had take out piece by piece. The port in MC body was completely blocked. This, however is now irrelevant as I followed Mighty Gryphon (thank you Sir!) and bought cheap aftermarket MC, which hopefully arrive by Saturday and I will try to modify according to Gryphon.
Title: Re: Rebuilding K75 rear master cylinder - plasting fitting with 45 degree angle
Post by: Kaos on May 13, 2025, 08:50:31 AM
i think the part you're looking for is: 110312720
There are several "restore rear brake cylinder" videos on the webs.