: Master Cylinder

05-03-04, 12:14 PM
In an earlier thread I described having trouble with a traveling pedal and how I beleived it was the master cylinder. Dave directed me to a website (kanter) that I could order a new one through. Ordered it last Monday and noticed my credit card had not been billed so decided to call. The answer I got is that they found out the master cylinder for the commercial chasis is unavailable. This cylinder is off a 69 Hearse (commercial chasis of course) I got out my shop manual and this is from the section regarding master cylinders on 69's. "In 1969 Series 697 and 698 (that's mine) cars are equipped with a check valve in the rear fluid outlet only." Then it goes on to explain about the removal of this check valve. Here is my question. Do I need to replace mine with the exact same MC. Is having that check valve THAT important. Can I go with a similar MC that does not have the check valve set up. Mine has a 1 inch deep bore and the mounting holes are 3 3/8 inches center to center. Will this MC work http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&category=33566&item=2475714061&sspagename=STRK%3AMEBWA%3AIT In my shop manual there is a picture of this same MC mounted to a power brake booster. Although this is not the one for the 698 series it was used on other Caddy's of the same year. In the power booster section the manual states "The Delco-Moraine tandem diaphram power booster brake unit used on 693, 697, and 698 series cars consists of a tandem diaphram vacuum power section and hydraulic MC. The design of the MC is basically the same as that used on the single diaphram unit." That's my question. As far as I can tell the only difference in MC's is that check valve. Is it that important. I might add my car has discs in the front drums in the rear. Thanks for any input.

Angela Desmond
05-05-04, 02:51 PM
I don't know about the check valve, but if I was in your situation, I'd try to find a place on the web that sells rebuild kits for masters and wheel cyl's. :hmm: That may end up being your best bet.

05-06-04, 11:17 PM
I am not 100% on this, but a friend of mine had a 69 factory "Executive Limo," and while I'm not sure of the chassis number, he ended up usuing a heavy-duty GMC truck master cylinder, it bolted right up and worked fine, he actually used quite a bit of GMC brake hardware, with no mods.... He said that's what GM used in the commercial Cads up until 70.... Don't quote me on this info, but it may be worth looking into.....