Saturday, April 30, 2016

What's Inside a Flexi Leash?

My good old 2006 Flexi Comfort retractable leash died recently. It stopped retracting at a speedy eye-injuring pace and began leisurely rolling itself back in with the occasional pause. Ten years of solid service isn't too bad, though today's Flexis come with a lifetime warranty. The responsible, adult thing to do would be to toss the tired, worn out leash and buy a new one. Obviously that's not what I did.

Flexi Leash Safety

broken Flexi leash
Years of Flexi propaganda had me convinced that within the case there lurked a Death Spring that could fly out and kill me and everyone I loved. Flexi leashes come with a lot of warnings, but I mostly stick with the more visible belt or tape ones, and only use them in places where my dog can safely be 15' away from me, so I like to think I'm safe from traumatic finger amputations and nasty cord burns. As long as the Death Spring Containment Case wasn't opened, we were all safe.

Then my Flexi leash stopped retracting and I threw caution to the wind, by which I mean I googled "flexi leash repair" and looked at pictures of other people taking them apart to bolster my confidence. Apparently the case could be cracked open without immediately unleashing the Death Spring.

Tool Time

prying open a retractable leash case
After removing the two screws holding the case together, I carefully pried the thing open with a screwdriver. No Death Spring in sight. Inside, there was a white plastic wheel holding the length of the leash, the brake and lock, and that was it.

I had hoped that an obvious and fixable problem would immediately become apparent when I opened the case. Maybe there was a twist in the leash, or something needing lubrication, something other than "spring's fucked, buy a new leash".
the inside of a Flexi leash

The Secrets Within

The leash remained functional with the case opened, so I was able to see the mechanisms and the action. I pulled out the tape and let it retract, during the pauses there was still something moving inside the wheel. Maybe the Death Spring was slipping?

Clearly the next step was to remove the white wheel. I had always envisioned the Death Spring as a huge coil, and I assumed it must be held between the wheel and the other side of the case.
retractable dog leash in vise

Convinced that the green peg in the center was all that contained the Death Spring, I trapped the leash in a vise while I pried the wheel loose. To my great disappointment, there was no great burst of primal energy, and the other side of the wheel looked pretty much the same. There was still no obvious reason why the leash wouldn't retract smoothly.

In the hole in the center of the ring though, I could now see a strip of metal with a big kink in the end.
internal mechanism of a retractable leash
The inner part of the white wheel was clearly a separate part that could be removed. This must be the lair of the Death Spring. By this point though, I was pretty sure that nothing was going to pop out at me. This spring probably wasn't even tightly wound anymore. 

I could spin the end of the metal strip around with a screwdriver, coiling it tighter until it popped back to its original position.
coiled death spring

It looked similarly nonthreatening with the cover removed. Just a piece of wound up metal. It's difficult to tell from the picture, but this is a very long strip of very thin metal. The coils together looked a lot like a solid cylinder of solid silver material.

With the cover off, I again spun the end of the strip around with a screwdriver and...

Retractable leash death spring

HOLY SHIT! It exploded out of the wheel in a huge jumble of twisted metal!

Death Spring Located!

I had been playing with the very end of this huge spring without realizing that the wheel around it was holding it in tension. As soon as I pulled it a tiny bit sideways, the whole thing shot out.
uncoiled retractable leash spring
See that straight bit at the bottom? That part has lost its tension entirely. It's likely the reason why the leash would reel in very slowly at certain points. While it's possible to re-tension a spring by hitting it with a hammer (I do this with clarinet springs), I don't think I'm up to the task of re-tensioning this monster. Even if I could get it contained again. Yikes!

So yes, the spring's fucked and I need to get a new Flexi leash. I'm saving this one for parts, though. I'm thinking we need a pink Flexi Vario with interchangeable end pieces that stretch or light up. Plus there's various attachment for the handle, like a cargo box and a flashlight. So many option! Flexis made after September 2011 have a lifetime warranty, so it could be the last one I ever buy. This green one is the only retractable leash I purchased new, all my others are thrift store finds because I walk on the wild side and use potentially unsafe equipment. 

Thanks for joining me on this journey of discovery!


  1. I used your article to repair my Flexi Long 3 without releasing its Giant Spring of Death. I was unable to find the cause of its refusal to retract, though it retracted as soon as I opened the mechanism.

  2. It's called a torsion spring. Commonly seen in watches, wind up toys/devices, and ... retractable things like tape measure and of course dog leashes.

  3. Such a great article!!! Sadly I read this expos-facto of liberating the coil precisely as you had done. I even pulled out that same pin thinking that was the key to it all. (For anyone wondering, that pin simply holds the non-business end of the leash to the plastic barrel).

    I made all the same moves as you- I may as well have been programmed via LOGO- made ALL the same moves, had all the same thoughts as you, got stuck where you got stuck... lol.

    i however spent another good 6 hours on and off trying to recoil the spring in the right configuration and ditto for the direction of leash-coil, as I played a game of whack-a mole trying to get both to finally work.

    Oh and then the whole pre-tensioning the spring game was a total fail and ultimately my spring snapped in half and still I persisted with maybe 60% of it's intestines left... and finally I had whaat I thought would work, and it did once, but then never again.

    Part of this process involves liberal use of proper lubricant all along both surfaces of that metal coil, or strip, as it was for me after i detangled it from exactly how it was depicted in your photos..

    No lube = no motion of spring. Tried everything in the house (and we have a modest collection of industrial slickers), and more nope.

    I was so tired and my hands hurting from working that spring over and over I had to skip work on Monday. So all in all this was a costly DIY and I TOLD YOU SO from she who ought to be obeyed.

  4. You're Hilarious!! Thank You for the humor AND instructions......

  5. This is the most riveting story of a broken leash I have ever read. I was on the edge of my seat.

  6. I had a wigzie retractable thatno longer retracted. Trying to fix it I killed it forever. There are hidden screws that can't be undone.
    I called a women at their 800 number who said you can't fix them! O it in the trash and I'll be damned if I buy another. Very very disappointing! I'll be sure to spread the word.