Speedometer solutions

[Guest RisqueRace?]

I have recently finished installing a 97 LT1 automatic in my 77Z this last Aug. Performance is stellar. I am very happy so far with this swap.

 

I had an instrumentation problem to overcome and did not want to change the stock appearance of the gauges( I love the 160 mph speedo) or lose the side indicators like the turn signal arrows or the brake and headlight dim indicators. I went off to a local instrument shop to see what it would take/cost to rebuild the two large Gauge assemblies with "updated guts" that will work with the electronic speed output of the tranny. Also regut the tach. Well, lets just say it takes time to convert these and time is money. He set me up with a computer box that converts the trans signal to a mechanical output to a speedo cable and is infinatly adjustable to any gear/tire combo out there.

 

This thing is kind of spendy but I can say it works Great. http://www.atrol.com/cx_era.htm

 

The LT1 has a tach drive tap that is not used right on the coil itself. It is the third pin that is not used on these newer LT1's Get a pin installed here and send this off through a 15k ohm resistor, as JTR states, and then to the stock datsun tachometer. Now you'll have to calibrate it against a known accurate V-8 tach. Do not hook up signal to both tachs at the same time. You'll have to switch back and forth adjusting the datsun tach as you go till they read the same. Also do not adjust the datsun tach with the key in the ON position. JTR spells this out clearly. So you'll have to take readings from both at a givin rpm,shut down(Key OFF), make a tweak to the datsun tach,fire up, compare tachs one at a time, shut down (key off) make another tweak, etc. I had no problem transferring the signal wire while the engine was running. just make sure to shut off before adjusting the cal screw on the datsun tach.

 

My speedo is right on and so is my tach. All the stock instruments are functional cept the dang clock. Also when I get to changing my suspension and decide on my tire size or ever change the tire size/gear ratio I simply recal the cableX box.

 

Just thought someone would like to know.

 

Bruce

[Dan Juday]

Thanks Bruce,

We had the same dilemma when we did the LT1 Tomahawk. Ended up going with the Autometer Sport Comp tach and speedo. Close match to the stock Datsun gauges only with orange/red needles instead of white. Speedo goes to 160 and tack to a ridiculous 10k.

 

The indicator lights got replaced with LED's. Two new ones were added: one for the PCM and one for a low oil level light since the LT1 has a float switch in the oil pan. Not too difficult since the Tomahawk has a removable fiberglass dash cover. I should have got pics before I delivered it, dang.

[Bishopsrock]

Thanks Bruce, your post from 2003 just helped me now in 2008!

 

I checked the Atrol website and they are still in business making the speedo adapter - they call it 'cable x'.

 

My conversion is the RB26 with a RB25DET tranny. I am making a total sleeper and so need the complete stock look to avoid letting the cat out of the bag - this product seems to be just what I need.

 

I have emailed Atrol for a quote so lets hope they will ship to the UK.

 

Cheers

[RUSSJZ-ZED]

Thanks Bruce, your post from 2003 just helped me now in 2008!

My conversion is the RB26 with a RB25DET tranny. I am making a total sleeper and so need the complete stock look to avoid letting the cat out of the bag

 

 

Instead of trying to make 30 plus year old primitive instruments work with modern ignition systems check out the modern stuff , it will work better.

the autometer Danjuday mentions that look close to original are one option. I used VDO cockpit series ,push button calibration/ programable over a measured distance available in 8000 and 10000 tacho's with matching speedo in either miles or kilometers 200K, 300K ,120MPH, 160MPH, easy to run off your ECU, I used the 8000RPM and 200K speedo because I don't like the idea of being in a 32 year old Dat, going past those pair of numbers!

Gotta be better than those Dat items that I suspect are powered by small insects(not getting any better with age either)

Fitting easy, I used them on a 1JZ conversion(Toyota powered section)

Not expensive either, cost $400 Australian the pair.probably about what it would cost to re-jig the originals (which would be sort of like attempting mouth to mouth resussitation after rigor mortis has set in.)

Pics of how to do/what they look like on the link to pic's below