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raf940 Offline OP
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calvin needs new tach for his 78 t140 is gwine to git an emgo one i know they 'pro-trude' about 1/4" above binnacle lip but wasn;t there a thread on here about how to shave the rubber nubs down or something to make it fit better? i cant find it
thanks


1972 Triumph T120
1968 BSA A65
1968 MGB Roadster
1979 Chevrolet Camaro Berlinetta
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Hi raf940, I think the trimming conversion was when fitting Emgo repro gauges you must cut the rubber shorter where the studs & nuts go. Emgo gauges are taller.

Some of the repro rubbers have a “knock out” for speedo reset. But it may be on wrong side sometimes. Like it was for another brand bike with reset knob on opposite side.

I find the hard part is cutting hole for trip meter reset. I calculate location best I can. I use a gasket hole punch to cut the rubber. Not so easy for me.

I’ve only done a couple sets. One was thin & floppy rubber. Left gauge rather floppy.
The other was thick like the originals. I guess it’s a crap shoot? I wish I knew who for sure sells the thick one. Would be bonus if knock out was correct also.
Don


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this is tach


1972 Triumph T120
1968 BSA A65
1968 MGB Roadster
1979 Chevrolet Camaro Berlinetta
1969 Honda Mini Trail
2004 Honda Shadow Aero
1949 Ferguson TE20 tractor
1975 yamaha xs650b
1971 SL 175 Honda project
2 olive drab WWII military bicycle replicas
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Hi, Duh… I should learn to read better!
What sucks is the stock light bulb holder won’t fit in light hole of Emgo tach or Speedo. As well as cutting the rubber at studs.
Good news is Emgo tach & speedo works well & have proven durable on the bikes a few of my friends have.
Don


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You would think that if Emgo was smart enough to copy the gauges they would also make the rubber boots to fit.


1968 T120R
1972 T120RV
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Hi Desco, You'd think..!!
I agree. Actually, you'd think they'd make can same length as Smiths & make the light hole the Lucas socket size. Obviously... I know nothing. What sucks is we have no choice. Send Smiths out for big dollars & you get back a Smiths gauge with the Smiths problems. Or Emgo with its fitment issues. Sure you can go with other brands electronic. I have no idea if they fit holder or not. They are costly. I don't know of any other new repro gauges.

Kind of gets down to rebuild original Smiths or deal with Emgo. Is that like when the mobster asks you which arm do you want broken?

Maybe at some point Wassell or someone can get these things corrected. I'm 71. I hope they hurry. At almost 40k miles, my gauges are living on borrowed time.
Don


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dont sweat the small stuff. put in something that tells you how fast you are going and just ride the motorcycle.

we ll all be dead soon enough.

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I have not had working speedos in years. I had one rebuilt twice in three months years ago and said to hell with it. I'm pretty good at guessing at it and where I live you can see for many miles so 80 0r 90 (guessing) is no problem. If you live where there is traffic just keep up with everyone else. I'm 78 so the days of sliding around bends on the frame are long gone. I still enjoy the ride, the exhaust sound and the the attention at the rest stops.


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1972 T120RV
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I'm at a crossroads. I know that the tach on my Trident reads high. It's a choice between disassembling and recalibrating the stock or getting a new Emgo.
Disassembling Smiths gauge, recutting a new glass (I might get the old glass out intact, but never get it back in without breaking it), having crimp marks around the chrome rim (sorry but I don't have a lathe or any tool to refit it "properly".) At least four hours, and the gauge would probably quit working next week. Don't ask me why Smiths couldn't locate the lighting hole 1/8" off to make the calibration screw accessible from the outside. crazy
Or I could spend $75 on a new Emgo tach and complain that it stands proud of the rubber.


"Gosh, it's not a 1/4 20, must be metric."

72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"

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Or you can send it to this guy;
https://joellevinecompany.com/
He's been around forever.
Not cheap but it will be right, both in size and operation. You've got all winter to save up some money.


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1972 T120RV
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Hi desco, That's who did John's gauges, about 8 or 9 years ago. Still working after about 17k miles. Cost was what it is. Not cheap.
The root problem with Smiths gauges is they are quite flimsy to begin with. Not really made for long term durability. In my estimation & from what Joe told John one of the main problems is the very small bushing under the speed/rpm needle.

Taking a junk speedo apart I was able to understand exactly what he's talking about. As the bushing wears the follower disc drops lower & gets closer to the rotating magnet. I think that's what causes the needle to read higher than it should. Finally the bushing wears so bad the shaft drops down & the follower actually rubs magnet which slams the needle to full mph or rpm. But depending on vibration & bumps you may be going over, it will loose contact and needle will drop down again. Also when bushing displaces the needle shaft can stick such it will read rpm or speed with bike or motor at standstill. Often if you look the needle is too close to the face. Eventually you'll see needle rub face. By then it's reading very bad in different ways if at all.

The spindle bushing for rotating magnet that cable goes into seems robust & takes minimal wear. It's the bushing for speed needle in cross piece under the needle return clock spring. It will wear totally out where you end up with no bushing at all. Not the tiny needle spindle is flopping about in a 3/16" hole in sheet metal.

Taking the chrome bezel off looks easy until you do it. Very hard to remove without a fair amount of distortion. You must be careful to not crack or chip glass. Then the glass is often stuck tight to the rubber gasket. Pry on it, will chip or crack glass. Not easy to slice rubber with razor blade, but I found cutting rubber to be the best way. So you'll need all new rubber gaskets, plus the rubber mounting bushings holding guts to can will be deteriorated.

Now you have guts out of can. Oh... the trip meter unscrews. That's easy. However everything else is riveted or crimped. Not at all made to take apart for repairs.

Adjust the modulator plate to adjust magnetic flux. Just turn the screw... However the screw has a star head that factory strongly stakes zinc casting into start to be certain it cannot change adjustment from vibration or the like. Should you turn modulator screw it breaks screw head or the zinc casting stake. Now it won't hold without restaking the screw.

I have no idea how long it takes the shops to fully overhaul tachs & speedos. There's a lot going on in there. Unlike the automotive speedos I've taken apart, everything in the Smiths unit is a fight. I don't know what spare parts they have, but it wouldn't surprise me if they have new castings &other parts made.

The tach is same internal casting as speedo, but they leave odometer parts out. The internal springs etc are calibrated for rpm.

My hunch is the shaking of gauges from vibration working the needle shaft up/down, sideways in the bushing is a great contributor to the wear of the bushing. Then needles don't move that much or that fast. But vibration is moving/wiggling the needle shaft hundreds of times a minute.

Trip meter problems is another subject.

For some reason Emgo gauges have proven more durable.
Don


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Regarding having a working speedo is personal decision. In my city of Pleasant Hill. You'd better not speed or the ticket will cost you more than new speedo. Tickets must generate lots of revenue for city as they are most strict on speed enforcement. Surrounding cities are the same. The canyons we ride often have 25 mph speed limit for the most part. Almost impossible to go that slow on these roads. So no body does. However... A few months back they were patrolling it. Two motorcycle cops followed me & John for about 5 miles. We pulling into parking area & they passed us. But, we had to go only 25 for the remainder of miles as they would surely be up there with their radar guns aimed at us. Indeed they were! I can't judge speed that well. I end up going faster & faster most the time. Pretty soon 33 or 34 mph feels like 25. Will they ticket you for 33mph? Yes!!
Don


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Originally Posted by desco
Or you can send it to this guy;
Or I could brag that my Trident revs to 8500 rpm. laughing


"Gosh, it's not a 1/4 20, must be metric."

72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"

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Originally Posted by TR7RVMan
Trip meter problems is another subject.
That's the only thing wrong with my speedometer. Maybe someone reset it by turning the wrong way? Could be, I'm not even sure which is the right way to turn that knob.
Of course, this is the only topic not covered in Blighe's book on repair. He seems to think that they never go bad.


"Gosh, it's not a 1/4 20, must be metric."

72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"

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Picture of the underside once the required butchery is complete.

[Linked Image from i.postimg.cc]

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Joel does excellent work


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