Unobtainium Supplies: Jack Handle Ring

Awhile ago, Kerry Chesbro asked if I could source the plastic ring that slips over the jack handle extenson's end. These frequently develop cracks at the hex opening's points & then break if you continue to use them. According to the various FPCs they're not sold separately. These are used in most of the tool kits for 308s, 328s, Mondials, & others.

I'm pretty sure that there was a thread on this, but am apparently not giving SEARCH the correct key words.

Anyway, as you can see from the attached pictures I just finished making a mold. To avoid the breakage problem, I'm offering it in a very firm rubber like polyurethane similar to that used for suspension bushings. The hardness is similar to tire rubber. It's hard enough to be useable, but has enough give so that the hex opening won't split out the way the OEM ones do.

However, if so requested, I can also supply it in the hard polyurethane I use to make the boot lid prop flex joints & the latch housings for the bonnet & boot latches. The hard polyurethane is quite a bit stronger than the OEM plastic, so if you twist it hard enough, it probably can be broken just like the OEM one.

Price is $35 each.

To order contact:
Orders(at)UnobtainiumSupply.com
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8valve,
Thanks for finding the older threads, spent half an hour trying to locate them before throwing in the towel.

I just had an idea. I'm going to visit the HW store & see if I can't find a metal ring of some kind that's just slightly bigger than the hex. If I can find one, I'll try embedding it in the hard plastic part. Should strengthen it, & even if cracks start, they'll be less likely to grow past the ring. Forgot to mention, the hard plastic also contains a high % of glass fibers.

 

BwanaJoe,
Of course I'll let you know.
Other than sourcing the ring, only problem I'm worried about is that I don't know of a way of centering it inside the casting thus it's likely to be near the surface, so might be visible if you look really close.

Just browsed McMaster-Carr & they've got something that should work. Will get some on order.

 

The ring must be pretty well centered around the hole to ensure stresses are distributed. If I just drop it around the mold's center, it'll be right on the hex hole's surface on one side.

I've ordered a supply of small sturdy key ring type rings. I'm going to try clipping a piece of wire or thread as a chord thru the ring, the wire will rest on the mold's center & help radially center the ring in the mold. Luckily one of the hex's flats is facing upwards, so the wire will be stable resting on it! Not sure how to ensure it's more or less axially centered, maybe can bend & use the wire's free ends somehow.

 

Radially centering the ring by a wire chord works like a charm, but takes some extra time.

BTW,Like most of my molds, this mold makes 1 part at a time, so production will be slow: Best case is about 2-3 parts/day.

If you want to order, please send me eMAIL with the address to ship it to & a phone # for the shipping co.
I'll send you a PayPal invoice unless you specify otherwise in the eMAIL. To send me eMAIL, just right click on my name & select [Send eMAIL to Verell].

 

CAUTION:
The mfg. tolerences on the handle's hex are pretty sloppy. One person just reported breaking his new ring.

When I measured across the flats of the ring & handle hexes I discovered that the handle's width varies widely. One pair of the handle's flats was 0.78 mm/0.030" wider than the narrowest pair of flats. The intermediate pair are 0.43 mm wider than the narrow pair.

I measured a new & my OEM ring. They measure identical within my ability measure them. They should be identical as I made the mold from my ring, the materials & process I use preserve dimensions within 0.001"/foot or better.The ring's hex is much more symmetric than the handle's, the widest pair of ring flats is only 0.3 mm/0.012" wider than the narrowest pair of flats.

My best guess is that the maximum manufacturing variation across handle flats is larger than my handle measured.

I suspect that this handle hex size varience is a major contributor to the OEM jack rings cracking as well.

I don't see any way that I could have forseen or avoided this particular problem. It's just Ferrari's usual poor quality tools(sigh).

RECOMMENDATION:
If your ring seems to be tight fitting, try several orientations on the handle. There should be an orientation where the ring slides onto the handle but isn't a sloppy fit. If necessary, I recommend using a small file to widen a pair of the ring's flats, & retrying. Repeat as necessarry. You probably won't have to remove much, maybe a few tenths of a millimeter.

If I try to make the new rings with larger hexes, then most likely they'll end up a very sloppy fit on a large % of the handles. A loose fit will also stress the ring & cause it to be prone to cracking.

 

I just checked some production parts & my OEM part. I don't see a flash line. Also, the mold doesn't have an joining seam inside the ring that would produce one.

However, please notice that the hex thru-hole changes size about 1/2 way thru the ring. On my jack handle, the smaller hex (13.8mm/0.55" width across the flats) fits closely onto the jack handle's hex, & the larger(15.3mm/0.6") hex slides up over the round part of the handle.

Joe, I'm wondering if your handle's hex is yet a different, slightly larger size than the smaller portion of the thru-hole, or maybe is the size of the larger hex part of the hole. If you have a caliper or micrometer, could you please measure across your handle's flats & post the size here?

Whoda thought that Ferrari could complicate something as simple as a jack handle ring?

 

Harbor Freight & others usually carry a 4" digital caliper for around $16. I've found that a 4" caliper is a lot more convenient size than a 6" caliper which is what the world seems to use. I've found that a 4" caliper handles 99.9% of my measurements. HF occasionally puts them on sale for around $10. I've got 3 of them, one for the lathe, the mill, & my casting workbench.

I do have 6" thru 12" calipers, but mostly they stay in their boxes with the batteries out. Altho, my LH 6" caliper also stays by the lathe. I bought it so I could easily measure workpiece diameters. Would have preferred a LH 4" there also, but have never seen one.

 

BTW, On the back side of the ring are a couple of mold marks that look like cracks. The original part was indeed cracked, the material I filled the cracks with before using it to make the mold had a slightly different surface texture from the original part, & a bit wiped out while I was smoothing it over. The mold picked up the difference in texture & depth & faithfully reproduced it.

The fibreglass composite polyurethane resin I cast the ring from doesn't change dimensions while curing, & there's no significant temperature change involved, so there's no mechanism for the casting process to produce cracks.

Joe,
That 14mm dimension is probably why the ring didn't want to fit, the ring's only 13.8 wide.

 

Yes, still available, thanks for the PM.

 

Possibly/probably, What have you broken?

 

You can always send me eMAIL...