Crankshaft/Crankshaft Seals

[bogey]

Hi All,

Decided to do the crank seals on my 500 and am in the process of stripping the engine. When I exposed the end of the cranks I notice there are bushes between the crank and the crank seals. I haven't come across this anywhere before and don't see any reference to these bushes in the parts manual. I put a link in to some photos of the crank ends , one has the bush slid out and the other has the bush still on the crank.

http://s750.photobucket.com/user/bonnyb ... Crankshaft" onclick="window.open(this.href);return false;

Be very grateful for any comments, info or advice on this arrangement.

Regards

B

[jackson.40]

Hi

item 12 on this link,part number 90560-25259 and still available from Yamaha

http://www.rzv500r.net/Tech_docs/47X-PL ... ge_29.html" onclick="window.open(this.href);return false;

Steve

[Speed Freak]

They are not really expensive, if you replace them you have new seals on new bushes = lifetime of the seal should be as new.
Mine are not really worn, but I will replace them because it`s easy and cheap.

And don`t try to pull out the seals without splitting the engine cases.
You have to take off the cylinders to reach all bolts.
If you want to save some money, only open the cylinder base nuts and take off the cylinders as a pair together with the head.
Base gaskets can be reused as they are metal reinforced rubber parts, not paper gaskets.
Clean them and put some -not too much- sealing silicone (three bond 1215) on it like it is in new condition of the seals (you will see the old sealing material on the cylinder base flange).

Advantage: You will only need a new clutch cover gasket
Disadvantage: No possibility for power valve service

[bogey]

Hi Guys,

thanks very much for that, I have heard and read lots about crank seals on here and elsewhere but don't recall mention of these spacers. First thing I did when I noticed them was look at the parts manual on the page with the cranks and no sign of them there. Started to think that this might have been someones way of fixing worn shaft stem on the crank/using newer better seals etc Anyway panic over for now.

Am I right in thinking that these are intended to avoid wear on the crank stem?? Also with all the issues with crank seals what about the joint between the spacer and the crank, is there not an issue with leakage there???

Finally is there a similar arrangement ozone the generator end of the lower crank???

Thanks for all your comments and help.

Regards
B

[tacky1]

Bogey, The sleeves are only on the clutch side of both cranks, The generator side on both cranks run seal to crank.

[Speed Freak]

Only the front crank has a seal on the generator side, the rear crankshaft (on most bikes) has no seal on this side as the crankshaft ends just behind the bearing.
As far as I have the design in mind the collars are pushing the first crank bearing against the crank web when the nut is tightened.
This bearings are also fixed in the crankcase (axial direction) and they are defining the position of the crankshaft in the engine.
All other bearings have no axial fixation, just the press fit which can`t be seen as an axial fixation.

Should be no problem regarding leakage, the tolerances of this parts are so low and the surface is fine, there should be no leakage even without a seal.
You can find the same design on a lot of modern gearbox output shafts (often without a seal, sometimes with an O-ring)

[silverstrom]

These are the lessons I have learned.

Once everything is installed and the primary drive gears are properly torqued there will be no leakage past the collar. If you were to do a leak down test without torqueing the nut it would leak air past the collar. Once you tighten the nut everything seals tight.

Remember to grease the crank seal lips before installing the collar. If you do not use grease the dry seal will quickly wear on the collar and will start to leak air almost immediately.

[Speed Freak]

Did you have this problem already that they strated to leak because they were not lubricated (Yamaha seals)?
I was thinking about this topic today in the train home...

"Modern" car crankshaft seals have the same design with a PTFE sealing lip, there it is forbidden to lubricate them in the mounting process - I don`t know why.
Example is my VW T4, in the official service manual there is a clear difference between the version from 1990-1995 (standard seal) and 1996-2003 (PTFE seal lip).
For the standard seal they say "lubricate it with oil", and "Version with PTFE seal lips: It is not allowed to lubricate the seal, remove the remaining oil from the crankshaft".

Is there any recommendation from Yamaha?

Edit:
http://www.victorreinz.com/EN/Service-D ... spx?region" onclick="window.open(this.href);return false;

[bogey]

Well I didn't have the problem already as such as I didn't do the cranks in one of these bikes before.After fixing a holed piston and putting my bike together and running it, it started reall easy and founded good but using some trannyoil which I reckon was being sucked into the rear right cylinder via the crank seal. Having starting the engine strip down and taking off the primary gears I noticed the spacers and took them out. There is some very light grooves or tracks/marks on the spacers where the seal lips have been wearing on them. The seals themselves actually look fine but I reckon the lip is probably shot and that with the very light scoring on the spacers are cause of the leak.

All tips and advice on rebuilding very welcome.

Regards

B

[silverstrom]

The point I was trying to make is that oil seals should be lubricated during the assembly phase. Otherwise, you have dry rotating parts inside a dry seal. This causes immediate wear of the seal. This applies to not only engine oil seals, but all oil seals, including the gearbox output shaft (drive axle) oil seal.

I have not seen where the RZ500 manual says to lubricate the crank seals, and this I believe is an oversight in the manual. RZ350 manuals and TZR250 manuals specifically say to lubricate the seals.

The RZ500 manual does say you must lubricate the gearbox output shaft seal. I think it is safe to assume that this practice should be employed with all oil seals, as is specifically required in other Yamaha (and other models) repair manuals.

RZ500N manual: Page 3-37 Para 7. "Apply grease to the collar (1) and oil seal lips and install it onto the drive axle."

Look at the photo they show and ask your self if that looks familiar. Why would they insist you lubricate there and not the others?

And yes, I have experience with not lubricating the crank seals. I did an RZ350 engine a couple of years ago and forgot to lubricate the right crank seal before installing the collar/spacer behind the primary gear. I pressure tested before engine start and the cases held 5 PSI for an hour. I tested it again 100 km later and the right crank seal would not hold more than 3 PSI. It would hold 3 PSI just fine, but when I pumped it up to 3.5 PSI suddenly the case pressure dropped to 0 PSI. Lesson learned.

Yamaha crank seals are not modern VW seals.

[Speed Freak]

PTFE does not need oil for lubrication, thats the advantage.
But I also can`t see a reason why it should not be lubricated - there is no harm to the PTFE if you lubricate it with the fluid which it should seal.

But there must be a reason why more or less all big seal suppliers say "don`t lubricate them".
Maybe to protect the "dry" side or the gap between seal lips and dust lip from oil which would accumulate dust?! This would be only valid for the generator side seal.
Can`t find any information about the reason.

Thanks for sharing your experience.
If Yamaha recommends to lubricate them in other service manuals (RD350 YPVS) then it can be seen as a recommendation for the RD500 as they are using the same technology and my question is answered

For output shaft seals it`s again a completely different world, there you need to lubricate the seal as it is a standard seal where the risk is high to destroy it without lubrication while mounting (as we all know, rubber has a high friction coefficient when it is dry).


By the was, here what the supplier says about their seals (direct translation Japanese => English by google translate):
PTFEsealing lip: High temperature · High speed rotary shaft · Low lubrication · Low torque
Double sealing lips: It is possible to seal two kinds of liquid or gas at the same time (2 cycle engine crankshaft, Separation of engine oil and mission oil...)

Sad that I do not have assembly recommendations available from them

[bogey]

Hi Guys,

I can't be certain but I think I recall seeing something in the Yamaha Service Videos about lubricating bearings and seals prior to assembly. Cant remember which video/section or if it referred to cranks but definitely remember something.

Thanks for all the comments.

Looking down the road a bit has anyone any recommendations on things you can do to preserve your crank seals???

One tip given to me was to always turn off the fuel after a run and let bike run out of fuel. This prevents any ethanol laden petrol sitting in the cases and perishing the seals?? Any comments or suggestions on this??



Regards


B