4 spring clutch shroud (swinging arm)

[Craigy]

Hi guys,

Sorry if this has been asked before.

The shroud that is spot welded onto the clutch has come adrift. Ive checked the parts book and it’s not listed.

Ive been told this part is not. Required but better for it to be in place.

It requires the clutch to be removed as it requires welding back in place - removal and welding are both beyond me.

Does anyone have any info on this? What job the shroud does and what are the implications of it not being in place.

I’ve provided pics for reference.

Many thanks

Craig

[Billybream]

It's a dry clutch, the cover shroud is to prevent oil contamination of the plates, the primary chain uses oil for lubrication and runs through the oil contained within the chain case.
If you are prepared to lube the chain via chain lube through the filler/inspection cap you could get away without the shroud, alot depends on mileage.

[Swarfcut]

 A backyard repair would be to drill the shroud at the spot weld points and plug weld the shroud back onto the basket. A mig weld would be fine, tacking it back in place  in situ with little or no heat distortion. Do the preparation yourself, ask around for someone with a mig. Reckon it could be done with no dismantling, apart from taking out the plates just in case, so an easy fix.

 Swarfy.

 Additional. Make sure the shroud is well away from the clutch lined plates tang slots. Too close and the plates will not be able to move freely, (look for witness marks) so the clutch will drag. Clutch may actually free off better without the shroud. This also applies to the infamous 6 Spring Clutch which also has a shroud. R.I.P.  'Nuff said about that damned device.

[limeyrob]

Yes, clean it up and take it to the local body shop and get them to spot weld it back on.

[JulianS]

I think the "shroud" is about adding strength to the clutch basket. The design is not sealed against oil with or without the shroud.

[Triton Thrasher]

It's a dry clutch, the cover shroud is to prevent oil contamination of the plates

To have a dry clutch, you have to keep oil out of the clutch.  Just telling people “It’s a dry clutch” is not valid engineering.

That tin hoop leaves gaps that let oil in.

[limeyrob]

Without the shroud I would expect the clutch cage to spread out. Its not on the C10-12 which are only about 10hp.

[jhg1958]

I was comparing it to my Triumph T100 clutch. These have a solid outer drum.  This did not keep the oil out. In fact because my clutch was getting sticky when left standing I was advised to clean the oil off the plates. 

It is obvious that the oil level lets the oil in bottom part of the clutch gets so I am not sure if this shield keeps any oil out.

. Tack welding does not smack of strength but then stoping the tangs on the basket bending outwards sounds like a fudge following a bad design. Definitely possible for BSA

John

[JulianS]

The "BSA "4 spring is basically the Triumph pre unit 4 spring which was introduced way back in the 1930s, but with a centre to match the BSA gearbox mainshaft.

[morris]

As an experiment I once tried it without the shroud. It’s useless. It only makes the sticking and slipping worse. Best cure is good quality plates and the right choice of oil.

[muskrat]

G'day Craigy.
As has been said it stops the basket spreading, nothing to do with keeping oil out (for that you need a plunger clutch).
I'd go with Swarfy's method.
A backyard repair would be to drill the shroud at the spot weld points and plug weld the shroud back onto the basket. A mig weld would be fine, tacking it back in place  in situ with little or no heat distortion. Do the preparation yourself, ask around for someone with a mig. Reckon it could be done with no dismantling, apart from taking out the plates just in case, so an easy fix.

Cheers

[Craigy]

G'day Craigy.
As has been said it stops the basket spreading, nothing to do with keeping oil out (for that you need a plunger clutch).
I'd go with Swarfy's method.
A backyard repair would be to drill the shroud at the spot weld points and plug weld the shroud back onto the basket. A mig weld would be fine, tacking it back in place  in situ with little or no heat distortion. Do the preparation yourself, ask around for someone with a mig. Reckon it could be done with no dismantling, apart from taking out the plates just in case, so an easy fix.

Cheers

Thanks very much. That’s the method in going with

[Colsbeeza]

The shroud is tapered down towards the outside where it is spot welded and helps hold the segments from expanding outwards. Presumably the thinking was that as the shroud leaves the oil, most is flung in towards the engine side from the shrouds largest diameter towards the chain. The shroud would also minimise the amount of oil entering the clutch. Note that the time spent in the dip is about 10% of time spent flinging surplus oil. Not a dry clutch, but no doubt has some effect. I note Morris's experience without the shroud.
Col

[berger]

i have a 4 spring for the berger build and it hasn't got a shroud nor any signs of it having one. i have also just seen a 4 spring for sale on evil bay without a shroud and from what i can see it has never had one , i am now very  dot com. what is going on?

[limeyrob]

Odd, my 4 spring clutch has got a shroud.