I had the idea to replace the needle bearings in the clutch arm with a PTFE bush. I had a second hand arm available and yesterday attempted to remove the bearings. Despite getting it hot the bearings were solid in their housings and I ended up with the needles being driven out and the brittle outer flanges broken off.

So how do you remove a hardened steel bush against a shoulder in a blind hole?

Yesterday afternoon, after many attempts, I had got nowhere; but this morning I had a flash of inspiration. Using a diamond coated needle file I filed two grooves through the bearing outer races...... they are only about 20 thou thick and each groove took about 10 minutes. It was then an easy job to prise out the two halves.

Now I just have to figure out how to hold such an awkward shape to bore out the centre to fit a long PTFE bush.

Paul.

Hi Paul,

Sounds like you got it sorted. There are special slide hammer tools (e.g. from the likes of Sykes Pickavant), which can be fitted with a variety of expanding collars, which have fine machined lips. You place it into the blind hole and when the collar is tightened up, the lips grip behind the bearing. You then use the slide hammer to pull said bearing from the hole.

There are various collar sizes, so one tool can be used for say head bearings and another for wheel bearings and so on.

Mike

Nice work Paul! I'm getting ready to to add a grease fitting to my arm, but this is another very good way to address the problem.


OG

Crazy Frog has an excellent way of removing these bushes, it may also be on the download section.

Thanks UG I'll take a look in downloads...

Coincidentally yesterday, as I was doing an oil & filter service, and once again noticed my gearbox oil had water in it, I've had to remove the clutch arm on my bike. I've known for some time that the culprit was a crack in the rubber boot and as you know the arm's gotta come out to properly remove the boot and spring, and to clean and grease the bearing.

I noticed the pivot shaft was a tight fit and took some effort to remove after the right hand side circlip and washer were removed. The tiny pivot bearings are gunna need replacing but I ride the bike to work daily (no four wheelers in my household) so I got some very fine sandpaper and took the rough spots off the shaft, greased the bearings, filled the new rubber bellows with grease as well and fiddled the entire apparatus back together with all three of my hands whilst lying on my back drinking a stubbie, propped up on one elbow.

I see a retrofitted grease fitting, new shaft and bearings in my immediate future.

Yep, mate that's exactly where I'm at right now with the old girl. Gawd, I miss being able to pop out to the dealer, chat with Jim, and have him overnight some little bit for me so I'm back at it quickly!

OG

I replaced the bushes, but also used a small diamond coated round file to score a groove (very much like we did in bronze bearings back then) on the shaft, which although not deep will retain some grease , also fitted a grease nipple onto the clutch arm, clutch now feels brand new.

I rode my bike into work this AM and although the bearings looked a bit flattened out - they had no lube in them at all - now at least there's some in there and the clutch pull definitely felt lighter and easier. Imagine what it'll be like when it's put back to original! Who needs a new motorbike!?



Just had a look-see on the great computer and BMW Australia don't have the bearings or the shaft in either warehouse, and at $21.36 for each of the two bearings and $38.40 for the "pin" it's not a casual fix for those light of wallet at $81.12 total. Let's see what the boys at 'Bins have to say about the price...

$24.35 plus postage translated from the £ at today's exchange rate. I can wait a week. Someone's smoking something somewhere at BMW Down Under.

"They want what for it?! Tell 'em they're dreaming"
~The Castle

Bought my bearings from a local supplier at half the price of

Bins or Works, but used the same pin.

The 'Bins sell a stainless steel version of the pin for £8/AU$12, the bearings £4.25/AU$6.20 each and since I needed a few bits 'n' bobs anyway I've placed an order, got two new circlips and the adjusting screw/locknut for £5/AU$7 which I noticed was 'dished' where it has been sitting in its adjustment span since time immemorial.

Those Grimeca 'pattern' rear disc brakes at £87.00/AU$127 are a pretty good price too so one of those is on the way. My current aftermarket disc is warbly and verging on paper thin. Metal Gear wants $229/$175 dealer price and I'd have to send 'em my current disc/carrier to get it fitted, two days down time on the bike - no time for that. With the (lately) almighty Aussie dollar at $1.07 US and .68P it's a good time to buy overseas again.

Love the 'Bins!

Nice work, this job's on my list in the next month or so.

BIG D

Hi mike d,

In a perfect world we would all have been given a complete set of Sykes-Pickavant extractors at birth........ but sometimes the fun is in sorting a problem (cheaply?) with the available tools. For the price of a suitable extractor one could buy 4 or 5 new clutch arms!







I drilled out the bearing hole today ready to press in the PTFE bush; I think I'll add a pair of 'O' rings in the bush to keep out all the grunge that collects in that area.

Paul.

Nice Paul! When can I send mine over for a PROPER refit!?


OG

Call in any time you're passing OG......

Paul.

Sounds good mate. Please post a pic or two when you get the arm done. I'm thinking about doing this myself now as the BMW bits are not cheap.

OG

Hi, What is PTFE

Teflon

Polytetraflourethylene to be exact, or teflon as we know it more commonly. It has a low coefficient, therefore is really good on shafts and the like cos its slippery and doesn't corrode.

Good stuff.

Paul,

Nice, does the stuff come in a range of ods or do you turn it down to
fit, then bore the id. I have a little lathe and looks like this is in
my future.

yankeeone,

Yes PTFE comes in various od's. It machines beautifully. I've also used some 'bronze loaded PTFE' in some model engineering jobs. I think the little bushes in our clutch and brake handlebar levers are probably PTFE.

Working on the premise that 'If a job's worth doing......it's worth over-doing' I've revised the pivot pin mounting today. It will now be clamped between the lugs on the gearbox.

Paul.

looks great paul .....

Nice Paul!! Where did you get all your little bits?

OG

A man and his lathe...amazing improvement on a sturdy design, and I thought I'd just be in for a replacement of the torn boot on my clutch release arm. Now I want to take it further like this, but hasn't the original design successfully survived a gazillion kilometres?! I reckon this is way better than a 'better mousetrap'!

But you didn't polish the lever Paul

hmmm who do we know with a lathe .....?

exactly what I having been trying to figure out all day mate!

charlie99 wrote:hmmm who do we know with a lathe .....?

OG I think he is talking about me

Hi Sidecarpaul,

I bet that machine cost more than a puller Looks like a nice piece of kit. I bought a load of BMW special tools (mostly unused and still in their original packaging), the deal included all kinds of pullers from Kukko and Sykes, and measuing instruments - all for £300. The guy was a retired University Engineering professor, who did a lot of investigation work for BMW in the 1970's, and as he no longer needed them he was happy to let the tools go to a good home.

I also hold the BMW Club UK stock of tools that we hire out to club members.

Mike

Very nice job Paul like the lathe, now if its not two cheeky could you tell us the diamentions of the bush I know a man with a lathe

BIG D

Hi mike d, sounds like a super selection of tools. I've also aquired loads of engineering stuff from old engineers who had no more use for them. Been in the UK BM club for 34years.....

BIG D, the dimentions aren't very critical but I drilled the arm out to 14.5mm (that was the first drill I picked up that looked about right), the bush is 48mm long bored 8mm for a standard pivot pin or 10mm for my mod.

K Freak, Now do you really think I would leave it like that? It's going to be painted a pretty gloss black before fitting (to match the swing arm and bevel box that I'm working on) It's nice to have some spares to prepare for future use.

Guest in the house,

yes of course I've been running two K's for over 25 years with the original bearings...... but it's fun to play with these little details.

Paul

Ahh The Castle just about my favourite film. This is one of the areas where I reckon the Dupont Krytox grease would be magic and the other would be the splines possibly with some WS2 mixed in as well.
Regards,
K-BIKE

Hi Paul,

You have been a member of the BMW Club for two years more than me. I'm surprised we haven't met up! I'm off to Midland Section meeting at Towcester in 15 minutes - In the car as the snow fall last night prevents two wheel use.

Mike

Hi Mike,

I'm not very active with the BMW club, more involved with other clubs. Today (snow) would be when an outfit has the advantage, but if I parked my bike somewhere today I might not be able to find it when I returned!

BIG D, just a thought, if you want to try this idea, you could get your 'MAN WITH A LATHE' to turn two PTFE bushes 12mm od x 8mm id x 10mm long and just replace the needle roller bearings, using the stock pivot pin.

Paul.