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Discussion Starter · #1 ·
2018 Mini Cooper that I swapped out the front right caliper. I was not sure if the threads need to thread tape or not. It did not appear that any were on it when I removed the brake line. It looks like a compression fitting for the brake line vs a banjo connector bolt with crush washers (which is what I am used to.) I tried a two-person pressure bleed which failed miserably. I moved to using a Motive Product pressure bleeder. I started once at the front right - a ton of air came out. I then moved to rear right, rear left, front right again, front left. Things seemed good but after 24 hours the pedal is soft again. I am wondering if I need 1) to tape the threads on the brake line, 2) maybe the line is not tight enough or 3) need to use a scan tool for ABS system bleed. I see no brake fluid on the garage floor. My theory is air is getting in and the only place this could happen would be the brake line attached to the new caliper? Any ideas on how to resolve? Thank you.
 

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Discussion Starter · #3 ·
I am going to try the Foxwell NT510 device. It's worth a try but I don't see what the ABS has to do with getting a soft pedal after swapping out a caliper...and then doing a pressure bleed at every wheel.
 

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Do not put ptfe on brake lines . If the pipe screws direct into the caliper then it will be a taper fit so Once tightened to the correct torque it will seal If fluid is not leaking out under pressure then air is not going in
If it uses a banjo fitting and two washers then always renew the washers and make sure the bolt mating surface is clean and caliper mating surface is clean and tighten correctly it will not leak .
 

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Ultimately a pressure bleed or two man bleed are all valid ways of purging air from the system. Did you replace the brake pads as well? If you did then a certain amount of sponginess is normal till the pads bed in. With regards to ABS pump bleed way that is way the dealership will carry out the procedure. The tech note in ISTA-D describes the procedure. ISTA is what is used by BMW Technicians.
 

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Discussion Starter · #6 ·
Yes, I did replace all pads and rotors on all 4 wheels. I did find it very odd that the two-man bleed process just would not work. I've done this process on tons of cars with no issue - except now the Mini. Pressure bleeding did show quite a bit of air coming out on the wheel where I failed at the two-man bleed. I've read at a couple of places that other people experienced the exact same problem with two-man bleed on the Mini. If so - I'm VERY curious what about the Mini would cause this. And I'm a bit skeptical that it can't be done (even though I experienced it first hand!) I would think the forums (which I just joined) would have lots of warnings to not do a two-man bleed, if for whatever the reason, it doesn't work.

James - have you had experience with the little nipples on the pads not lining up correctly where the caliper is putting pressure on the nipples instead of the directly and fully on the pads? Some youtube videos show exactly that, although they don't say what brand of pads they bought. I only buy Raybestos or Bendix. AND I have never had an item from RockAuto not work as designed. These people that had this problem filed the nipples off the pads and said that fixed their spongyness - which makes sense - the caliper is now in full contact with the pads. I am going to double check where the calipers are touching the pads. I believe those nipples are there as a safety feature so that you do not reverse the order of the pads - the larger one should be in contact with the piston (and has the slot for the brake pad wear sensor.)

We own this Mini - so I better start figuring out the odd things about it.

I also expected the brake pad warning (brake light on the dash and the text on the console saying the pads are worn and need to be replaced) to immediately go away now that the brake pad sensor is no longer in contact with the rotor. I wasn't sure if you needed to drive on it for so long (like with some TPMS) or if you have to turn off the light manually with a scan tool. It sounds like these sensors also have a finite life as well (and seem a bit difficult to chase back to where they unplug. I don't know why the plug couldn't be right there instead of chasing it under the under-carriage.)

Thanks for you help!
 

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I only fit pads from BMW, so I cannot comment on the “nipples” you describe. The pad warning light and distance to change, you have to reset the ECU. You will need to do that with your scan tool.
 
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