Speedometer glass sealant

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stag-gered
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Speedometer glass sealant

Postby stag-gered » Wed Aug 25, 2021 2:09 pm

Hi,

Having removed the two chrome rings from the speedometer (1969 car), the front ring has a sealant between it and the instrument glass that has oozed out and gone hard. Can anyone say whether this was originally a rubber gasket/ring or some form of mastic sealant. Any suggestions on what I can replace it with? I don't want to go to the expense of sending it to an instrument restorer.

Thanks in advance.

geoberni
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Re: Speedometer glass sealant

Postby geoberni » Wed Aug 25, 2021 2:23 pm

I've seen mention in the past that the original wasn't a huge O ring, but a hot poured mastic.
There's places on ebay that sell 'rubber cord' of the right size. Just search for 'Smith Speedometer Bezel seal' and I'm sure you'll find something.
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les
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Re: Speedometer glass sealant

Postby les » Wed Aug 25, 2021 2:54 pm

Mine has a rubber O ring, I’ve assumed it was original. I’m sure it would be a quicker solution in production, just a guess !

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Re: Speedometer glass sealant

Postby geoberni » Wed Aug 25, 2021 3:59 pm

les wrote:
Wed Aug 25, 2021 2:54 pm
Mine has a rubber O ring, I’ve assumed it was original. I’m sure it would be a quicker solution in production, just a guess !
I've found a place where it's mentioned as a sealant. Whether it's true or not, I can't say. Certainly I've seen some where the 'rubber o ring' seemed stuck in and totally perished.
https://www.mgcarspares.co.uk/smiths-technical-32-c.asp
When these instruments were made the void between the bezel and glass was sealed with a sealant. .We are unsure whether this was hot poured rubber or a sealant. This material hardens hardens and also seeps out onto the glass. We have found a sponge cord is the best replacement is available in our shop.
I guess it depends when the gauge was made, I've seen another comment that the guy found a paper gasket under the bezel.....
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win
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Re: Speedometer glass sealant

Postby win » Wed Aug 25, 2021 5:36 pm

Hi
I have a good seal, you can have it if you PM your details, or are you attending any events.
I am at S70, if you are nearby.
Regards Win
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stag-gered
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Re: Speedometer glass sealant

Postby stag-gered » Thu Aug 26, 2021 7:23 am

Thanks for all your swift responses. The description from the MG instrument page describing the sealant melting and oozing out onto the glass and bezel is exactly what has happened with mine, to the extent that i thought the bezel was severely corroded. Upon dismantling and closer inspection the crud just chipped/scraped off.

As you can see this is my first post (classed as a 'Newbie' despite 39 years of owning our Morris), so now i have to figure out how to PM Win.

Thanks all for your help.

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Re: Speedometer glass sealant

Postby don58van » Thu Aug 26, 2021 9:00 am

Hi Stag-gered

Welcome to the message board.

I have refurbed quite a few of these speedos. I think it is likely that they all had rubber seals. They (the seals) break down over time and begin to ooze and then dry out to form a brittle, hard substance. I replace them with rubber seals with circular cross-section and of exactly the right size that I source from China on eBay (I couldn't find any other source). I do the same with the Smiths 2" instruments.

If you are taking the glass off, you might consider servicing the working parts of the speedo mechanism while you are in there. The original lubrication hardens and eventually causes failure. Don't try if you are not used to working with delicate instruments, though.

Don

stag-gered
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Re: Speedometer glass sealant

Postby stag-gered » Thu Aug 26, 2021 10:26 am

Thanks Don. That sounds like good advice re the lubrication. i had assumed that as it was all working okay when taken off the road, that everything would still be fine.

Alan

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Re: Speedometer glass sealant

Postby don58van » Thu Aug 26, 2021 12:00 pm

i had assumed that as it was all working okay when taken off the road, that everything would still be fine.
It might well be fine for years to come without any maintenance. I only mentioned it because to my way of thinking, it is good opportunity while the speedo is out and apart. In my experience, the odometer mechanism tends to seize, causing the speed mechanism to misbehave.

PM me if you want further advice.

Don

geoberni
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Re: Speedometer glass sealant

Postby geoberni » Thu Aug 26, 2021 12:07 pm

stag-gered wrote:
Thu Aug 26, 2021 10:26 am
Thanks Don. That sounds like good advice re the lubrication. i had assumed that as it was all working okay when taken off the road, that everything would still be fine.

Alan
When I brought my car the Odometer was busted, and had been for 7 years. It had been getting regularly MOT'd but the mileage never changed 2010-2016.
Who knew a working Speedometer was a legal requirement, but not the odometer. :roll:

I took it apart and found the small plastic gears on the odometer broken, because the grease was rock hard and they gave out.
Hence I now have a reconditioned Speedo.

Annoying because I had the skills to fix, but not the parts......
Basil the 1955 series II

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Re: Speedometer glass sealant

Postby jagnut66 » Thu Aug 26, 2021 12:44 pm

1954 Series 2: 4 door: "Sally" -- on axle stands needing more welding......
1955 Series 2: Traveller: "Elsie May" -- on the road and enjoying her 'as is' for now but I see work ahead......
1970 Triumph Herald 1200: "Hetty" -- driven back from Llangollen in Wales

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Re: Speedometer glass sealant

Postby don58van » Thu Sep 02, 2021 4:16 am

Hi Alan (stag-gered)
I have replied to your PM.

Don

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Re: Speedometer glass sealant

Postby stag-gered » Thu Sep 16, 2021 9:01 am

Hi Don,

i have sent another PM relating to the next stage of dismantling.

Thanks,
Alan

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Re: Speedometer glass sealant

Postby don58van » Sat Sep 18, 2021 11:20 am

i have sent another PM relating to the next stage of dismantling.
Reply sent. :)

Don


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