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MG MGA - Non-working Dick King Jack

I have recently acquired a non-working Dick King B1077 jack. As far as I can tell the jack is lacking the c-clip that attaches to the bottom of the large lift screw. The purpose of the c-clip appears to prevent the lift screw from rotating when the jack handle is rotating thereby making the jack screw extend up or down. Is this correct? What prevents the c-clip from rotating around the jack screw post?

Does anyone have a good picture of the c-clip or underside of the B1077 jack? I didn’t find any information on Barney’s site. Steve Gyles jack DB has a picture of the underside of a King Dick B1881 that might be similar if not identical to the B1077?

Thanks,
John
John Backman

John

You are totally correct. The 'C' clip's protruding arms should ride up a channel or lip inside the jack body, preventing the screws rotating with the winder. I have noticed that more jacks are missing this type of clip than have them. They are only relatively important in the early part of winding up a jack until the jacking point makes contact with the chassis, then all works as advertised.

I guess the clip could also prevent over extending the screws - a safety factor. Many jacks also had their lower threads deliberately distorted during manufacture to prevent this happening.


Steve
Steve Gyles

Probably worth adding that with all these multi tier screw jacks the smaller screw(s) should be manually wound out first to make contact (or as close as possible) with the chassis, then the winder used to extend the larger, outer screw. I get endless queries from people who think their jack is broken because the inner screw does not extend automatically. They are basically quite crude tools, nothing so elaborate! The same holds true with most hydraulic jacks that have a screw extension in the hydraulic piston.

I have wondered if that 'C' clip was also meant to be a steady to stop the main screw rocking on its pivot (the winder), but as it only makes loose contact with one side of the jack I think this is unlikely. I have seen the occasional jack that has a clip with two opposite shoulders that run up and down channels on both sides of the jack - that makes more engineering sense.

Seems those clips are as rare, if not rarer, than jack handles. Over the years they have parted company.

Steve
Steve Gyles

For those who have no idea what the C-clip looks like and what we are talking about in this thread I have attached a picture of my MGA Shelley LJ23 jack.

The top picture shows the clip in place and able to run up and down the cast shaft inside the jack.

The lower picture shows the slackness in the engineering that allows the screw shaft and clip to move out of alignment whilst positioning the jack etc.

The later MGA jack (Shelley LJ225) has two shoulders. Unfortunately mine is missing the clip(s) so I am unable to comment.

Steve


Steve Gyles

This thread was discussed between 11/06/2016 and 12/06/2016

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