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Re: Speedometer rubber grommet – part No: 021798

Posted: Thu Mar 16, 2017 7:36 pm
by Mick D
Hi

Check the seal doesn't foul at the front where the speedo is recessed into the headlight before you apply the silicone.

Regards Mick

Re: Speedometer rubber grommet – part No: 021798

Posted: Thu Mar 16, 2017 7:46 pm
by Rob Harknett
clive wrote:I certainly would not try scraping what looks like a highly finished paintwork. The rubber basically needs to be between the speedo bezel and the headlight to allow the clamp to pull it down. With the dimensions you quote you are never going to get it to fit. Instead I would cut off the bottom part of the grommet and put a few turns of gaffer tape round the body and tighten it up. Job done and no-one will know, well ok we will :rofl:
Scrapping the metal edge should not damage any paintwork Clive. But I have done it a lot during my job. On metal and plastics. Using home made scrapers, made from old steel rules. ( rules that I'd forgot to take off a guillotine table and cut a bit off ) Use and sharpen like a wood worker's scrapper. They make a nice smooth edge finish on plastics, like your fairing, that will then burnish as shiny as the surface. Also used the scrap method to open an aperture to min tolerance, say for a speedo to drop in. I worked on wood working machines, not engineering, which could reach very fine tolerances. But I often got engineering drawings to work to with + / - engineering tolerances, which were some times nil.
Perhaps, do not scrap unless you have a very steady hand, sharp not blunt tool. You may slip and damage paintwork.

Re: Speedometer rubber grommet – part No: 021798

Posted: Thu Mar 16, 2017 7:54 pm
by McMaz
Mick D wrote:Hi

Check the seal doesn't foul at the front where the speedo is recessed into the headlight before you apply the silicone.

Regards Mick
Mick, just offered up the top section of the grommet to the h/lamp shell and see what you mean – it's too large a diameter and doesn't lay flat on the surface towards the front. I'll follow your advice and use the lower section which makes a good seal and looks far better, thanks

Re: Speedometer rubber grommet – part No: 021798

Posted: Thu Mar 16, 2017 9:45 pm
by Expat
Don't wish to muddy waters :o , but is it possible to cut a sliver out of the grommet to reduce the diameter, then fit it with a smear of silicone to seal the join?

Re: Speedometer rubber grommet – part No: 021798

Posted: Thu Mar 16, 2017 10:42 pm
by Rob Harknett
Surely a water tight seal is not that important, the rubber really only to stop metal to metal rattle.

Re: Speedometer rubber grommet – part No: 021798

Posted: Fri Mar 17, 2017 10:23 am
by JEAN-NOEL
I have had the same problem 20 years ago. I agree with Mc-Maz and Mick D : I had removed the bottom lip of the grommet.

Re: Speedometer rubber grommet – part No: 021798

Posted: Fri Mar 17, 2017 2:00 pm
by McMaz
When I first started this topic I asked if the size of the opening in the headlamp shell changed at some point after 1955, I think I have found the answer.

In the article ‘ Year by year changes' (http://www.jampot.com/article_read.asp?id=20) it states that in 1955 “A new headlamp shell was introduced, basically a torpedo shape, and accommodated the speedo towards the rear.”
This new design headlamp shell was used until 1960 when “A new Lucas 12-amp-hour battery of compact design was used and a more compact headlamp was fitted. It still housed the speedometer.”

This would seem to explain why I and other members with post 1960 machines have found it impossible to fit this grommet successfully. The grommet is listed at AMOC parts as ‘SPEEDO HEAD RUBBER GROMMET 55-‘ should this be ‘55-59'?

Re: Speedometer rubber grommet – part No: 021798

Posted: Fri Mar 17, 2017 2:43 pm
by Stuoyb
The grommet 021798 is still listed in the 1960 parts catalogue and no alternative parts are shown in subsequent supplements.

Re: Speedometer rubber grommet – part No: 021798

Posted: Fri Mar 17, 2017 4:06 pm
by Rob Harknett
Mc-Maz wrote:When I first started this topic I asked if the size of the opening in the headlamp shell changed at some point after 1955, I think I have found the answer.

In the article ‘ Year by year changes' (http://www.jampot.com/article_read.asp?id=20) it states that in 1955 “A new headlamp shell was introduced, basically a torpedo shape, and accommodated the speedo towards the rear.”
This new design headlamp shell was used until 1960 when “A new Lucas 12-amp-hour battery of compact design was used and a more compact headlamp was fitted. It still housed the speedometer.”

This would seem to explain why I and other members with post 1960 machines have found it impossible to fit this grommet successfully. The grommet is listed at AMOC parts as ‘SPEEDO HEAD RUBBER GROMMET 55-‘ should this be ‘55-59'?
Wrong. Prior to 1955 a different headlamp and speedo was used. The speedo did not fit in the headlamp prior to 1955.. The 55/60 headlamp hole for the speedo is 3 5/16" ( 184 m.m. ) dia. Smiths list the speedo as 3" dia

Re: Speedometer rubber grommet – part No: 021798

Posted: Fri Mar 17, 2017 4:41 pm
by Janet
Rob Harknett wrote:Wrong. Prior to 1955 a different headlamp and speedo was used. The speedo did not fit in the headlamp prior to 1955..
No-one said the speedo did fit in the headlamp shell prior to 1955. Sean is comparing the models from 1955- with those from 1960 onwards.
The 55/60 headlamp hole for the speedo is 3 5/16" ( 184 m.m. ) dia.
I assume you mean 84mm? Sean has already said that the diameter of the hole in his headlamp shell is 81mm.