Hydraulic Reservoirs

The brake reservoir caps house electrical connections for the float operated switch for the brake fluid warning light and appeared to be quite corroded. It was only once they had been opened that it became clear that what I thought was corrosion was probably crystallised hydraulic fluid.

The float should be enclosed in an aluminium cylinder but most of this had corroded away. I had little option but to replace the reservoirs which was a shame. Replacements are readily available however an alarming number of people had reported problems with them splitting and the resulting leak causing havoc with the paint work.

Reading other people’s woes with the repro products, I think the splitting might be initiated either when the black low pressure rubber tubing is pushed on, as a reasonable amount of force is required, or by over-tightening the hose clamps. Basically the new parts are not particularly good quality and no doubt originate from China.

The original bottles had a metal insert inside the supply protrusion/outlet which would avoid the over-tightening issue. The insert also had a gauze nylon filter, again missing from the new ones.

The clutch reservoir was better as the fluid hadn’t crystalised, which I’m now thinking might be caused as the aluminium float shroud corrodes. However there was a lot of gunk at the bottom so I thought it wise to replace as well.

I decided to salvage the metal inserts by cutting the bottles in half. These were zinc-nickel plated along with the bracket clamps before being inserted into the new bottles. The method I use to insert them was to pass a piece of string through the supply outlet to act as a guide.

A rod was then used to carefully push the insert home while supporting the other side to minimise the stress on the plastic bottle. The reverse was done when pushing on the low pressure rubber tubing, opposing the pressure with the same rod. Hopefully it will be ok.

I couldn’t work out a method of refitting the nylon gauze filter on to the metal insert once it was in place. The filters were not in the best of shape so they have been omitted.

However this does lead on to my next dilemma. As the calipers have been reconditioned and the reservoirs and hydraulic pipes replaced, I have the opportunity to switch from DOT4 to silicone brake fluid.

I like the idea of using the silicone fluid to avoid potential future problems with leaks damaging the paint work, especially in light of the problems others have had with the new reservoir bottles. Conversely there are views that the rubber seals can be damaged over the long term by the silicone.

It seems there isn’t a general consensus on which is the best way to go and it’s difficult determining whether advice is based on fact or merely that the person went down that route themselves and therefore it must be the right choice! Hmmmmm ……