Setting up the double sided front drum

[Db7gtgrigio]

I have checked the archives and cannot find any instructions or tips on setting up the front drum on my 1974 Sport. I have not ridden a bike with a front drum since the Honda H100 I learned on in 1984, and the front brake on my Sport is not confidence inspiring......initially there is little force but then all of a sudden it applies with great force and seems to increase in force. Very hard to modulate compared to the Brembo 08 callipers on my other old Italian bikes (which feel like wood compared to the modern anchors on my Aprilia RSV....)

Can anyone point me to a how to guide to set up the twin sided Grimeca on early Sports please?

[EVguru]

The first thing to do is to strip the backplates to clean the cam spindles and bearings. There's no provision for external lubrication and there can be a lot of friction due to neglect. A water resistant grease would be good here.

The cables need to be nice and smooth and correctly adjusted so that the whiffletree in the splitter box is close to level when the brakes are applied. Clean and lube the splitter box too.

The self servoing effect can be reduced by putting a chamfer on the front edge of the leading shoes.

The brake is really too big. I had one on my Motobi Tornado 650 and it was probably too big for that (The MK1 version even had a duplex TLS version and was recalled in the USA to be retrofitted with the SLS). A contemporary magazine test found that it took several laps of Cadwell to get it up to temperature. A friction material that works better from cold might be an improvement. NLM might have something, or one of the relining specialists.

[pedro]

I obviously agree with all that Paul says, but would just like to add that they can be a very nice brake indeed, mine certainly is. One thing that is absolutely vital is the chamfering of the leading edges, without that you will certainly get the nothing, nothing, brick wall effect.

[Brett]

I have the 1974 Sport and the drum works fantastically, likewise the same drum on my 1974 Benelli Tornado and 1970 Laverda 750GT and all three work well, yes the setting up of them is paramount for effect, but once done they a very good. Also remember there is a greater braking distance required compared to your disc braked bike, this is a challenge in todays traffic.......

I only have one disc/abs braking bike so on that one it always a challenge to remember the gearing, braking and indicators......

Cheers

Brett

[Db7gtgrigio]

Thanks for the helpful suggestions as usual.

I finally got some time to remove the front wheel. The shoes look almost new and had not been chamfered on any edge, so I chamfered all of them with a file. I cleaned and lubricated the cam and the cables and splitter box. I set the brake up by increasing tension on each side until I could discern that the shoes were JUST touching the drum as I rotated the wheel, then backed off the adjuster an 1/8 if a turn.

This gives quite a long travel on the brake handlever, but it does not quite touch the bar when compressed with the bike stationary.

I only had time for a quick spin around the block however initial impressions were of a vast improvement. Brake feels more progressive and has lost that "nothing nothing EVERYTHING" feel...........

Is it usual to have a long travel at the lever with this drum set up. It's been 25 years since I last rode a bike with drum front brake.........