Replacing Lift cables

[WARP TEN]

Well after 8 years of trouble free operation of my Direct Lift Pro Park 8S four post lift, I noticed that one of the twisted wires in one cable looked loose. A little hard to see in the picture but was obvious to me when operating the lift the other day. Called Direct Lift, got a local installer recommendation,called them and they will be up first thing next week to replace all the cables. Total cost about $750 but of course worth it. After spotting the cable problem I used the lift one more time to swap cars to get the BMW sedan down and will now wait for the repair before using it again. Should be good for another 8 years or so, by which time it will probably be my heirs' problem.... --Bob

[efnfast]

Broken wire rope could be a big problem.

[WARP TEN]

Originally Posted by efnfast

Broken wire rope could be a big problem.

I agree. As soon as I noticed it I called the repair folks. When one strand of a wire rope pulls out of a swage fitting it potentially can mean that the others will loosen shortly and the whole cable will pull out of the swage. The primary mechanical safety stops on the Direct Lift are substantial, with additional backups to them, so I am not worried that the top car would fall down more than the six inches between stops if it let go. But it would be an extra pain to have to somehow jack it up for repair. After I noticed it I used it once more to swap cars and get the BMW down and put the Z06 up. I did notice while lifting that by putting strain on the remaining strands in that cable that the loose one seemed a bit looser--I could see light under the one strand. But it didn't give way. Still, I don't want to use it any more and I am all set until the repair sometime next week. Besides the weather is cold and not conducive to a spirited Z06 drive.--Bob

[A26B]

Crimp should be the last component to fail, if it was done correctly. It's just a dead pull, no flex. Typically, cable problems appear at the section which runs over the sheaves, and appear as broken strands from flex & wear.

[WARP TEN]

Originally Posted by A26B

Crimp should be the last component to fail, if it was done correctly. It's just a dead pull, no flex. Typically, cable problems appear at the section which runs over the sheaves, and appear as broken strands from flex & wear.

I agree, Jerry, that swage crimp failure is not common, but I have seen it before in other applications, and the repair folks said they have seen it before in a other brands of lifts as well. When they change the cables next week I will inspect where they contact the sheaves but so far my regular inspections have not turned up any broken strands anywhere. I have found the other three swages to be fine, but I am replacing all cables just to be prudent. And the one that loosened up lasted 8 years and was probably used in this condition for a while before I noticed it. So I am not too unhappy that I need to replace the cable set. I figured that at some point I would have to do some maintenance like this. So far, including the new cables, my lift cost will have amortized out at less than $500 per year, which I consider OK. --Bob

[A26B]

Originally Posted by WARP TEN

I agree, Jerry, that swage crimp failure is not common, but I have seen it before in other applications, and the repair folks said they have seen it before in a other brands of lifts as well. When they change the cables next week I will inspect where they contact the sheaves but so far my regular inspections have not turned up any broken strands anywhere. I have found the other three swages to be fine, but I am replacing all cables just to be prudent. And the one that loosened up lasted 8 years and was probably used in this condition for a while before I noticed it. So I am not too unhappy that I need to replace the cable set. I figured that at some point I would have to do some maintenance like this. So far, including the new cables, my lift cost will have amortized out at less than $500 per year, which I consider OK. --Bob

I hear you Bob, just bothersome and a by-product of cost control. There are better methods of cable end attachment, but they are more costly.

The good thing is... your sharp eye and attention to detail caught it before something really bad happened.

It's just a thought, but 2 things crossed my mind;
1. Are the replacement cables going to be tested before they are installed?
2. I wonder if there is any benefit or detriment to applying some high strength Loctite product to the cable before it is crimped in place. Off hand, only detriment I can think of is the cable end test should be delayed until past cure time.

[WARP TEN]

Originally Posted by A26B

I hear you Bob, just bothersome and a by-product of cost control. There are better methods of cable end attachment, but they are more costly.

The good thing is... your sharp eye and attention to detail caught it before something really bad happened.

It's just a thought, but 2 things crossed my mind;
1. Are the replacement cables going to be tested before they are installed?
2. I wonder if there is any benefit or detriment to applying some high strength Loctite product to the cable before it is crimped in place. Off hand, only detriment I can think of is the cable end test should be delayed until past cure time.

Yes I am glad I noticed it, too. In my youth I used to make stays for sailboat masts by swaging stainless steel wire, usually with a loop on a thimble (that actually might be one of your "better ways" to secure the cables, rather than the direct crimp, but probably more expensive). Anyway, I got used to noticing if anything seemed out of whack. I would recommend that anyone with a lift that is a few years old do regular inspections looking for both broken strands around the sheaves or a loose sub-cable like mine. I put a little tension on the cables and the loose one was a bit more obvious. There was some luck involved--it was on a cable on the same side as the lift controls so in my line of sight when operating the lift. If it were on the other side I am not sure I would have noticed it when I did. Every time I used the lift I looked down the car towards the cable. I was used to seeing a uniform width cable, so when the loose one became visible it was because it made the cable look less uniform, a bit lumpy.

As to your two questions, I do not know if the cables are all tested or perhaps randomly tested when manufactured. I presume that some sort of verification of the strength of them was done at some point. And while I will defer to more talented engineers here, I would think that putting anything, even Loctite, between the swage and the cable would be detrimental to the pressure and friction bond between them. Kind of like putting some anti seize lubricant on a spark plus changes required torque settings. But that is just a guess. --Bob

[WARP TEN]

A follow up. The main distributor (and owner of Direct Lift) Rotary says they are short one cable so it will be a week or two until I get my cables replaced. If it drags out too long I may go for three cables for now, unless of course the missing one is my broken one. Oh well, we'll see, And Jerry, I spoke at some length with the technical support guy at Direct Lift and he agreed with you that the more common cable failure is fraying of individual wires around the sheaves, but he has seen the larger twisted wire swage loosening I have a half dozen times or so in the last four years. So it is less common but still happens. Overall the lesson here for lift owners is, inspect your lift cables regularly just in case. --Bob