Rear Brake Line Flaring

[polskamafia mjl]

I'm trying to replace the rear passenger side caliper on my 850 but I've rounded off the brake line nut at the caliper. I would like to cut the existing hard line, replace the caliper, and splice in a new section of hardline. From what I've read the hardlines are 3/16 inch or 4.75 mm.

When I brought my new caliper to the auto parts store I couldn't find a flare nut fitting that would screw into the caliper. Does anyone know what thread the hole in the caliper is? I've also read that the P80's use a bubble flare. Does that mean that the new hard line needs to have a bubble flare at the end that connects to the caliper? Autozone and NAPA only have hard lines with 'standard' flares. Is that going to cause sealing issues at the caliper end?

My other question is about connecting the new hard line to the old one. Do I need a double union flare for that?

Any other tips or tricks are also greatly appreciated.

Thanks!

[xHeart]

cn90 is your man. Meanwhile, see this diagram for conversation: https://parts.volvocarslisle.com/a/Volv ... 67887.html

[cn90]

BMW and Volvo use bubble flare... 4.75 mm line.

I just did the brake line on my 2006 BMW X5. I wrote a detailed DIY for my BMW below.

HTH...

https://www.bimmerfest.com/forums/showt ... ?t=1350813

[cn90]

Also, with the car this old, consider replacing the rubber hose above the Delta Link "while there"...

[polskamafia mjl]

There's a lot of good information in your Bimmer write up. That will be very helpful.

Does anyone know about the flare nut that connects the hard line to the caliper? That's my main hang up at the moment.

[cn90]

Making flare in situ is a big pain.
Things can go wrong all the time (metal tubing not clamped properly and slides, creating bad flare).

If you want avoid making flare, the buy an ATE caliper seal rebuild kit for $10-$15 and rebuild the caliper in situ. I posted a detailed DIY brake caliper rebuild about 8-10 yrs ago in forum...

[xHeart]

Brake line end-to-end uses M10 x 1.0mm.

[cn90]

Mafia,

The flare but is metric, exactly like I mentioned in the BMW write-up. Just buy a short section of metal line, cut it and now you have 2 flare nuts.

I called these "bolts" in the BMW write-up...bc it looks like a bolt...

[polskamafia mjl]

Brake line end-to-end uses M10 x 1.0mm.

Thanks. I had seen those specs on a different forum but when I tried an M10 X1.0 thread checker at the store it felt very loose. Is that normal? Another forum had the thread listed as 3/16 inch British Thread but I have no idea what to make of that.

@ cn90

I see that your BMW write up does mention the M10 X1.0 bolts but I have no way of knowing if those bolts are the same on the 850's.

[xHeart]

Brake line end-to-end uses M10 x 1.0mm.

Thanks. I had seen those specs on a different forum but when I tried an M10 X1.0 thread checker at the store it felt very loose. Is that normal? Another forum had the thread listed as 3/16 inch British Thread but I have no idea what to make of that.

3/16 in (0.1875) = 4.75mm, refers to copper/steel line size.
All fasteners, male/female, use M10 x 1.0