G

Gandalf

Well Known Member
I am trying to understand the mechanics of how the brake line couplings work. The tapered end on the 90 and 45 degree fittings I get. It is torqued and threads sealed to the master cylinder.

It is the nut coupling that I am not sure about. Looking at the flexible line coupling I assume that the outer sleeve is supposed to be pushed toward the coupling until it CONTACTs the 45 or 90 degree fitting and then say one flat of extra compression. Is that correct or is it really finger tight and one full turn?

If I do only finger tight and one full turn the outer sleeve will not contact the 45 degree fitting.

Also what can I use on the fitting as a lubricant. I do not want to waste a whole quart of Royco 782 just to tighten the fittings. Does anyone know if Mobil 1 Synthetic ATF or DOT 5 synthetic brake fluid is OK to use, just a drop on the outer sleeve if I plan to use Royco 782 to fill the brake lines later?

Thanks,
Jeff
 
UPDATE

I decided to tighten the brake lines before I install the upper firewall and I am posting my thoughts before I actually tighten the lines to see if I am way off base. I see from searching this forum that leaks from the brakes lines are problematic.

I now believe that it is the metal to metal contact that seals the line so the tubing really needs to stick out _only_ about 1/8 inch or the tubing will interfere with easy metal to metal contact using finger pressure.

The only way I could get the connector to 1/8 inch was to use an arbor press on the tip of the tubing and a large crescent wrench as a temporary backing plate under the nut. This technique forces the little metal tube flush into the plastic tubing. Using 3.5 times magnification, I see no obstruction to flow with the insert flush to the tubing.

I bought some Royco 782 from Vans and plan to use this to coat the metal contact points. So I do believe the proper technique is to tighten the connector with a wrench until there is metal to metal contact. Then remove the nut to visualize good metal to metal contact. Then coat the metal to metal contact surface with Royco, reinsert and tighten the nut to finger tight and then use a wrench to tighten one full turn beyond contact (360 degrees as opposed to one flat).

What do you guys think? I am way off base or should this work?

Jeff
 
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Are you putting the bead on the line?????

The seal is between the bead (ferrule) and the tapered inside of the nut and the fitting. The bead is compressed onto the line to seal also. The inner metal tube is to keep the plastic line from collapsing as the bead tightens down on it.



concom_Assembly.png
 
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Wow a timely post! I've been fighting this for the last couple of days.

I can't seem to get the brass insert started into the tube without using a little punch to widen the inside of the tube a little. Boiling doesn't help much, but I suspect my altitude is shooting me in the foot there (at least it sounds good). Our water boils about 199 degrees instead of 212 degrees. I did get one of the 45 degree fittings on but it was the one that had a little 'help'. Without it I'm stuck.

If I wasn't building ELSA I'd just buy the Flightline brake lines and forget about it! :D

Bob
 
Mike S said:
Are you putting the bead on the line?????

The seal is between the bead (ferrule) and the tapered inside of the nut and the fitting. The bead is compressed onto the line to seal also. The inner metal tube is to keep the plastic line from collapsing as the bead tightens down on it.



concom_Assembly.png
Click to expand...

Yes and your diagram is very helpful. You folks must have really strong hands as the only way I was able to get the bead down to 1/8 inch was with an arbor press! So to be clear. I put the tubing in boiled water, removed the tubing, pressed in the inner metal tube and then use the arbor press to position the bead.

brakeFitting.jpg


Note the rotated position of the wrench. Do remove fingers before compressing.
Jeff
 
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The arbor press was a great idea!

I rushed over to Harbor Freight as soon as I saw and picked up a half-ton arbor for $36.00. I cam home and tired it and - success!

The heck with boiling water!

Thanks!

Bob
 
There is another thread dealing with brake lines HERE
Some people have applied a VERY thin film of Locite 567 to the the ferrule. Do not contaminate the brake fluid. The fewer times that the fitting is tightened and loosened, the better. I would only tighten once. If it leaks, then tighten a little bit more. The ferrule does the sealing, not the threads.
Joe Gores
 
Looking at the link above and seeing Ken's drill method gives me much relief.

I used a tapered punch to open the end a little; just enough to get the brass insert started and then in the arbor. No heat, no sweat!

Great ideas - I can't tell you how much time I wasted on this before I saw the light.

Bob
 
bhassel said:
The arbor press was a great idea!

I rushed over to Harbor Freight as soon as I saw and picked up a half-ton arbor for $36.00. I cam home and tired it and - success!

The heck with boiling water!

Thanks!

Bob
Click to expand...

Hi Bob... I am glad the press worked for you. Having pressed all the fittings I will say that the press works fine on the free ferrule fittings. On the integrated nut/ferrule seen on the 45d connectors look VERY carefully with say 3.5X magnification for a thin film of tubing that can be sliced off. This should probably be removed without damaging the ferrule since it could interfere with the ferrules mating to the nut and fitting.

UPDATE: The new section 5 of the plans calls for a new technique that involves using a #29 drill bit. This may avoid the need for an arbor press.

Jeff
 
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