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27-04 Step 3 Brass Insert

Mich48041

Well Known Member
Forcing the brass insert into the nylon brake line tube was difficult for me using the boiling water method. I found an easier way is to push the insert with a hot aluminum nail. I held the nail with vise grips, heated it in the center with a propane torch and pushed. Only a very small flame is needed. As soon as the insert starts going in, move away from the flame. Do not push the insert in too far or else the end of the tube will mushroom. Not much heat is required. Even a lighter or candle might work, but I did not try them.
Joe
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brass inserts

In an article written by KEN SCOTT in the 2 - 2009 issue of RVator quoted below, is an easier way to insert the brass inserts into plastic brake lines. It is too bad that I did not read that before working on the brake lines.
Joe

Now, working on small soft plastic parts with a
hammer just offends some people?s engineering
sensibilities. When Ken Krueger heard this, he
looked into the problem. What he found is the
plastic tubing, as manufactured, varies significantly
in wall thickness. Sometimes the inserts
will push in with your thumb, sometimes they will
actually be loose, and sometimes they fit so tightly
it seems impossible to get them in. Ken?s method
was simple and direct: drill the last ?? or so of the
tubing with a #29 twist drill. If it pulls shavings out,
the finished wall will be no thinner than the thinner
walls resulting from production variation. If it
doesn?t?well, there you are. In either case, the
insert will insert -- no boiling water necessary.
The building plans/manual will be revised to
include the ?drill bit solution?.
 
I must have got some proper sized tubing. I just started them in the tube, then pushed them the rest of the way by putting the brass up against a table edge. Tight, but no boiling water stuff.
 
Re: brass Inserts

I wish Ken had published that defore I did the brakes on 120241. Boiling water just did not work. I worked the tube and insert, helper appkied heat with a heat gun. We found out that there is such a thing as too much heat!

Apply heat slowly, once the tubing starts to "give" it softens quickly!

Wayne 120241
 
Seating the inserts

I've been using the boiling water method to try to get these inserts into the tube. They are TIGHT!! Can anyone tell me if the insert is meant to be completely flush with the end of the plastic tube, or just pushed in until the base of the lip contacts the the tube. Some of mine pushed in a little more easily and are flush. Others were more difficult (none were easy), and the lip or part of it is visible.
Which is correct or doesn't it matter? The instructions (27-04) say `until it bottoms against the end of the plastic tube', but it's not clear (to me anyway) if they mean the top of the lip or the base of the lip. Is it critical?
 
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They mean up against the end of the tube. I found boiling water did not help a bit actually, so adopted the "push it in" tactic. Worked very well for me and my size tubing. It needs some force to push it in, but up against a solid surface it was not too bad.
 
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I thought you put the brass tube in the nylon line before you slid the compression sleeve over the line. Have I been doing this wrong?

I always put bead on the tube, (along with the nut) first, but slide it back enough it is not in the area of the inner tub. Then insert the brass insert, and lastly slide the nut and bead toward the end of the tube, final location will be determined when you put the tubing into the fitting, bottom the plastic tube in the fitting, slide the bead, and nut forward, and tighten them down.

I find it makes things easier to put a very slight chamfer on the inside of the bead------if the bead seems to be tight on the plastic tube.
 
Its all in the details!

Next time use a heat gun and warm that plastic hose up as much as necessary. The brass insert helps to stabilize the plastic hose cause when you tighten the nut onto the elbow it crushes the brass sleeve onto the plastic hose making a nice seal. So if you have the brass insert pushed in to where you have stated then it will probably work ok. This statement is based on the authors personal experiences and other opinions may very. As a reminder there has been a lot of discussion about using thread sealant on the connections so you might want to research that. I'm not sure what you have available in Australia;)
 
Can anyone tell me if the insert is meant to be completely flush with the end of the plastic tube, or just pushed in until the base of the lip contacts the the tube. Some of mine pushed in a little more easily and are flush. Others were more difficult (none were easy), and the lip or part of it is visible. Which is correct or doesn't it matter?
The purpose of the insert is to prevent the nylon tube from collapsing when it is squeezed by the compressed sleeve. So the insert needs to be completely inside of the sleeve when assembled. Plus or minus one millimeter is not going to make much difference. The lip of the insert does not have to be inside of the nylon tube. I have had success stopping leaks (in non-aircraft applications) by wrapping the sleeve with Teflon tape.
Joe Gores
 
The purpose of the insert is to prevent the nylon tube from collapsing when it is squeezed by the compressed sleeve. So the insert needs to be completely inside of the sleeve when assembled. Plus or minus one millimeter is not going to make much difference. The lip of the insert does not have to be inside of the nylon tube. I have had success stopping leaks (in non-aircraft applications) by wrapping the sleeve with Teflon tape.
Joe Gores

Thanks Joe. That answers the question.
 
Next time use a heat gun and warm that plastic hose up as much as necessary. The brass insert helps to stabilize the plastic hose cause when you tighten the nut onto the elbow it crushes the brass sleeve onto the plastic hose making a nice seal. So if you have the brass insert pushed in to where you have stated then it will probably work ok. This statement is based on the authors personal experiences and other opinions may very. As a reminder there has been a lot of discussion about using thread sealant on the connections so you might want to research that. I'm not sure what you have available in Australia;)

Thanks John. Should be good to go with the inserts then. I'm using Loctite 567 on the threads.
 
They mean up against the end of the tube. I found boiling water did not help a bit actually, so adopted the "push it in" tactic. Worked very well for me and my size tubing. It needs some force to push it in, but up against a solid surface it was not too bad.

`Some force' is right Don. My solid surface has got little circle impressions in it. :)
 
Brake Line brass insert

I just did this today. My experience was this: If you try to put the compression ring on at the 1/8th inch mark, then try to push in the brass insert (after putting the tip in boiling water of course), YOU CANNOT GET THE INSERT ALL THE WAY IN. However, if you push the nut and compression ring way back, and then boil, with strong fingers you will have no problem getting the insert seated all the way in pushing against a hard surface. THEN you can pull your nut and ring up to the 1/8th inch mark with a bit of hard pulling and you're done.
 
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