Honda-SOHC
SOHC.co.uk Forums => Project Board => Topic started by: exvalvesetdabbler on July 31, 2025, 05:14:52 PM
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I have been thinking about adding a volt meter for a while now and have sorted out the wiring and done a temporary lash up just to see how useful it will be.
There is lots of stuff out there, either too big or don't match the styling of the other instruments or just plain tacky. The off the shelf volt meter I tried had an orange display and is not easy to see in bright sunlight. Based on previous experience blue should be better.
Here was the temporary setup.
https://www.sohc.co.uk/index.php/topic,32075.msg311762.html#msg311762
I have had a play around with a 0.28 inch led volt meter which was the smallest I could find, and been trying out different contrast filters and housing. Currently prototyping with black plastic before moving on to aluminium. The objective here is to find the smallest aperture that doesn't obscure the display. This one is 23mm.
Bare module
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Prototype housing
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The contrast filter is a disc cut from some 3mm grey tinted perspex. I do have some blue tint to try as well.
This will be a slow burning project as and when time permits.
Regards
Dave
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I find a voltmeter quite useful and routinely use them in cars, type that plug in cigarette lighter (although those are disappearing too) as it just gives instant status of charging etc.
Yes, orange and red led can almost be completely obliterated in bright direct sun light.
A friend made a mimick of Suzuki GT 750 water temp gauge housing (when 750 F2 Honda was contemporary) to mount a clock. Effectively recessed into a black tube with a turned rear aluminium plate, a smaller version of the existing Honda clock rear chrome disc, looking very "factory " original when complete.
You could mount the DVM recessed in that fashion, if would also shield it from extraneous light in that way, like those deep set traffic light shroud.
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Mounting is the tricky bit. Currently split between a stainless bracket coming off the two bolts that hold the bowls for the gauges and the voltmeter sitting just forward of the idiot light console or mounting off the handle bar bolt, but the bending might to complicated to ensure that its bezel sits no higher than the existing gages. Plan is to paint the upper part same as the gauges with the exposed mounting bracket looking like the crimp ring on the gages and a profiled bottom piece in stainless to match the bowls the best I can. Talent may run out but I feel the need to try.
Regards
Dave
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Made a start on machining up the housing for the voltmeter from a piece of aluminum round bar. Big waste of time that was, the piece of round bar had a crack running through it like Brighton rock. Waiting to see what the fleabay seller has to say. Dangers of buying offcuts on auction sites I guess.
[attachimg=1]
While waiting for that issue to be resolved I made a start on mounting bracket version 1 this morning , using CAD - cardboard aided design and a piece of scrap 2mm aluminum sheet.
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What I am trying to achieve is to have the volt meter angled the same as the clocks and the bezel height about the same.
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Just need to work out what height the clock body needs to be now. I was originally going to make the bracket out of stainless but something painted satin black might blend into the surroundings better, and aluminum is a lot easier to bend and drill. Just needs a good rub down to remove a few scuffs before painting.
Regards
Dave
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Finally gat around to machining the main body this morning after receiving some replacement aluminium.
I had to use a file and emery cloth to smooth out the curves a bit. Inside is stepped to accommodate the contrast filter, module and the termination board.
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[attachimg=3]
Regards
Dave
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Neat work there Dave, that’s going to blend nicely. I had a temporary one fitted after replacing my rectifier on my 550K3 just to monitor charging. Removed it after a few runs as it was not quite blending.😜
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Machining the base today out of a piece of 316 stainless, not the nicest stuff to machine and one 3mm drill bit broke. It's tough stuff and you need really sharp tools.
Components for the base and cable entry.
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The underside
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Test fit onto bracket. I amazed myself, screw holes on all 3 pieces line up. I did make a template for the screw holes to use for the drilling pattern. Holes are on a 32mm pcd.
[attachimg=3]
The jury is still out on fasteners
Dome nuts or countersunk screws ?
Components for cable termination. Couldn't find any brass eyelets in the junk box so I machined a couple from the shank of an old woodscrew. This is needed to anchor the thick incoming wires to the very thin wires that attach to the led module.
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Cable termination PCB fitted into housing. There is a step in the housing to stop the board going in too far and the black plastic ring gets sandwiched when the whole thing gets screwed together.
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Just waiting for paint to dry on the bracket and housing upper part.
Regards
Dave
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Nice work on the project.
I'd use countersunk screws given free choice.
Could you turn a small half circle depth groove in the face of aluminium to allow for a seal against the stainless ? Then squeeze silicone sealant around there to assemble, which would form, effectively, a "O-ring" weatherseal between the two.
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Could you turn a small half circle depth groove in the face of aluminium to allow for a seal against the stainless ? Then squeeze silicone sealant around there to assemble, which would form, effectively, a "O-ring" weatherseal between the two.
That would be ideal but there was no way my lathe was going to cut an o ring groove in that stainless using a rounded tool without a lot of tool chatter. I had already settled on a smear of gadget goo on each face or if it comes to the worst a paper gasget impregnated with some grease. If I was making a housing for submersible sensors I would normally put in a groove and use a silicone o ring, but to do it's job it would need to be on the inside or outside of the threaded holes.
When I was a kid our old lawn mower with a Villiers 2 stroke engine survived years with a base gasget made from a paper hoover bag smeared with red Hematite.
Regards
Dave
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I didn't realise that the stainless was smaller in dia than the alloy, so was looking at that flat outside the three holes. I can now see your view of it.
Yep, stainless is really resistant to cutting isn't it. We were taught to use a lot of rake on top face of tool to minimise the cut shear distance in apprenticeship. Swarf came of in long continuous ribbon with razor blade sharpness as a lethal to fingers byproduct :)
Its good to play around with engineering and design to get something you want.
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Sliced my finger just tidying up the stuff on a couple of occasions and yes tools need to be razor sharp and have a steep angle to get under the work hardening of the previous cut.
431T is even worse to machine on a small lathe.
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Test fitting before final coat of paint. Dome nuts are on some threaded rod with red locktite so they are 'dome screws'. Easier to swap out for other screw types if I have a change of mind.
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Regards
Dave
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That's a nice bit of work there!
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Time to fit the contrast filter to the housing.
First figure out to cut a disc of perspex to the right size.
[attachimg=1]
It was easy enough to saw a piece near to circular as possible an compress it between a flat piece in the chuck and a flat adapter piece in the live center in the tail stock. Just needed to take light cuts on a slow speed.
Then glue the filter into the housing with epoxy adhesive.
Once pressed in it was necessary to clean off any excess with alcohol followed by a brush and neat washing up liquid before it cured.
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Regards
Dave
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Really nice work, looks genuine Honda.
Thanks for the tip about maching stainless 👍
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WOW that's a great looking volt meter and going to blend in very well with the bike when its done . 👍
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My solution was different, I mounted the same type volt meter inside my tacho, keeps it out of the rain etc.
(https://i.ibb.co/dshwXRjx/IMG-2540.jpg)
Not decided on final colour yet, I have red, blue, yellow and green. I need to dim it a little as well.
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That looks great Ken proper job 👍
Great to see your back home & to see your on the forum I think I can say WE all missed you here on the forum with your help and guidance
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My solution was different, I mounted the same type volt meter inside my tacho, keeps it out of the rain etc.
(https://i.ibb.co/dshwXRjx/IMG-2540.jpg)
Not decided on final colour yet, I have red, blue, yellow and green. I need to dim it a little as well.
"The dogs" I think is the term. Even better you are well enough to he back on here Ken. Thats the dogs too? Maybe one with 3 though.😳
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Welcome back Ken, pleased you're on the mend, must have been scary. Got the wife nagging me to get my pneumonia and shingles jab booked in now I qualify.
I had thought about that but not confident on making a tidy job of the cutout.
Did you wire it back to the battery through a relay or take the feed from the headlight shell and calibrate for the voltage drop under normal running.
Regards
Dave
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Assembly Time
The module was first calibrated to account for the voltage drop between the battery and the switched live in the head lamp shell. Ideally one should run a separate wire from the battery through a fuse and relay that follows the switched live. The voltage drop between the battery and the module will be minimal and more accurately follow the battery voltage under all load conditions. For now I have calibrated the module to read right with normal running without headlight. There is a small potentiometer on the module for calibration.
The LED module was glued into the housing with RTV silicone and allowed to set over night. The original wires dropped off early on when test fitting a few times so I replaced them with something more flexible and matching the bikes electrical colour scheme. They are also anchored with a blob of hot melt adhesive.
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Drop cable from the headlight shell attached to the terminal board. The wires were salvaged from an old clutch switch.
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Wires from module soldered to terminal board
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The mounting holes in the bracket are slotted to allow some adjustment of the alignment.
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It was then just a case of screwing it all together after placing a smear of silicone on the faces of the top and bottom parts.
Regards
Dave
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Test fit.
Assembled Volt Meter
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Fitting.
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Here's a walk round video. Its a tight squeeze and hopefully it will blend into the background, well at least until it lights up any way.
https://www.youtube.com/shorts/KdYEToTqvYA?feature=share
I know, my battery is rubbish.......
Regards
Dave
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Nice job Dave, blends in lovely. I’d buy one but judging by the amount of work involved I probably wouldn’t be able to afford it.😜