Head Lamp Stay Rubber Grommet CB750F - Alternative replacements?

[Pedro26]

Hi,

Just dismantled the front end lights etc and one of the rubber grommets where the head light stay locates into the bracket on the front forks is missing. The actual grommet is like an upside down top hat shape, which locates in the hole in the fork bracket. Previous USA owner had just wrapped a load of black insulation tape round the end of the rod on the bed light stay that locates in the hole. I’ve tried all the usual part places that deal in classic Honda spares, but it’s a discontinued, unavailable part. Is there another, available, rubber grommet that might be re-purposable for this? Off an Honda or indeed any bike?

Thanks

[Oddjob]

Which model of F is it, F1 or F2 for example.

I might just have one of those, is it a sort of metal ring with rubber bonded onto it. Top rubber or bottom? I'm thinking top.

[McCabe-Thiele (Ted)]

On my 500 the insides of the fork ears were rotted out where the rubber sections fit.
I kept some of the inside bits I will post a picture when I find them - if they are any good for a 750 they are yours free plus postage cost.

[McCabe-Thiele (Ted)]

I've taken photo of both sides - still in one piece might need some TLC if they can be restored at all.



PXL_20230501_173436648 by Macabe Thiele, on Flickr

[McCabe-Thiele (Ted)]

PXL_20230501_173423429 by Macabe Thiele, on Flickr

[Pedro26]

https://www.cmsnl.com/products/grommet-light_61312392000/

Shows images of the grommet, and I’ve screenshot it, please see the attached image.

As you can see it’s an inverted top hat shape, well it’s inverted when pressed into its location. (There’s a hole in the top hat which allows rain water to drain.)

It’s part no 61312-392-000 which is on page 42 in the parts manual here http://manuals.sohc4.net/cb750f/technical_reference/PL750F.pdf

My bike is supposedly an F0, but instead actually appears identical to the F1 models that followed the F0.

[Oddjob]

Not what I was expecting at all.

You got any dimensions? the CB1300 uses a very similar system to stop the headlight from vibrating, it essentially acts as a damper between the frame and the headlight.

Check out 19113-MB1-870 and have a look. Looks similar but may not be the right size.

[Pedro26]

I’ll measure the hole’s, ID, in the fork bracket, and the dimensions of the one that’s still in the forks tomorrow and I’ll post it here.

[Pedro26]

As shown in the attachment these are the dimensions of this inverted ‘top hat’ grommet.

The diameter of the ‘brim’ of the top hat shaped grommet is approx. 21.8mm
The outer diameter where it slides into the hole in the fork bracket is approx. 16.1mm.
The length of the bit that slides into the hole in the fork is approx. 13.6mm.

The thickness of the brim of the grommet is about 3.1-3.2mm.

The internal diameter of the hole in the grommet is approx. 10.4 mm
Overall length/height of the grommet is approx. 16.1 mm

The diameter of the headlight stay rod, (actually a tube), is approx.  10.2-10.5 mm

The internal diameter of the hole in the bracket on the forks that the grommet fits into is approx. 16.2mm.

The height of the fork bracket is 20.68mm.

[Oddjob]

No, sorry the CB1300 one is smaller. However you could try making one out of a door stop. Shouldn't be that hard to do, I'm doing something similar with a VT1100C which is missing a grab rail isolating rubber.

[Pedro26]

That’s a good idea ! Nice one, just need to get a new batch of Stanley knife blades, less chance of accidents. Doing the inner hole might be tricky, but I could do that first, might be able to drill it. Then paring it down to fit.

[Oddjob]

Drill it, should already be a screw hole central in it. Or screw a long screw in it, put the screw in a drill and spin the rubber, you should be able to sand it down with rough then smooth sandpaper or even a sharp chisel, then drill the hole last.

[McCabe-Thiele (Ted)]

I burn holes in rubber using a slightly narrower bit shaft - often it's not straight rubber but a plasticy type material. I put drill bit in vice warm with my blow torch until it well hot. I use a plumbers heat mat to hold rubber as I burn the hole.

[Pedro26]

I got these from Homebase. They’re not solid rubber, but that is an advantage. 2nd attempt was successful I cut off the lower part just to where the main hole ‘bottoms’, without cutting into the rubber for the larger hole’s base,  then pared away around the sides until the top disc was sufficiently thin, which is just a tad below the actual original shoulder. Also if you leave too much of the door stop’s strengthening walls, it works against you, even though the rods fit the hole as if it was made for this, (no drilling required) and they fit into the fork bracket hole.  Too much rubber round the lower periphery on the newly fashioned grommet, and you struggle to line up the top holes of the stays, where the speedo/tachometers bracket mounts with those threaded pins.

Anyway, result. First result is in the photo, successful one is on the bike, shorter in overall length/depth than the one shown.

[Bryanj]

As The A team said "I love it when a plan comes together"