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QwkTrip 11sec Club
Joined: 17 Feb 2004 Posts: 3942 Location: Peoria, IL
1989 Pontiac Firebird
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Posted: Sun Aug 31, 2014 11:30 pm Post subject: Brake line fitting size ??? |
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I think the rear brake line is a very odd size of 6 mm. Can anybody confirm this?
I am also having difficulty determining the specs for the nut. I think it is M12 x 1.0 but not sure. |
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aaron_sK Member
Joined: 23 Jan 2006 Posts: 8834 Location: Back in beautiful Tacompton
1987 Chevrolet Camaro IROC-Z
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Posted: Mon Sep 01, 2014 7:31 am Post subject: |
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It's been awhile but as I recall it's the closest metric equivalent of 1/4" (which would indeed be 6mm).
I tossed the stock nuts and put ones with a normal thread on when I reflared the lines.
Are you running the rear into an aftermarket prop valve? |
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QwkTrip 11sec Club
Joined: 17 Feb 2004 Posts: 3942 Location: Peoria, IL
1989 Pontiac Firebird
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Posted: Mon Sep 01, 2014 10:11 am Post subject: |
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aaron_sK wrote: | Are you running the rear into an aftermarket prop valve? |
Yes. And roll stop.
6mm tube is slightly smaller than 1/4" tube. From what I can tell, you can drill out the 6mm nut to work on 1/4" line, but you can't go the other way or it could leak.
I've not been able to find the correct adapter. And unfortunately, most the adapters are too generic in naming convention and just call out M12 x 1.5 bubble flare. Well, that thread is used with both 6mm tube and 1/4" tube and are not interchangeable. |
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iansane Member
Joined: 16 Jan 2004 Posts: 5740 Location: Bothell
1991 Pontiac Trans Am
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Posted: Mon Sep 01, 2014 11:47 am Post subject: |
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QwkTrip wrote: | I've not been able to find the correct adapter. And unfortunately, most the adapters are too generic in naming convention and just call out M12 x 1.5 bubble flare. Well, that thread is used with both 6mm tube and 1/4" tube and are not interchangeable. |
This is how I knew I was never going to make it as an engineer. When I did the prop valve/line lock install I'm pretty sure I just put standard nuts and re-flared the lines. I'd be willing to bet that the phrase, "Close enough" was uttered a couple of times.
Although I have put at least 100k on the car since then if that is indicative of how 'close enough' can work long term. _________________
Quote: | Sometimes I actually think I'm slightly retarded in the mouth. |
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QwkTrip 11sec Club
Joined: 17 Feb 2004 Posts: 3942 Location: Peoria, IL
1989 Pontiac Firebird
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Posted: Mon Sep 01, 2014 12:11 pm Post subject: |
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By "standard" nut, you mean 7/16" - 24 double flare?
Last edited by QwkTrip on Mon Sep 01, 2014 6:10 pm; edited 1 time in total |
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Twilightoptics Hardcore (12sec Club)
Joined: 13 Jan 2004 Posts: 9191 Location: Auburn , WA
1987 Chevrolet Camaro IROC-Z
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Posted: Mon Sep 01, 2014 12:30 pm Post subject: |
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I've always been able to flare the stock line to the next nearest SAE with SAE nut for whatever fitting I'm working with... AKA linelock. Just make a good inverted flare and clean your edges/inside dia after the tubing cutting does it's work. _________________ A redline a day keeps the carbon away! |
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QwkTrip 11sec Club
Joined: 17 Feb 2004 Posts: 3942 Location: Peoria, IL
1989 Pontiac Firebird
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Posted: Mon Sep 01, 2014 12:49 pm Post subject: |
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That's what I was hoping to hear. The American threads seem pretty straight forward with few choices. The metric threads are a bastardized collection of formats. |
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aaron_sK Member
Joined: 23 Jan 2006 Posts: 8834 Location: Back in beautiful Tacompton
1987 Chevrolet Camaro IROC-Z
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QwkTrip 11sec Club
Joined: 17 Feb 2004 Posts: 3942 Location: Peoria, IL
1989 Pontiac Firebird
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Posted: Mon Sep 01, 2014 3:42 pm Post subject: |
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I measured everything and made this diagram. This appears to be the hardware I'm starting with stock. All metric bubble flares.
- All front lines are 3/16" which will take a 3/8"-24 SAE double flare without problem.
- The rear lines are 6 mm. Seems like there is enough experience here that if I make new flares I can change the ends to 7/16"-24 SAE double flare like what is used with 1/4" (6.35 mm) tubing.
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