Upgrading the tachometer, to remove that bounce Options

[ThePaintedMan]

Might as well take the chance to give another bump to a great member and an awesome service. Send Tim your gauges for all your needs. Even if you don't do the LEDs, his refresh of the gauges is second to none. And of course, he's an awesome guy who's helped out a lot of folks here.

[timothy_nd28]

I have some bad news as it seems that AutoZone has recently jumped ship with their gauge supplier. They're now stocking a tachometer that looks very much like the Sunpro Super Tach II but internally it's nowhere near the same. AutoZone's replacement tachometer called the EQUUS (picture below) is completely digital as it has a micro-controller. Changing a resistor value will have no desirable effect with this tachometer. The SunPro tach is still available thru eBay and Amazon, but it's just a matter of time before this supply dries up too. So a heads up for those contemplating with the current tach upgrade, I would do it soon.

I will mess around with this EQUUS tach, it's still only 30 dollars. I will make available a new DIY for this tach conversion as soon as everything is figured out. With this said, I'm not a computer programmer. The new tach uses a micro controller called "ATTiny 24a". I would need to find out a way to extract the current code (chip is surface mount), then modify the code to work with our 914 gauge face and with 914s with different engines, and finally write the modified code back to the chip. Any programmers willing to help, please chime in or PM me (IMG:style_emoticons/default/beerchug.gif)

[craig downs]

I got mine thru Summit a few months back and it was being clearanced for $5.00. I looked at Autozone and they didn't have it so I looked online and found it at Summit. I figured that they were being fazed out. I did the conversion and couldn't find a 490k resister and ended up using a 510k. Seems to work fine.

[Optimusglen]

Good news for anyone wanting to do this. I recently picked up a Bosch mini tach and stripped it down. Looks to be the identical guts.

Bosch FST 7904

[Optimusglen]

Packaging and face

.

[Optimusglen]

Taking another approach. Thought I would share.

I was liking the idea of a different color gauge face a'la the Singer Porsches. (er, some of them) I thought that instead of messing around with the resistor, why not change the face to display the lines/numbers in the same orientation and spacing as the aftermarket tach, ya know, since I was changing the face anyway.

I measured out the Bosch tachometer in the two previous posts and created a drawing with the lines at the same angles and spacings. The only difference is the face is sized to fit within the VDO tach, and I used VDO style text and lines.

I placed my redline where I wanted, from what I could tell this is the proper redline for the engine I'm putting in, from a 1971 911T. Obviously this can be changed easily to match the engine/car.

Black
(IMG:http://www.914world.com/bbs2/uploads_offsite/c1.staticflickr.com-19709-1521140463.1.jpg)

Blue
(IMG:http://www.914world.com/bbs2/uploads_offsite/c1.staticflickr.com-19709-1521140463.2.jpg)

The workflow here would follow the same steps for removing the selector switch on the rear and routing the wires. It would skip the resistor change. You would still follow the mounting bracket instructions. And you would add the new face.

I have a really high quality printer at home, so I'll try printing my gauge face on high quality luster paper first. If that doesn't turn out I'll probably look into having the image printed on aluminum.

If anyone else is interested, I can send you the SVG file I made. This is a vector file that you can open using Adobe Illustrator ($$$) or Inkscape (free) With this file you can change your redline, gauge color, line/number color, or even add other graphics. Just shoot me a PM with your email address.

[mepstein]

I'm giving it a shot. Still have a lot to learn with even the very basic stuff but got a good start thanks to glen.

[timothy_nd28]

Wow, i thought the sunpro's were long gone. Thanks for doing the leg work with the Bosch tach. Keep posting pics, I love to see your twist on this conversion.

[Bartlett 914]

This is a good approach. This would also work with the Equus Tach wouldn't it?

Taking another approach. Thought I would share.

I was liking the idea of a different color gauge face a'la the Singer Porsches. (er, some of them) I thought that instead of messing around with the resistor, why not change the face to display the lines/numbers in the same orientation and spacing as the aftermarket tach, ya know, since I was changing the face anyway.

I measured out the Bosch tachometer in the two previous posts and created a drawing with the lines at the same angles and spacings. The only difference is the face is sized to fit within the VDO tach, and I used VDO style text and lines.

I placed my redline where I wanted, from what I could tell this is the proper redline for the engine I'm putting in, from a 1971 911T. Obviously this can be changed easily to match the engine/car.

Black
(IMG:http://www.914world.com/bbs2/uploads_offsite/c1.staticflickr.com-19709-1521140463.1.jpg)

Blue
(IMG:http://www.914world.com/bbs2/uploads_offsite/c1.staticflickr.com-19709-1521140463.2.jpg)

The workflow here would follow the same steps for removing the selector switch on the rear and routing the wires. It would skip the resistor change. You would still follow the mounting bracket instructions. And you would add the new face.

I have a really high quality printer at home, so I'll try printing my gauge face on high quality luster paper first. If that doesn't turn out I'll probably look into having the image printed on aluminum.

If anyone else is interested, I can send you the SVG file I made. This is a vector file that you can open using Adobe Illustrator ($$$) or Inkscape (free) With this file you can change your redline, gauge color, line/number color, or even add other graphics. Just shoot me a PM with your email address.

[Bartlett 914]

I purchased the Bosch 7904 and it does look like the the right one. I did the full mod and it went real well....until I went to install the pointer. The 914 tach shaft is .5mm and this one is 1mm! A solution will be to drill out the 914 pointer but this will be tricky ans I may end up gluing it onto the shaft.
Were all the 914 tachometers the same. Has anyone run into this? I have a couple more tachometers I could tear into but I don't want to if they are all the same

An thanks Tim for showing us this. I also did the LED lights (IMG:style_emoticons/default/smilie_pokal.gif)

[Montreal914]

Added small detail to this excellent thread (IMG:style_emoticons/default/smilie_pokal.gif)

This is a screenshot of Bosch webpage showing the 3 variations of that tachometer.



FST 7906 (black face) happens to be in the mid $30 range on Amazon.
I couldn't find the FST 7904 (white face) on Amazon, and it was in the $50 range on other websites.

Order placed (IMG:style_emoticons/default/sunglasses.gif)

[Dominic]

@timothy_nd28

Tim,
Are you still in the business of updating Tachometers?

Thanks,
Dominic

[FlacaProductions]

It appears that Tim hasn't logged on here since 20th June 2022.

[fiacra]

It appears that Tim hasn't logged on here since 20th June 2022.

He does have an email link in his profile and that might still work