Monster Tacho, Alfa Style

[Colin Byrne]

My standard mechanical tacho has always been very inaccurate and with the new engine on its way I thought it was time to sort it out, also liked the idea of getting a shift light.  Had a look around and to get anything that looked decent was going to cost over $200 and then you could add another $100 for a shift light.  A quick search on eBay located  a 5" "Monster" tacho with integrated shift light for $45.  After a few modifications I managed to squeeze the internals of the new tacho into the original alfa case and then finished it off with a sticker from the alfaclub shop.   I've bench tested it using a signal generator and all works well and is very accurate, just need to get some nice LED lights to make a neat shift light

[Ray Pignataro]

Colin get a high intensity led and mount it in a plastic shoo roo with super glue and black silastic

[alfagtv100 (Biggus)]

Good job Bob.

[Davidm1600]

I am going to sound really ignorant here, so please excuse me , but why do you really need a shift LED light to tell you when to change gears, can't you tell by feel and engine noise when it is required to change gears ?  I don't rely on the Tach to tell me. Told you it was a silly question.

[AikenDrum105]

Doesn't valve bounce count as haptic feedback ?      Seriously - looks awesome !! 

[Evan Bottcher]

I am going to sound really ignorant here, so please excuse me , but why do you really need a shift LED light to tell you when to change gears, can't you tell by feel and engine noise when it is required to change gears ?  I don't rely on the Tach to tell me. Told you it was a silly question.

I might also sound a bit ignorant here, and that's because I am.  IMO a shift light on a road car is a ridiculous w***.  On the racetrack (which is where Colin's car is driven when it's not on Targa) a shift light is very useful.  The light gives you a precise indication of a specific revs, and allows you to change at a consistent point.  On the track personally it gives me a great indication of when I've improved a corner exit, as I can observe that the shift light will come on at least a couple of inches earlier after the corner exit, maybe even half a metre.

Okay several metres.

Okay many metres.

[Davidm1600]

Cheers Even I had that was the answer to both points.  Absolutely have to agree for road cars such a thing is for tools driving ricers with gauges growing up the RHS front piller or out of the bonnet.

It was in a way a Rhetorical question for I suspected I knew the answer re for race purposes, albeit, from my extremely limited experience I would tend to have thought one would be spending more time watching the track and other competitors around you than watching the clock, but perhaps I am wrong   

Anyway it is certainly one impressive Tach.

[Brad M]

It was in a way a Rhetorical question for I suspected I knew the answer re for race purposes, albeit, from my extremely limited experience I would tend to have thought one would be spending more time watching the track and other competitors around you than watching the clock, but perhaps I am wrong   

David, that's the point the light goes off in your peripheral vision and you know you're at that poiint in the rev range. Means you aren't distracted from what's happing on the road around you.

[1750GTV]

What does the Speedo look like ?

Chris

[Colin Byrne]

installed

Speedo is going to be removed and replaced with my data logging screen (phone) and a small push bike speedo.

[jimnielsen]

Nice work Colin, I see that the speedo goes up to 140 MPH (that should almost be enough)  - and that the car is already doing about 10 mph in the shed!! Good work on the suspension points, looking forwards to seeing the finished results!

jim ~

[ACP]

installed

Speedo is going to be removed and replaced with my data logging screen (phone) and a small push bike speedo.

Just Got to source a bike speedo that can go fast enough... The old man mounted the sensor on the prop shaft, and a small section of tube behind the ash tray, to which the computer is mounted.  Works pretty well, the only big problem is you can't see it at night as it isn't back lit...

I have thought of mounting a Garmin Edge HRM inside as an alternative, does speed, cadence(rpm?) heart rate, has data logging, but that would be frowned upon for events where GPS is not permitted.

Cheers,
AP

[Colin Byrne]

Just Got to source a bike speedo that can go fast enough..

I've been using the "sigma" brand that Anaconda sells.  Max speed is 200km/hr and i think they start at around $30.  I've got 2 in the rally car, one for me and one for the nav. in case we have a failure with the primary rally .  I've also got one in the 105 road car.  because they are designed for slower speeds the calibration resolution is incredibly accurate.  As far as back lighting goes, the rally car is very rarely driven at night but  a couple more LEDs should do the trick

I'm on the lookout for an old Speedo as all i really need is the backing tin and the silver ring and it would be a bit of a shame to destroy this one for just that.

[alfagtv58]

The VDO range of bike speedo's can also go up to higher speeds.  Not backlight though.

[Sam]

Hi evewryone,
I noticed Colin used a Signal Generator to test / calibrate his tacho.

Does anyone know where I can get one and how much they cost?

I've cchanged the tacho's 'guts' but left the same face plate.
The tacho I'm using has a trim pot to calibrate it, but I'm not sure how to do it without a signal generator.

The other way could be to drive at 100K and adjust the tacho to read about 3000 but it wont be very accurate

Thanks in advance
Sam