Speedo pickup busted

[lemppari]

Anybody ever had the worm gear pickup for the speedo bust? The speedo needle suddenly dropped to zero and I found that the collar of theangled gear had loosened itself so I wound it tight on the roadside, but the speedo stayd dead. Back home I tested it with a drill and yes, it works. So there is only the worm gear pickup left.

 

The importer in Finland advised not to dismantle it for fear of dropping something inside the gearbox, but according to the parts cataloque pictures there shouldn't be any loose parts like shims or whatnot. In the old five speeder, you had that all important small pebble to worry about, but I couldn't see anything like it in the picture of the six-speed gearbox. The thing I'm mostly afraid is wether the rotor has dropped loose in the gearbox.....

[stormsedge]

Anybody ever had the worm gear pickup for the speedo bust? The speedo needle suddenly dropped to zero and I found that the collar of theangled gear had loosened itself so I wound it tight on the roadside, but the speedo stayd dead. Back home I tested it with a drill and yes, it works. So there is only the worm gear pickup left.

 

The importer in Finland advised not to dismantle it for fear of dropping something inside the gearbox, but according to the parts cataloque pictures there shouldn't be any loose parts like shims or whatnot. In the old five speeder, you had that all important small pebble to worry about, but I couldn't see anything like it in the picture of the six-speed gearbox. The thing I'm mostly afraid is wether the rotor has dropped loose in the gearbox.....

 

I had the peened "cap" give way on my RM at just about the century mark, resulting in the up gear on the angle falling out somewhere along a long straight back road in Florida. Ordered a replacement angle gear assembly and replaced it...an easy fix. I think it was $80-90USD. No loose bits to fall inside the gearbox that I remember. k

[lemppari]

I had the peened "cap" give way on my RM at just about the century mark, resulting in the up gear on the angle falling out somewhere along a long straight back road in Florida. Ordered a replacement angle gear assembly and replaced it...an easy fix. I think it was $80-90USD. No loose bits to fall inside the gearbox that I remember. k

The angle gear is intact and working as I tested it using a drill. It's when it is in place screwed tight to the worm gear pickup housing when the speedo doesn't work. I just hope that when half loose, the rectangular pin might have worn out the corresponding slot in the upper end of the worm gear shaft and nothing is loose inside the box.

[lemppari]

Ok,the worm gear pickup works per se. I put the lower shaft from the angle gear in the pickup housing and it rotates evenly and doesn't have excessive play. PHEEW! What a relief! No need to dismantle the gearbox.

 

After inspection I put it all together and did a test run. After 30 metres the speedo needle suddenly dropped to zero again. I measured the height of the lower shaft when dropped into the pickup housing and the depth it needs to sink into the angle gear from below and there it was. It would need a 1.5 mm shim as not to drop so low that it doesn't connect.

 

I have a similar pickup in the whinig gearbox which I took off from the bike, so I could swap the parts, but I still wonder why the importer advised against taking the worm gear off by myself.

[lemppari]

Ok,the worm gear pickup works per se. I put the lower shaft from the angle gear in the pickup housing and it rotates evenly and doesn't have excessive play. PHEEW! What a relief! No need to dismantle the gearbox.

 

After inspection I put it all together and did a test run. After 30 metres the speedo needle suddenly dropped to zero again. I measured the height of the lower shaft when dropped into the pickup housing and the depth it needs to sink into the angle gear from below and there it was. It would need a 1.5 mm shim as not to drop so low that it doesn't connect.

 

I have a similar pickup in the whinig gearbox which I took off from the bike, so I could swap the parts, but I still wonder why the importer advised against taking the worm gear off by myself.

Just found a metal ring from my million-box and it fits as a shim. Now it's the dreaded 50 meter testride once again....

 

EDIT: the first 50 meters went well, until I stopped reversed and turned around. The speedo needle didn't move after that. I stopped, turned around again and the speedo started playing but suddenly dropped to zero again.

 

When tested separately with a drill, the speedo works fine even when suddenly stopped. Driven through the angled gear likewise. Putting the lower shaft in the worm gear housing, I couldn't stop it in any way from moving when the driveshaft revolves.

 

When all these separately working bits are together, see above. Really starts pissing me up, does it!!

[richard100t]

This happened to me a few years ago. I think you may not have your speedo cable housing pointed in the right direction. If its not headed back towards the speedometer I think the cable gear loses contact with the worm gear, causing your problem. I'll send you a pic of how mine looks but you'll have to pm me. The file is too big to post here.

[docc]

Also worth checking is the circular metal plate that is staked into the plastic housing. These tend to loosen then, finally, pop off spitting out the contents as Stormsedge has noted. Best to press them in and epoxy as with JB Weld.

 

There is an identical angle drive on the speedometer end that you should also have a look at. From that end it is easier to extract the cable and be certain it has not become a two-piece unit.

[lemppari]

Also worth checking is the circular metal plate that is staked into the plastic housing. These tend to loosen then, finally, pop off spitting out the contents as Stormsedge has noted. Best to press them in and epoxy as with JB Weld.

 

There is an identical angle drive on the speedometer end that you should also have a look at. From that end it is easier to extract the cable and be certain it has not become a two-piece unit.

Yep, it was just as you said, the plate was out and the worm gears inside had lost contact. Didn't understand it at first because the plate was visible already when I bought the bike. Having gotten accustomed with peculiar solutions made in Mandello, I couldn't see that the plate had protruded some mils more! It's pressed together now and the speedo works again. Thanks for your input! No doubt there will be more peculiarities in the future, but I can always count on getting support and advice here.

[docc]

You're about 100 Euro lucky the thing didn't just spit apart! Time for that coat of epoxy to make it permanent!

[lemppari]

You're about 100 Euro lucky the thing didn't just spit apart! Time for that coat of epoxy to make it permanent!

Rumbling through my things, I found a tube of Super Epoxy which is to be applied liberally on the bottom of the gear casing and basta!