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The tail-in-the-air club (big photo)


azpilot06

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...another one joins.

2uyg50h.jpg

 

Finally got cool enough here, and I finally got sick enough of the slippy clutch, that it was time. She's in half, with her tail in the air.

 

Old clutch disc measuring 4.6-4.8mm...just below service limits. New disc is 6mm, so I guess that 1.2-1.4mm makes all the difference. Apparently that 1.2mm is in finely ground powder at the base of the bike in this photo :eek: .

 

Splines in surprisingly good shape, and no evidence of leakage on engine rear main or trans seals. I'd been thinking I had contamination slippage, since this one had a clutch not too many miles ago. I'm guessing this RT-P did a stint as a trainer before she was retired, and some noob motor transitioning from a Kawasaki just thrashed it riding in the friction-zone.

 

A word to the uninitiated if you're trying this on an RT-P. When you jack up the bike to remove the crash-bar support plate, make sure you re-install the bolts that serve as the forward motion limiters for the centerstand. DAMHIK, but it was almost very messy, and involved me hanging on the the front brake for dear life with one hand, while trying to re-position and actuate the jack with the other hand.

 

Drawing from car experience, when re-using the clutch plates (only replacing the disc), do people usually scuff up the mating surfaces with sandpaper, as one would with a car clutch (assuming one didn't re-machine the flywheel on a car)? The plates are decently glazed, and I'm thinking some 150-grit would be a good idea to knock that off there for the new disc.

 

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Drawing from car experience, when re-using the clutch plates (only replacing the disc), do people usually scuff up the mating surfaces with sandpaper, as one would with a car clutch (assuming one didn't re-machine the flywheel on a car)? The plates are decently glazed, and I'm thinking some 150-grit would be a good idea to knock that off there for the new disc.

 

First off......Welcome to the club :grin:

 

I suppose it wouldn't hurt to scuff up the mating surfaces, but I have never done it with any of my car clutch replacements. I've only done three (1 Subaru and 2 BMW 325's), but I never had any adverse effects.

 

I just replaced the clutch in my '86 BMW 325es last year at about 230k miles. It was still the original as far as I could tell (parts had '85/'86 date codes on them). I didn't even put a NEW disk in it.......I tossed in a used one that I had sitting on the shelf from a car I parted out. Now it shifts good as new.

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azpilot06, obviously a glazed PP or flywheel surface is not an ideal friction surface for the new clutch disk to bed into.. I usually replace all the clutch parts on the BMW oil-heads due to the extensive amount of work required to access the clutch..

 

On other vehicles that I replace the clutch disk “only” on I usually just hit the glazed parts with a Scotch pad & some brake clean to get the greasy crud off,, then do a quick de-glaze using a DA sander & 280 or 360 paper (it takes a few papers as the glazing is hard on the DA paper).. I like to see some sort of original looking surface to properly allow the new disk to seat properly..

 

 

Twisty

 

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I have been turning wrenches on bikes for 29 years. All kinds of bikes Honda, Harley, BSA, Triumph, and Moto Guzzi. After owning this RT for a few short months it is my opinion that the bike was designed to mazimize the amount of money in labor to be extracted from the owner to perform the most routine of tasks. To have to remove the front nose to remove the master cylinder from the handle bar because you have heated grips is crazy.

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I have been turning wrenches on bikes for 29 years. All kinds of bikes Honda, Harley, BSA, Triumph, and Moto Guzzi. After owning this RT for a few short months it is my opinion that the bike was designed to mazimize the amount of money in labor to be extracted from the owner to perform the most routine of tasks. To have to remove the front nose to remove the master cylinder from the handle bar because you have heated grips is crazy.

 

 

Boz, no different than modern automobiles.. The main focus of modern design is not service,, it is cheap easy assembly.. If the manufacturer can save a few cents or save a few steps on quicker or easier assembly that is the direction taken..

If the master cylinder including heated grip goes on before the nose then why design a connector near the grip as that adds nothing to the ease of assembly.. Longer pig tails on the main harness could add to assembly issues or harness handling issues..

 

I know, makes no sense but that is the modern way..

 

Twisty

 

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I have been turning wrenches on bikes for 29 years. All kinds of bikes Honda, Harley, BSA, Triumph, and Moto Guzzi. After owning this RT for a few short months it is my opinion that the bike was designed to mazimize the amount of money in labor to be extracted from the owner to perform the most routine of tasks. To have to remove the front nose to remove the master cylinder from the handle bar because you have heated grips is crazy.

 

With all due respect Boz, the bikes you list are all pretty basic antiquated bikes. If you compare like for like (Honda Pan European, Yam FJ1300, Kawasaki 1400, Gold wing etc), I think it is fair to say they are all pretty major in terms of 'in depth' work.

Have you tried fiddling with the valve shimming on a 1200 Bandit for instance? I think for the most part, general work on the oilhead is a real doddle. However, clutch access is obviously less easy (to say the least), due to the general layout of the bike.

So credit where credit is due. Doing the valves is the easiest bike you have ever done, No?

 

Andy

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That view looks VERY familiar. I was such a great mechanic, my bike was like that for over six months (partly due to the time it took to get the outsourced rebuilt tranny back, and partly because of the home-mechanic).

 

One suggestion, and I KNOW you won't want to do this, but I went ahead and pulled my fly wheel and R&R'd the seals (two, inner and outer). The inner seal was leaking, and the outer seal, though basically intact, was in fact sweating. Getting the seals back in without the special BMW tool took some creativity. I ruined one new inner seal before I figured out how to use a coke can, PVC drain screen/plug, and block of wood to set the seal. Plus, properly torquing the flywheel was unnerving (I couldn't find a wrench with a dial on it, so I created my own to rotate the -new- bolts to the # of degrees past torque required).

 

Anyway, if your RT-P was as abused as my rodeo training bike (my assumption), you won't want to seal that thing back up without replacing those seals.

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Tail in the air club? I'm a member too! From a few years back.

<a href=teardown022emailwg0.jpg' alt='teardown02

 

 

Yeah, I can see why, that BMW looks real sick - its barrels have twisted upwards!

Andy

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  • 4 months later...

So after being a slug all "winter" (it's Arizona...we don't have a proper winter), the tail is out of the area, and we've run our first laps around the block. Now it's time to take care of a few other small items while her dress is still off, and then button back up for the warm weather!

 

For some reason, putting everything back together was -much- less painful than taking everything off! :)

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Clutch and brake are very similar. Some of the friction material diffuses into the steel parts. Your clutch and brake surfaces are much more complex than just glazed. The surface is mixture of clutch and steel. If you keep the same brand of clutch, not really much of an option here, and the glaze is uniform, no cracks , spray with brake cleaner and reuse. The coefficient of friction is really quite high even though they appear glazed. Repeat, no cracks, or heat checking. The clutch is quite close to your feet, if the pressure plate were to explode, it could easily become ugly. Never heard of this happening on a beemer, but I have seen it on a car, and it was NOT pretty. Just ask ole Three Toes Larry.

 

If you want to sand, use garnet paper, supposedly residue from other types of sandpaper is bad, I do not know why. In my opinion, minor grooves are just more surface area. Taper is another story. You can measure the clutch, if the friction material is tapered more than maybe few thou I would replace things. The taper occurs because of the different slip speed between the outside and inside of the disk.

 

If you reuse the pressure plate and flywheel plate, you will need to ride easy for a few hundred miles to let them bed back in. They will not break in nearly instantly like all new. If you have a bit of taper or grooves, the surface area is reduced, If you get it to slipping and keep it there, you will burn it up. after a few hundred miles, you should be good to go, do a higher gear roll on and watch the tach for slippage to be sure.

 

If you feel you can not do all this, just get all new wear parts, the job is too big a PIA to do again.

 

Also, consider replace or renew the brake slave cylinder, or new clutch cable and release bearing Check for oil leaks or renew seals etc.

 

Kinds sounds like the all new camp is the safe route now, doesn't it.

 

Rod

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