Clutch and Front Brake Cable Routing

Information relating to the Matchless G12 or AJS Model 31 650cc twin
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Clutch and Front Brake Cable Routing

Postby Chessiegolf » Thu Nov 19, 2020 3:52 pm

On my standard G12, the clutch and front brake cables are routed through the holes in the top yoke, along with the choke and dip switch cables. Is this the correct route? Having just had a solder connection give way on the clutch cable and in extricating the cable it occurred to me that the route puts quite a strain on the ends of the outer cables and perhaps the holes are only there for electrical cables, not bowden cables.

Can anybody comment please, and before I remove the choke cable to check, can someone confirm that the nipple at the handlebar end will pass through the hole. I was going to order a made-up cable from Venhill, then thought that if I do will I be able to get the cable through the hole with the nipple attached.

Thanks in anticipation

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Re: Clutch and Front Brake Cable Routing

Postby cbranni » Thu Nov 19, 2020 6:42 pm

I use the holes for all the cables, control and electrical on my G11 and G12 without issues.

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Re: Clutch and Front Brake Cable Routing

Postby Chessiegolf » Sat Nov 28, 2020 8:59 am

I bought a new clutch cable from AMC Classic Spares and fortunately it came with a slotted barrel so was able to feed the cable through the hole, one problem solved I thought.

The clutch action seemed a little heavier than before (the previous cable was teflon lined) but I went for a ride to see if all was ok. I covered 61 miles and by the time I got home the action was so stiff that I was crashing the gears. I oiled the cable and now it seems a bit lighter but there is a graunchy feel to the action, almost as if I can feel the spiral strands riding over the coils of the outer sheath.

My first plan when the cable failed was to get custom clutch and front brake cables from Venhill but according to their website they are busy and I could be waiting some time.

Has anyone used Venhill 'featherlight' cables and would you recommend them? They are 3 times the price of standard cables but if they live up to the name I would think it money well spent and with winter here now, the lead time wouldn't be such a consideration.

Thanks

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Re: Clutch and Front Brake Cable Routing

Postby clive » Sat Nov 28, 2020 5:19 pm

sounds as though there is a sharp bend in the routing somewhere.
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Re: Clutch and Front Brake Cable Routing

Postby SPRIDDLER » Sat Nov 28, 2020 5:26 pm

I go for efficiency rather than 'correctness' and run the cables in the most sympathetic route for lightness of h/bar lever action.
I can operate my clutch with my little and ring finger which is handy as I need the other two for the brake lever above it.
(The photo shows a feeble brake cable (the top one) which is just the one I had to hand whilst experimenting. Note the bunching of the newly fitted new cable covering at the ferrule where it enters the lever. This is a proper but cheap autojumble brake cable. The cable outer (the conduit) crushes causing binding against the inner wire anywhere there's a bend at any section of the cable, plus lost lever action and a spongy feel at the brake lever. The heavier clutch cable below it is a Venhill one).

K-Lever on Marigold (640x480) Bunching.jpg
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Re: Clutch and Front Brake Cable Routing

Postby Reynard24 » Sun Nov 29, 2020 9:46 am

If clutch operation is that heavy I’d check for correct adjustment and type of the springs and that you are using the correct 7/8” fulcrum levers but having said that, I use Venhill Featherlight clutch cables on all my bikes with the AMC clutch from a G3 up to a G15 and they really do make clutch operation much lighter, even more so than properly oiled standard cables.
I buy their N01-3-105 cables which are slightly longer than standard and the nipple will not fit through the top yoke hole. The extra length means that I fit them through the gap between the headlamp and headstock and route them on the timing side under the tank, this gives a very nice slight curve.
If you have the correct 7/8” fulcrum levers it gives a very light operation but even with the wider 1 1/8” levers the clutch operation is transformed.
They must not be lubricated as this causes the cable to bind in its sheath.

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Re: Clutch and Front Brake Cable Routing

Postby SPRIDDLER » Sun Nov 29, 2020 10:44 am

Reynard24 wrote:If clutch operation is that heavy I’d check for correct adjustment and type of the springs and that you are using the correct 7/8” fulcrum levers

Quite so. Overtightening the clutch springs isn't necessary. I adjust mine as light as I can get away with. You don't have to get kitted up to ride the bike on the road, just test by trying to drive the bike against an immovable stop (tree, brick wall etc.).


I used to run my cables under the tank

Clutch cable under tank (640x480).jpg


This produced a sharp bend at the gearbox

Clutch cable gearbox bend.JPG


It now runs more sympathetically with a bracket at the acorn nut on the rocker box inspection plate.
It's also easier to replace the cable when it fails away from home.

Clutch cable bracket.JPG
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Re: Clutch and Front Brake Cable Routing

Postby g80csp11 » Sun Nov 29, 2020 12:42 pm

Nev , is that your bike indoors ?

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Re: Clutch and Front Brake Cable Routing

Postby SPRIDDLER » Sun Nov 29, 2020 1:07 pm

g80csp11 wrote:Nev , is that your bike indoors ?

I assume you're referring to the fallen Mutchless, Thrifty :?

Yep. Thanks for the offer but my younger sprog came round and put it in the shed, but he had to put strap-on ice spikes on his boots in order to get any grip on the slippery ramp.

Ice spikes.JPG
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Re: Clutch and Front Brake Cable Routing

Postby Chessiegolf » Sun Nov 29, 2020 3:35 pm

Thanks for the suggestions and confirmation that Venhill cables are superior to standard. My box is an AMC one which has the clutch cable inlet angled slightly rearward, the cable then curves quite gently round the rear of the carb intake and up along the frame cross tube, then curves around the headstock, through the hole in the fork yoke and into the clutch lever - to me this all looks good and I wouldn't expect it to cause undue stress on the cable.

The fulcrum is 7/8", so that's one potential trouble spot out of the way. I did think that perhaps the clutch springs are too tight, the whole clutch assembly has been renewed, although the clutch was acceptable before the nipple pulled out and the cable was replaced. It certainly has never been a little and ring finger job though so I will slacken the springs and check for clutch slip using the tree/wall method, that's a very good idea. The surprise was that having replaced the cable the action stiffened up to an unmanageable point within a 61 mile ride. The fulcrum screws on both the brake and clutch are ordinary ones (no shank) so I've ordered proper stainless ones from Acme, that may help slightly as well as being an engineered, rather than bodged, solution.

I will also do more washing up and ironing to earn brownie points and seek approval for Venhill teflon lined cables. Teflon probably wasn't available, or AMC management couldn't justify the cost in 1960, but I see no reason not to use modern solutions to solve old problems.

Thanks again for the suggestions.

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