blakngold4life

My master cylinder only has one reservoir cup on top, most of the cars I have seen have two, not sure if its because its an early 86, non z51, or if it was replaced previously for some reason. Is it worth it to upgrade to the two cup style one, if so is there anything else that would need to be changed aside from adding the other cup?

1986coupe

To my knowledge all 1986's had a single cup on the master cylinder. The car brakes just fine the way that it is. No need to replace it.

billybonesmusic

Take it from a guy that just replaced two cups on his master cyl.
ONE IS BETTER!

blakngold4life

Im about to install the DRM brake bias spring and flush the fluid so I figured now would be a good time to do it. Just looking for cheaper ways to improve the braking, the car does see track time so I am looking for better performance and not just the look of two cups.

billybonesmusic

It does seem a little strange why they would eliminate the other cup though. My FSM says Two outlets are for the front served from the front reservoir and one outlet for the rears served from the rear reservoir. don't know why they would eliminate the safety here.

tunedport85inject

According to my knowledge one type reservoir it's a 87 one year feature,they then come back to a 2 reservoir type in 88' and on...my 85 has 2 reservoir,84 too

billybonesmusic

Yeah, what the heck, go back to the two. Better safe than sorry. Especially if she sees track time.

blakngold4life

Did some research and it looks like this is factory for all 86 and 87's, however no replacement reservoirs are available so most people upgrade to the dual cup when they need a replacement. All 84-91's seem to have the same part number for the master cylinder itself regardless of the cups. I went ahead and ordered new cups to go with the two cup design as it should be safer incase I boil some fluid on the track.

Jimbo 89

I have front cup bleeding into the back one...wanna trade?

Chuck Tribolet

The single cup reservoir has a dam so that if the fluid gets low, the
front and rear have separate supplies.


Chuck

tunedport85inject

imagine to have to pull inside this 1 cup reservoir onto your master cylinder... probably the little connecting pipe would breack while you'r forcing the cup into the two grommet...it's a pain to push that cups into

Cliff Harris

I went with the dual reservoirs because I wanted to be able to spot a problem in the front vs. the rear. I also wanted more fluid volume because I went to the J55 brakes.

oldalaskaman

its not difficult, a little lube does wonders, as prev stated the single is less expensive.

blakngold4life

Got the cup out and replaced one, unfortunately one of the grommets was destroyed in the reinstallation process so I'm waiting on that now. Everything does fit for anyone interested in upgrading.

NaplesZ06

Any pictures of the change to 2 cups?

Any issues with the conversion so far?

Thanks in advance.

Cliff Harris

I did the 2 cup conversion about 10 years ago with no issues.

I did notice recently that my cups are slightly melted from the fire I had...

blakngold4life

I don't have any pictures, but it just looks just like any other vette with the two cups, it looks like it was made that way. No issues from it so far, I haven't had it on the road a whole lot since the upgrade due to other issues, but no issues over a couple autocross events and a track day. I can't comment on if it made a difference or not, I had less brake fade then from a year ago, but that could be from switching to DOT4 fluid more than the separate cup.