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Accelerated wear on brake lines

 


chuckakers  (D 10855)

Jul 26, 2012, 2:17 PM
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Accelerated wear on brake lines Can't Post

Just curious if anyone else has had this problem.

I recently bought a new Velo with standard Vectran lines and have noticed the brake lines are wearing VERY prematurely in the area above the toggles that interacts with the risers. I also recently purchased a set of UPT risers that feature shur-lock toggles.

I have inspected the areas that could be chewing on the lines and have found nothing unusual. One of the packers thought the wear could be from he excess line stow webbing sewn to the back side of the risers. They are made from thin nylon webbing (like trim tape) that tends to have a "sharper" edge than fatter webbing. The theory was that the edges of the line keepers could be causing a lot of friction on that part of the lines as I release the brakes.

Anyone else experience this wear? If so, how did you fix it?


Deyan  (D 322)

Jul 26, 2012, 2:46 PM
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Re: [chuckakers] Accelerated wear on brake lines [In reply to] Can't Post

In reply to:
Just curious if anyone else has had this problem.


I have inspected the areas that could be chewing on the lines and have found nothing unusual. One of the packers thought the wear could be from he excess line stow webbing sewn to the back side of the risers. They are made from thin nylon webbing (like trim tape) that tends to have a "sharper" edge than fatter webbing. The theory was that the edges of the line keepers could be causing a lot of friction on that part of the lines as I release the brakes.

Anyone else experience this wear? If so, how did you fix it?

His theory is right. I see this from time to time. I don't think that has something to do with the thickness of the tape. More likely the cause is the hot knifed edge. You've got 2 options.

#1, get rid of the tape and sew some elastic there
#2, sew the tape with the hot knifed edge outside, so the line is not going to have contact with the hot knifed edge.

I guess there are many ways to fix this, but for me those 2 are the fastest.

Just for the record....I've seen reserve risers worn out by a melted thread .

Good luck fixing those line keepers


(This post was edited by Deyan on Jul 26, 2012, 2:47 PM)


likestojump  (D License)

Jul 26, 2012, 3:19 PM
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Re: [Deyan] Accelerated wear on brake lines [In reply to] Can't Post

Option #3 - make new Type 3 tape excess keepers from wider tape, and fold it in half and install with the fold facing up so there's no raw edge for the line to wear against.

I'd also check the insides of steering line guide rings for any wear.


Gene03

Jul 26, 2012, 3:31 PM
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Re: [chuckakers] Accelerated wear on brake lines [In reply to] Can't Post

How do you stow the excess line?

I've retrained some folks to just put the line straight in from the top.

For some reason they were stowing it from the bottom up so it had to make a 180 degree turn while being pulled out.


theonlyski  (D License)

Jul 26, 2012, 6:31 PM
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Re: [likestojump] Accelerated wear on brake lines [In reply to] Can't Post

In reply to:
Option #3 - make new Type 3 tape excess keepers from wider tape, and fold it in half and install with the fold facing up so there's no raw edge for the line to wear against.

I'd also check the insides of steering line guide rings for any wear.

Option #4 - remove the keeper tape from the front of the riser, sew them on the back of the riser (between the toggle and riser).

That fixed mine and I was having the exact same problem.


floormonkey  (D License)

Jul 26, 2012, 8:22 PM
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Re: [chuckakers] Accelerated wear on brake lines [In reply to] Can't Post

Do you mean above the cat-eye or below the cat-eye?

Most of these responses assume below (the actual BK-TOG section), where your description seems to indicate the lower portion of the LSL (lower steering line). (Yes, I know it is a continuous brake line, but I also know Chuck has been jumping for a long time and will understand what I am saying).

If it is the BK-TOG section, examine what happens when you release your brakes (when the loop is under load). If you follow directions and insert the excess from the top, through both pieces of tape and then stowed by the pin, then when you release your brakes, your brake line "drags" across the top of the excess keeper, thus creating a friction point. If you stow by inserting your excess from the bottom, then when you release the brakes there is no friction or dragging against the keeper, thus causing less wear.

Making a bend in the line will not cause excess wear, unless it is on the "shoulder" of the fingertrapped line. Even then, it normally only causes the fingertrapped section of line to work it's way out.

My Velocity with Vectran brake lines have not needed a replacement until recently, around 600 jumps. (This is beyond manufacturer recommendations.) I'm just doing a lineset. My previous VX w/ Vectran brake lines, same story.

Other jumpers at my dz who stow "correctly" while having type III keepers (UPT,VSE style) have to replace them closer to 350-400. Well, not have to, but most riggers would recommend it. I find it seems to accelerate wear on spectra lines as well.

Risers with elastic keepers tend to have less of an issue in my experience. However, sometimes the bulk of the elastic makes it more difficult to pull your slider down, depending on the design.

FTR: Velocity, HMA lines, Vectran brake lines, VSE risers

If it's above the cat-eye, then it may have something to do with your slider grommets or how you handle your slider after opening. For instance, if you have "hats" and pull your slider down, the excess bulk may cause extra friction. Examine the lines above the soft link. Are they dirty/showing signs of accelerated wear? Examine the slider grommets for nicks/abrasions.

Good luck, and let us know what the result is. A picture would be nice, if you are able.


(This post was edited by floormonkey on Jul 26, 2012, 8:36 PM)


pchapman  (D 1014)

Jul 27, 2012, 5:35 AM
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Re: [floormonkey] Accelerated wear on brake lines [In reply to] Can't Post

In reply to:
DIf you follow directions and insert the excess from the top, through both pieces of tape and then stowed by the pin, then when you release your brakes, your brake line "drags" across the top of the excess keeper, thus creating a friction point.

Good point, but the released brake line eye is going to yank quickly upwards under canopy pressure, while the jumper is yanking the toggle downwards, starting from zero speed but accelerating - and some pull a short distance, some pull further. So the brake line may move up at first. So stowing from the top might be at least as valid as stowing from the bottom, but off hand I don't know which works out best.

Either way, having keepers with a softer edge sounds like a potential improvement.


chuckakers  (D 10855)

Jul 27, 2012, 5:51 AM
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Re: [Gene03] Accelerated wear on brake lines [In reply to] Can't Post

In reply to:
How do you stow the excess line?

I've retrained some folks to just put the line straight in from the top.

For some reason they were stowing it from the bottom up so it had to make a 180 degree turn while being pulled out.

I already put the line in from the top, as UPT prescribes.


theonlyski  (D License)

Jul 27, 2012, 8:19 AM
Post #9 of 9 (538 views)
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Re: [chuckakers] Accelerated wear on brake lines [In reply to] Can't Post

In reply to:
In reply to:
How do you stow the excess line?

I've retrained some folks to just put the line straight in from the top.

For some reason they were stowing it from the bottom up so it had to make a 180 degree turn while being pulled out.

I already put the line in from the top, as UPT prescribes.

Using my method I've managed to seriously reduce the amount of wear on my BK-TOG lines (that I had to replace because they were getting pretty worn with only about 200 jumps on them)

Part of the problem is that the hot knifed ends of the tape were sharp and catching the lines, the other part is my slider (not sure if yours has bigger grommets or not) would get stuck trying to pull it past the toggle because the line was now being jammed into the side of the riser. When I took the tapes off, I sewed them back on but with a wide enough zigzag that covered the end of the tapes and prevents the line from coming into contact with them. Also the slider comes down much easier because it's not having to jam the lines into the riser to get past them.
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