ES2 clutch spring length

Hi George, I don't have any singles info but have had spring problems that were down to the gauge of wire being a fraction too big and springs being over tempered. The stiffness of the spring being no guide to the suitability of the part. Try RGM.

Hi George

Just measured my M50 spring length.............1.760" Dia .104" My bike is 1960, slimline so may not be the same as yours, and maybe the 500s had bigger/stronger springs? .............Hope this helps

Regards John O

George, what makes you think your springs may be not of the correct length? are you getting clutch slip? if so, just tighten them a bit (make sure the spring does not become 'coil bound' when you try to disengage the plates).and try to check that the clutch disengages evenly, ie same pressure on each spring.

I fitted a diaphragm clutch and belt drive quite a few years ago, hence I was able to measure my old springs easily, I have no idea how many miles the clutch has on it, but before I changed to a diaphragm type it didn't give any problems.

Regards John O

Year 1948-1949: Spring free length in inches: 1.8 Wire diameter: 0.104

Year 1950-1956: Spring free length in inches:1.781: Wire diameter 0.116

Year 1957 - : Spring free length in inches: 1.781. Wire diameter 0.104

Dominator 650: Spring free length in inches 1.700. Wire diameter 0.116

Previously anthony_curzon wrote:

Year 1948-1949: Spring free length in inches: 1.8 Wire diameter: 0.104

Year 1950-1956: Spring free length in inches:1.781: Wire diameter 0.116

Year 1957 - : Spring free length in inches: 1.781. Wire diameter 0.104

Dominator 650: Spring free length in inches 1.700. Wire diameter 0.116

The data applies to all non-racing bikes post-war up to the first 650 Twins.

The data applies to all non-racing bikes post-war up to the first 650 Twins.

That's a handy bit of info.

Something I have tried in the past to equalize the throwout on the pressure plate is to shim under the bolts. Easy to figure shim thickness by backing off the bolts(which should be fully tightened) til the plate spins evenly when disengaged and translate the tpi of the bolts back into a shim. Hope this makes sense.

Seems like there is enough discrepancy in dimensions of all the components here that even if the springs all measure the same, you don't always get an even throwout and some tweaking may be required.

The source for the clutch spring lengths is from a factory publication.

Thanks Michael. Do you happen to know the tpi of the clutch bolts?

I think they're cycle ie 26 tpi.

A useful mod is to replace the 3 clutch spring studs with the equivalent parts from the AMC clutch. The sleeve nuts (replacing the hex bolts) are not bottomed out so each one can be set individually to achieve even lifting of the plates. Russell Motors can supply them. Easier than faffing around with shims under the bolt heads.

Ian McD

hi george,i agree with ian,on my 55 m7 with the laydown box i changed from the original set up to the amc mod.well worth it,after a bit of tweaking a nice square lift is achieved,no clutch drag now. exchange the screws for the amc studs and nuts,keep the original springs if good, les

Good question. The '57 Instruction Book says to tighten them right home but I'm not convinced as the main advantage of the design is that the sleeve nuts have an anti-rotation "pip" that catches the open end of the spring coil so will not move in service. This means that individual springs can be adjusted so that the plates separate evenly. You end up doing it by feel: tight enough for the clutch not to slip, loose enough to maintain a light action on the clutch lever. From memory mine are tightened so that the studs are protruding just a few threads beyond the top of the sleeve nut. You need a broad screwdriver with a slot filed in the centre of the blade to allow the stud to protrude. Purpose made adjusting tools are available.

Ian McD

I would not bother with the "purpose made tool" these are often made from some sort of metalic cheese. I bought a huge screwdriver for £8 and using the small angle grinder cut a slot in it for the stud. Much better in use and still good as a screwdriver!.