Repairing a Tachometer

[Jkilla71]

My tachometer cable snap yesterday and it was only a month old. I checked the tachometer with a broken piece of cable and the drive is stuck.
I found a DIY and took it apart:
http://members.shaw.ca/randell/Smith/Speedo.html

The bezel came off rather neatly and the instrument came right out of the cup. I tried spraying some WD-40 in and around the shaft and it freed up for 5-10 turns but then it stuck solid again. I then became "chicken " about taking the needle and face off the tachometer so I could get at the shaft so I stopped there last night. I want to buy some small tweezers and some sewing machine size tools and start from there later.

In the meantime I bought a replica tachometer 3003/01 off of ebay for 76.00 so I am not tempted to rush through fixing Smiths one and have to pay someone for my mistakes. I searched the forum for a write-up on these replicas but couldn't find anything, is there any reviews posted anywhere?


http://www.ebay.com/itm/261133900977?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

 

[CarlS]

Re: Tachometer

Good post. I have no experience with the replica's and I have a professional do any rebuilding I need done on Smith clocks.

 

[Rocky]

Re: Tachometer

You're braver than I am to take it apart. It's really a job for an "expert," but good luck.
I don't think the issue of the replica tacho has ever come up here.
Sorry, I don't have any leads for you.

 

[grandpaul]

Re: Tachometer

Get kashif to make you a repair video!

 

[Jkilla71]

Re: Tachometer

From what I have been reading and from what I can see with the tachometer out of the cup it doesn't seem that complicated but some really careful work/patience is needed. I do have a backup plan that if I can't do it with all the information on the internet, I am going to buy "Magnetic Speedometer Repair" By Graham Blighe and lastly there are many companies that rebuild smiths instruments so if all else fails, I will send it out to be fixed but I am confident I will get it working in time.

 

[CarlS]

Re: Tachometer

Please document the repair and post it.

 

[Jkilla71]

Re: Tachometer

Please document the repair and post it.

Let's just hope it doesn't turn into an example of how not to fix your tachometer.

I kind have an added advantage but he is 80 years old and has depleted vision now a days. My old man was an aircraft mechanic/machinist that when not restoring his old aircraft happened to love British bikes, I have seen him tear down and fix many speedometers from triumph motorcycles and cars so I will have a little help with the rest of it and one of the reasons I stopped where I did.
Here are some pictures of where i am at:




From the pictures I have seen of bezels removed online, I am very happy with the condition of my bezel after removal.

 

[The Seeker]

Re: Tachometer

I'm surprised you got the bezel off without the glass cracking or chipping!

The replicas work very well, but the drawback to them is that the bulb is dim and doesn't light them up enough at night to be able to read them very well.



Posted using Tapatalk 2 via my RAZR

 

[Jkilla71]

Re: Tachometer

I used a slightly different method than what I have seen online. I used a very small screw driver but pried very slightly straight down but only the width of the lip on the back never into the side of the bezel and went around the bezel about 75 -100 times in that fashion, i would say on my 30th lap around it came loose so the bezel rotated freely but not until about 30 minutes of this without counting rest breaks until I had it off. I must have pried lightly a couple thousands times total but I saw progress so i didn't get discouraged or impatient and kept at it.

 

[Rocky]

Re: Tachometer

I used a slightly different method than what I have seen online. I used a very small screw driver but pried very slightly straight down but only the width of the lip on the back never into the side of the bezel and went around the bezel about 75 -100 times in that fashion, i would say on my 30th lap around it came loose so the bezel rotated freely but not until about 30 minutes of this without counting rest breaks until I had it off. I must have pried lightly a couple thousands times total but I saw progress so i didn't get discouraged or impatient and kept at it.

Good stuff
Slow but sure wins the race.
Good luck with the rest of it.

 

[CarlS]

Re: Tachometer

Great report and photos. Nice work.

 

[Jkilla71]

Re: Tachometer

My new replica tachometer arrived and I promptly messed it all up and only after 3 beers. The first attempt I made to damage the new tach didn’t work, I took it out of the box and placed it on the table and it rolled off on to the floor but no damage. Then I go out to the garage to install it. The tachometer comes with a 2 wire light installed with a rubber plug, well I wasn’t about to cut the oem one wire light but the hole in the tach’s cup was too small and had an internal lip so the oem light would go in. So in my infinite wisdom I began to file the lip off and make the hole bigger. Yep, I actually created metal shavings inside a magnetic tachometer, not a good combination. I only realized it when I hooked the tach up to the bike and it shot up to 10k rpm and stuck there without hitting the gas. I immediately realized my mistake, so I took the bezel off this one too, it was a lot easier doing the 2[SUP]nd[/SUP] time. I took the tachometer apart and could see metal shavings in the channel of the magnet. I thought about it how to approach it for a while and I tried using a vacuum that I decreased the size of the vacuum hose with a piece of fuel line to suck out the shavings in the channel and it somewhat worked. However, there was still some shavings I couldn’t get at although the needle would drop now but not all the way to zero so I set it down and didn’t look at it again until I came home from work today. Well lying right next to the tachometer on the table was an old post-it note with part numbers written on it so I got the idea to use the sticky part of the post it in the channel and rotated the shaft. When I pulled it out I could see most of the shavings stuck to the post-it so I repeated it 3 more times with fresh sticky parts of post-it notes until I saw no more shavings. I tired the tachometer with a piece of cable and it works again, now I have to figure out how to get the bezel back on. BTW- the replica tachometer has a smaller circumference and the cup is a little taller than the stock tachometer so I can’t make a Frankenstein version.
I am taking the oem tachometer up to my old man’s house on Sunday so hopefully we can get it working.
These are pictures of the replica, I am going to paint the cup again.

 

[otherwise]

A steep learning curve.
Ya won't do that again, well we hope you don't.

 

[Jkilla71]

My most brilliant moments usually begin with me drinking multiply beers and coincidentally all of the broken bones I have had can be directly linked to drinking beer too.

 

[CarlS]

That is a good write up. You humor is great!

 

[Rocky]

Amusing write-up
Good luck

 

[DaveM]

Well I suppose this is how we learn about stuff watching others make the mistakes before we do Although thinking about it I would probably make the same mistake even after reading about it anyway

 

[Rocky]

Well I suppose this is how we learn about stuff watching others make the mistakes before we do Although thinking about it I would probably make the same mistake even after reading about it anyway

Naaaa Dave, we all know you're too clever and too much of g(r)eek to do that

 

[Jkilla71]

I got the replica tach on the bike and it works fine. If you look closely you can see that the tach is taller but it is hard to tell that it is slight smaller circumference



Since the stock tachometer was painted white on the inside I sprayed the inside of the replica cup white before I put it back together and I quickly sanded the outside and threw a couple coats of black to cover the chips I made taking off the bezel.

 

[CarlS]

Very good and nice work. All's well that ends well.