Master Cylinder Cover

[David W.]

I looking to replace the Master Cylinder brake cover and gasket on a 78 and I have noticed the original is vented between reservoirs and to outside edge on one side. Many repro covers state they are non-vented for the year. Does it really make any difference vented vs. non-vented? Are pressures such that PB need relief? I have replaced system with silicone brake fluid.

[Joe L.]

Re: Master Cylinder Cover

I looking to replace the Master Cylinder brake cover and gasket on a 78 and I have noticed the original is vented between reservoirs and to outside edge on one side. Many repro covers state they are non-vented for the year. Does it really make any difference vented vs. non-vented? Are pressures such that PB need relief? I have replaced system with silicone brake fluid.

David-------


ALL 1967-82 Corvette master cylinder covers were VENTED and that's the only style of cover I would use. The venting has nothing to do with relieving pressure inasmuch as there exists no significant pressure above the master cylinder reservoirs. I believe the venting is to allow atmospheric pressure to be maintained in the dome between the cover and diaphragm. In this manner, the airspace in the reservoirs (which increases as fluid level decreases due to pad wear) is filled by the "accordian" bellows of the diaphragm.

The last available GM cover, GM #18060017, is discontinued but you may still be able to find one around.

The diaphragm, GM #5455516, is also discontinued but available in the aftermarket.

[David W.]

Re: Master Cylinder Cover

Thanks Joe.............I was able to find a GM cover #18060017 thru GMparts Direct.

[Joe L.]

Re: Master Cylinder Cover

Thanks Joe.............I was able to find a GM cover #18060017 thru GMparts Direct.

David-------


It will be interesting to see if they can actually supply it.

[Jerry B.]

Re: Master Cylinder Cover

What finish is on the orginal cap?

[Joe L.]

Re: Master Cylinder Cover

What finish is on the orginal cap?

Jerry------


I can't speak for the cap on David's car. However, I can tell you that ALL 1967-82 master cylinder caps were zinc plated with a chromate ("gold") over-plate. However, the appearance did vary somewhat over the years.

[David W.]

Re: Master Cylinder Cover

Yep I received a DISCONTINUED update on the cap like you said Joe. Mine is as you stated chromate gold plating. The replacement for 67-82 is a NON-VENTED cap with the DOT 3 warning on the flat area not the domes as per the original. So whats with this vented vs. non-vented. Not needed??

[James B.]

Re: Master Cylinder Cover

David,

Have you checked out Corvette Stainless Steel Brakes? Here's a link. http://www.cssbinc.com/mastercylinde...cessories.aspx

Jim

[David W.]

Re: Master Cylinder Cover

No I haven't checked into ss. The brakes are fine I just need to replace the master cap. The car is a low mile survivor and mint so I want to maintain originality. Thanks

[Joe L.]

Re: Master Cylinder Cover

Yep I received a DISCONTINUED update on the cap like you said Joe. Mine is as you stated chromate gold plating. The replacement for 67-82 is a NON-VENTED cap with the DOT 3 warning on the flat area not the domes as per the original. So whats with this vented vs. non-vented. Not needed??

David------


I don't know why there would be non-vented covers on the market. As I mentioned, all 1967-82 Corvette covers were vented. The covers and configuration of the vents did change a bit over the years.

[Terry M.]

Re: Master Cylinder Cover

No I haven't checked into ss. The brakes are fine I just need to replace the master cap. The car is a low mile survivor and mint so I want to maintain originality. Thanks

David,
James pointed you to SS Brakes because they sell a reproduction of the cap you are talking about. I believe he was suggesting you check out that item.

[David W.]

Re: Master Cylinder Cover

I talked to various tech support people and many are vented but some are not so its good to ask. SSB does have a vented cap so does Ecklers. The venting has changed quite a bit. Its tough to see the small holes on the domes. No more tunnels like the OEM which are obvious. BTW I found an NOS cap for $229 :-) Think I'll pass........... Thanks guys.

[James B.]

Re: Master Cylinder Cover

David,

You might want to try a part number search on PartsVoice for a source near you. https://www.partsvoice.com/

I had typed in Joe's referenced part number and my zip code and I was able to get a local hit (Llewellyn Obsolete Northridge GM) in Northridge, CA. Phone number: 818-363-5094

Good luck.

James

[David W.]

Re: Master Cylinder Cover

James I did the same thing with my zip and got the same outfit as you. i called and left a message. We'll see.

[Steven B.]

Re: Master Cylinder Cover

Jerry------


I can't speak for the cap on David's car. However, I can tell you that ALL 1967-82 master cylinder caps were zinc plated with a chromate ("gold") over-plate. However, the appearance did vary somewhat over the years.

Correct Joe. My original owner early '77 and early SA '78 each are plated as you say and identical in finish. I recently looked at an original '79 appeared to be a little lighter in color but who knows what happened over time.