Sunday, April 13, 2014

MTD 12B-443F500 Stiff/Stretched Control Cable Rectification

I have an elderly mower with a stiff/stretched control cable. The stretching has rendered the cable inoperative -- it has so much slack to it that can't displace its lever sufficiently. The stiffness is causing the cable's bail to bend at the through-hole where the bail tugs on the end of the cable.

I took up the slack by giving the cable a single wrap around a short screw with two oversize washers and a nut on it, like so.

That works fine. I just need to reassemble it with threadlocker so it can't come apart on its own.

The stiffness problem isn't so easy to deal with.

Off the mower, the cable's operation seems to be free-moving enough. But once installed and put to work at its actual application, the cable is very stiff. (It's impossible to get the cable out of its jacket for proper cleaning and lubrication.)  The cable operates a strongly-sprung lever; unless cable motion in its jacket is nearly frictionless, the overall operating force of the mechanism becomes very high. (I should actually replace the cable, but I'm trying not to spend any money, here.) The best I can think to do about it is to modify the bail so the cable's stiffness at least doesn't have such an ill-effect on the bail. Stiff operation I can live with; a ruined bail I can't.

Here's a view of the current situation where the cable end meets the bail.

Note the bend in the bail -- that's not good.

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Here's what I've come up with for now.

That 1" length of steel flat with two holes in it takes much of the bending stress off the bail. The slack tightener has been rendered a little less effective by this, but it looks like it'll still be adequate. I've assembled both items with blue threadkocker, so this much of the mower should be ready to go.

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I tried it out and it works; the control cable operates its lever as it should, and the engine can run. That said, I really should replace the cable with a new one soon.

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