Brake fluid

[cliffords]

I did a search and there are many views on the subject so I phrase my question carefully. This is not a debate on mineral verses silicon, I hope.

Is Comma Dot 4 synthetic brake fluid ok for my jag brakes and rover master.
reepower slave and girling master ?

as ever thanks in advance.

[dingocooke]

Generally the higher the DOT number the higher the temp it will take, for your brakes DOT 4 or DOT 5.

For the cluthc you can use the same, but the clutch doesnt get any significant hiogh temps, and DOT 3 (if you can find it) or DOT 4 (not 4.1) has higher lubricating properties for the stroking slave cylinder if think about the brake pistons they dont storke far but get v hot, whereas the clutch has a long stroke each time but stays at engine temp or thereabouts, so lubrication is more important.

Im talking mineral fluids, not silicone.

[cliffords]

Thanks for the reply.
is Is Comma Dot 4 synthetic brake fluid , mineral ?

[Miket]

Originally Posted by cliffords

Thanks for the reply.
is Is Comma Dot 4 synthetic brake fluid , mineral ?

Yes it is synthetic, Comma Dot 4 is the correct fluid you need. :thumb:

They do a Mineral based version which is called LHM, no good for your application.

[TINKA]

The main thing is not to mix the 2 as it will bugger all your seals.:drive:

[slogger]

As I understood, it is not wise to use silicone brake fluid with the older applications, ie XJ Jag, because there is a problem with the way this fluid reacts with the rubber seals. You do not get the required swell from the rubber and therefore can get seal problems and early failure. Not sure what happens if using the newer XJ40 setup.

I could be totally wrong! So all I will say is that my local brake specialist who is well up on older cars and bikes said don't bother. Dot4 mineral is fine!

[Miket]

Originally Posted by slogger

As I understood, it is not wise to use silicone brake fluid with the older applications, ie XJ Jag, because there is a problem with the way this fluid reacts with the rubber seals. You do not get the required swell from the rubber and therefore can get seal problems and early failure. Not sure what happens if using the newer XJ40 setup.

I could be totally wrong! So all I will say is that my local brake specialist who is well up on older cars and bikes said don't bother. Dot4 mineral is fine!

DOT 3 Synthetic Brake Fluid

Standard requirement of vehicles until the early 1980's.
Suitable for use in Drum, disc, tandem brake and hydraulic clutch systems.
Can be mixed safely with DOT 4 Fluid.


LHM Plus
Mineral based fluid for hydraulic systems.Suitable for certain Citröen, Peugeot and Rolls Royce & Bentley models (where components are coloured green).
CAUTION: Check owners manual for application.

[slogger]

Originally Posted by Miket

DOT 3 Synthetic Brake Fluid

Standard requirement of vehicles until the early 1980's.
Suitable for use in Drum, disc, tandem brake and hydraulic clutch systems.
Can be mixed safely with DOT 4 Fluid.


LHM Plus
Mineral based fluid for hydraulic systems.Suitable for certain Citröen, Peugeot and Rolls Royce & Bentley models (where components are coloured green).
CAUTION: Check owners manual for application.

Thanks Miket. As I said, could be wrong. I have always used Castrol Universal. This very issue arose when I had total brake failure due to my E Type master. Did not want to damage my new one.

[Miket]

Originally Posted by slogger

Thanks Miket. As I said, could be wrong. I have always used Castrol Universal. This very issue arose when I had total brake failure due to my E Type master. Did not want to damage my new one.

I think you will find that Castrol Universal is synthetic. :thumb:

[slogger]

Originally Posted by Miket

I think you will find that Castrol Universal is synthetic. :thumb:

Hmmm..........but not Silicone? Can't get to anything to go and have a look at the bottle. Builders....Aaaaaaaaaaaaaaaaaaa.