how about this grommet. Hole too big?

emzdogz

emzdogz

Aunty Em
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Hi folks, I've been gone, because I haven't worked on my bike much due to the long hot sticky wet summer here in FL. I work in a carport which floods, and well, it's just unpleasant. But now the weather is good, and I'm back on my project '80 chopper.

Am working on wiring.
Wanted to create a harness or a couple of harnesses that could easily be removed and put back on the bike, rather than just running wires.

My last problem (looooooooong ago) had to do with the banjo style rear brake switch not working. Problem more or less fixed - if it has enough pressure, it works. Rear caliper will need to be rebuilt during the teardown prior to paint.

Here's what this post is about: I'm thinking about going ahead and making 2 holes in the main frame tube, to run wiring from under gas tank to exit on rear of main tube somewhere below where airfilters would be and the mount for regulator rectifier. About where the stock frame has those pieces coming out into a "Y".

The most convenient thing would be to use these 3/4" rubber grommets I have. But they require a 1 inch hole. That seems kind of big, right? Under the tank the place I need a hole is on the underside of the main frame tub, pretty far back - almost to where the bottom tube connects in with that massive slab like support.

So then I found these grommets, which would require a 3/4" hole (instead of a 1") hole. What do you think? Could 3/4" holes compromise the strength of the frame? I mean what could happen? the tube would actually buckle?
Hard to imagine, especially in front where that tube is so supported by the connection to the other tube.

http://www.wiringproducts.com/universal-nylon-grommets-10-pieces.html

What do you say? Holes too big? Reason I need a fairly big hole, rather than a 3/8 in or 5/16ths hole, is I'm wanting to run these connectors. So they'd have to be able to pass through whatever hole I drill.
http://www.wiringproducts.com/trailer-connector-2-pole-molded-1-pc.html

What I really wish is I could find some oval shaped push in grommets. Then drill two 5/16ths holes stacked, and then use the dremel with cutting wheel to create an oval or long but narrow hole with rounded ends.

Have been searching for some elongated rubber grommets, about inch by say 1/4 in.
Anybody know where such a thing might be available? I guess I could cut a tiny section out of the round grommets I have and maybe they'd work in such a hole.

So what do you think. Are 2 3/4" holes too risky?

thx
Em
 
Hi,

On the Bobber I built last winter i did just that although the holes used were 1/2"

A bit of MIG wire and a fiddle pulled all the wires through. personally I wouldnt go bigger than 1/2"
 
this would be the frame hole location. Sorry the proportions are obviously a bit off.
 

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hi Paul, thinking I need to find the smallest sized grommet that that connector can be pushed through. I guess if I lube it before trying to push it through, maybe it could go through a 3/8" holed round grommet. (which uses 9/16ths panel hole) I have 3 of these that need to go through. I will try putting them through 3/8 sized ones with "lube". Maybe I can shove them through with the grommet not pushed into place in the frame. Push them through frame then grommet, then push grommet in. If they fit I'll be lucky.
 
weekendrider said:
You might try these folks.
http://www.manuf-rubber.com/products/grommets/
Click to expand...

hey, thanks, I'd looked on that site also, as well as McMaster Carr and a couple of other sites, but can't seem to find any oval or oblong shaped ones, even though that site you linked does mention oval ones. Do you see the page that actually shows oval ones?

A light bulb just went on in my brain. I believe my Sportster uses oval or slit shaped grommets for the bottom of sidecover. Seems like I've seen oblong rubber grommets somewhere on the stock XS, too...I just can't recall where. hmm....
 
If you pinch a round grommet, it will become oval.
 
Pinching the grommet works well. Many oblong holes in aircraft start with a round grommet, and it often helps to split the grommet at a 45 degree angle to install it, then glue it in place with rubber cement. Just figure the perimeter distance of the oblong hole, or, alternatively, use a larger grommet and cut the un-needed length off when joining it with the 45 degree cut. the angled cut is used so if it shrinks from heat or exposure, it's much more difficult for a wire to work it's way into the gap and chafe on the raw edge.
http://www.aircraftspruce.com/catalog/appages/an931.php?clickkey=50667
 
I think this may give you a workable hole area 1/4" wide and 1" long but you would have to check with them. I may not understand the sizing chart.
 

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jd750ace said:
Pinching the grommet works well. Many oblong holes in aircraft start with a round grommet, and it often helps to split the grommet at a 45 degree angle to install it, then glue it in place with rubber cement. Just figure the perimeter distance of the oblong hole, or, alternatively, use a larger grommet and cut the un-needed length off when joining it with the 45 degree cut. the angled cut is used so if it shrinks from heat or exposure, it's much more difficult for a wire to work it's way into the gap and chafe on the raw edge.
http://www.aircraftspruce.com/catalog/appages/an931.php?clickkey=50667
Click to expand...


wow good stuff on that site. The u-channel strips look very useful too. Maybe as god as a grommet.

Thanks, guys.

Will go home and pinch the grommet.
:doh:
 
The U-channel strips in nylon need to be heated to grab the best. The newer ones (Boeing design) with the metal attach flanges are more of a bitch to get on, but they are just as hard to remove, and stay in place very well without adhesives.
 
Thanks Em :)
Mine were tight, so I popped them in hot water for a couple minutes them lubed them with WD40 and they went in. Lollipop stick wittled into blunt shapes are your friend ;)
 
If you just thread the wires and not the connector a small hole could be used. I would silicon the wires in the hole keeps out moisture and protects the wire.
 
hey thanks everybody for the info, and opinions and general conversation. I discovered last evening that the connector I gave the link to (connector as used on Battery Tender pigtail) can be pushed through a 3/8 hole grommet, if pinched. But heating the rubber a little would help and yes, lube did work.

But I think what Scabber wrote is probably what needs to happen - that is make the final connections after the wires are already in.

Which means I have to get the frame painted or powdercoated first.

Had hoped to come up with a nice finished wiring harness before taking it apart for paint, etc. I guess I can do that with the exception that the connectors on one end of whatever runs through the frame will just have to be twisted and elec taped, until the final installation into the painted frame.
No biggie, I guess.
It's only like 8 wires that need to go through there.

thx again
Em
 

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