72 SF brake linings

khaal

khaal

New member
Location
Norway
I am trying to find out what the reccomended brake lining thickness is for my 1972 SF. Does anyone know what the factory recommandation is or have other suggestions regarding this?
 
Hi
I had the same question about the thickness  for my 1972 SF and I finally go to 5 mm.
I  hope the new brake pads will arrive next week.
I'll tell you about the result.

Safe riding
 
Khaal, a forum search will probably bring up some relevant stuff. The best bet is to find a reputable brake service place that can bond on and then machine down the excess material to give maximum contact area. You give them the whole wheel with axle, brake plate etc. The type of lining to use may need some research. Piet has his front drum working a treat apparently, he may have some ideas. For best effectiveness all the moving parts need to be good, lubed, adjusted etc.
 
Hi

Received the parts today : the brake is ok  :  :so the right thickness ( for a 1972 Laverda brake ) seems to be 5 mm
The french technical book : lenght 235mm  width 30 and  thickness 5 mm
the green book is wrong that says : 3 mm  :o!!

My question is what is the lenght of the spings ?
Mine seems too smooth and the lever don't comes back to the correct position and the wheel remains locked .....


Good mechanics
 
Just had this issue with my SF2.  When the rear wheel was rotated forward the brake appeared to start to bind (not when rotting backwards).  When I took the brake apart the shoes had two small springs from the shoe to the brake back plate and these did not seem to give a positive return to the shoes.  I fitted two longer springs from each shoe to the other shoe and this was a much stronger return.  Problem solved!

Also, having tried for at least half an hour to get the springs fitted, even with a spring puller i got really fecked off.  Had a little think and come up with a new "tool" which got each spring on in 5 seconds flat!!  Got a 6mm rod and drilled a hole in the end (with a centre drill and lathe) the same width as the spring wire and only a couple of mm deep.  Bent the end of the rod o provide a handle and then put the spring end into the hole.  Using the tool I pushed the spring on to the shoe with minimum fuss - result.
 
I remember the mechanics tip (source was Phil T) of placing washers between the coils.  This can be achieved by bending the spring alternate ways to seperate the coils.
 
haven't done this in a while, but is it not possible to install the springs across the shoes and then install the assembly onto the backplate, using levers etc?, that is how I have done almost all drum braked stuff that I have ever come across, the last being out two tonne box trailer last January, prior to a trip to Italy.
CLEM
 
The shoe return system differs from the 1st series to 2nd series Laverda drum brake, as does the adjustment procedure.

1st series has 2 springs located in the conventional manner between the shoes.  2nd series has only 2 small springs locating the shoes sideways to avoid having them flop around, the actual return spring is on the lever linking rod on the brake plate.  US market bikes had a single spring fitted in the conventional manner in addition to the external return spring.  Incorrect fitment of the 2nd series return spring is very common, with washers and nuts placed incorrectly on the rod.  Sometimes a wonder the brake worked at all!  Not at all harmful to replace said spring after 4 decades... valve and clutch springs have happily been replaced several times by then.  Brakes don't seem to be so important.  ::)

Assembling the 1st series requires a bit of force to spread the shoes over the locating posts, 2nd series is a lot easier.

The Lav drum brakes, especially the 2nd series, have recieved a lot of flak over the years, imho they can be made to work extremely well.  All that is required is attention to detail, ALL slop must be eliminated and decent linings need to be machined exactly to drum dimensions.  Still won't have the fierceness of a double disc, but more than able to handle emercency stopping.  Choice of handlebar lever is critical, the stock late Tomaselli works quite OK.  Condition of operating cables should also be checked regularly, again, no mistake to renew after a while.  Old cables with high internal friction can ruin an otherwise well set up brake.  Oil/grease can disguise shortcomings for a while, a new cable can be a real revelation!  Again, 1000s of $ are often spent on engine and paint work, but old cables re-pressed into service... I see it all the time!

piet
 
My 3c had a poor rear brake with the crazy long cable used for the right side rear brake peddle. I changed to the left side rear brake and it became REALLY powerful with the direct linkage instead of the crossover 1 mitre long cable.
I had a talk with the Eades shop blokes and they gave me a pair of much stronger return springs between the shoes and that tamed it to just reasonably strong. That was the same mod done to Husky rear disc brakes, you used the exhaust header springs that were stronger to reduce the chance of rear brake lockups. Its called The Merryman mod after Kiwk ace Steffen Merryman. Good brakes are important
 
Perhaps you just needed a new cable Vince, not necessarily a shorter one. The rear drum on Tim's 3C with crossover cable works pretty well. It's almost too bloody good - will easily lock the rear wheel with not much pedal pressure. It's way better than the rear disk on my Jota, which needs a lot of foot pressure to squeal the tyre.
 
Highly likely, the left foot gear linkage was flogged out to hell as well, false neutrals were the norm till it went back to a right gear change. The bike was 12 years old by then and I was surprised just how worn out all those links were, shame they didnt get a grease nipal and some grease.So in 12 years, it got enough friction to become a sloppy mess.
 
I know the rear disc on triples has been sorted by my learned friend from Jockland, the one and only Keith (the sweaty) Nairn using some form of Jap master cylinder. I have ridden a Corsa with his recommended, mod done by a local one man classic bike shop on a friends bike, and I was mightily impressed. Well done to you sir Keith and what a gent to freely offer the information to Pat of Viking Motorcycles.

As far as I know a solution has yet to be found for the 180's, I am a willing fabricator/tester if anyone has a plan, that would appear to treble the braking force (on paper) for me to try out in practise. needs to retain standard brake pedal (and quadrant) plus standard disc, but that's about it. Boffins stand up.
CLEM
 
The rear disk brake on my Jota (with the usual rearsets) works as well as it needs to. As I said, it'll squeal the tyre.  It took a bit of re-engineering of the standard components to get it that way though (basically relocation of the M/C and re-jigging of the rearset linkages).

I don't rely heavily on rear brake so it's OK for me. But for anyone who likes wheel locking ability with a light touch of the toe, it would most likely need a different M/C as Clem suggests.
 
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