1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Tachometer for 10k RPM

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Old Oct 13, 2023 | 02:45 PM
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Tachometer for 10k RPM

Hi all,

I'm building a 13B PP to stick in my series 3 and have come across a conundrum. I'm getting the rotating assembly balanced to 10k RPM and would like a tach that goes that high. However, I think most aftermarket tachs looks really sleazy and I'd like to keep the original tach style (mine is the yellow on black background). I know you can adjust the tach to a certain point and I'd like to know; Is it possible to adjust the tach to read from 1-10k RPM, and if so, does anyone make a replacement for the original tach face in the same style?
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Old Oct 13, 2023 | 05:47 PM
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never bought anything from them, but take a look at: www.speedhut.com
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Old Oct 16, 2023 | 06:06 PM
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The "easiest" thing would be to put an aftermarket tach in the stock location. The stock tach can be wildly inaccurate, and this inaccuracy not only has a variable skew, but the tach lags a fair amount too.
this is probably why the spec is something like -50/+500 RPM at 7000, the tach lags so much that in the lower gears it can be accidentally accurate if it is calibrated to read high.

I like a 5" tach on the right side of the cluster (center of car) because the Go Pro picks it up better that way


Edit: just noticed your location. It helps/hurts that the North American S3s have a truly crappy instrument cluster, dark red on black. And there are two different gauge fonts! The tach and speedo are different, and the other four gauges are a mix of those two. Once you see it, you can't un see it.

Last edited by peejay; Oct 16, 2023 at 06:16 PM.
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Old Oct 17, 2023 | 07:20 AM
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All the matching yellow/red tachs I'm aware of are hand made by adjusting the very inaccurate gauge and scratching off the old letters and hand painting your new digits accordingly.

The one I imported (for too much money) doesn't even match... oops
The most practical option is definitely an aftermarket tach mounted outside the cluster like peejay described.
The most elegant might be doing something like Nate Rist on
I think he's on here too I just don't know how to send you that way/use the forum yet. :p


Last edited by milk0247; Oct 17, 2023 at 07:28 AM.
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Old Oct 17, 2023 | 12:27 PM
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Originally Posted by peejay
The "easiest" thing would be to put an aftermarket tach in the stock location. The stock tach can be wildly inaccurate, and this inaccuracy not only has a variable skew, but the tach lags a fair amount too.
this is probably why the spec is something like -50/+500 RPM at 7000, the tach lags so much that in the lower gears it can be accidentally accurate if it is calibrated to read high.

I like a 5" tach on the right side of the cluster (center of car) because the Go Pro picks it up better that way
Gotcha, I might be leaning towards integrating an aftermarket tach into the original spot as I've found a couple with styles extremely similar to OEM. Do you happen to know what diameter the S2 tachometer is? We were weird in the UK, all our S3 cars got S2 dashes
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Old Oct 17, 2023 | 08:52 PM
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Everybody in the world, as far as I know, got the S1/S2 dashboard and S2 cluster except for North America, Mazda was trying to turn the RX-7 into something like the 280ZX/300ZX for us fat unsporty Americans, and the Canadians could just take whatever they felt like giving the US, if they considered the Canadian market at all other than cold weather packages.

The dash pad on the North American S3s does not crack, which is the nicest thing I can say about the interior

I've personally got no idea what diameter the tach is, other than that it is a lot smaller than the FC and is probably the same size as the first series MX-5 given that Mazda tried very hard to make a '90 MX-5 look and feel like a '79 RX-7.
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