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Tach Drive on Bugeye

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I was wondering if anyone else has had this problem. It seems that about every 6 months I will be driving and my tach quits. I have replaced the tach drive about three times since I have owned the car for about two years. Are the tach drives from Moss just not made well and is there another source for a better tach drive.
 
How is the drive failing? Are the gears stripping or the drive tang shearing off? If you remove the cable, can you verify the drive is not turning while the engine is running? Maybe the drive is not the true problem, just a symptom of another problem.
Jim
 
When I first bought the car it had a generator on it that did not have a tach drive. I put in the correct generator with the tach drive. The tach it self was frozen so I had it refurbished and everything worked fine and the after awhile it would just quit. I would replace the tach drive and it would work again. I can make the tach move by spinning the wire with my fingers. If I attach the tach drive and try spinning the wire through the tach drive with my fingers it won't move the tach dial so I am sure it is the tach drive. The tach drives I have been using from Moss motors are either made in India or China and just don't last long. I was wondering if anyone new where you could get a rebuilt Smiths one.
 
Can you take the take drive apart to inspect the internal parts, so you can at least figure out the actual failure (are the gears stripping out)? That NOS one would be nice to compare to the Moss one, but it is about twice the price, but if it would fix it, it would be worth it. I still would like to know what the actual failure is, so I would take the adapter apart to check the gears.
 
healeyblue said:
Can you take the take drive apart to inspect the internal parts, so you can at least figure out the actual failure (are the gears stripping out)? That NOS one would be nice to compare to the Moss one, but it is about twice the price, but if it would fix it, it would be worth it. I still would like to know what the actual failure is, so I would take the adapter apart to check the gears.
Click to expand...

Some of the original boxes are bolted together and can be disassembled, others are crimped and can't. The drives usually fail when the gears seize up and eventually strip. This can be caused by the drive being improperly aligned so the cable puts side pressure on the drive or, alternatively, by a lack of lubrication in the drive (I use "lubriplate") I think I'd gamble on a NOS one over a repro, but to be fair, the originals used to fail with regularity as well.
 
Well so far Moss has replaced the tach drives that broke under warranty, so i have ordered another one from them. if it works I will use it for now, but I will keep in mind the NOS one for $140.00. I will let you know when I install the next one from Moss. I know when to shift gears just by the sound of the engine, but I like seeing the tach reving. Thanks for all of the ideas.
 
I went through two separate spates of failed tach-drives. Here's some of what I found:

The repros come with what looks like a tiny dab of plumber's grease inside them. the two halves are not close to flat where they meet. Once they get hot, that little bit of grease liquifies and drips out of the seam and that's it....

I've been using a repro tach-drive off the back of an original Lucas generator for two years now. I took it apart, cleaned it, lapped the two halves on a granite surface plate and then made a thin paper gasket to go between the two halves. I used JD Cornhead grease to lubricate. So far, so good.

Also, the repro generators are suspect with regards to failed tach-drives. If the armature isn't quite the way it should be, it can eat the tach drive in seconds. To their credit, Moss replaced my reproduction generator when I called and explained what I was seeing happen to one tach-drive after another (that they were also replacing) AND when I explained that I didn't want to waste my time/money sending the offending generator back and then wait for the replacement because it was the prime of my driving season, (can drive w/o tach but not generator) they agreed to send the replacement parts after I sent them a couple of digital pics of the failed parts that same day. I was very happy with that resolution.

Also, make sure you don't tighten the big brass nut very much, it needs just enough and no more. If you overdo it, even a good Smiths unit will fail fast.
 
Well I installed a new tach drive from Moss and the tach is up and running again. This tach Drive is made in Taiwan, not India or China so we will see what happens. thanks for all your comments.
 
Well my new tach drive from Taiwan lasted 13 days and then stopped working. I am getting another replacement. I guess I will keep putting on the ones that Moss sends me and hope that I eventually get one that works for a long time.
 
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