Is a Tach Necessary?

[Switch_knuckles]

I was tossing around the idea of installing a full set of gauges. I like the Autometer Phantom series. I know the functions of a tach, especially in a vehicle with a manual trans. However my xj is an automatic. Is it really necessary to have one, I can't think of any reason why I would need it. If I am missing something please educate me. Thanks guys!!!

[OverEasy]

My XJ came with one in it and I never look at it. Its also a auto. Now in my samurai I have a small tach and have set the light (I have them separated) to come on at a certain RPM but the tach I never watch, I just look for the light when using the skinny pedal. The Sami is a 5 speed.

[prerunner1982]

Even in my manual XJ I can drive without the tach, heck all my gauges have gone out for months. If you have driven it long enough you can pretty much tell by the sound how fast and when to shift.

There is also very little/no reason to have one on an Auto....

[LizardRunner]

I think a tach is only necessary if your racing, cause you usually don't have a spedometer. They make you look like you have a hot machine though and that is just cool factor.

[OverEasy]

I think a tach is only necessary if your racing. They make you look like you have a hot machine though and that is just cool factor.

Ya, that's why I have my tach hidden and just the light mounted on the dash.

[Switch_knuckles]

My VW was a manual and I learned to listen to the engine as well, so I would not have to look away from the road.

i just wanted to make sure there was not some aspect I was missing. Knowing that will help me plan out my gauge setup. Thanks guys.

[OverEasy]

:thumbsup:

[4.3LXJ]

I have one. I need to hook it up. They aren't really necessary, but they are nice to have when setting up gears and tires etc. Another plus is that once you get used to the rpm and speed if the speedo quits you can adjust speed by the tach.

[Switch_knuckles]

How would you use a tach to work with gearing and tires?

[4.3LXJ]

You need to set a target rpm at a speed such as 60 mph. When you get your tires mounted, you will notice that the speedo is not true any more. Use mile posts on the freeway to time yourself at 60 mph, then divide your real time by 60 sec and multiply by 100 to get what your speedo gear is off by. Use this percentage to multiply your gear ratio is to see what you need for gear ratio. Pull your speedo gear and multiply by the decimal or percentage number to figure out how many teeth you need after regearing. If you don't regear, us it to correct the speedo anyway.

[Mudderoy]

Hmmm I wouldn't like it too much if I didn't have a tach.

Things I like to check...

What RPM is the motor turning at speed "x".

Is my torque converter locking and unlocking.

Did the over drive kick in or am I still in 3rd gear?

When the TPS acted up I was able to clearly see it on the TACH as I came up to 4k RPM in 1st gear! lol

I look at it as more information is handy when you need it. I would have a TACH.

[bigjim350]

The best basic answer is, yes it is nice to have a tach, but not a necessity.

[Switch_knuckles]

Very good and useful points, thank you both!!!

[default83]

everyone always told me that if your speedo went out use your tach, but in never use the tach enough to know how fast im going at what RPM.

the only time i ever use the tach is when im trying to get on the interstate and have to push it in a gear to make sure i dont red line (which is very rare).

[Mudderoy]

everyone always told me that if your speedo went out use your tach, but in never use the tach enough to know how fast im going at what RPM.

the only time i ever use the tach is when im trying to get on the interstate and have to push it in a gear to make sure i dont red line (which is very rare).

If your speedo went out, you'd learn gear/rpm=speed pretty quick. ;)

[rguignard]

well if you have a rev limiter then the tach is not really necessary but with out one i would say yes i like to know what rpm's im turning when trying to get through that big mud hole or up that big hill.

[LizardRunner]

Ok, I've had to rethink my previous thoughts on a tach. Having done a little muddin this weekend I noticed I pay close attention to it when running the revs up. So, for wheeling, I would have to say they are pretty necessary for not over reving the engine. for the street use I still think they are nice but not required.

[ice_cold]

I have the factory set, replace the idiot lights on mine..I did the AW4 mods to give me control off the transmission....sometimes, I think its because of old age, ask my wife, I forget to flick the switch and I am still in 2nd or 3rd, or the converter is manually locked. THE Tach is a quick check...If things dont sound quite right, a quick peek and ...tah dah!!