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Tue Jan 02, 2024 8:22 am

Happy New Year! Took some time over the break to get back into the bus project and nearly last step before wrapping up the brake system is replacing the brake booster and MC. I adjusted the push rod depth and shes ready to put back together. Only issue is that I noticed the gasket on the new MC is damaged and now I'm trying to sort out the best option for moving forward. I cant tell if its a manufacturing defect or was damaged prior to shipping, but its definitely not in good shape.

Are there suitable alternatives to ordering an overpriced replacement gasket for this? A gasket compound, like permatex or similar? I assume that RTV is a no go here but figured Id see if there are any good ideas before proceeding.

Thanks in advance for any guidance and HNY!

Tue Jan 02, 2024 8:40 am

Some good hardware stores have gasket/o-ring collections, one near you may have a match.
The original was rectangular in cross-section, to match the channel in the m/c, but I see no reason a round o-ring of proper size wouldn't work. I've seen both kinds used.

If nothing local, there's https://www.theoringstore.com/store/

Tue Jan 02, 2024 9:00 am

You will not get a gasket or o-ring for this of the correct material at any hardware store.

I agree that a simple round o-ring could work fine but it MUST be made of EPDM and no other rubber material or a single drop or brake fluid either from spilling on the outside or leaking from the master cylinder will eat any other rubber.

That being said, take it the old o-ring to a flaps or any bearing/seal dealer and have them put it on their sizing tool to tell you the size. A bearing/seal house can easily get you an EPDM o-ring. They may also be able to get you a square profile o-ring.

If not you can get EPDM o-rings at McMaster Carr. You will probably have to buy a packet of 10 but it will be maybe $10.

If you can measure it and find the size I can see if the place I have recently gotten correct EPDM u-cup seals for clutch slaves would have a flat profile o-ring. Ray

Tue Jan 02, 2024 9:34 am

Teflon paste might make a decent enough temporary fix until you can find something better. In normal use this o-ring sees only air/vacuum so even hardware store orings should last quite a while. I do agree with getting a correctly sized EPDM o-ring in the long term.

Tue Jan 02, 2024 11:04 am

Thanks for the quick feedback, much appreciated.

Tue Jan 02, 2024 11:07 am

a year of the bus would be nice. There could be a part number for that gasket. My 1977 had an o-ring.