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D7 front brake cam. To grease, or not to grease ?.
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Stoo63
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December 8, 2019 - 4:54 pm
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Absolutely, Spaced smile

'52 D1 direct lighting plunger; '58 Square Four (project); '55 D3 Battery; '59 D1 direct lighting plunger;  '59 Tiger Cub; '60 5TA;  '76 FS1-E '97 Honda Sky SGX50.

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Tezza175
Newark , Notts.
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December 9, 2019 - 3:35 pm
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Hi all,

I have just received and fitted the brake shoes to the front brake plate.

I realised that the existing shoes did not have a chamfer on neither leading or trailing edges, whereas the new ones do.

Hopefully this will aid the braking performance ( providing the leading / trailing edge sequence works okay ).

I have applied the copper grease ( just about see it on the cam ! ).

Also , just for information,  the outer diameter of the pads now measure 5.407 inch ( 137.34 mm). I hope this is sufficient a new pair of shoes.

Finally, I looked on our forum to see if there are torque settings for fixing the fork lower clamp bolts to secure the wheel spindle. 

If not, I will be wary of overtightening them.

20191209_144009.jpg20191209_132458.jpg

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My d7 might be super one day !

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SpacedMarine
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December 9, 2019 - 3:59 pm
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Yes be careful with those bolts and dont do what I did 🤣Screenshot_20191209-155728_Gallery.jpg

What's 7/16 in mm again?

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Tezza175
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December 9, 2019 - 5:07 pm
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I'll try not too !!

My d7 might be super one day !

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Ringting
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March 5, 2020 - 3:44 pm
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Hi folks, just reading through old posts for entertainment and feel I should comment on the idea of cutting back the trailing shoe. My background is in cars and in particular, old ones. An old rear wheel drive car would have 2ls brakes on the front and sls on the back. The brake balance would be around 70pc front, 30pc rear. The rear drums would normally be a little smaller than the front. 

From this it can be deduced that a 2ls brake is about twice as efficient as a sls. So, why? Simply,  Self servo action. That is, the action of the drum rotation pulling the leading shoe in harder and pushing the trailing shoe off.   If you've worked on old cars you'll know that the wear rate of the leading shoe is far greater than the trailing shoe. On a car with hydraulic brakes this is not a problem because the hydraulic wheel cylinder will adjust to the difference. A bantam Has a fixed mechanical cam and shoe anchor so cannot allow for the difference. Therefore there are 2 problems.

1. The trailing shoe is trying to push the actuating cam off.

2. Once the leading shoe has worn down a little, the traling shoe will limit the pressure the cam can exert because it has more lining thickness.

So reducing the length of lining at the cam end of the trailing shoe does make sense in terms of helping it to work to it's best ability. The shorter shoe would have a wear rate more like the leading shoe and wouldn't fight the cam so much in trying to apply the leading shoe.

I very much take the point that deviating from standard on a braking system could land you in a tricky position regarding accident culpability and the modification is very much at your own risk. As a halfway house, simply reducing the thickness of the trailing shoe lining, especially at the cam end by rubbing it down with a course grit paper would allow the leading shoe to act as it should. If the shoes are symetrical then simly switching them around should help improve efficiency. BRAKE DUST SHOULD NOT BE INHALED. WORK OUTSIDE AND WEAR A MASK.

One final note is that brake fade due to heavy use (heat) affects the leading shoe adversely but not the trailing shoe. So you are never going to make a racing brake from a bantam drum.

The above is my opinion and not endorsed by the club.

D1, D14/4, Guzzi LeMans, Triumph Trident 900, Maserati 160 t4. Mk1 Mini Traveller, Berkeley T60.

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NeilB
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March 6, 2020 - 5:15 pm
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Tezza175 said  
Finally, I looked on our forum to see if there are torque settings for fixing the fork lower clamp bolts to secure the wheel spindle. 

If not, I will be wary of overtightening them.

I'll go look in my Haynes in a sec, but I seem to recall it being something low, like 12lb ft? 

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