I will be replacing the front callipers on my 5 over the next week or so. I’m fine with clamping the hoses and the removal and re Instalation… Ive replaced or upgraded quite a few callipers over the years but Only on Motorcycles.
Obviously I will need to bleed the brakes and will change the fluid at the same time.
When doing the bikes I used just simple clear tubing so I need to know please which size / diameter I need.
Quick scan on ebay shows loads of pipes with non return valves. Should I get one of those or just do it with a simple section of clear pipe ?
If you are going to do the job yourself, I would suggest a proper bleeding kit, something like sykes pickavant with a non return valve so you can pump the brake only to bleed.
If you have a helper you can bleed with just a tube with the helper pumping the brake on your command and you opening and closing the bleed nipple with a spanner.
In the past, for solo bleeding, I’ve used a bit of silicone tubing and a jar full of brake fluid. The supplied plastic tubing in the bleed kits, even with the little clamp, just seemed to fall off the nipple. Speed bleeders work great on the calipers; you replace all 4 nipples with these replacement items, which have a built in non-return valve. Attach tubing, empty jar, slaen nipple, pump a couple of times, job done. Bench bleeding the calipers also helps.
I find the old method works very well provided your helper sticks to your up and down commands on the brake pedal and you can operate the bleed nipple lock/unlock with spanner effectively. You are also on hand to make sure nothing goes astray and pressure in the tube is limited. Pays to check all bleed valves prior to this process and soak in easol or similar if corroded up.
I’ve not really thought about the order of bleed as long as you make sure that new air bubble free fluid expelled from the nipple before moving on. The fluid will naturally move to the area of least resistance ie. the open bleed nipple whichever quarter it is. Hopefully there will be sufficent colour/shade difference between the old and new fluid to make judgement that new fluid is coming through very easy. Let the reservoir run low before topping up with new fluid but not too low. Drawing in air at that point will be very annoying.
If you are replaceing both front calipers and doing a complete brake fluid change, I would
First bleed the nearside rear, then the offside rear caliper.
Put some soft plastic on the top of the master cylinder and put the top on.
I would remove both front calipers and replace with the new ones.
Remove the plasic from the top of the brake master cylinder and top up.
I would bleed the nearside caliper first, problem is some brake fluid is darker than others and the new fluid may not be apparent when you have flushed out the old fluid. The colour of the new fluid being lighter is not a given and that has caused me issues in the past.
Buy a cheap plastic cooking baster before you start and use it to empty the reservoir of old fluid, then fill with new. It minimises mixing and saves the effort of pumping all the old contents through the system at the start. I changed the brake fluid on my car a while back and used a £5 ‘Vizibleed’. Works fine.