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Fri Nov 09, 2018 11:55 am

Hello all! Many people want to put a tach in, and I figured a light how to would answer the smaller questions. This wasn’t a perfect install, and isn’t totally finished yet, but here’s the pics anyways 8)

First, run the green wire front to back. The wire needs to go from the 1 terminal, or the negative side of the coil.

As seen plugged in here after I added the terminal end:
(Coiled wire is points, straight wire is the tach signal wire)

Next fish it through this hole behind the steering pitman arm (the steering box lever up under the front pan)

Then drag the wire up to the dash tucking it away from moving parts and keeping it from hanging loosely...:

Next is the gauge...but since I’m posting from my iPhone I’m going to do a few posts to keep from loosing it all on accident.

Fri Nov 09, 2018 12:05 pm

To set the gauge up, you will need to set the dip switches seen here to run a 4 cylinder signal, not a 6 or an 8, unless you have a engine swap like corvair or something with more cylinders...

Note the directions for your specific tach, mine was in order left to right:
Signal, ground, and 12v switched source power. This means there only power to the gauge when the key is ON.

I tagged the source wire into the last terminal on the fuse panel, where a couple other gauges snagged their power from as well. I got luck and it ended up being switched power without pulling out my multimeter...but check your year and find the proper power source. Many fuse terminals have spades on the back to plug cleanly into without cutting any stock wiring...

I tied both the gauge ground AND the dash backlight ground into the gauge pod grounds seen here with those nasty blue connectors. Yummy!

The dash light wire is a gray and red wire for every year bay bus, unless I’m mistaken. I like using piggy back spade terminals to take power from original wiring, but someone else was already in here and left me a nice already stripped red wire, so I put a terminal on it and plugged it into the first black pod for the dash lights. NOW...if you look close you will notice I wired the two lights in SERIES, meaning power goes in, then the ground goes to power the next light, then that light grounds. This cuts the voltage from 12v to 6v per bulb. Since most VDO gauges are MUCH to bright in comparison with a stock dash light, this should even it out. Going to have to test and report tonight. If you want full brightness, simply give each bulb that 12v source, then their own individual grounds.

Fri Nov 09, 2018 12:12 pm

Now, seen here is a clever NLA part...a VDO mounting ring from the late BUSBOYS!

Don’t worry, if you didn’t buy one before they gave up on life, you can simply use the original blank plate tabs cut as flush to the circle as you can, you can use them as basic clamps to hold a gauge in. Takes a bit of cleverness and such, and common sense, but you can do it. I have pics of one I did once but that’s long buried somewhere hard to get to from my phone...

You’ll need to remove the old blank plate...:

Make sure you put the gauge in nice and level!

One note...

Often the needles bounce and are optimistic when revved suddenly. There’s a thread around here on how to put a diode in place to smooth it out and steady the needle. The justKampers tachs will need this as well...look for them via a search, maybe someone will post a link ....

Fri Nov 09, 2018 1:20 pm

Pretty solid DIY! Would have been good to have this when I installed mine.

Do you have part #'s and desc. for the VDO gauge and Bus Boys ring?

Fri Nov 09, 2018 1:59 pm

mikewire wrote: Pretty solid DIY! Would have been good to have this when I installed mine.

Do you have part #'s and desc. for the VDO gauge and Bus Boys ring?

This VDO was VDO-333-151 but I would suggest the justkampers original looking ones. Same tach with a matched gauge, very clean installed!

No on the ring.

Fri Nov 09, 2018 2:40 pm

I used the existing ring fill piece for my 2 1/8" tach. Turned it over and used a hole saw to cut a proper sized opening. Painted it flat black. Works fine.
The diode to stop needle bouncing was a Radio Shack stock item. If someone finds the part number I'm sure its on Amazon.

Fri Nov 09, 2018 3:09 pm

I've seen the ring for sale lately. When I find it I will post.

Fri Nov 09, 2018 11:48 pm

Per telford Dorr, the electrical guru around here...:
Quote: 1N4004 or better. 1N4007 recommended

A diode for the input signal side of the tach.

Sat Nov 10, 2018 2:20 pm

Went over to aeromechs place for something else, and he whipped out out a diode for us! Installed at the coil and now this tach is perfectly smooth and accurate 😎

Sat Nov 10, 2018 3:47 pm

Stuartzickefoose wrote: Went over to aeromechs place for something else, and he whipped out out a diode for us! Installed at the coil and now this tach is perfectly smooth and accurate 😎

the diode between the spade connectors is quite clever!!

Sat Nov 10, 2018 5:32 pm

Aeromechs idea, not mine. One of the best San Diego VW guys for sure ;)

Mon Nov 12, 2018 9:58 am

Great - were do you get the diode in the picture from?

Mon Nov 12, 2018 10:08 am

Balmoral1958 wrote: Great - were do you get the diode in the picture from?

Aeromech had them made but google a 1N4007 (or whatever that number was...) and you can likely buy one for pennies from amazon or eBay etc.

Also, if your tach doesn’t read perfect right away, be sure to give this thread a read:

https://www.thesamba.com/vw/forum/viewtopic.php?t=353646

Tue Nov 13, 2018 9:17 pm

Good instructions. I “plan” to run a length of trailer wire from HD for my gauges..gives several wires inside a weatherproof sheath eliminating several loose strands running the length of the bus for all the gauges...

That’s the plan anyway..we shall see.

Wed Nov 14, 2018 9:11 am

curtp07 wrote: Good instructions. I “plan” to run a length of trailer wire from HD for my gauges..gives several wires inside a weatherproof sheath eliminating several loose strands running the length of the bus for all the gauges...
That’s the plan anyway..we shall see.

That ^^^ is what I did -- has worked well.

Wed Nov 14, 2018 9:22 am

Just make sure you run the correct wire for the CHT sender to the gauge at your dash.

The trailer wire harness has 4 14 gauge wires and they are color coded. Tach, OP, OT and a spare.

I put mine in 3/8" wiring loom (from Home Depot and buy 2 since they are each 10' long) electrical tape it up. I secured mine to the under side of the bus basically to the frame about every 8" with zip ties. Came out in a hole witha grommet I drilled in front of my left foot location.

Fri Nov 16, 2018 11:12 am

For the wiring from back to front, I cut the ends off a 3-wire outdoor extension cord.
Green wire for signal (coil -)
White wire to engine block (ground)
Black wire to coil +, which is switched.