Reservoirs – 1, 2, or 3? Bling or period correct?

Cobra brake and clutch reservoirs

We’ve seen a number of posts recently asking if it is OK to use a single reservoir. One user even took it to the point of combining the clutch reservoir – one mass storage device.

Before we get onto a rant regarding period-correct looks under the hood, some comments on the reservoirs

Brake Reservoirs

Dual reservoirs provide redundancy in the case of failure. Separating the front from the rear, if one system fails and loses fluid, the other, while not 100% effective, still has the ability to stop the vehicle. Yes, you could save some space and a couple dollars but is it worth the risk? You can’t predict if it will ever be needed and this is one time it is better to err on the side of caution.

Clutch Reservoir

This is an entirely separate system, independent of the brakes. Yes, it may use the same style fluid, but merging the two systems is just asking for problems. Clutches (and their fluid) are much more prone to leakage and problems. Don’t even think it is wise to marry them.

Reservoir sizing

There are a number of different standards that offer basic minimums for reservoir size. In our case, the size was dictated by AC Autocars when they designed the vehicles. We are just following their design. No reason to go larger and it would be difficult to get much smaller.


Are you building / driving a 1962-65 replica cobra or are you driving a 2019 “I-built-it-myself”. The look under the hood is very likely to be different. When was the last time you saw a polished billet aluminum reservoir on a 60’s era automobile?

We are not throwing stones at some of the very finely built hot-rods, some modern cobras included. But billet has its place. The 60’s English cars used Girling brake components, for the most part, they were rudimentary. Reservoirs were made from tin cans, not injection-molded plastic or billet aluminum. The lids were pressed aluminum, not machined and polished.

The period-correct discussion should center around if the cans had Girling decals and how many or were the lids painted or bare. Not a discussion on which billet reservoir to use.


Some history

In a preview of a section we will be offering in the very near future, these are some shots of the reservoirs used on various original cars

Stay tuned to new things coming to assist you in your pursuit of authenticity.


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