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Rebuild Speedometer & Tachometer - mechanical or electronic?

Magyar

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I need to do something with my speedometer and tachometer in the 62 Sprite. The Sprite is not original, nor a “show” car, just a fun little ride. It does still have the generator “looks” mostly original under the hood. I’m trying to decide, in the process of having the gauges refurbished, do I update the speedo and tach to electronic or keep them mechanical? What are the pros and cons of each? I’m leaning towards updating to electronic so I’m not needed to deal with the cables. However, I do like to keep things as original as possible. Any thoughts, comments, or suggestion are welcome.

Thanks, Magyar
 

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Yoda
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I rebuilt... or, more correctly, fully cleaned up the tachometer on my Bugeye. There is a thread here about it (with pics). > Tachometer seize? <
I do like the idea of updating with electronics and even possibly keeping the existing face (though I've seen some nice modern ones posted here somewhere).
 
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Take a look at the BugeyeGuys web sight if you are thinking about electronic.
 

Desert Rat

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The electric gauges are nice and I can’t say anything bad about them but they’re not my thing, I’ve got a soft sport for the originals.
I have all my gauges restored by West Valley Instrument Specialists in Los Angeles and they’re awesome, no needle bounce, accurate, and I’ve never had to worry about them.
 

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Yoda
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My repairs allowed for any needle-bounce to stop (on the tach). Haven't tried pulling the speedo.
 

Desert Rat

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My repairs allowed for any needle-bounce to stop (on the tach). Haven't tried pulling the speedo.
I considered doing mine but all my gauges were in some stage of inaccuracy so I had them all done at the same time.
I’ve got a BJ8 speedometer on my workbench that I’m going to try my hand in rebuilding.
 

Pythias

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When I went to the 5 speed (Datsun) I had the gear drive made (well Paul A. did anyway) for the tire and wheel combo I was running at the time. I later changed the rear end from the 4.22 to the 3.9. That threw off the speedo and the tach. Changing wheels seems to have thrown it of even more. In fact, the speedometer and the odometer were off by DIFFERENT amounts, one by ~15% and the other by about ~20%. I got tired of having to calculate my speed by looking at the tach, which, by the way, varied it's readings depending upon the ambient temperature and would change as the car warmed up under the dash.

I went with tach and speedo from bugeyeguy and haven't looked back. (also got his programmable gas gauge and have it set to read empty at about 5 gallons of use)
 

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Yoda
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In my own case, Paul Assgerson had a speedometer gear drive made up for a 3.9 differential... and is SPOT ON (comparing with the GPS app on my phone). He could be rather secretive about certain things, and I'm pretty sure he had a local shop make it for my diff and wheel size (likely at the old Speedometer Repair in NW Portland).

Remembering Paul, he had the most cluttered (packed) garage out-building in north Portland (just a few feet away from his house). I was there on two or three occasions and marveled at all the stuff in there. Paul was "old school" - could be a little grumpy but a good guy that used simple methods for everything. Bill, I remember you telling me of his method of enlarging the tunnel: stick a broom-stick in there and let is flail around. LOL [I didn't do that. :smile: ]
 

Pythias

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Yes, he had it done at the Speedo shop in NW Portland.. .. They stopped doing it for him in his last couple of years of business and he was looking for someone else.

Part of my problem has been getting tires. 175/70 13s are generally only available for mini vans and as such they are not "performance" tires, but utility ones. The shoulders are too square and they aren't sticky. .. .. I ordered Pirelli CN36 from Longstone Tyre and had them shipped from England, but they are available now in the states. . Changing tire brands changes the outer diameter. .. If you recall, Paul actually measured rolling distance on the ground when it was time or order the angle drive. ..

By the way, before he passed I had an extra speedo cable made up,.. you know metric on one end and imperial on the other to fit the Datsun to Smiths conversion.. .. let me know if you need one.
 

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Yoda
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Thanks.
 

svtmikey

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I personally am tired of screwing around with mechanical gauges and decided to go straight electronic. Mechanical gauge drives are a pain in a butt. Electronic are way more accurate and adjustable , look just as good, actually pretty much the same, except my existing ones have Black bezels and these are chrome, but I'll just swap them out.
As much as I like to work on the car, I also like to drive it and autocross it, whenever that comes back, and I have a bunch of other cars that I have to work on. Tired of the GT6 being on the lift so I have been upgrading everything I can, like getting rid of the roto-flex coupling and putting CV joints, aluminum radiator, Mikuni Carbs (Highly recommended), and a bunch more stuff. Next will be a 5 speed tranny.
Just my opinion and certainly a bit of venting
Cheers
 

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Yoda
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I can see how the GPS-based ones (they use it?) are fantastic... except maybe going up/down a steep slope because one isn't moving horizontally relative to satellites. "DigiHUD" is a really a good app (for at least checking a speedo).
 

svtmikey

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No not GPS based, I put one of those in my Bronco, and it's, well "ok" very accurate, once is finds the satellites, but that takes time sometimes which is a problem.
I am talking about a Smiths Digital Speedometer. It uses a Hall Effect Sensor, which senses something like a drive shaft bolt that passes by it. Moss sells them, although I they have been on back order for 1-2 months. I think they make them for a whole array of cars. I have used this type of Speedometer in a couple of other cars and they worked extremely well. Never used the Smiths, so hopefully they are as reliable a the others
See below
1616277922657.png
 

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Yoda
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Oh, right. Thanks. Those are slick.
 

Scargo

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I went from a 4.2 diff to a 3.7 which caused my speedometer to be off.

Then I went from a tach drive generator to a tach drive GenAlternator. During the switch-out I noticed that the keyway on the steel pulley was severely worn and the pulley itself had a bit of a wobble. So, I purchased new aluminum pulley from Moss, which had a slightly smaller diameter which then caused the GenAlt to spin quicker which in turn threw off the tach.

My solution was to go with electronic instruments which I purchased from BugeyeGuy. These are made by Speedhut, the faces match those of the original Bugeye faces and the speedo is GPS driven.

I am extremely pleased with the accuracy as well as the looks.
 

svtmikey

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Great info!
I went to both sites, never heard of the GenAlternator before, and SpeedHut looks like a a "keeper sight for the gauges!

Thanks
 
OP
Magyar

Magyar

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Thank you all for the great comments and information. I really like the idea of “rebuilding“ or at least giving the gauges a thorough cleaning. I appreciate the link for the tach, Thanks Boink. If it works, that’ll be a great learning experience. If not, I’m not out of any $$$. If I need to spend $$$ on a gauge, I’d rather upgrade it to a new electronic, more dependable unit. I’ve been checking out the various site, Bugeyeguy and Speedhut seem to be the most popular for Sprite style gauges, and it seems as several pioneers have paved a pathway for the artwork. Thanks
Magyar
 

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Yoda
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Here were my tinkerings with the mechanic tach (that turned out fine):
 
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