14 replies to this topic

[insultaco]

Hi
I have a M159 Bultaco 350 and have consulted both Haynes and Clymer manuals

Please can anybody give me a tip for removing the following bobbin that has attached itself to the crank, presumably with the O ring that appears to have died inside it?


This bobbin is not mentioned anywhere, but I assume is common as the steps in the crank at this end appear common to more than the 159.

Also, please confirm:

1. Remove bobbin
2. Replace O ring (about an inch in diameter)
3. Replace seals in carrier
4. Replace bobbin
5. Replace weight and re-assemble the rest of it etc..

It's just No 1. I can't find any reference to and am struggling to remove!

Cheers
Mick


 crank2.jpg   672.92K   4 downloads

Edited by insultaco, 15 January 2012 - 03:56 PM.

[Naichuff]

The bobbin you talk about is a wear sleave for the seal to sit on rather than groove the crank Yes there is a small O ring between it and the bearing to seal the sleave and shaft. Cannot remember if there is alip on the outer side against the flywheel as I have not had mine of for along time

[PSchrauber]

The bobbin (Kurbelwellenbüchse) should been removed to replace the the inner O-Ring as you said.

May be you need a gear puller to pull it out.

After intsalling the crank seal it is first possible to mount the bobbin as the outer surface of the bobbin is the running surface of the outer crank seal. How did come the oil seal of the crank seal off if you did not detach the bobbin? As the seal has to slip over the edge of the bobbin it must have been not so easy?

May be it's just some corrosion use some penetrating oil and wait, while attaching a puller small strokes with a small hammer might also help, (no force!). I personal would not try to heat up the shaft of the crank, might change the hardness of the crankshaft.

Edited by PSchrauber, 15 January 2012 - 03:26 PM.

[insultaco]

Hi and thanks for the replies!
I've got gear pullers, but the inside of the bobbin (wear sleave..) has a rounded flange on the outer rim, meaning the pullers have nothing to snag, they just ride over the flange and pop off!
I've tried applying some small heat and also pulling it with soft face grips, but it really is stuck fast and I don't want to over do the heating in case of really screwing it up.

Has the wear sleeve got a smooth internal bore or is in a fixed rotation?

Are there wear sleeves available anywhere? I think this may be the route cause of it eating crank seals.

Thanks again
Mick

[insultaco]

 crank1.jpg   381.13K   3 downloads

I think the O ring must have been put on the outside of the wear sleeve by my mate who fitted them last time. Or they have migrated from inside the sleeve to the outside. Either way, I think they are the glue that is holding it together.

[Naichuff]

Itis just a push on fit straight shaft Thereis two lenths depending if your motor has one or two drive side bearings my 175 has the short one but had an older 250 it had a longer one enquire at In Motion a site sponcer

[PSchrauber]

If your gear puller is fitted with an additional joint it is nearly impossible, If you have a puller with straight arms mounted to a rectangle arm where they can be fixed in a adjustable position it should work as it stucks normally not very much?

May just a little bit of heat or better warming up to get the rubber soft and then turning with a good plier on the edge not the surface for the oil seal?

To the part itself, may be Bultaco UK have them, if not Orlando Calonder should have them, or just refabrication, not a so difficult part to reproduce as it is round and you "only" need a lathe.

[rhinouk]

insultaco, on 15 January 2012 - 03:50 PM, said:

Hi and thanks for the replies!
I've got gear pullers, but the inside of the bobbin (wear sleave..) has a rounded flange on the outer rim, meaning the pullers have nothing to snag, they just ride over the flange and pop off!
I've tried applying some small heat and also pulling it with soft face grips, but it really is stuck fast and I don't want to over do the heating in case of really screwing it up.

Has the wear sleeve got a smooth internal bore or is in a fixed rotation?

Are there wear sleeves available anywhere? I think this may be the route cause of it eating crank seals.

Thanks again
Mick

[rhinouk]

Hi i recently had the same problem on my 151 tried pully extractor etc it would not budge,so took it to local garage who have gas welding kit ran the torch around for only a few seconds and it fell off.
Regards Gary

[B40RT]

PSchrauber, on 15 January 2012 - 04:20 PM, said:

If you have a puller with straight arms mounted to a rectangle arm where they can be fixed in a adjustable position it should work as it stucks normally not very much?

This type I think ?

http://www.google.co...ved=0CF0Q8wIwAA

[PSchrauber]

Yes this is one I believe, I'am not so familiar with the brand,
there are different puller models available, here some others that also will do the job without arms popping off, this one is very study and helpful also in other situations:


This one would do the job getting off any smaller bushes or bobbings from axles too:

[insultaco]

I'm looking at one of these, coupled to my existing pull jig should do the job, £14.99 + VAT from machine mart. Hopefully avoiding the side slip of a two tooth puller as above.

Opinions would be welcome and thanks for all the replies so far!

 puller.jpg   25.66K   4 downloads

[John Collins]

Hi Insultaco

Everyone has given you correct advice re sleeve and seals etc – fit TWO seals back to back when you replace – not the original crap double lipped one.

To get off your sleeve – refrain from heat if possible

Also to save money on a new puller

I would find something with a half circle cut out of it and two holes – difficult to describe – but of you think of the top handlebar clamps on your bulto – ie solid bit of metal with half circle cut out of one side – top flat and two bolt holes going through

If you find two of these ( need to have bigger dia if possible- or get two similar from scrap yard and file ) and then but them around your sleeve and insert the two bots – you will “ trap” the sleeve between them – as long as they are not to wide you can then get your normal puller behind and pull off. You really need the two “half” circles to be as close to outer dia of sleeve as opossible

If the h/bar clam thing sounds complicated –or my description of it – just look around a good hardware dept or BQ for two similar type clamps that can be used to hold a pipe to a wall etc – two of these of approx size will do job, bolted around your sleeve, or if you have access to welder, just cut a small piece of metal pipe in half longways and weld two nuts on each side on each – and then again encase the sleeve and use your normal puller

As others have said make sure you get the correct length sleeve – they do vary – I have loads of s/hands one if you get stuck

[insultaco]

insultaco, on 15 January 2012 - 09:14 PM, said:

I'm looking at one of these, coupled to my existing pull jig should do the job, £14.99 + VAT from machine mart. Hopefully avoiding the side slip of a two tooth puller as above.

Opinions would be welcome and thanks for all the replies so far!

puller.jpg

I got a set of these and the sleeve took pressure all the way the end of the shaft. Clerarly there is a problem here given how "loose" it should be. I got a new sleeve from BultacoUK 30mm long for reference on my M159 1976 325cc Sherpa. This may help others somewhere down the line.

New O ring and seals are now fitted and it sounds much better and "crisper" than before. At least the engine shuts down with the throttle now, which can only help!

Just needs warming up, some oil for the clutch and we're away!

Thanks for the help everybody, much appreciated.

[insultaco]

Hello all

My problem repeated (and has been a constant problem since my original purchase), even with the new wear sleeve, the bike chewed the new O ring up and it started with all the symptoms of blown seals again.

I stripped it down again (now able to do blind fold) and started re-assembly. While I was doing this, I noticed that the gaskets on the inside of the crank seal baskets were well used, so I contacted BultacoUK for a new pair.

The bike had arrived with me 15 months ago as a none starter and no matter what I replaced, renovated, twiddled or buggered about with, I kept having this same old problem with knackered seals and the stuck wear sleeve described earlier in this thread. When I got the bike it had gaskets on the left and the right beneath the crank seal retainers and also had the two sets of O rings left and right. When I ordered the full gasket set I got new everything I needed for the complete engine with a couple of extra bits, as normal when you buy generic gasket kits and so on I went with the re-build and re-re-build and re-re-re-build

The guys at Bultacouk are very knowledgable (like many of you people reading this I have to also state) and when I asked for the new gaskets described above as a one off order, they quite rightly explained that my model didn't have any!

I THINK this is what has been my problem all along, I've been repeating the same mistake made by previous owner(s) who have twice sold it on as a none runner. The gap of around 1/4-1/2mm created by the gasket on the right hand side where the sleeve sits has been preventing a full seal when the wear sleeve is compressed around the inner O ring. I think the hot gasses from the crank bearings have been getting in to the O ring therefore welding it on to the crank with the melted rubber and this has been causing the constant blown seals and stuck wear sleeve.

Time will tell, but this is a lesson on reading things like the manuals carefully and not taking anything you find for granted! If this is what my problem has been all along, then they have been a very expensive set of gaskets that I shouldn't have had on in the first place!

Cheers
Mick