1275 gearbox input shaft oil seal conversion

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moggiegeek
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1275 gearbox input shaft oil seal conversion

Postby moggiegeek » Thu Oct 31, 2019 6:42 pm

While everything is dismantled there is an opportunity to add this conversion. Do people think it's a worthwhile mod?

philthehill
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Re: 1275 gearbox input shaft oil seal conversion

Postby philthehill » Thu Oct 31, 2019 9:28 pm

https://www.moss-europe.co.uk/cover-gea ... soc=405871

At £99 plus I personally would not spend the money.

Only if you park facing down hill does the seal really come into its own as the scroll inside the front gearbox cover does not return the oil to the gearbox when the first motion shaft is not turning.

I have done a similar conversion but using an original front cover for a friend and he seems happy with it.
gearbox front plate 3.JPG
gearbox front plate 3.JPG (1.58 MiB) Viewed 930 times
gearbox front plate 4.JPG
gearbox front plate 4.JPG (1.48 MiB) Viewed 930 times


oliver90owner
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Re: 1275 gearbox input shaft oil seal conversion

Postby oliver90owner » Fri Nov 01, 2019 12:12 am

If you have it apart, why bother with a new cover? It should not cost £95 to have the cover machined. The oil seal will be less than a fiver, I would think.

Visit your local model engineering society and make an offer of a donation to club funds?

Phil,

What swing over the bed is required?

philthehill
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Re: 1275 gearbox input shaft oil seal conversion

Postby philthehill » Fri Nov 01, 2019 7:50 am

The seal used for the conversion was 20mm x 30mm x 4mm and springless and was obtained from Simply Bearings.

The swing of the lathe required is least 8".
The gearbox front cover was secured to the flat face plate and a suitable revolving centre was used to centralise the front gearbox plate.
A small boring bar was then used to open out the front cover to accept the seal. The seal has to be an interference fit in the front cover as there will be no backstop for the seal to seat against.


pgp001
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Re: 1275 gearbox input shaft oil seal conversion

Postby pgp001 » Fri Nov 01, 2019 7:54 am

Moggiegeek

I have sent you a PM with an offer that may be to your advantage.

Phil

moggiegeek
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Re: 1275 gearbox input shaft oil seal conversion

Postby moggiegeek » Fri Nov 01, 2019 8:50 am

Many thanks for the offer. Key question is whether the 1098 and 1275 front plates are identical?

philthehill
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Re: 1275 gearbox input shaft oil seal conversion

Postby philthehill » Fri Nov 01, 2019 8:57 am

The front gearbox plates are not physically the same but for the purpose and process of fitting a lip seal they are the same.


IslipMinor
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Re: 1275 gearbox input shaft oil seal conversion

Postby IslipMinor » Fri Nov 01, 2019 11:56 am

Phil,

I thought that the front cover for all the 'ribcase' gearboxes, 1098 and 1275, has the same part number? I have 22G118 as the part number. If that is not correct, please let me know, as I quite often post this information, believing it to be correct!

The 948 'smoothcase' gearbox front cover was 2A3087, and has been superseded by 22A224.
Richard



philthehill
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Re: 1275 gearbox input shaft oil seal conversion

Postby philthehill » Fri Nov 01, 2019 1:27 pm

Richard
You are correct about the part numbers but when I fitted the seal to the front cover(s) I did find variances in the boss that contains the scroll which meant that I had to machine the front covers slightly differently. If I remember correctly the front covers were made by different casting companies which results in different boss profiles both external and internal around the first motion shaft hole.

The front plates containing the lip seal offered by MOSS/ESM are completely new castings with more metal around the seal housing and which have a back seat/stop for the seal.
Phil


Propshaft
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Re: 1275 gearbox input shaft oil seal conversion

Postby Propshaft » Sat Nov 09, 2019 7:06 am

Can this seal conversion be carried out if you have a smooth case gearbox

philthehill
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Re: 1275 gearbox input shaft oil seal conversion

Postby philthehill » Sat Nov 09, 2019 8:12 am

The answer is yes but you may have to get a machine shop to do the job as there does not appear to be a off the shelf modified front cover available for the 803cc/948cc smooth case gearbox.

Richard
In answering this post and checking against your gearbox parts list/chart - the front gearbox cover being modified by myself and pictured above is marked Pt No: 2A3087 which is not listed on the chart. Your chart lists the front cover for a 948cc smooth case gearbox as 22A224.
The gearbox front cover Pt No: 2A3087 was given to me to modify but I did not see the actual gearbox it was removed from but it was removed from a 'A' Series gearbox.
I have a couple of additional front covers awaiting modification I will check their part numbers.
Last edited by philthehill on Sat Nov 09, 2019 8:34 am, edited 1 time in total.


Propshaft
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Re: 1275 gearbox input shaft oil seal conversion

Postby Propshaft » Sat Nov 09, 2019 8:29 am

Hi I have an myford ml 7 lath which I thing will just about take the casing so I will have look at it next week . Will the seal be the same as stated previously .

philthehill
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Re: 1275 gearbox input shaft oil seal conversion

Postby philthehill » Sat Nov 09, 2019 8:38 am

If your Myford has a gapped bed it should take the front cover. The seal will be 20mm x 30mm x 4mm or 4.5mm. The seal must be a good interference fit into the housing but not tight enough the tear the outer rubber cladding of the seal.
An alternative seal that can be used is 23mm x 35mm x 7mm. The seal used will be determined by the thickness of the metal around the boss being machined. This thickness and shape of metal can vary around the boss as I referred to above.


Propshaft
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Re: 1275 gearbox input shaft oil seal conversion

Postby Propshaft » Sat Nov 09, 2019 1:43 pm

Yes my myford has the gapped bed

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Re: 1275 gearbox input shaft oil seal conversion

Postby Banned User » Sat Nov 09, 2019 1:43 pm

Heathrow Transmissions can supply the modified cover for the smooth case gearbox.

philthehill
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Re: 1275 gearbox input shaft oil seal conversion

Postby philthehill » Sat Nov 09, 2019 2:16 pm

PoolGuy
Thanks for that
https://www.ebay.co.uk/itm/Austin-Heale ... SwOI5dFGvu

The seal appears to be metal cased which means it can be secured in place with Loctite bearing loc.
May be worth getting a replacement seal from Heathrow Transmissions and bore your front cover to suit.



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