The 'E' Type Forum

Just a thought as I'm about to embark on my brake stripdown this weekend - see "Sticking front brakes" thread below, regarding Brake fluid and the Red Rubber Grease used in assembling and lubricating brake parts.

In some of the posts I read, there used to be a Girling Crimson Brake fluid - which Chris Storey thought had potentially elements of the Red Rubber Grease added to aid the brake components overcome friction and maintain lubrication. Can anyone confirm this idea or state why this cannot be undertaken on modern Brake fluid ?

I understand that modern Brake fluids have less lubricity and that Dot 4 is preferable to Dot 5 in master cylinders to aid the action of the seals in the bores, but just wondered if we could improve on that situation in today's world using yesterday's technology.

Ready to get shot down here, but if Red Rubber Grease is compatible with Brake fluid, could a very small amount, (< 1%), of Red Rubber Grease be pre-mixed and diluted in a solution to be added to the brake fluid on the final part of the brake bleeding process in order to enter the master cylinder as an aid to the lubrication of those internal parts ?

regards,

Dave

I think, but can't be sure, that someone else on here has previously said that they already do this. Was it not in the same thread that mentioned the old red brake fluid? I am going to try it but have not checked yet how well the grease dissolves in brake fluid. I used a liberal amount of the red rubber grease in the re-assembly of my master cylinder and servo cylinder and all seems to work well but surely the grease will be flushed through when bleeding the brakes?

Unless of the silicon nature (Dot 5), brake fluids are notably fond of water, so they quickly absorb water vapour when exposed to air and become unfit to work.
If you intend to make the mix you are talking of, be sure that you avoid as much as possible exposure to air during the process.

DOT 4 brake fluid is indeed fond of water and should be changed every two years (max) and ideally yearly. Personally I would council against mixing anything with a good quality fluid just to make it look red - it already has a composition suitable for lubricating the seals used in the brake system and minimise corrosion. Adding additional ingredients won't help. The red rubber grease is a grease designed not to harm rubber and can be used on any rubber component not just brake parts. If you are assembling e.g. brake cylinders then, if they are old, remove all rubber parts and renew them, clean the cylinder and piston etc with methylated spirit. Dry, wipe the cylinder with fresh brake fluid, fit new rubber sealsto the piston and re-assemble. Keep everything meticulously clean. Dust seals can be fitted using a smear of red grease. Then install and flush the system.

Don't store opened bottles of fluid for any length of time (months) as they do absorb moisture. Keep your fluid reservoirs tightly sealed and flush the system regularly.

Peering at the interweb there are products out there that appear to be red in colour although the colour is just a dye.

I'm afraid that dot 4 is not as good as earlier fluids at lubricating the seals , and is the cause of stiction in older type master cylinders. This particularly applies to the cylinder in the remote servo on 4.2 litre cars which are usually the source of dragging brakes ( along with the vacuum valve). I regularly dissolve red rubber grease in modern fluid which provides adequate lubrication, and since the seals should be assembled with a liberal coating of the grease, and the grease is fully miscible with the fluid , it can do no harm to put some in the fluid . Incidentally , be very careful with methylated spirits : although in the past it was denatured wood alcohol, modern commercially available spirits tend to be mineralised, and will lead to seal degradation

agreed re meths....don't wash seals in it (or anything else really) - just metal bits.