Thread: Clutch M/c - S/c Lubrication

Shirley it only becomes "corrosive" if it's not replaced as specified & has a high water content?

I am sure if the seals for the cylinders were made from an appropriate material, engine oil would work. Not much point in doing it though, as brake fluid works perfectly well and you don't have to modify any parts to do so.

As 4bee noted, brake fluid only becomes problematic when it isn't changed regularly enough and water causes corrosion. Pure brake fluid won't degrade either the seals or the cylinders.

For what it's worth...

Had my M/C changed on the 110 last week as a precaution. Mechanic told me that correct pedal height was important as if you had the pedal too high, the push rod in the M/C had the tendency to over centre and wear seal M/C prematurely. My pedal now sits abour 1 inch lower than the brake.

For the money, I'd replace the whole M/C with an aftermarket one (was quoted $150 for LR genuine). I've tried the seal kits in the past and found they don't last that long and for the bit extra money, you can buy the whole assembly.

Originally Posted by 98-110

........

What did occur to me was why not use a good lubricant like engine oil in the clutch system rather than highly corrosive brake fluid ?

Any thoughts??

An interesting suggestion. Of course, as stated by 4bee, the fluid only becomes corrosive when it absorbs water, which is why it should be changed regularly (less of a problem as far as corrosion goes with brakes, because the fluid gets hot, but it is still a problem as the absorbed water lowers the boiling point and may lead to total brake failure if it boils under heavy braking).

When hydraulic brakes were first introduced around the end of WW1, the ONLY material available for seals that would work was natural rubber - there were no synthetics. This meant that a fluid had to be found that was compatible with the rubber and worked in other respects. But with developments in synthetic rubbers in the 1940s, it has become possible to use more conventional oils. The problem is that there is little incentive to change - the problem you have encountered does not happen if it is changed regularly, and synthetic seals are more expensive, and the elastic properties not as good. Then there is the scope for dangerous errors in servicing if both types are in use at the same time.

There is at least one example of it being done. Citroen introduced a sophisticated hydraulic system in 1953 on the Traction Avant, reaching its full extent in 1955 with the DS, where an integrated system operated the suspension, steering, brakes and gearchange, all running on a heavy duty form of brake fluid (LHS2). In 1967 Citroen changed from using this fluid to using a mineral oil similar to ATF (LHM). This meant changing all the rubber parts in the system, and this is still used today. Interestingly, Rolls Royce, who were making suspension and brake systems under Citroen licence did not change, and as far as I know still have not. Consequently the only place you can get LHS2 compatible fluid for your old Citroen is from a Rolls Royce dealer.

But it seems to me unlikely that other manufacturers will change - it is too big an operation with not much payback, if any.

John

Originally Posted by isuzu110

For what it's worth...

Had my M/C changed on the 110 last week as a precaution. Mechanic told me that correct pedal height was important as if you had the pedal too high, the push rod in the M/C had the tendency to over centre and wear seal M/C prematurely. My pedal now sits abour 1 inch lower than the brake.

One of the brake workshops I contacted made the point that the aftermarket m/c did not have teflon coatings and the bore wore out prematurely. That partly led to my query about oil rather than brake fluid.

But he said nothing about adjusting the pedal height to ensure the rod pushed straight into the m/c. This explains why most members use aftermarket m/c's successfully.

Thanks 'isuzu'.