Brakes ... Master Cylinder Cap

I took off the master cylinder cap and discovered it's not made of steel. The cap seems to be made of some kind of rubber/plastic like material. So, after checking the fluid level, I couldn't get it to thread correctly (I think it had already been cross-threaded). It simply seemed so cheaply made. Are there some nice metal caps with strong reliable threads ? I've done a bunch of searches, but haven't found anyone talking about it, or offering an alternative. Maybe a machinist could make one up. I've seen one other jeep cj MC cap, and it had the same problem.
Any advice or comments from y'all ??

 

The early (single, underfloor) ones i'm familiar with were a lightweight "pot-metal" and frequently were destroyed when people tryed to unstick them.

They might be scarce, unless someone knows a source for new ones.

I'm wondering if your plastic one wasn't a misfit replacement to begin with.

 

As mentioned above, the original frame-mounted single master cylinder had a pot metal/white metal cap that was infamous for seizing to the iron threads of the MC.
There were replacement master cylinders (maybe Wagner?) in the 1970s thay were identical to the OEM stock part, except they had a plastic cap. I know because I bought and installed one around 1974.
-Donny

 

Ah ha ! What Keys5a said sounds quite likely. A replacement hadn't occurred to me, ... mine just looked original & untouched. Thanks Donny.
Oh, and yeah, it's a single reservoir.
I wonder, .... it's just a simple cap. How hard would it be to machine a nice threaded steel cap ? Perhaps with a hole in the cap to attach a line up to a remote reservoir. I saw that novel idea during my search for knowledge. (maybe here?) Thanks everybody ! This is a great site, with such a wealth of information !

 

I saw a remote reservoir mounted on the fire wall with a line down to the master cylinder, on a willys truck, some time ago. Not sure if they drilled the original cap or if it was all in kit form from some place. maybe a google search will turn something up. Wouldn't be hard to plug the hole in the cap in such a kit if it exists.

 

Yeah, the more I think about it, I imagine most everyone who messes with one of these old frame mounted MCs would love a remote reservoir. What were they thinking ? Such a PITA to get to. Or, maybe if the engineers had simply put a larger access hole in the floor ?!!? I don't know if that's a good idea or not. I've heard some say to check a junkyard for a later year remote reservoir from any number of different vehicles. I'm gonna keep an eye out for one.

 

Might this work..........


https://www.macsautoparts.com/ford_...VzFqGCh2u9wXDEAQYASABEgJ9D_D_BwE&gclsrc=aw.ds

 

Take a look at motorcycle reservoirs ; around $8 new on ebay.

 

Good ideas, ... Thanks you guys, I'll look into it

 

Welcome from Michigan, I seen a replacement single like what you have on E-Bay while surfing just this week, if that is what you want, for now. It was in Willys Jeep parts. I made a tool for my plastic cap, I can't get it loose by hand working in the factory hatch door. I want to up grade to duel master cylinder next, and a remote reservoir, would be something to consider, Good Luck

 

Let us know what you come up with for your solution. I'm sure others will run into the same problem.

 

I ran into this issue and ended up having to buy a whole new reservoir because I couldn't find the cap for sale anywhere.