Triumphrat

snatchpiece · 07-20-2008

I've removed the primary chaincase cover to examine the clutch on my 1959 5TA, I've noticed that whereas the pressure plate is firm, the basket/sprocket has quite alot of play, it's almost as if it's floating, with end float and sideways play, is this correct? (it's my first time with a brit bike clutch).

snatchpiece · 07-20-2008

I've taken it all apart and measured a couple of the rollers and the hub bearing diameter.

Rollers: Dia. = .250" Length = .235"

Hub Bearing Dia. = 1.373" / 1.378"

I am taking the sprocket inner ring into work tomorrow to have the the internal diameter measured. To be honest nothing looks really worn out.

snatchpiece · 07-21-2008

I don't believe there was a thrust washer fitted when I stripped it. I've been onto Tri-Supply web site and they sell two sorts of clutch centres for unit twins, one is for pre-thrust washer models and as my 5TA is an early one I assume it doesn't require one. However how can I be sure that the clutch assembly is original and not a later type replacement?

I've had the internal bore of the inner ring measured in four positions with the following results;
1.8749" 1.8743" 1.8749" 1.875"

This to my reckoning is only going to give 0.001" clearance which I think is acceptable. The inner ring is a nice press fit in the sprocket, it's not loose but neither is it an interference fit.
I'll wait till I receive my hub puller, and once the hub is removed I'll assemble it off the bike to try to understand what caused the wobble, maybe it just wasn't assembled correctly, there is a cupped washer behind the mainshaft nut that should have the cup facing outwards (I believe), and as it fell out when I was stripping the clutch I have no idea which way it was fitted.

GrandPaulZ · 07-21-2008

Are you sure your mainshaft isn't bent?

NHOJ from Maine · 07-21-2008

i'm with grandpaulZ...
could easily be a bent mainshaft..
the way they usually get bent is the primary chain breaks, winds up around the clutch basket and wedges between the chain case and clutch basket, thus tweaking the mainshaft.
happened on my bike.

snatchpiece · 07-21-2008

The mainshaft appears not to be bent, anyhow the free play I'm describing is between the hub and the sprocket and the clutch centre. It appears it could be normal for the early unit clutches, see this post I received on another forum.

"SP -
The key here that no one caught, except John, is the "1959" which used a 4 spring clutch with the lip in the rear of the cush hub. The action you describe is completely NORMAL for a pre-unit clutch. It can lead to a lot of primary chain slop, and additional primary noise. Welcome to 1959 !!

If it really bothers you, simply grind off the lip on the rear of the cush hub and insert 1 extra clutch plate into the basket. Thereafter, the clutch basket will only wobble during disengagement and will pull up tight after engagement like a 3-spring unit construction clutch assy.

Or, the best way is to completely convert over to a modern 3-spring clutch assembly, using only the chainwheel from the original unit."

I'm going to rebuild it as it was, because it seemed to work OK and was not noisy at all, I seem to remember the guy who sold it me saying that the clutch was quieter than was normal on these bikes.

Many thanks to all who have replied,

Mick.