Problems with fitting a replacement PX Mk1 Speedo cable

[wink]

Hi all, I've just fitted a new speedo cable to my PX mk one and I have replaced all the various components.

When fitted from top down (headset first down to hub),  I can turn the cable manually at the bottom of the cable and the speedo works fine, but as soon as I fit the cable into the hub the speedo stops working. Conversely, when fitted from bottom up, the cable turns freely at the headset end, but as soon as I connect it to the actual speedo it doesn't work.

This is driving me around the bend so any help would be very much appreciated.

Thanks in advance

chris 

[sime66]

Mate, I am a bit of a novice myself; would like to help, but don’t want to lead you astray:
I’ve had similar; they are fiddly, a couple of things I’ve found to rectify on a couple of occasions:
1) Try rolling the front wheel back as you put the cable end in the drive, just gently, to ensure its in the square hole and the drive is meshing properly.
2) More likely as you say the drive is working - It might be that your new inner is slightly too short; I have overcome the problem you have by cutting the outer, very slightly, by about 5mm at lower end.
Treat this advice carefully, it’s just things that have worked for me before.

[rab]

Im with sime on this one

[henri]

yep,same answer from me ,have had replacement cables supplied over long before ,as sime said about 5mm, but best to cut 2.5mm twice an try it as ya go, an def remember to pull inner out first ,best tool ive found for job is a dremel with cutting disc,but a junior hacksaws ok,used lightly an squarely ,an dont leave a burr on inside to rub on inner , H

[vespasco]

Edit:

Wrong post?
Eh?
Sorry

[wink]

Hi all,

Well I adjusted the outer cable and the speedo is still not working, I can actually hear/feel the inner moving in the outer cable so I can only assume that the actual speedo is buggered (it was old and untested).

Looks like I'll have to try and get hold of another working mk1 speedo, to test it against. If anyone has got one for sale or that I could borrow then please pm me


Thanks again for the help,

Chris

[sime66]

Things to think about before blaming speedo:
Was your speedo OK before you changed the cable?
You said in your first post that speedo was OK if disconnected at bottom and cable turned manually; has that changed now?
Did you give cable plenty of lube?
Did you change inner and outer?
Have you reinspected the plastic drive?
You’ve definitely got enough inner poking out both ends now?
Maybe your manual turning is strong enough to overcome (combination of?) poor lube/manky outer cable/speedo resistance, and your plastic drive isn’t up to it, or is knackered now?
You can test with a drill, but I’ll let others say if it’s a good idea, or how to do it.

[henri]

that above an the old "kiss" (keep it simple stupid) ,me not you sime, as it can be a bugger to get the plastic clips to engage from the cable to back of speedo, with wiring still attached theres not much room to get a hand in an see it, its poss to push it in an the springiness of clips will hold it ,but not far enuff for them to click into the groove there suppose to ,leaving the inner rotating in space , give the outer a little tug an if it moves down more than a mm it wasnt in proper ,an like sime said earlyier use 1 foot to spin wheel so inner is rotating an will slot into the drive hole in speedo,
you can get a mate to do this ,but its more entertaining just to get em round to watch/film ya trying to contort an do it all yaself ,
there is another option taken by a nameless few (no names=no pack-drill) who get sick of vespa speedo's breaking often, dont fix it an gauge ya speed by the speed the fag clenched in ya teeth (gums in my case)burns down ,an i know thats not just me ,speedo not fag,as theve fessed up on here before , H

[swm]

To test your speedo with a drill is easy enough.

Just put the inner in your drill chuck (not too tight) and give it a quick blip in reverse.

But this will only show that the inner is connected properly at the top and the speedo works.

Same as spinning your wheel will only show that the inner at the bottom is meshed with the drive in your hub.

I did both the above with mine before connecting both ends to test.

It worked ok for about 2 miles ! 

Its a case of making sure that your outer's not too long and all is well in your hub then trial and error I'm afraid.

Mines now on the growing 'jobs to do list'.

It would be nice to have a working speedo but at least its not part of the MOT so it doesn't stop you riding !

[px21]

I had the same trouble with my mk1 speedo  narrowed it down to the drive gear in the hub , it looked ok but must have been worn down on the OD . but be warned i went through a couple of these in a very short period of time ( e bay ) then i got a decent one if i remember rightly from beed speed its worked fine now for over a year .hope you get it sorted soon