I've been looking at other 65 convertible 98s and comparing to mine, I have yet to find a master cylinder with a screw on cap like this one. I'm assuming that maybe it has been changed at some point? From talking with my family about the history it's been in the family for probably 40+ years I was told it wasn't bought new. Do any of the oldsmobile gurus have an input on the screw on master cylinder cap? Also any suggestions to track down title/ owner history kinda like a pre 1980s carfax?

 

65-66 88's and 98's all used one circuit master cylinders. I've never seen that screw cap on anything later than a '65 in my 40 years or so of playing with big Olds. It may well have been carried over from the 1963-1964 era without a change.

To my knowledge all '66 big cars were built with the bail cap single master at the factory. The bail cap is sort of a hemispherical shape with an indent to hold a retaining spring wire in place. It was common to GM for at least the next 25 years, until plastic brake reservoirs came in. I've never seen that screw cap on a '66.

The real tale here is that in '67, probably due to federal regulations, Olds and the other manufacturers moved to the much, much safer dual circuit master cylinder. The key advantage was (and is) if you blow a brake hose, you still have half your brakes.

If you're driving whatever car this is in, I highly recommend going to a 1967-1969 Olds big car (88/Starfire/98) brake drum dual master cylinder for safety.

Chris

 

The dual master cylinder is definitely in the plans before I put that land yacht on the roads. I know that's a whole lotta iron to be slowing / stopping in a hurry. How well do the 4 drum brakes work? I've never driven something with all drum brakes so I was thinking of trying to convert the fonts to disc. Is there any front disc brake spindle setups that will bolt on with little or no modifications?

 

For a great deal of detail, look here:

https://classicoldsmobile.com/forums...e-cars-132879/

The short version is disks stop better but the rotors and gear are nearly impossible to find. So much so that I had Cadillac Rotors machined to work. Highly custom and safe, but not cheap.

Until/unless you opt for disks, 1) leave a lot of room between you and the car in front of you. 2) Get used to jerks cutting in front of you with the space you need to stop. 3) Everything, everything on the road these days stops shorter than you.

Chris

 

The screw-top M/C is not factory. That's been replaced sometime in the last half a century or so.