- Joined
- Mar 18, 2006
- Messages
- 3,014
- Age
- 70
- Location
- Ilkley, W Yorkshire, UK
- Bike
- 2013 ST1300 A9
- 2024 Miles
- 000679
Ditto. There will be air in the system. It sneaks in in the same way that water sneaks in, and of course, water contains dissolved air. The plunger end of the SMC creates an air trap. Bubbles will float up to it and accumulate if the SMC isn't tilted.
But exercising the SMC is also really important. The fluid enters through the inlet port and is expelled through the outlet, but that leaves a small pocket of brackish fluid between the (normally) upper end of the SMC bore and the inlet port. It stands a chance of never getting changed if you just pump fresh fluid through. The same idea applies to the pocket behind the forward rear piston, and behind the lowest piston on the front calipers. See-saw the outer pistons to sluice out the grotty old stuff.
Disclaimer. I don't know this for a fact. But I do know people who have changed their fluid and still had problems that are normally associated with old fluid. I always do the above every fluid change - usually yearly - and I've never had such issues.
So I put two and two together. Up to you to decide whether I have come up with the right answer.
But exercising the SMC is also really important. The fluid enters through the inlet port and is expelled through the outlet, but that leaves a small pocket of brackish fluid between the (normally) upper end of the SMC bore and the inlet port. It stands a chance of never getting changed if you just pump fresh fluid through. The same idea applies to the pocket behind the forward rear piston, and behind the lowest piston on the front calipers. See-saw the outer pistons to sluice out the grotty old stuff.
Disclaimer. I don't know this for a fact. But I do know people who have changed their fluid and still had problems that are normally associated with old fluid. I always do the above every fluid change - usually yearly - and I've never had such issues.
So I put two and two together. Up to you to decide whether I have come up with the right answer.
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