G5 Front Brake

Information relating to the Matchless G5 or AJS Model 8 350cc Lightweight
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timeveritt
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G5 Front Brake

Post by timeveritt »

I've never driven a bike with a single leading shoe front brake before, but I have driven old cars with them so I know they can work. The trouble with the one on my bike is that it doesn't. I've read all the posts that I can find on the subject and the opinions on the front brake vary from "I can lock up the wheel" to "well it sort of slows me down a bit". Mine is definitely in the latter category. To stop the bike quickly from 40mph I need both brakes on as hard as I can get them. The back will eventually lock up, but no way can I get the front to do the same.

On the assumtion that it really should be better than this, to begin with I'm trying to establish that everything is as the manufacturer intended. Even without taking the bake apart, I can see that it's not. See photo. The cable is coming out of the adjuster at quite an angle and rubbing hard against it. Pulling the brake on only makes this worse.
P8170345.JPG
I'm assuming that the brake torque stay is correct?

I'm pretty sure though that the cam operating lever is not, though. It measures 4 1/4" in a straight line from centre to centre. I guess a previous owner thought extra leverage would help, but in fact it's not.

Does anyone know where I can get old of the correct lever? Part no 043274 - I think.
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Rob Harknett
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Re: G5 Front Brake

Post by Rob Harknett »

In theory the longer lever will need less strength to operate the brake. But, look how the cable runs on of line because of this. I do not have a G5 , my G2 CSR has about 3 3/4 " centres on the U shape brake lever. This would make your cable exit better. Your wheel, looks more like a G2, not the same as my G2CSR either. I think you need the correct lever. There's plenty of adjustment let on the cable. You could put thin washers under the brake shoe mushrooms to give more. Your linings and drums have been standing unused ??? They need a very good clean. Even then, first test ride, hold the front brake on, let it wear in until it starts to bite. Do this every time on both brakes if you do not use the bike much.
cbranni
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Re: G5 Front Brake

Post by cbranni »

Two things I can see .....the lever is too long as you said and the torque arm is wrong should have one fixing bolt, so the brake plate is wrong, if you look close enough you still see where the front mudguard stay should be, G5 doesn't have a front stay.......... so front end looks a bit of a mixture, of what I am not sure.

All anchors on :o to slow at 40 sounds about right to me and going down to box to help :D

Cheers Colin
only dead fish go with the flow
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Janet
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Re: G5 Front Brake

Post by Janet »

Rob Harknett wrote: Your wheel, looks more like a G2, not the same as my G2CSR either.
If Timothy's bike is a G5 as he says, the wheel wouldn't look like a 250CSR as the brake is on the opposite side.
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Rob Harknett
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Re: G5 Front Brake

Post by Rob Harknett »

I never checked a G5 as I do not have one, but, the wheel and brake just does not look right. I would had thought the two fixing at the bottom of the torque arm would had been seen as wrong without question. Perhaps the wheel may also be the wrong diameter. The 250 CSR brake is on the opposite side. The brake lever is smaller and no hole, like the lever in question. It may be possible to drill a hole at 3 3/4" centres and grind off the excess, to bodge the lever.
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Janet
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Re: G5 Front Brake

Post by Janet »

Here's a photo showing how one member's front wheel looks.

Image


The brake arm is different, as is the way the cable attaches. As Cbranni says, the G5 mudguard only has one stay. I suspect the front end on your (Tim's) bike has been changed. Apart from upsetting those who demand originality (which I would if I'd paid loads of money in the belief it was, but not if I just wanted the bike as seen) It should be possible that it rides alright but you certainly need to sort out the cable route or the cable will wear.

Whether or not it will stop the bike as you want will only be known when in use. My G2CSR front brake would violently lock up, which I didn't want but some work to chamfer the ends of the shoes soon stopped that and gave me more control. I don't know what bikes you're used to riding but forgive me for the next comment. These bikes will never perform like a modern bike. The brake shoes are quite small so there's not a lot of stopping power anyway, therefore it needs setting up as best it can be. The rear brake is rod operated so a good stomp on the pedal with a big boot can apply a lot of pressure but the front works via a cable which has a tiny amount of stretch* when the lever is pulled. It may help to find someone who knows these bikes to try it and see what they think of the braking power.

*coupled with a potential tiny compression of the cable outer.
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timeveritt
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Re: G5 Front Brake

Post by timeveritt »

Thanks to all for the input so far. At least now I know that I do not seem to have a G5 front brake - though what it is remains to be seen. And I now at least know what it should look like. I'm not trying to make this stop like a modern bike (I already have one of them) but I do want the brake to work as well as it possibly can, so I'm open to any advice. As a start though, does anyone have a correct cam operating lever knocking around that they don't need?

Just to add to my confusion, though the Workshop Manual refers to a "brake torque arm", I can't find any reference to this part in the parts list.
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robcurrie
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Re: G5 Front Brake

Post by robcurrie »

The brake torque arm is the piece of steel that prevents the brake plate from rotating, it also locates your brake cable outer.

Rob C
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Rob Harknett
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Re: G5 Front Brake

Post by Rob Harknett »

timeveritt wrote:Thanks to all for the input so far. At least now I know that I do not seem to have a G5 front brake - though what it is remains to be seen. And I now at least know what it should look like. I'm not trying to make this stop like a modern bike (I already have one of them) but I do want the brake to work as well as it possibly can, so I'm open to any advice. As a start though, does anyone have a correct cam operating lever knocking around that they don't need?

Just to add to my confusion, though the Workshop Manual refers to a "brake torque arm", I can't find any reference to this part in the parts list.
Sadly we are left with only that which has survived. Any errata's which may had only been loose within a parts list book, have been lost. The front hub illustration does not even show where the brake torque arm fits. So no mention of the torque arm, bolt and washer in the parts list.
These parts are within a supplement, but only for the G2CS http://archives.jampot.dk/book/Spares_l ... o.1960.pdf
Yes the brake is on the opposite side on the G5 but perhaps the G2CS parts were left or right hand and used on the G5. Your guess is as good as mine. Unless someone has a supplement parts list or errata. These parts remain a mystery.
Ashampoo_Snap_2016.08.18_18h54m08s_001_.png
Ah well, I guess Janet is cooking dinner, as my wife also named Janet cooks mine, so with nothing better to do before dinner is ready, mystery solved. see part numbers for G5 torque arm , bolt and washer above. Found in a supplement parts list. Opps its a nut, its a bolt on my older bikes
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