1981 1200 in Spain

bazzee said:
Is it necessary to use brake fluid in a hydraulic clutch system? The fluid does not need to withstand the heat generated by braking. It may of course be best to use brake fluid to prevent confusion.

Cheers,

bazzee
Click to expand...

I remember the old mother fucker single cylinder car hoist mechanics used to use, I seem to recall they were hydraulically water powered.  https://i.pinimg.com/736x/ec/bf/4f/ecbf4f33bccac698c4f4301a24a02821--album-vintage-old-gas-stations.jpg
 
bazzee said:
Is it necessary to use brake fluid in a hydraulic clutch system? The fluid does not need to withstand the heat generated by braking. It may of course be best to use brake fluid to prevent confusion.

Cheers,

bazzee
Click to expand...

You need to be careful if you want to use something other than brake fluid in your clutch system.

Systems designed for Dot 3, Dot 4 or Dot 5.1 have elastomers (rubber parts) that are compatible with the polyethylene glycol and borate chemicals in the brake fluid. Those elastomers won't be compatible with mineral or silicon based oils. SO it would be unwise to swap to an alternative fluid.

Dot 5 is a silicone based fluid. The seals in a Dot 5 system may be compatible with other oils, but you really should check before assuming it'll be ok. There are various rubber/chemical compatibility charts on the web, such as here http://mykin.com/rubber-chemical-resistance-chart but you need to know exactly what material your seals are made from before you can make an informed choice.

Dot 4 is the default fluid for our old Laverda hydraulic systems. The simplest solution is to use the same fluid in both clutch and brake systems.

Edit:
In an emergency, you could use just about any liquid in either brake or clutch systems. You could piss in it if you can't find anything else. It'll get you home OK.

I recall my (late) brother Bob telling me about a camping trip he and his mates did in an old VW Kombi. They were way out on some remote bush track when the brake system developed a leak. It needed constant topping up to keep it working. They weren't carrying any spare brake fluid but they had a flagon of sweet sherry so they used that. It kept the brakes working well enough to get them a couple of hundred km back home again.
 
Dellortoman said:
I've heard this mentioned before but it seems to me like it can't possibly work if your hydraulic system is in good condition.

Pulling the lever in obviously pushes the MC piston into its bore, closing off the reservoir feed hole and pressurising the system. You now have a closed system with nowhere for air to escape. 

The only way air can get out in the above scenario is via leaks in the system. For it to work at all as a bleeding method, the only leak that's going to be useful is leakage past the MC piston seals. You're relying on air rising to the top of the hydraulic line, entering the MC and leaking past the piston. All a bit haphazard if you ask me. If your MC rubbers are good and there's no leakage back past the piston, you'll achieve nothing.
Click to expand...

"Leakage" is relative; a good hydraulic system in automotive applications is sealed or static only over relatively short periods of time. Whilst the leakage isn't noticeable over short duration applications, over time there is some leakage. Air is compressible whereas the fluid is not. Air under pressure air will eventually find it's way past the MC piston seals and effectively self bleed the system.

A similar example is the storage of wine or champagne that is sealed with a cork. In the short term the seal is adequate, however, the cork is marginally porus and so needs to be kept wet to effect a good seal. If you store (corked) wine upright it goes off and if champagne is stored upright it will go flat in less than a year.. (don't ask how I know ::) )
 
Hi Carlos,

Try to change part 27 in the drawing at the same time.  Pound to a penny, it's failure is the cause of the O-ring failure.

1200b.jpg


P.s  Don't worry too much about the clutch fluid going grey.  It's chain grease getting behind the seal and as Steve Winterton once told me, "They all do that".  IME, it doesn't affect the operation of the clutch.

Others may have another opinion, of course ...  :-X
 
the grey colour eventually turning the fluid black is the degradation of the seals in the system, that's why it also happens in the brake circuit's.
new fluid is quick and cheap to install and boiling fluid which happens because the fluid absobs water over time, is not a pleasant thing to deal with, try braking for Creg Ny Baa after a spirited drop down the steps from kates at maybe 120MPH and the lever comes back to the bar, when your last minute braking is about half done, not nice, 2 or 3 years and change the bleeding stuff (sorry about pun)
CLEM

ps Creg Ny baa is a famous Isle of man corner for those that don't know. Is that anyone reading this?
 
Clem,

As you said, it?s not difficult at all. We?ll see on reassembly!  :'( . Your instructions were fantastic!

In any case, the engine case is a perfect crap trap. Full of sludge, old oil, sand and grease



The rubber cover seems to be intact (now is also clean)


The piston came out easily with compressed air, and hit me in the face in the process. No damage, but full of grease!


It?s a 30mm piston



And yes... the seal is knackered (wrong focus, but can still be seen).



What is the correct size for the oring? 30x3,5? (that?s what it seems to be the old one). I?ll renew the brake fluid (will stick to DOT 4 despite temptations) so it?s not grey anymore.

Thank you all for the help!

 
Just ordered 2 EPDM 30x3,5 orings at a local shop. Will be here on Friday. ?1,5 each. If anybody wants one (or more) let me know ASAP so I can ask for more

Cheers.

Carlos
 
Happy Xmas everybody!

Well. Clutch o?ring is here, assembled easily, and I am going through the pains of adjusting the gearchange. I "think" I?m starting to get a hold of it, following Stevio?s hints and a couple of very helpful threads in the forum, such as:

http://www.laverdaforum.com/forum/index.php/topic,59248.15.html
http://www.laverdaforum.com/forum/index.php/topic,53986.30.html
http://www.laverdaforum.com/forum/index.php/topic,40781.msg52995.html#msg52995
http://www.laverdaforum.com/forum/index.php/topic,40781.15.html

When (if) I get completely desperate, I will post back for help. Main issue right now is that I can go through all gears right now (rear wheel in the air, no oil in engine), but sometimes, I wont be able to shift to second from neutral, and suddenly it will. I am playing with the eccentric bolt. Will see.

However, what has shocked me and wanted to ask you all, is that I seem to be missing the 2 spacers and the o?ring at the shifter. You can see them in this picture:

http://www.laverdamania.net/images/selec3.jpg

They were not there when I took the covers off... and I am wondering if they should be there or not (1981 1200 laverda). I?ve taken measurements from Laverda Paradies, and they seem pretty standard (can?t really measure the thickness).

 
The 'o' ring and outer spacer should sit to the outside of the triangular cover, between the cover and the gear lever.
 
tom3c75 said:
On my 3C:
Washer - OD=22mm, ID=14, thickness = 1.3mm
O-ring (used, approx measurements) - OD = 19mm, ID=14, thickness = 2.6mm.
Click to expand...

Thanks a lot Tom. Got some washers (almost same thickness measure) and got them in. If I put one inside, the cover will not seal against the engine (that is probably the reason why it was not there in the beginning). I got a washer in the outside, and found there is an oring "inside" the gear shaft "channel", so it?s there now.

Sealed the engine, got new oil into it (changed to Motul 5100 15w50) and started it to check for leaks. So far so good! I?ll fill up the clutch circuit tonight, and give it a run tomorrow. I have to say that the engine is a lot more silent with the Motul oil (coming from Elf 20w50 cruise).

With a bit of luck, I?m done!

 
Well.. just a couple more pictures for future reference... clean (spotless) covers, and a bit of polishing...



And



I?ve got a few cracks around the clutch bleeder, but they seem to hold fluid... so I won?t touch them!
 
carlitox33 said:
Thanks a lot Tom. Got some washers (almost same thickness measure) and got them in. If I put one inside, the cover will not seal against the engine (that is probably the reason why it was not there in the beginning).
Click to expand...

Something wrong then... invitation for future problems.

piet
 
Grant said:
The 'o' ring and outer spacer should sit to the outside of the triangular cover, between the cover and the gear lever.
Click to expand...

Grant, should there be an additional washer inside, in addition to the oring and washer (spacer) outside?

Cheers
 
http://www.laverdamania.net/images/selec3.jpg

In the photo the spring plus the adjacent washer should be inside the triangular cover, and as you now have, the 'o' ring and second washer outside, between the triangular cover and the gear lever.
 
carlitox33 said:
Well.. just a couple more pictures for future reference... clean (spotless) covers, and a bit of polishing...



And



I?ve got a few cracks around the clutch bleeder, but they seem to hold fluid... so I won?t touch them!
Click to expand...

Well... they didn?t. For some reason those cracks decided to give way today, just as I was bleeding fluid out of the system; and my bleeder housing is destroyed. In addition, I have two cracks to each side of the bleeder; so it seems my clutch cover has finally died.

I?ve been searching the forum, and found some interesting information (http://www.laverdaforum.com/forum/index.php/topic,67298.0.html)

I understand that the cracks can be soldered, but my biggest concern right now is how can I "repair" in some way the bleeder housing. Any ideas / suggestions?

Cheers.

Carlos
 
You must log in or register to reply here.
Back
Top