Aftermarket Tach

99 TJ 2.5 LT.

Does anyone know what is involved in hooking up an aftermarket tach ?

Thanks

Reply to
Kevin
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3 wires. Seriously.
Reply to
Shaggie

Reply to
L.W.(ßill)

Normally you twist the panel light and switched 12V line together cuz you're lazy. :-) Cuz you can't see the back-light light in the daytime anyway.

Reply to
Shaggie

I thought it came with a tach stock. What would you need an aftermarket one for? Just curious, not trying to be rude.

Eric

Reply to
Eric

Reply to
Jim85CJ

Reply to
L.W.(ßill)

Reply to
L.W.(ßill)

LOL!

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Shaggie wrote:

Reply to
Mike Romain

After reading all of the threads about how the stock TJ gauges are filtered thru the computer , and are not real time , I am going to replace the sending units and gauges with direct reading aircraft insturments for real time readouts.

Reply to
Kevin

Go retro, use CJ7 gauges.

They are direct and I will guarantee are no more accurate then the TJ ones....

The mechanical gauges all use a dampening agent, usually thick grease on the pivot points. This effectively gives a delay in the readings.

If they were a direct read, then every bump or angle change or air bubble would have say something like the gas gauge going insane up and down all the time. Now it only raises or drops on a long off ramp or long hill.

I would be almost ready to bet money that the newer digital gauges and readouts are more 'real time' than the old style direct read ones.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's
Reply to
Mike Romain

I used to work for the manufacturer that builds all of the Sunpro tachs on the market. We also supplied many aircore movements to other, well-known tach/gauge manufacturers.

The typical aftermarket tach is driven by an aircore movement, lubricated with silicone grease. The grease provides dampening action. Without it, a tach would be exhibit a very annoying needle flutter and bounce. There's a fine line between proper dampening and responsiveness. Extensive testing was performed by my former employer to determine the ideal viscosity of grease for tachs and other gauges. The aircore movements in other gauges, e.g. fuel level, have very different requirements.

Don't assume that a digital tach would be more accurate. It's easy to think that a digital readout of 2,453 is more accurate than an analog gauge indicating the same rpm. Not necessarily so. You're still dealing with tolerances within the constraints of high volume manufacturing. Would aircraft gauges be more accurate? Maybe. Is it worth the extra cost? Probably not for the typical automotive application.

It's reasonable to expect a quality tach (digital or analog) to indicate within 100~200 rpm of actual rpm.

Best regards, Dave Rose Cactus Cowboy Big Wonderful Wyoming '49 Willys Pickup (parts truck) '62 Willys Pickup 4WD 226 '98 XJ Sport '04 WJ Limited 4.7 H.O. O|||||||O

Reply to
cactuscowboy

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