Drum brake 750 speedometer drive disassembly & noises

[jko_78]

Somewhat unfortunately the simple "new fork seals" turned up some other niggles.
While everything is disassembled I figured I would clean the dirty mess that is is the speedo drive, but the nut securing the assembly is really tight. Since it is brass or something similar in aluminium I don't want to go too crazy.

I can't really imagine why, but before I go furher I figured I'd check if it could be left hand thread before proceeding?

Thanks!

 

[Schurminater]

And tread with caution or this may happen!............all started with a speedo cable issue

You are right to be cautious as if its the same set up as the triples this might happen!

The brass or worm drive gear fitting should be a normal thread ie not left handed.......does certainly pay to keep it clean and regreased as general maintenance.I would if you can't disassemble it just remove the whole assy and clean and repack with fresh grease.......that way you shouldn.t break anything.

 

[Jo]

Hi Jeroen, as Schurminater says it's normal thread. Maybe a little warming up would help.
Here's a pic from Andy Wagners page:

 

[jko_78]

Thanks, that was really quick and helpful! I using a good (thin) ring spanner I was able to carefully loosen it, it helps if you know you're turning the right way around.

Sadly it seems it isn't in great condition though, when greased and re-fitted it still makes krrr----krrr----krrr---- sounds.
Turned out those sounds were hiding noisy wheel bearings -replaced these as well. Cable seems to be a bit heavy turning, lots of sticky grease in there. I'll clean that up and see what it does -hopefully the speedometer itself is still OK...

 

[piranha-bro2]

If you want the best out of your drum brake you'll need to read up a little on set up. At the very least you must centre the backing plate on the axle before tightening the axle. With the wheel elevated spin the wheel and pull on the front brake - this sets the backing plate in a position where the pads are in full contact with the drum. Retain the pressure on the brake lever and tighten the axle. With the wheel back on the ground bounce the front and up and down a few times to setterl everything nicely and do up the pinch bolts.

If linkages and pins are worn you will really need to look at reconditioning the whole assembly - or you'll never get the brake functioning well (and with drum brakes the = safely!)

 

[jko_78]

I hope a new cable and good setup as you described will work -but with high-milage bikes and mechanics it's always a surprise. The hub/brake is not original to the bike (was swapped after my fathers accident) but you never know with old mechanical devices.

Not sure about the speedometer drive -it does make some very light noises but works otherwise. Should it be completely silent & is this a cause of concern (after fixing the cable and/or having the instrument itself checked)?
Here's how it looks prior to cleaning/disassembly and greasing/assembly.
Definately didn't run dry! You can see some wear in the middle I guess.

Edit: forgot to take a photo of the wheel side. Looks pretty much the same, but not nearly as bad as this: https://laverdaforum.com/threads/nd-speedo.105046/page-2

Is this a cause of safety concern? I don't really want to end up with a jammed front wheel.

 

[Paul Marx]

I hope a new cable and good setup as you described will work -but with high-milage bikes and mechanics it's always a surprise. The hub/brake is not original to the bike (was swapped after my fathers accident) but you never know with old mechanical devices.

Not sure about the speedometer drive -it does make some very light noises but works otherwise. Should it be completely silent & is this a cause of concern (after fixing the cable and/or having the instrument itself checked)?
Here's how it looks prior to cleaning/disassembly and greasing/assembly.
Definately didn't run dry! You can see some wear in the middle I guess.

Edit: forgot to take a photo of the wheel side. Looks pretty much the same, but not nearly as bad as this: https://laverdaforum.com/threads/nd-speedo.105046/page-2

Is this a cause of safety concern? I don't really want to end up with a jammed front wheel.
View attachment 103437

No worry.
Paul

 

[sfcpiet]

I hope a new cable and good setup as you described will work -but with high-milage bikes and mechanics it's always a surprise. The hub/brake is not original to the bike (was swapped after my fathers accident) but you never know with old mechanical devices.

Not sure about the speedometer drive -it does make some very light noises but works otherwise. Should it be completely silent & is this a cause of concern (after fixing the cable and/or having the instrument itself checked)?
Here's how it looks prior to cleaning/disassembly and greasing/assembly.
Definately didn't run dry! You can see some wear in the middle I guess.

Edit: forgot to take a photo of the wheel side. Looks pretty much the same, but not nearly as bad as this: https://laverdaforum.com/threads/nd-speedo.105046/page-2

Is this a cause of safety concern? I don't really want to end up with a jammed front wheel.
View attachment 103437

The thrust washers are incorrectly installed. Should be one on either end of the gear! Might be the cause of your noises... I've seen the axle bush literally eaten up by the gear because of an omitted thrust washer.

piet

 

[jko_78]

There are 3 washers at the moment one on the cable side, 2 opposite as seen on the photo -so there should be only 2? Won't it be to loose then?

 

[sfcpiet]

Didn't recognise that under all the muck. A little axial play is of no concern, actually better than risking the gear binding whichwill ruin both gears quickly. The washers should be hardened steel. Thousands of Laverdas have survived just fine with just two washers.

Under forward movement, the gear will bear on the rear washer and stay there, until you push the bike backwards into your garage.

piet

 

[jko_78]

That black muck was another reason for disassembly... I'll remove one of the washers later this week. I also cleaned up the cable yesterday, it was full of similar black sticky goo, when I cleaned it all it, even without lubrication it runs a lot lighter. Looked like there was really old and thick grease in there. The speedometer seems to be fine, fortunately, when I use a small screwdriver to turn it ~20 times or so. Maybe I do have some luck after all! Turns out the revv counter cable was similarly full of this greasy stuff... did that as well.

Thanks for all the info, will update hopefully later this week.

 

[jko_78]

I removed one of the extra washers and re-fitted the wheel -noises are still there. Removed the assembly again, re-fitted the wheel, no more noises so it can only be the speedometer drive causing the krrr-krr-krrr noise. After cleaning out the black goo from the cable and inserting it while slowly turning it there's a resistance spot at around 3/4 length. Will get a new cable.