DSE master cylinder uses a 37 degree flare???

[jlwdvm]

The directions I have for my DSE master/booster combo say to use a 37 degree inverted flare with the 3/16" line to metric fittings provided for the master cylinder lines. I'm confuse...is this a typo and should I be using a 45 degree double flare like the rest of my lines?

[dontlifttoshift]

The metric fittings you are talking about are just the flare nuts that come with the assembly, correct?

I believe that is a typo, I have never seen a 37* inverted flare fitting, seat, or tool to make one. I have never seen a 37* flare in any OEM application.

[jlwdvm]

I talked to tech at DSE this morning and they didn't instill much confidence. Evidently, GM used a 37 degree flare on the C6 corvette master cylinders. He said they use a 37 double at their shop, but a 37 degree would be fine. Still questioning what flare to use. They send M12-1.0-3/16" fitting nuts with the kit, but I need to know what flare to use since I have to make my own lines to run from the master to my Wilwood proportioning valve.

[dontlifttoshift]

Weird. I don't have an answer. Officially, the two flares are not interchangeable. Real world I have gotten away with it for fuel lines, using 45* on AN/JIC 37* fittings......never tried it on brake lines.

I went and looked at my flare tool and it will do 37* inverted/double flare, so I misspoke earlier.

[badazz81z28]

Weird. I don't have an answer. Officially, the two flares are not interchangeable. Real world I have gotten away with it for fuel lines, using 45* on AN/JIC 37* fittings......never tried it on brake lines.

I went and looked at my flare tool and it will do 37* inverted/double flare, so I misspoke earlier.


Thats odd, just installed my DSE master cylinder/booster a couple months ago and use my standard 3/16” brake line flaring tool with their provided fittings (same tool for the entire car). I Didn’t think twice about it and haven’t had any leaks. Shot down the drag strip and sped down the road course.....

i have never heard of a 37 degree double flare for brakes before. I would think if I flared the lines to 45 degree double flare and stuck it on a 37 degree cone, I would have had a serious leak.....

I don’t see why the corvette would be unique?? I would call “inline tube”

I think It’s a typo and the DSE tech doesn’t know...how can they say use one angle, but the other angle is oktoo?

http://www.fedhillusa.com/webnuts/common%20flares6.pdf

[badazz81z28]

It’s a tough google search...so it appears the 37 degree double flare is a Japanese standard. USA is 45 degree...I just find it hard to believe the brake lines are 3/16” (not metric), M12x1 and uses a Japanese standard 37 degree double flare? I just can’t find it in my self to think that’s accurate on a Chevy Corvette.

[jlwdvm]

I thought that I ran across some info in my search this weekend that said that there are certain C6 vette master cylinders that use a 37 degree flare for the fitting at the master. I have a Rigid 37 degree single flare tool, but broke done and ordered a 37 degree double flare die for my Eastwood flare tool.

[badazz81z28]

I thought that I ran across some info in my search this weekend that said that there are certain C6 vette master cylinders that use a 37 degree flare for the fitting at the master. I have a Rigid 37 degree single flare tool, but broke done and ordered a 37 degree double flare die for my Eastwood flare tool.


Im curious as to the 100% answer...I’m no kidding using a 45 degree flare and no leaks.

[jlwdvm]

I'm using Cu-Ni line and tried to make a 37 double flare by doing the first 2 steps in my 45 die, then placing the line in my 37 tool....it kind of worked, but why risk it or go through the time to bend up lines only to have them leak (my luck). There is info on the CorvetteForum that states that GM did use some different flare fittings for a run of the C6 Vettes. No one knows why. If you tightened the fitting enough, you may have pressed and sealed the flare as you tightened...especially if you are using soft line like Cu-Ni. The Tech guy I talked to at DSE put me on hold to talk to a guy in the fab shop about it and he concurred about using a 37 single or double flare on their builds.

[badazz81z28]

Do you have the link by chance? I really didn’t tighten the fittings any tighter than I normally would. Maybe that’s why it seals? I guess I will leave it.



I'm using Cu-Ni line and tried to make a 37 double flare by doing the first 2 steps in my 45 die, then placing the line in my 37 tool....it kind of worked, but why risk it or go through the time to bend up lines only to have them leak (my luck). There is info on the CorvetteForum that states that GM did use some different flare fittings for a run of the C6 Vettes. No one knows why. If you tightened the fitting enough, you may have pressed and sealed the flare as you tightened...especially if you are using soft line like Cu-Ni. The Tech guy I talked to at DSE put me on hold to talk to a guy in the fab shop about it and he concurred about using a 37 single or double flare on their builds.

[jlwdvm]

Heck if I can find it now! Let me know if anyone gets you info on your thread in the Corvette forum.

[badazz81z28]

I just got a hold of Inline Tube, who I would regard as brake experts. They said there isn’t a 37 degree double flare application...lol.

[jlwdvm]

I called DSE again and 2 guys confirmed that it is a 37 degree flare because the master is based off of a C6 vette (which used a 37 and not a 45 or a bubble flare). That's what I'm going with.

[ilikeike]

Isn't 37deg. the standard for -AN fittings ?

I used AN adapters on my calipers. If you go all AN should work great, and look nicer than regular brake fittings.

[jlwdvm]

Yes, 37 degree single is also used for AN, but those lines usually operate at a much lower pressure (fuel lines, oil lines, etc). Double flares and bubble are standard for braking systems...I think there is a difference. I have AN fittings on my calipers that I attach the steel braided flex lines too as well, but I think the master cylinder is a different situation.....Kind of like I wouldn't compare the working pressure of the tubing and 37 degree fittings that I plumbed my fire suppression system with to that of my braking system....and if they would happen to leak a little it wouldn't be a big deal. Leaking break fittings would be a little more concerning.

[badazz81z28]

Wish there was something online I could read. I trust DSE, but another expert would be nice to put this to bed.

[dontlifttoshift]

I use AN 37*, single flare for brake lines all the time. Single flares use a separate tube sleeve to back up the flare, giving it strength.

With a double flare, you don't need the sleeve as the tube is flared upon it self, adding strength.

[badazz81z28]

I used a 37 degree single flare in a couple of my Wilwood Brake applications. Seemed to work fine.

I use AN 37*, single flare for brake lines all the time. Single flares use a separate tube sleeve to back up the flare, giving it strength.

With a double flare, you don't need the sleeve as the tube is flared upon it self, adding strength.

[badazz81z28]

Wow! Hours! And I can’t find anything online about 37 degree inverted flares for brakes lines...let alone for a corvette.

[oleyeller]

How about this....

[badazz81z28]

Got anything on the corvette?



How about this....

[jlwdvm]

164406Used 37 degree double flare...no leaks!

[badazz81z28]

Don’t know what to say...37 degree no leaks...me 45 degree and no leaks...did you use NICOPP?

[jlwdvm]

Yes...Ni-Cu. I wonder if you can get by with the wrong flare because the line is soft and it forms a crush seal when you tighten down the line. I still think that a double 37 is the correct flare.

[ilikeike]

Is that a catch can on the passenger firewall, I can't tell how all the plumbing is on that one, is there manifold vacuum to it or is it just a breather?

[badazz81z28]

Yes...Ni-Cu. I wonder if you can get by with the wrong flare because the line is soft and it forms a crush seal when you tighten down the line. I still think that a double 37 is the correct flare.


I don’t. I just can’t...Considering every brake system in America uses 45 degree inverted or bubble. A few C6 cats are unique? I don’t buy it. I find it easier to believe you flare a line at 37 degrees and put it in a 45 degree seat and it the line will open up and seal. The opposite I don’t see happening so easily as you would need to close the opening on the line.

[dhutton]

Where’s Tobin when we need him? I’d trust him to know the correct answer....

Don

[jlwdvm]

I don’t. I just can’t...Considering every brake system in America uses 45 degree inverted or bubble. A few C6 cats are unique? I don’t buy it. I find it easier to believe you flare a line at 37 degrees and put it in a 45 degree seat and it the line will open up and seal. The opposite I don’t see happening so easily as you would need to close the opening on the line.

The C6 Corvette did have a 1-year only use of 37 degree master flares as far as everything I have found. For some reason GM went away from the bubble flare for that year. I tend to believe DSE as well. Frankly, I could give a crap now. My master doesn't leak with a 37 degree double flare and that is all I care about!

[badazz81z28]

The C6 Corvette did have a 1-year only use of 37 degree master flares as far as everything I have found. For some reason GM went away from the bubble flare for that year. I tend to believe DSE as well. Frankly, I could give a crap now. My master doesn't leak with a 37 degree double flare and that is all I care about!

for argument sake. The 09-13 corvette used the same MC, wouldn’t that mean 4 years it would have been different? If it wasn’t and one year was different if I had the one off year, bought a new MC I would have a problem. But no notes from anyone selling this MC mentioned a 37 degree flare.

Can you post the link to the info you found?

[jlwdvm]

I would think that DSE would have a lot of high-end builds leaking brake fluid from the master cylinders if they were doing things wrong.

[badazz81z28]

The guys building the cars are not the guys on the phone. Perfect example is the issue with my rack fittings in the emergency room forum. I went ahead and contacted Tobin at Kore3, in-line tube, the company that makes Corvette line locks and neither if them support it. Still nothing on the Corvette Forum. Just weird. Not saying one way is right, I’m looking for info to support DSEs instructions. It’s a OEM part...cant be this hard.


I would think that DSE would have a lot of high-end builds leaking brake fluid from the master cylinders if they were doing things wrong.

[jlwdvm]

I had the guy on the phone ask someone in the fab shop. Who knows....but again, I don't care since I am not seeing any leaks.

[ilikeike]

37 deg AN fittings work on fighter aircraft,at least the ones I worked on, should work on your brakes ? Get an adapter and go to a 45 deg if it's not working for you ??

[oleyeller]

Metric Vs SAE Flares
Metric double flare and SAE double flare fittings are constructed from the same principles but with different angles. Referring back to the schematic, SAE double flare uses a 45 degree angle:



JIS metric double flare, as used in Miatas and other Japanese-manufactured vehicles, employ a 37 degree angle.

The far right image on the above illustration shows an SAE double flare with a metric (M10x1.0) tube nut. This is not to be confused with a metric double flare with the same metric tube nut - the angle of the flare itself is critical for the junction sealing.

A proper flare junction uses the same flare type on both male and female ends. Cars like Miatas are configured like this from the factory: they employ M10x1.0 tube nuts and female JIS metric double flares on hard lines and male JIS metric double flares on soft lines.

Issue arise when one mixes SAE and metric fittings and fasteners in a single brake system, because in the US the SAE fittings and fasteners are more commonly available. Due to the differences in flare angles (45 vs 37 degrees), the junction of an SAE inverted flare and a metric inverted flare will not seal properly if tightened to normal specifications. However, if the tube nut is overtightened, eventually one of the ends will form the other end to the same angle, thus creating a seal. In my experience the female end of the hard line alters the male end of the soft line.

Because higher than normal force is required to squish the mismatching flare ends together, assembling a junction in this fashion increases the risk of rounding off the tube nut. Subsequent disassembly also carries increased risk of rounding off the tube nut as it was tightened to a higher than normal torque. Furthermore, as the shape of the tube itself is changed during assembly it is possible to reduce the size of the opening below the diameter of the tube, though I believe this to be rather unlikely given that the angle change is relatively small (8 degrees, from 45 to 37).

On the topic of tube nuts, if one uses SAE flared hard lines with SAE tube nuts the size of the tube nuts - 3/8" or 9.5 mm - is close to the 10 mm size of the metric tube nuts but not quite the same. Attempting to loosen SAE tube nuts with the metric 10 mm flare nut wrench, especially if the SAE nuts were overtightened to compensate for the flare angle difference, is likely to result in rounded off tube nuts during disassembly.

[jlwdvm]

Huh???....you lost me/us. The facts: DSE says that the master employees a 37 degree flare and sends metric adapter nuts to use with a 3/16" line. I used a 37 degree double flare on my 3/16" Ni-Cu line and currently have no leaks and I didn't have to apply 100lbs of torque on the master nuts. Others have stated that they have used a 45 degree double flare on their lines and have had no leaks as well. We still have no definitive answers.