Wits end ...and past it

Anything related to Lambrettas... ask tech questions, post helpful info, or just read and learn.
nellyboyo
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Fri May 17, 2019 12:47 pm

Well that's a BGM bearing that came with the seal fitted ??? the spring is facing the gearbox ??
I think that's in correctly ?
Ive taken the mesh out of the oil filler plug so its just straight through ...so should be no pressure build up there

nellyboyo
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Fri May 17, 2019 12:54 pm


Muppet
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Fri May 17, 2019 2:05 pm

It looks the right way round but is the inner lip sitting against the inner track as it should; only ask as some seals can be squished going in
im not a complete idiot
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.
s me of the piec s are mis i g

Mrnice71
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Fri May 17, 2019 2:29 pm

Just because its pre-fitted doesn't mean its fitted correctly , buy a new seal & fit it yourself

nellyboyo
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Fri May 17, 2019 3:32 pm

Well, that`ll be about the 4th seal tried ...I used a double lip seal last time on the other MB bearing ....OK , when you fit the seal . does the inner lip sit up or down if that makes sense. I carefully ran my nail around the inner seal to poke it down on one seal , then span the inner race and the lip wanted to sit up ...I then ran a fine pick just inside the lip so the whole thing sat up a little ...I even poured oil into the bearing sitting on the vice and span it a little to see if it held.......
That seal failed.....I took the bearing over to my mate as I was doubting myself at this point and had him fit a seal for me .....which failed again .... That's when I bought the MB type with the seal fitted as my patience was seriously going ......

Bit of a saga I know ...

Mrnice71
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Fri May 17, 2019 5:38 pm

l would speak to Mark as that bearing may use a different seal , the inner lip sits down and some hub bearings can have a sharp leading edge , also are you using seal grease on assembly as a seal fitted dry will quickly fail as the bearing goes tight once the seal is fitted

Warkton Tornado No.1
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Fri May 17, 2019 11:00 pm

Seals usually have a 'smooth' face on the 'outer' side with any information, such as manufacturer & size moulded into it.

The reinforced 'patterned' side is therefore usually on the 'inner' side (along with the spring).

The image posted depicts what appears to be the patterned side. That kind of pattern is the normal convention.

I've never seen a seal like that, so please excuse my ignorance! :oops:

If the seal is correctly sized & fitted, the only thing that occurs to me is that the surface that the seal runs on should be not too smooth (as well as not too rough). The reason is because the surface needs to retain oil to act as a lubricant for the seal lip, which will otherwise fail.

warts
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Sat May 18, 2019 5:52 am

As mentioned, seals should be lubricated before assembly.
The actual sealing lip is very fine and fairly fragile. When I worked at a place that made lip seals, we were told to avoid touching the lip.

Where possible I have always made a seal guide to gently expand the lip over a polished surface to avoid damage going over the possibly sharp or rough leading edge of the shaft. Examine closely the relevant surfaces with a lupe/magnifying glass.
Even a wrap of wide, greased masking tape is better than nothing.
Which raises the question, is the surface on which it bears, polished and concentric? Once they don't work, you have to be meticulous in tracking down the problem. It could be an all but imperceptible burr or nick doing the dirty on you. Or a fairly gross misalignment or eccentricity.
Just because it seems unlikely, does not mean it is impossible.

Should the wear surface be knackered, SKF (maybe others) make Speedi-Sleeve, which is a very thin, snug fitting, replacement wear surface. They allow the original size seal to be fitted. Not cheap, but I never had one fail. Care is needed on installation as they are themselves rather fragile, being very thin.

johnny650
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Sat May 18, 2019 8:30 am

well spotted WT No 1 ;)
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nellyboyo
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Sat May 18, 2019 8:40 am

Well , I agree , I`m annoyed that a pre-fitted bearing seal appears to be the wrong way around ..thats just ridiculous . I`ll look into getting a new rolf seal and some kind of guide to get the innner sealing lip facing downwards .

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