26 Sept 2023
I got in my 109 yesterday for a Dr appointment, a few miles into the drive I noticed the speedo was not moving. I figured I knew what happened, the input bushing froze up .....again, for the third time.
So today I set out to at least change the busted cable if the bushing wasn't the issue.
First thing was to drop the dash and see if the cable had just fallen off.
No such luck! I put the end of an old inner cable in the input and tried to turn it.. Frozen solid! So I pulled out the speedo and took it in my shed and tore it apart, thinking if I couldn't get it unfrozen I could swap parts from a couple of my spares.
Mine has a trip meter so it is a little more complicated. I/you can get a lot of good information from;
http://triumph.daveola.com/NOTES/Speedo_Repair.pdf I read in many years ago and only screwed up a little. But I got it apart.
The input shaft had near solid paste on it and took some working back and forth to remove from the main frame. I also had to remove 2 brass screws holding it by the mounting flange. You can see the input shaft and main frame in these images.
At first I thought the easy way would be to just swap parts, so I looked at my spares, One wouldn't work at all as it was for a Series 3, so I took apart my other. Here I found another difference, the mounting plate was riveted on not screwed on so I was back to trying to fix my original. I did drill out the rivets to see if I could use that input and to be able to test and find out where mine was binding up.
Access to the back of the rivets;
During dismantling I discovered 2 hairsprings which control the motion of the trip reset and the odo timing. The 2 brass screws are for the mounting plate.
I cleaned the old grease off my original(rt) and compared it to the spare(lf) with flexible grease and did some testing by spinning them both in each others mainframe. I figured that there might be some wear on the original as it kept binding going in and out. I used some 1500 grit sandpaper to clean it up, yet the binding was still there.
The binding was only with the original mainframe. I had to figure out how to sand inside it! What I came up with was wrapping 1500 sandpaper around a small drill bit, putting it in my drill. Then with the drill held firmly in a vise I had 2 hands free to control the speed and the movement of the mainframe. I lightly reamed it, rinsed it with acetone and tried the input shaft. SUCCESS! It spun freely!
I used Phil grease to lube the input shaft. The speedo pdf just calls for light grease.
Then unbeknownst to me came the hard part! Oh, no problem putting the input shaft and mounting flange back on the mainframe. It was those tiny little hairsprings! Remember them?
I tried this way and that and couldn't for the life of me get the first one on, then it took a flier and I didn't see where too. No problem I have a spare, right? My tools were too big and unwieldy. I finally decided I needed something like chopsticks only toothpick sized. I went in the house and got chopsticks and toothpicks. Toothpicks did the job, I was able to hold the spring on the toothpick and set one end, then using another pick I held the end on so I could mess with the hook end. On 1 spring I was able to use the toothpick to set the hooked end, on the other I had to use a dental pick to lift it into place and slide it into the hole with the flat end of the toothpick.
Ok so that was the first one, time for the spare spring,..........wait it doesn't have any springs, different model, I'm screwed.......getting a powerful flashlight I started a search through the crap in my shed looking for a tiny spring........After about 3 min, lo and behold I found it next to my grinding wheel stand. And using my newfound technique with toothpicks I re-installed it. You guys with nice workshops and garages don't know how nice you have it!
In this last image you can barely see the hook end of the spring in the hole by the #7.
Despite my best efforts I got it done. I finished pulling the outer cable and getting the broken end out of the speedo drive and re-installing my spare complete cable. Then put the dash back together, I moved the 109 in the driveway enough to see the needle move.
So I'll see how well I did and how long this one lasts! I'm getting too old to do this.......I'm sore an tired!
