C15 - to gasket or not to gasket

[DAVE BRADY]

Hi,

To gasket or not to gasket?  That is the question.
So BSA never fitted a gasket to the inner timing case on the unit singles. Hence they are not supplied in a gasket set yet there are plenty available separately.
Do I replace the home made one or try without?
Who has been successful in keeping the oil in without one?

Dave.

[MadPete]

I vote for not fitting one. if all else fails and one needs better sealing then I would use Hylomar blue, &c. YMMV.

[rhyatt]

Does the non original gasket go between the crankcase and the inner face of the inner gbox cover?
If so, does it /will it affect layshaft and mainshaft end float?

Personally , on my 2 c15s , I only used wellseal and oil stays in on all those boxes faces

Then on both bikes , between outer face of inner box cover and very outer cover , wellseal again.

Remember , the front section of outer cover is part of the breathing and has oil mist in there

[Derek996]

With no gasket I'd recommend Threebond 1215. It is grey and virtually unseen after you've wiped off any excess. It cleans off easily and is far better than Wellseal and Hylomar in my opinion.

[Derek996]

Missed the link to the Threebond product information. Threebond 1215

[DAVE BRADY]

Hi,

The gasket was between the crankcase and inner face of gear box/timing case.
A gasket that compresses to say 15 thou will result in that much increase in end float.  I have managed to get my shims so that I can turn the main shaft by hand with the gasket and screws done up. So no 'feelable' end float.
Now I have to decide to go with a gasket or keep fettling my shims.

Dave.

[DAVE BRADY]

Hi,

I decided to go without a gasket but that meant a lot more 'thinning' of the thrust washers.  I have used two as the thicker ones I have would have taken me until Christmas to get right or and engineer would have been needed.
So now without a gasket and the case tightened up, the shaft is free to rotate with finger and thumb with a barely detectable bit of end float/clearance.
Once some sealant is used it should work out spot on.
I have decided to use 'Permatex Aviation' to seal the joint.

Dave.

[Barnsey]

I was just having the same dilemma myself.  I ordered a gasket having done without last time, but the general consensus seems to be to go without.

[DAVE BRADY]

Hi,

It did take quite a while  to get the shims right.  I have put the gear cluster back in and tightened the screws.  Still a barley perceptible bit of end float so that should be fine.
Just the rest of the primary to do now.

Dave.

[Barnsey]

I watched a video about end float but it was with the engine on a bench and on its side.  Can you check and set the end float with the engine in the bike?  I don't know know how you might attach the DTI, even a magnetic one won't stick to an aluminium block. 

[DAVE BRADY]

Hi,

If you have the primary cover off see if the whole clutch can pulled/pushed in and out. The shaft does not have anything holding it so it can float from side to side.
When the clutch operated it pulls the shaft to wards the left so the shims serve as thrush washers as well.  Otherwise on the timing side with the outer cover off it can be measured using the end of the shaft where the clutch pushrod comes through.
The dial gauge I have is an old analogue one with a spring loaded pointer and the adjustable arm has a 1/4" hole a the end.  I used a 1/4" BSF screw and two nuts. Put one nut on the screw, then the gauge followed by another nut. Use the most convenient screw hole and use the nuts to lock the gauge in the best position. If the clutch is still on then use that to move the shaft otherwise just push and pull the shaft.

Dave.