A different Tach?

Greetings.

I think that most of us are aware of the shortcomings of the Veglia tachometer that came with most 80s - 90s era Fcars.

Can a different tach be hooked up to to the RPM sensor somehow?
I have an 86 TR, and right now mine is not operating correctly at all, and never was very accurate anyway.

Has anyone done this mod? I want to check my idle but the tach doesn't work at idle.

TIA.

 

Someone on this board replaced ALL of the gauges with VDO gauges on a 308, Try a search for VDO.
I think he had to replace all senders with VDO senders to make it work. It was an excellent idea, if you don't mind giving up originality.(I guess it could always be reversed)

 

Well, you can't toss the RPM sensor on the TR or the engine doesn't work.

 

I believe you can replace the tach with any aftermarket unit that will fit. I believe that the only difference is you do not use the sensor on the FI cars. You would hook up the aftermarket tach to the coil as is done with the earlier carb cars. But I don't know if by disconnecting the tach wire from the sensor will not allow the engine to run. So before you go through the process of replacing the tach maybe you should just disconnect the tach wire and see if the engine runs. If so then you are good to go and all you need to do is tape up the disconnected wire and run a new wire to the replacement tach. My thoughts here.

 

I'd be interested in a replacement tach instead of recalibrating the stock one to work with the MSD box I have . . . the "recal" box I bought for $75 doesn't work above 6000-7000 rpm.

I'll check Summit.

Sean

 

My 87 328 GTS tach started reading low, I sent it to Palo Alto Speedometer and they fixed it right up. How accurate do you need? I have never tested it, but would suspect as long as it is within +- 100 rpm that is "close enough".

 

Slightly off topic, but anyone know what dies in the stock ones? Mine was hooked up to an MSD and I think it cooked it. Is there a simple way to test a stock points ignition tach on the bench?

 

Not really if your restriction is "simple" -- need a waveform generator and a power supply (but that still doesn't tell you what range of input signal amplitude the tach electronics are capable of accepting without problems).

Gabriel -- If your multi-meter has a frequency (Hz) capability, you can also determine engine RPM from the flywheel RPM sensor signal (although measuring this when plugged in isn't easy either). Since the ring gear of the flywheel has 146 teeth, 1000 RPM corresponds to 2433 Hz (and for a data point, my tach reads ~10% low at the low side).

 

Kept the speedo and tach as OEM original, but changed their needles to match the VDOs.

See "before" and "after" below.

HIGHLY recommended swap!

Yes, you do need to also use the corresponding VDO sending units for all gauges, and yes, the old OEM Veglia gauge stuff is stored in a box, ready to be installed by some hypothetical fussy "purist" future owner.

Cheers - DM
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So you are writing that the tach is the same with a different needle?

Thanks for the reponses guys, but none of this helps me.
My tach is inoperable and at this time I do not know the cause and cannot set the idle mixture.

 

You need to check the wire that comes off the coil pack............one of those runs the tach.......and if you needed you could use another more reliable tach to set the rpm at idle, mine is a little high, it likes it like that, or maybe my tach is off....no biggy...runs great!

 

Without getting too involved, I have not been able to just check the wires that run into the coil module.
The connectors are very small and my jumpers don't fit onto the pins or receptors.

I'm going to try again, but I failed at making jumper wires fit before, plus I switched the coils and modules left to right with no change.

As far as I can guess, the idle can't be above 300 -500 RPM.
In fact I'm amazed that it will idle at all like that.

 

Why not just assume it is broken, remove and send it out for repair. If it works, they will simply return it.

 

I hate assuming things.

 

I think Summit sells an rpm meter with an induction coil you put over one of the spark plug leads. Easy, accurate. Not sure who makes it...

As an aside, has anyone added an rpm limiter to 12 cylinder car? Not sure if my tach is accurate or not, but there is never a cutout at high rpm. Kind of ruins the driving experience a bit. Hard to drive when accelerating briskly without constantly looking at the tach. Some previous posts mentioned that the TR has a rev limiter built in...but I don't find that to be so, unless my tach is WAY OFF... . The best sound/acceleration seems to happen within a 1000 rpm of redline, and it makes me feel like I am skating on the edge of a razor blade....