hello all as I finish up dissassembly of my 82 GTSi, i have found a couple of the brake fittings to be so stuck that a couple of the fittings are being mauled by my tools to get them broken loose. it looks like the lines have not been touched since new. The metal lines look to have bubble flares, not inverted flares. although the heads of the fittings are metric (11mm), the threads seem to be identical to loose line nuts i have from previous projects, which I though were english, not metric. Main question is, does anyone know the proper thread for the fittings for the hard lines if I order? i am guessing the ones close to the wheels are 10 x 1.0 metric threads? If I make up new lines, i think i can use standard 3/16" metal line. the metric equivalent is 4.75mm. When i restored my Pantera, I changes all the fittings from bubble to inverted flare, and make all new lines up myself. it was quite a project. Does anyone know if anyone makes pre-made metal lines for the 308? the usual vendors (inline tube and classic tube) do not appear to. also, are bubble flares more likely to leak when re-assembling? should I not even try to re-use the old lines, on the ones where i did not destroy the nuts. (In all honesty, i have only messed up 2 nuts) justin
They are bubble flares, 3/16 line is good, bubble flares do not leak on reuse unless they have been previously overtightened. It’s worth some effort not to mess up the short S-shaped lines right at the calipers, the tight curves make reproducing these without kinking difficult. It’s hard to tell 3/8-24 from M10x1.0 by looking at them (but you will strip threads and ruin stuff if they’re mixed up).
thanks makes sense 3/8 is just about 10mm, and 24 threads per inch is just about 1mm per thread i wonder if the fittings are made differently or if they are the same, but labeled differently when sold. regardless, i'll buy the metric fittings because it's not worth taking the chance
NO. They are not the same. It is really unfortunate that they are close enough to be confused, it’s enough of a trap for the unwary that FedHill (a vendor that I highly recommend) even has a tech note on “Common crossthreads”.
Take one of the fittings to ACE Hardware. You can check the thread size there. Or just buy an M10 x1 and a 3/8 x24 nut and see what fits.
The 3/8-24 will screw in smoothly until it feels ready to be snugged up, and then when you do it will strip threads. This is an 82 GTSi original brake lines…. They’re gonna be metric.
JKG, this is what you need to produce fittings that work -eak free (DIN bubb-e f-aring too- and metric M10 x 1.0 bubb-e f-are nuts). See pic be-ow. The DIN too- produces a f-at backside to the bubb-e f-are which mates to the f-at surface of the bubb-e f-are nut. (Sorry for using a "-" because my keyboard just broke and some keys are not working.) I had to do the same repair on my 1986 Testarossa, but unfortunate-y I cou-d on-y find the DIN f-aring too- overseas. EDoug Image Unavailable, Please Login
thanks for the advice. i have a fancy flaring tool - i will take a closer look. i have used it for inverted flare fittings, but never did the bubble flare, although i think the bubble is the first half of the inverted flare, but not sure.\ anyway, thanks for the suggestions everyone. i feel more confident now
[QUOTE="jkg2101, post: 150277331, member: 173783"... i have a fancy flaring tool ... i have used it for inverted flare fittings ... i think the bubble is the first half of the inverted flare ...[/QUOTE] JKG, I am gad that you posted this
JKG, yes your inverted flare tool's "first half" creates a bubble, but the "second half" DOES NOT create a flat surface to mate to the bubble flare nut's flat sealing surface. Your inverted flare tool second step will create a cone shape and that is why it cannot create the proper seal against the bubble flare nut flat seal, and ultimately be the cause of a leak. Look closely at the pic of the DIN tool schematic and you will see how as the punch is screwed into the brake line end it will create the bubble inside the punch end, and then the flat sealing surface. Look close at your inverted flare tool schematic and you will see why your second step cannot. Hope this helps. EDoug
Thank you for the thorough explanation. My hydraulic flaring tool set has both metric and standard fittings and the bubble flaring has just the details that you are describing to make it flat on the back and bubble flared at the connection. It makes perfect sense to me now that you explained it
