Whilst searching for a supplier of small quantities of 'bronze filled PTFE', I came across a supplier of (new to me) 'glass filled PTFE'.

As this is likely to be a tougher version of plain PTFE, I just had to buy some.

And then, of course, I had to find a use for it, so I thought it would be a good replacement for those needle roller bearings in the clutch operating arm. Some years ago I bored out the clutch arm on the outfit and fitted a long PTFE bush, but the solo still has the needle rollers, so the spare arm to which I fitted these bushes will eventually find it's way on the solo.

A few minutes on the lathe, the material machines beautifully by the way, and I had a pair of bushes to press into the arm.

The bushes are nominally 12 mm OD x 8 mm ID x 10 mm long.



If you don't have any facilities for making such bushes, I've just searched for 'Oilite bronze bushes' and there is a standard size of
 12 mm OD x 8 mm ID x 8 mm long which should be a straight replacement those horrible needle rollers.

Paul.

Which is alright if you can get the buggers out in the first place...

Is the problem with the needle bearing that it is not up to the job or the fact that all the spray from the rear wheel destroys it? I make up a shield from the front of a 5 litre oil can and secure it to the two prongs on the rear mudguard. John

Just cut through them with a diamond needle file and peel the bits out. 

Paul

I am about to embark on a rear end rebuild on the K, up to and including the rear engine seal and clutch and already made out my parts list for what I definitely want to swap out. I put in new bearing in early 2014 and its now failed, about 38k miles on it. I would like it to last a bit longer. Am I right in reading the bush replaces the bearing?

Olaf.

Glass filled bushings?!  Isn't glass abrasive?  Are you sure they are for bushings and not meant for something else?  Granted, the clutch arm doesn't rotate that much, but glass?

I drilled my clutch arm and installed a press in grease fitting so I can give it an annual shot of lube each year.  Didn't even have to remove the arm to do it.

Point-Seven-five wrote:Glass filled bushings?!  Isn't glass abrasive?  Are you sure they are for bushings and not meant for something else?  Granted, the clutch arm doesn't rotate that much, but glass?

They look more like ceramic bushing to me.

A word of warning! If that is PTFE then you would not get me cutting or machining it in any way. 
I have spent my life in aircraft engineering and if there was ever work to be done cutting PTFE then it was done in a chamber with gloves plastic suit and mask on. The problem is that if any fine bits get on you or your clothing they can be dangerous later. If you are a smoker and PTFE dust gets onto your cigarette, then you will be sucking in phosgene gas, a chemical weapon that was used in WW1. 
If you don't believe me then look up PTFE (teflon) and phosgene on Google.

92KK 84WW Olaf wrote:Paul

 Am I right in reading the bush replaces the bearing?

Olaf.

Yes Olaf, the Oilite bushes would just replace the needle rollers, they would be 2 mm shorter but, compared with the bearing surface of the needles, there would still be a greater bearing surface.

Here's the link I found on UK e-bay:-
http://www.ebay.co.uk/itm/Genuine-Oilite-Metric-Plain-Oil-Filled-Sintered-Bronze-Bush-6mm-ID-to-8mm-ID-/222159801082?var=&hash=item33b9c18afa:m:mfjEuACV9NtgJkFZtMT_icg

Paul.

Thanks Sidecar Paul - really useful post.

I have only just bought a pair of replacement clutch arm needle bearings - £12 (from James Sherlock - same price from Motorworks)!! 

At less than half the price (£5.12), I have now ordered a pair of Oilite bushes from your eBay link. I'll fit the Oilite bushes to Heidi and the needle bearing set to Gretel and see what difference it makes to clutch lever effort. 

The problem with the needle bearings does seem to be the lack of greasing ability (once they are fitted) and the fact that they live in one of the worst places on the bike. I will be looking at the option of fitting a grease nipple to the arm as point-seven-five has.

After riding though stop start London traffic 18 months ago, I noticed my clutch was getting quite heavy and making my hand ache .

I removed my clutch actuating arm and removed the shaft.

From the look of it  I doubt it had ever been removed and lubed before.

The shaft and needle bearings were in good condition albeit covered in muck .

Having cleaned and greased everything I now have lovely light clutch action .

I would like to fit a grease nipple/ PTFE bush for a more long term solution, but for now I am happy with it though time will tell.

My bike did not have the side stand retracting cable fitted, so I cut off the cable arm from the actuating arm, and shortened the pin, adding a new circlip groove to keep the pin in place , which makes  it easier to get it out in the future.


Bob

audibob wrote:
From the look of it  I doubt it had ever been removed and lubed before.
The shaft and needle bearings were in good condition albeit covered in muck .
Having cleaned and greased everything I now have lovely light clutch action .

Bob - I suspect that when I get into Heidi's I will find it in a similar condition to how yours was (I expect Sgmayhew did maintenance on Gretel's when she was his...her clutch is certainly much lighter and easier on the hand than Heidi's).

As the cost is relatively low (albeit expensive for what it actually is), I ordered a pair of new needle bearings and the pin & circlip. I hate getting into a job and then find that an essential part is horribly corroded and then having to wait for the required spare to be sent. 

I will look at the condition of the old parts though - if they can go in the ultrasonic bath then get greased up and get a new lease of life, then that is all good for me...for use sometime in the next 25 years (if I can still find them)!

Installing the grease nipple in my bikes was pretty easy.  I got a press-in nipple.  Drilled a hole just big enough to be able to lightly tap it in.  I drilled the hole with the arm in place while the bike was up on the centerstand.

Job takes about 10 minutes and cost about $6, and that included a new drill bit.

You want to keep those bearings running freely.  A slow clutch engagement caused by dragging in those bearings is probably the biggest contributor to clutch wear from a slippy engagement.

sidecar paul wrote:PTFE - an acronym for Polytetrafluoroethylene - is a high molecular weight polymer, one of the most versatile plastic materials known and useful for a large range of products for applications excluded to other materials. Commonly referred to as Teflon - PTFE has extremely low coefficient of friction

Main properties of our range of PTFE sheet, rod and tube are:


          High heat resistance

          High resistance to chemical agents and solvents 
          High anti adhesiveness 
          High dielectric properties 
          Low friction coefficient 
          Non-toxicity
 
PTFE is generally considered a thermoplastic polymer; at 327°C it maintains a very high viscosity, thus requiring particular transformation techniques for manufacturing of finished and semi-finished goods. PTFE can be employed at any temperature from -200°C to +260°C

Other lengths and diameters are also available.




BobT

This is an extract from the data sheet of a plastics engineering company, as a non-toxic material I have no qualms about machining it. 

That is fine then Paul as long as others are aware of the dangers as indicated on many websites that can be accessed using Google.
I'll bet that quote from a plastics engineering company was sales pitch and not a risk assessment fro those who might want to cut or file it.

BobT, have you ever read the MSDS on PTFE?  The only indicated toxicity is from exposure to fumes produced when it is burned.  Symptoms are listed as being similar to grippe(respiratory irritation) and the treatment is listed as moving the victim to fresh air.  Otherwise, it appears to be pretty benign.

Did you happen to work in a union shop in a big organization/company?  My experience indicates that those environments spawn some ridiculously over the top work rules based on "safety". 

There is also a movement afoot, lead by trial lawyers who haven't been able to adequately cash in on people slipping on icy sidewalks, to demonize the use of Teflon cookery.  They are driving a lot of PTFE hysteria in the media right now, setting things up for some big court room paydays.

No unions where I worked, quite the opposite. I was an aircraft engineer in the Royal Air Force for 23 years and then worked in the same role in the MOD. Our remit was to get aircraft back in the air as quickly as possible, but when it came to PTFE or Beryllium, we were very careful. 
If yo go and use a hacksaw on the stuff then dust can get on you or your clothes, the danger is if you smoke or go and cook afterwards, that is when the phosgene gas happens.

In order to release the phosgene you would have to set your clothes on fire which I am pretty sure would probably create a whole new set of health problems for you.  Just be real careful when you are cooking after working with it and don't set yourself on fire to light up a cigarette.  It probably wouldn't be a bad idea to wash your hands before a smoke break either.

http://www.polymerplastics.com/images/msds_sheets/Teflon_PTFE.pdf

The heating becomes relevant in pipework where ptfe tape is regularly used on joints or welding steelwork where it is sometimes used to make a slip joint. High temperatures can be reached in these environments. Site gas and arc welding on pipework carries this risk and BobT is coming from that type of background. We encounter it in our work.