caliper change - plugging brake line, to reduce loss/air in system/ease bleeding

[jpaul]

Doing a caliper change, have only previously done bleeding/fluid change with a friend pressing brake pedal - now purchased an eezibleed.

Seems to be recommended to stop excessive fluid loss by plugging undone brake line - any preferred technique ?
- DIY with ear plugs (apple buds ?) , even bits of polythene folded over end with a tie around tube
- purchase some specific hydraulic plugs eg https://www.ebay.co.uk/itm/314512770935
- ensuring there is a good vacuum on fill reservoir cap (piece of cling)
- keeping brake pedal half pressed (how ?) which will block additional fluid from reservoir getting introduced in system


I'll make a trial using eezibleed for a simple bleed first, to get familiar, before caliper change - any pitfalls in their use ?

 

[jpaul]

Use a proper hose clamp like everyone else does..

had already read that putting clamps on flexible brake lines may degrade their strength (especially if they are not new), so wasn't considering it ?

 

[jpaul]

clamp like suggested or I just usually wrap a "finger" of a rubber glove with cable tie -

thanks good idea, just looking, too, at some brake fluid friendly epdm/silicone rubber tapered bungs that should fit internal tubing diameter 3.34-4.58 mm

I use a piece of wood between the seat and brake pedal to block the supply of fluid from the reservoir.

good pic - thankyou - did that stop most of dripping ?
e: thinking of those adjustable ski poles

 

[jpaul]

The main concern about bleeding (beyond our vatican statues) would be if the ABS unit gets air in it -
whilst I think older BMW units don't need OBD stimulation to run the ABS motor , newer units do I believe, like VAG.
I thought all the solenoids are open/free-flowing under normal operation (fail safe if power failure) so not sure why air maybe an issue.


At a minimum probably need to do a test drive and try the ABS, to avoid surprises in the field.


[
ski pole to prop the brake pedal seems to work ..
just inspected a new Halfords professional flare spanner 10/12 right .. next to an older used williams 11/13
where is this junk made .. are they forged ? look at the imperfections on the jaw face , I'm afraid it could knack a flare nut; does their lifetime guarantee reimburse me for that.

]

 

[jpaul]

In a professional situation bleeding is quick I imagine - you have car on lift/sills and whipped all 4 wheels off (I usually just have one wheel at a time !)
plus a pro bleeder, with large capacity, so greater fluid loss is less of an issue ... what do you use ?

How do you check any air in ABS system ?

 

[jpaul]

sounds like if the ABS system had air you'd always get a soft pedal, even without having to test ABS

Basically just put a bungee cord around the brake lever, left it a few days, then pump the lever a few times, tie it up again, wait a few days, repeat. After about 4-5 days the system sorted itself out and was fine.

so you had to hold up the pedal ... and the air eventually migrated into the reservoir ? versus usual bleeding where you are hoping air is pushed out along with pressurized fluid

I guess abs units are designed without intentional pockets in the roof of the device that might trap air.

 

[jpaul]

What if there's an earthquake whilst the caliper is off?

the 6'P phrase, we apply in engineering, comes to mind, mr southgate

 

[jpaul]

no do tell - I'm imagining virtual reality rehearsal for the actual work .... the weather isn't playing ball today.

but looking yesterday evening at car - seems I need to change a couple of corroded bleeds screws cracked two rears, but front two have little grip
they're now well plus gassed, but I think I will need to cut tops off and drive a small socket on ?
after getting some replacements ...
I don't understand that oem number matching parts/34116758107 I find on google all have bigger nuts 9mm than the existing 7mm of ones on there now

 

[jpaul]

I had mentioned plastic ... but the electrical level detector on the cap descending into reservoir interferes a bit.

You should be able to get a deep socket on the bleed screws no problem to crack them open. A tap with a hammer should shock it off nicely. I would also invest in the proper "crow foot" type spanners for brake bleed nipples.

I had bought some line/flare/crow spanners for the other nuts in the braking system,
for the 7mm caliper nipples, a ring spanner (but its 12ogv, not secure 6) reaches over the nipple, by design, I guess;
7mm good quality flare spanners seem rare, facom/elora ranges start at 8 ! (I love the feel of the genuine facoms I have in my set)
e: handling a snapon is on the bucket list

....

removing stuck bleed - versus the undersize socket I am consider mole grips / bacho water pump wrench, and some heat.

 

[jpaul]

but I see we’re still trying to design the rocket

as I said - the front bleed valves don't want to budge (for follow on bleeding) so that+rain has stopped play ;
need to double check w/caliper bleed valves I order will be correct size
eezibleed works fine, though, had let a small amount out of rears.

(a double garage would be nice)

 

[jpaul]

Have you tried calling local motorfactors?

it's either a m10x1 or probably m8x1.25 .... there's enough of the thread visible to measure with a caliper .. which I should have done on Friday;
often, adverts tell you it matches oem part number but don't say/confirm what size it is (like buying tap valves)