Primary chaincase

[step2534]

 Could someone please tell me the year Triumph Bonnevilles crankcase breathed into the primary chaincase?? Ive read varying reports one said PRIOR to 1969 and the other said AFTER 1970. Thanks a lot

[Revband]

I am not 100% certain on this but if memory serves me correctly it was 1968.
IKBA applies.

[L.A.B.]

It was 1970 model year.

[Rex]

IKBA applies.

Looks like someone uses the RC forum...

[step2534]

Thanks, LAB does that mean from 1970 on?
The reason for asking is ,my 1971  T120 has been re built after the seizure.
I was using 20/50 classic oil with 20/50 in chaincase. I put new plates in the clutch and set it up correctly.
I was told whilst running in to use straight 40 monograde in the engine and change it after 250 miles I did this, now on the first 250 miles eveything fine ,no problems with clutch.
I changed the oil and because a leak had developed on the chaincase I took it off and re sealed it, I didnt touch the clutch or alter the settings.
I then re filled the chaincase with fresh 20/50 measured to 150 cc. after a run the plates werent freeing when it had cooled down.
What I was wondering was if it was possible that the 40 grade had breathed into the chaincase and it was now too thick for the clutch??
But it was OK for the first 250 miles thats what I cant understand, Does that make sense??
Secondly  Why would you have to put a measured amount of oil into a chaincase if its NOT sealed surely the level keeps altering to some extent, also whatever grade you use in the chaincase will alter as the engine breathes into it too some degree anway.
Would that be correct or am I loosing the plot.  Thanks for your replies

[L.A.B.]

does that mean from 1970 on?

Yes, basically if it's got the breather outlet at the rear of the primary case-then there wouldn't normally be any oil seal between the crankcase and primary case.     

I was using 20/50 classic oil with 20/50 in chaincase. I put new plates in the clutch and set it up correctly.
I was told whilst running in to use straight 40 monograde in the engine and change it after 250 miles I did this, now on the first 250 miles eveything fine ,no problems with clutch.

I then re filled the chaincase with fresh 20/50 measured to 150 cc. after a run the plates werent freeing when it had cooled down.
What I was wondering was if it was possible that the 40 grade had breathed into the chaincase and it was now too thick for the clutch??

As the engine breathes through the primary case, the oil mist from the engine would eventually mix with the chaincase oil-so there's not much point using different oils in each. 

But it was OK for the first 250 miles thats what I cant understand, Does that make sense??

No, not really. I can only suggest you remove the plates and clean them.


 

Secondly  Why would you have to put a measured amount of oil into a chaincase if its NOT sealed surely the level keeps altering to some extent

You need to add oil to the primary if it's been drained.  Althouth the two compartments are 'open' at the bearing (and three small level holes) it would still take a while for the engine oil mist to fill the empty primary case back to it's normal oil level-so the primary chain would be running more or less dry for quite a while if the initial fill of oil (150cc) was not added to the primary case. 

[step2534]

 Thanks very much for the reply LAB What you say does make sense. I will clean plates and go back to 20/50 in both engine and primary. Cheers

[L.A.B.]

Also check the clutch pressure plate is lifting properly and that it is lifting squarely (doesn't wobble as it rotates when lifted).

[Gromit]

Also .... I was told by Les Wotsit at Norvil never to put a modern multigrade oil in the chaincase as the wear improving gloop they put in it to make engines run better makes the clutch slip.

Cant do his trick on a late model Triumph as I think they are inextricably linked and the chain case drains back into the crankcase after a certain date.... there is a hole between the two low down to keep the chaincase oil level correct so it runs in whatever you put in the oil tank eventually anyway.
The measuring business filling the chaincase is to make sure there is some in there when you first run around like a maniac following the first start after you change the chainincase oil.

So if you can confirm it does not mix then use automatic gearbox fluid in the chaincase as it has no wear gloop and is made to make ferrodo and cork material clutches stick ... that's wot makes an auto box auto ...lots of them, and lubes gears etc well too . and thinner so you get a little more in the HP dept.

Regards Gromit

must stop answering the question with an epistle

[L.A.B.]

I was told by Les Wotsit at Norvil never to put a modern multigrade oil in the chaincase as the wear improving gloop they put in it to make engines run better makes the clutch slip.

But, thats only half the story, as one wouldn't generally use modern multigrades which contain friction modifiers with wet clutches-and not all modern multigrades do. Most modern motorcycles have wet clutches so 'motorcycle' multigrade oils do not usually contain friction modifiers.

 

there is a hole between the two low down to keep the chaincase oil level correct so it runs in whatever you put in the oil tank eventually anyway.

There are usually three small holes in a horizontal line, however they are hardly any lower then the lowest part of the open D/S bearing.

[rogerwilko]

And always free your clutch up before starting, to avoid that first gear crunch! After a layup anyway.