One of the next jobs to do on my Big4 is to sort out the clutch, the Big4 must have quite a lot of torque so I need to get this right.

I definitely need new springs as mine are badly corroded

I also need the rollers and cage, but will they fit my presumably worn other clutch parts?

Should I replace the cork friction plates or will cleaning them be sufficient? or should I buy modern non cork plates?

Where is the best place to purchase these bits other than Russels who I have never delt with, not having a fax machine.

Rob

email (option): robmiller11(at)yahoo.co.uk

Rob, it's not just the friction material that could be worn on your old plates, there is also the tangs round the edge. Also I have a feeling (but haven't checked) that there should be a steel band round the clutch basket to stop it spreading open?? You're better off phoning Les at Russells rather than fax. Or I can phone him for you as I know him quite well. Maybe you could cross reference parts with 16H as I suspect some are the same.

Ron

email (option): ronpier@talk21.com

Hi Rob...If none of the inserts in the clutch sprocket are loose and the teeth/plate slots are OK wash this out thoroughly with some petrol and leave to dry thoroughly before reuse...
If the metal plates are not worn thin, have reasonable driving tangs, a good surface finish after cleaning and, crucially, are flat, they could be reused after bead blasting.
I would ditch the original cork inserted plates and replace with new bonded ones if available...Likewise with the springs...new ones...
The pressure plate etc. should also be flat and have a good contact surface for the plates...
From your photo it is apparent you have a shock absorber center very similar in construction to the Triumph type...Wear in the component parts of this can result in a sloppy action and excessive movement..I'd have to see that and assemble it to assess it fully...but if it is worn and you can still get the parts I would think towards replacement of this assembly..or at least parts of it..The best thing to do with the rollers is buy them (with a cage) and then fit the clutch together with your other original parts...This will soon determine whether the remaining parts are worn or not.....Ian

email (option): ian@wright52.plus.com

It hadn't occured to me that the big4 had a different clutch to a 16H but looking at two random spare parts lists there are a few different numbers?

clutch sprocket with inserts big4 2271 16H 3337 is there a different number of teeth?

Rob

email (option): robmiller11(at)yahoo.co.uk

As Ian says the Clutch body back cover plate has been worn by the clutch body centre so this brings me to two possible problems

Firstly if the centre can't climb out of this groove will the cush drive actually work?

Secondly will this give too much play causing the clutch to move in and out inside the primary cover?

I could machine flat the worn face which would solve the first problem without it making the second problem any worse?

Any thoughts?

Rob

email (option): robmiller11(at)yahoo.co.uk

Rob, Norton clutch parts are not the biggest problem as they were used across the range and continued post-war on the Laydown gearboxes and even the later AMC pre-Commando clutch shares a number of parts.

Added to this, the clutch was used on the Inters and Manxes and they have a whole industry supporting them.

Biggest difference with the later 'Atlas' clutch is that the drum became plain and the backing plate had bonded friction material. There are also versions with driven friction and driven plain plates. However, provided parts are interchanged as a set, it's not critical.

I didn't know that the WD Big 4 had a different part number - Pre-war and WD 16H all had 3337 and all were 42t - Does the Big 4 M&I manual state different ?

I found Ken McIntosh in NZ very useful on clutches. Paul Norman at 'Racing Norton' has some parts and so do RGM Motors.

In addition, Andover Norton now make complete pre-Commando clutches and sell all parts separately which should mean that you can replace the spider and backing plate with decent quality new stuff (the complete clutch is a bit lumpy, price-wise).

http://www.nortonmotors.de/ANIL/Norton%20Website/norton/price-list.php?criteria=clutch&Submit=Search

The steel band fitted to the WD clutches is only tinplate and simply an oil-exclusion band. The Norton clutch was designed to run dry on the 'Comp' bikes but they then proceeded to design an oilbath chaincase for the road models without any of the complications of good design such as Ariel's system.

If using modern bonded friction material rather than 'Ferodo' inserts, the oil band is not needed as the modern material runs quite happily wet. Incidentally, WD Norton clutches all had Ferodo linings as original. They were never cork.

Thanks Rik

My clutch basket has 42 teeth as does the one shown in the big4 spares list, but that is just a drawing.

The fricion plates also have a different part number, big4 2272 16h 3346, I can only guess the difference is the type of insert used?

I will start shopping around.

Rob

email (option): robmiller11(at)yahoo.co.uk

Rob,

Never found any differences between 16H and B4, so the answer might lie in stronger inserts, different material as you say.

There are other differences in part numbers, that are the same, could also be a marketing thing, that the Army would order "proper" B4 parts, instead of taking them of the 16H shelf.

The illustrated parts lists also show a picture of a 42 toothed basket.

Hope this helps,

Lex

email (option): welbike(at)welbike.net