Pre-unit crankcase question...

I was wondering the same thing re: whether you can safely run an engine w/o those.

British Only has them. I think they run about $7 a piece. They aren't really necessary. I only really bother with them when I am reaming cam bushings.

-Shaggy

they were considered surperfluous in the T140's.

(ha!!.. how bout that one Clay!!)

i'm in a similar position so am relying on them not being needed.

when i was thinking of replacing them i was going to try and source an allan heaeded screw; flat head screw in that position is just dumb!

'59 said:

i'm in a similar position so am relying on them not being needed.

when i was thinking of replacing them i was going to try and source an allan heaeded screw; flat head screw in that position is just dumb!

Click to expand...

Someone actually made these at some point in the past. I previously had an engine with allen head screws in it. They weren't generic ones, but specifically made for the application, with the funny tappered heads on them. I don't think they were a one-off, as the rest of the engine was nothing special.

-Shaggy

Thank you, I'll try British Only but if not I think I'm just gonna go without them....

I would have thought that the 8 nuts around the base of the cylinder and the 8 studs/bolts around the cases do a pretty good job of holding the motor together, but I guess they put that screw there for a reason. Overkill? Maybe.

...I have 2 normal Allen screws in my pre unit
bought in a hardware store
you do not need any special screw

What size screw?

I would think they are 1/4"-20

Tony the torch said:

I would think they are 1/4"-20

Click to expand...

Yup, that would do it. The spec from Triumph's inventory on that part is:

E1647 - Screw, 1/4 BSW X 20 X 3/4 crankcase inside boss

That is one of the few, actual Whitworth fasteners found on a pre-unit Triumph. The other common ones are the timing cover screws, primary cover screw, gearbox cover screws, and the one engine case bolt (as opposed to the studs). Just about everything else on the engine (and the bike as a whole) is CEI thread, usually being 26 threads per inch.

The standard US corse thread 1/4 bolt and screws aren't exactly the same as the Whitworth ones (the shape of the thread is a little different), but they work fine. This is the reason that just about every pre-unit engine you see has 1/4" allen head cap screws on it to secure the timing cover.

-Shaggy

I have UNC allens in the timing cover and in the Drive side
only in the gbox I have couple of BSW
Also have couple of BSF on some other parts of the motorcycle.

with taps and dies you can do marvels.

Tony the torch said:

they were considered surperfluous in the T140's.

(ha!!.. how bout that one Clay!!)

Click to expand...

HAHAH, I totally missed this. Superfluous is a pretty good one.

ergo the late responce...