Author Topic: Gearbox sprocket oil seal fitting  (Read 1133 times)

Online chaterlea25

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Gearbox sprocket oil seal fitting
« on: 15.09. 2014 23:51 »
Hi All,
Am I the only one who has encountered this problem *????*

Ok so, when I go to fit the circlip after putting the seal in place the circlip will not engage in the groove in the casing
I measured the lip thickness on an old seal at 1.2mm and the new at 1.6mm
I fitted the circlip and measured near enough 1.35mm between circlip and bearing
Previously I have had to file the seal around the perimiter so as it would fit the case
On this one I rubbed  the inner face of the seal on a sheet of abrasive paper until it was a a little over 1.4mm
Even then it took a lot of effort to get the circlip seated properly in the groove all the way round

Perplexed  at this I went to look at a couple of other gearboxes (for rebuild) in the workshop
neither of these two had the circlip properly in place  *eek*
The seal needs to be tight between the bearing and circlip to prevent leaks, so neither of the two would have been anyway oiltight
In the photos the larger gap between the ends of the circlip can be seen when the circlip is fully home

John
1961 Super Rocket
1963 RGS (ongoing)

Offline John D. Edwards

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  • 1961 BSA A10 "Royal Tourist"
Re: Gearbox sprocket oil seal fitting
« Reply #1 on: 16.09. 2014 04:54 »
I have have experienced the same problem you describe.

As you have noted, the currently available replacement seals are too thick to allow the circlip to seat properly in the gearbox recess. I ended up re-using my old seal as it was still pliable and relatively unworn. 

I think some research into available seals from various sources is called for; I am assuming that there might be several makers, but I have no knowledge. I think it's safe to say that if you order a gearbox output seal, there is a strong chance that it will be a problem to fit.

 *sad2*


1961 BSA A10 "Royal Tourist"  F/N: GA7.12981 E/N: DA10 13801

Online Brian

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Re: Gearbox sprocket oil seal fitting
« Reply #2 on: 16.09. 2014 05:44 »
Me too, I can only assume the seals we get are thicker than the originals. I have done the same as you John (Chaterlea), rubbed them down until they fit and used a bit of sealer on the back when I installed them.

I wonder if it would be possible to get a seal that was the correct od and do away with the circlip, must have a look at that next time.

Offline duTch

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Re: Gearbox sprocket oil seal fitting
« Reply #3 on: 16.09. 2014 10:05 »

Yep- if I recall,I had a similar, and (think I..)did the same as J.D.E.,and sealed it with three-bond, seems ok-ish but also think the O.D. of the flange of the replacement was a bit tight/bigger, so didn't use it- pending analysis, like now *smile*

 I think the difference is that the original seals didn't have the 'rubber' under the flange as the replacements do...just plain metal..?? I'll know when I pull it out again....!..
 Having said that, I was playing with my other box recently -(yeah, I know!!!), and the replacement seal went straight in...(OD-wise)
 Also, unless you use same circlips, it's hard to find (in Oz- well where i am!) imperial size circlips.
When I was at the bearing/seal shop, I asked about Holden front hub seals, and they are fairly close, but have a 'prolapsed bit' that needs slicing off....!! have a Part# somewhere....

Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

Online bsa-bill

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Re: Gearbox sprocket oil seal fitting
« Reply #4 on: 16.09. 2014 13:42 »
yep had that too, in my case the seal was a tad to large (diameter) and would not go in far enough so kept the circlip from getting into the groove.
Ground a bit off from around the circumference and all was well
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online chaterlea25

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Re: Gearbox sprocket oil seal fitting
« Reply #5 on: 16.09. 2014 20:13 »
Hi All,
Thanks for the replies,
It feels better to know I,m not all alone with this  *problem*
One gearbox finished and only four more to go  *eek*

 *beer*
John
1961 Super Rocket
1963 RGS (ongoing)

Offline Zander

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Re: Gearbox sprocket oil seal fitting
« Reply #6 on: 02.04. 2017 10:48 »
I've just fitted a new seal, but having had the bike on the centre stand with all gearbox surfaces clean and dry it looks like the oil leak may be from the casing joint face, so I reckon it'll have to come out to sort it. Naturally, I'll be checking over the internals while it's off, but I was hoping to get away with just the main seal. 
'59 GF