9 replies to this topic

[Tamworthbay]

We have completed derusted our calipers including behind where the seals sit, it was only light surface rust but I don't want a repeat. Does anyone have a suggestion for what to use to keep this area corrosion free in the future?

[Dan]

Change your brake fluid frequently, 2 years maximum.

[MRA]

Brake fluid is "hygroscopic" and as such absorbs moisture............ click the link

http://en.wikipedia....wiki/Hygroscopy

[andydclements]

You can use the special grease.
Topic
http://www.theminifo...p;#entry2065282

[Tamworthbay]

Change your brake fluid frequently, 2 years maximum.

It will be used for racing so running on DOT 5, opinions vary on change interval for DOT5 when racing, some say never, some once a season (sounds better)

You can use the special grease.
Topic
http://www.theminifo...p;#entry2065282

Do you know if the stuff mentioned is Hellerine oil? I have a big bottle of that but wasn't sure if its compatible with brake systems (blooming great for fitting windows though!)

[dklawson]

You realize of course that the bores of the calipers only guide the pistons and they are not a sealing surface. The bores can be pitted and/or gouged without impacting brake function as long as the pistons can move freely and the seal seat in the bore is clean and rust free.

If you are running DOT-5 and you have cleaned these bores up, you should not see any further rust. As a footnote, most racers I know will not run DOT-5 on the track.

[andydclements]

Do you know if the stuff mentioned is Hellerine oil? I have a big bottle of that but wasn't sure if its compatible with brake systems (blooming great for fitting windows though!)

I've not encountered Hellerine oil, but I would say the rubber grease is very thick and so stays where you put it, would oil not slowly move away?

[Guess-Works.com]

Use dot 4, it's far more user friendly

[Dan]

Red rubber grease is not Hellerine. Hellerine is mineral oil for lubricating cable insulation and cable sleeves. You can't put just anything in a brake system because if the chemicals turn out to be incompatible you may well end up with no brakes. Grease will do nothing to protect a surface in a system constantly exposed to oil though, grease is disolved by oil. It just washes away. Just change the fluid often, like it says in the service schedule of nearly every car ever made.

If you intend to use DOT 5 you won't get any rusting as said above, DOT 5 is hygrophobic. It repels water rather than absorbing it. I assume you are aware it is completely incompatible with mineral brake fluids and you must very thoroughly flush through the system if it's ever had mineral fluid in it. Some advise stripping and cleaning all the components and rebuilding them using a silicone rather than mineral fluid as an assembly lubricant. You should still replace the fuild regularly though because while it repels water, DOT 5 absorbs air which can give a spongy pedal that no amount of bleeding will improve. It can also trap pockets of water around the system because it won't absorb any.

Are you certain you don't mean DOT 5.1?

[andydclements]

I've taken it that the area he's referring to is between the seals that run against the piston and the outer dust seals. In which case there shouldn't be any brake fluid oil etc getting there and so rubber grease will help keep it protected from water.
If it's the "wet" side of the piston seal, in other words inside the hydraulics of the calliper, then grease would be unnecessary and ineffective, and the brake fluid changed at the required interval should be sufficient to minimise rust.