750 brake lining & axel spacers

gtlsteve

gtlsteve

Full member
Location
Blue Mountains Australia
Been checking the front and rear Laverda drum brakes on the GTL, back works fine the front is a bit average .

Green book has the brake linings at 3mm thick. Now I've checked mine front is 3.5 and the rear is 4.5 mm.

Any idea what the should be?

Also on the wheels what spacers and washers are used and where are they fitted on the front and rear axel. I think I've got something missing. Gap on the back wheel looks wrong.

Steve
 
You want to check amongst other things, the diameter of the actual drum, may need oversize linings after all these years. Oversize linings then turned down to adequate diameter in a lathe.
Paul
 
Steve,

Rear axle should have a washer each side of the LH chain adjuster, then a long spacer to the brake backplate.  RH has a spacer of about 5mm to the inside of the chain adjuster, the large 36mm hollow axle nut bears directly on the chain adjuster and should stand just a little proud of the hollow axle when tightened.  Should be a thick washer under the RH axle nut.  This washer must be able to withstand the tightening pressure or it can deform and damage the end of the dummy axle thread.

The inner of the LH washers is often omitted, (when pulling the axle, it probably rolls across the shop floor and under the bench, never to be seen again!) causing the swingarm to be bent when pulling everything up, but leaves a substantial gap when loosely assembling.  Swingarms done up this way usually need a bit of persuasion to accept the inner washer again.

When fitting new linings, it's ALWAYS a good idea to machine them to a true circle, it would otherwise take decades for them to wear so far that the entire friction surface has contact to the drum.  Most aftermarket brake shoes have enough lining attached to allow for this without reaching wear limits.

Action/performance of the front brake depends largely on brake lever dimensions!  Eliminating slop in the linkages also enhances braking power/feel.

piet
 
Peit
Your on the money, the washer on the inner LH side is missing. Explains the large gap. Lucky I only rode it up the road.

I gather it is just as thick as the outside one 3mm.


I checked the site Paul thanks it shows better break down them the one i am using. Seems the manual I have shows only one washer .

Steve


 
Yes Steve,

Same washer inside and out, part# 33116061.

Andy W. uses the original parts book illustrations.

piet
 
Thanks guys

The front brake drum may need to be machined if I am going ride it any distance. As it is just not up to it.

Does the wheel need to be de spoked to machine it?

Now I just need to find someone in Sydney who can do it.

 
gtlsteve said:
Thanks guys

The front brake drum may need to be machined if I am going ride it any distance. As it is just not up to it.

Does the wheel need to be de spoked to machine it?

Now I just need to find someone in Sydney who can do it.
Click to expand...

When you do find the right person in Sydney to do this could you please let me know, as I have to do a front and rear drum at some stage.  i had been looking through local bike magazines with no joy and asked a couple of people out at the Barry Sheene Festival of Speed, with no joy there either.

Yogi
 
gtlsteve said:
Thanks guys

The front brake drum may need to be machined if I am going ride it any distance. As it is just not up to it.

Does the wheel need to be de spoked to machine it?

Now I just need to find someone in Sydney who can do it.
Click to expand...

If you intend to respoke in the near future, do it first since respoking could pull your drum out of true, needing skimming first; will need checking at least.
Paul
 
Laurie Alderton at Smithfeild or  Chivos at Gradville can do the spoking and maybe the drum machining as well.
Piet are the wheel spacers the same on the 3C rear twin leader spoke wheel,is there any chance you could measure the thickness of these washers and confirm there order.Mine and Marty's appear to be different to what you listed above,its defiantly going to affect the wheel alignment I am doing if its not assembled in the right order or are a different size.
 
Thanks VInce , Will drop in to them on the way to work, let you know what gives.

Ok found the missing washer under the BMW!

Looks like the 2 on the LHS are 17x5mm washers.

Spacers was 46.5mm plus 5mm washer = 51.5 mm from drum hub to chain adjuster.


The one on the RHS is 17x3mm washer.


That lines  with Andys drawing. All good well almost.

Spinning the rear wheel around with the bike on the centre stand, grinding noise coming from I think the sprocket housing/hub .

If it is the two bearings can some one tell me what size they are ?

Hope I can get them local.

Need to get it ready for the Hill End ride in may.






 
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