i'd do 50-75 the slowly move up 1 dollar at a time lol

 

So this isn't really all that helpful, but today I pulled the tach sensor off a truck at the junkyard. I'm going to use it to replace the one on my truck (which works but has an unshielded/partly pulled out wire). If anyone wants the tach sensor that I'm taking off my truck (assuming the one I pulled today works) then I can drop it in the mail. PM me if you want it.

 

Thanks but I do already have a new one on the shelve, I am just missing the cluster. So far no luck.

 

I checked my junkyards again with no luck.

But curiosity got the better of me and I decided to grab the 4,000 rpm tach out of the F700. I posted on a thread in the 80-86 forum and on oil burners to see if anyone ever got one to work with a diesel input. I made quite the *** out of myself exposing just how ignorant I was about how tachs work, and how absurd of a question that was. But I ended up learning something...

Hall effect gas tach sensors pulse once per cylinder every other crank revolution, so the number of cylinders divided by 2. Gas V8 tach receives 4 pulses per crank revolution. IDI tach reads off the IP gear which has 53 teeth, 52 valleys. It revolves once for every two crank revolutions, so the tach receives 26 pulses per crank revolution. 26 vs. 4, not close at all. Diesel input on a gas tach would peg it immediately at idle.

I gave up. I saw some threads on how to completely rewire the circuits on VW tachs to make them read correctly with an alternator input, but nothing for other diesel applications except buy some expensive signal converting computer from Dakota digital.

Then I got a tip from OBN. One guy said you can use a gas tach by building a bracket and mounting just about any 2 wire crank position sensor or ABS sensor so that it reads the four bolt heads on the crankshaft pulley. Boom, 4 pulses per revolution. I googled that, and the threads came pouring in. Many, many diesel swap, now how do I get the tach to work kind of threads. All were variations on this theme. How to make gas tach work with diesel. This is not a perfect science, most of the home made set ups require fiddling and adjusting things to get them reading correctly, but that is to be expected from home engineering.

Jan, I know you probably want to hold out for the correct tach. I am mostly hi-jacking this thread for the benefit of the other readers looking for this same rare tach. You can use a gas 6,000 rpm tach but it may be a little noisy. The 300 I-6 guys complain of this even with the correct 6,000 rpm factory tach. But if you can't find a diesel tach, look at the large F600-F900 trucks in your junkyard. They had 4,000 rpm tachs that would be perfect for a stock 6.9/7.3 IP governed at 3,800 if you built a crank pulley bolt sensor system. Here is the one I pulled from a 1980 F700. If I get the chance I might play around with it just for amusement and my own personal education on tachs.

 

I am starting to think all this forum chatter has inflated the eBay market. Here is a really nice cluster that would be perfect, diesel tach, km speedometer and odometer with trip odometer, for manual transmission. Even red line and orange needles not faded too much BUT $300 HOLY S***!!!

http://m.ebay.com/itm/221749095198?nav=SEARCH

 

^^^^ Hmm, maybe I'll offer $100, just as a joke. And if he takes it, I'll swap my MPH speedo into it, and send the km/h speedo head to Jan.

 

Well, it was not exactly cheap but putting a tach in a 85-86 truck that has the wiring and IP gear housing port was ~super easy. Sensor, printed circuit film, tach unit, done!






(Video)

 

And the sweetest part is it is in my truck. Thank you Jonathan

 

You are welcome. I think you are going to really like it. You know, searching down some of these 7th generation diesel parts has given me a whole new appreciation for what I happen to have in my truck, and an inspiration to make it into something nice. I will miss your truck when it is gone, it really is a beautiful time capsule.

 

Great news Jan. By the way, here's an eBay listing for a speedometer head that claims to be a KPH - 83 84 85 86 Ford F150 Speedometer Head Only KPH from 11 82 w O Trip Odometer | eBay . I would message the seller and get a pic of the actual part just to be sure.

I'm envious! Fellow member sent me a FREE tach sensor, and I ordered what SHOULD have been a tach diesel cluster from a junkyard in Oregon last week (even the pic showed a tach dash). Must've been some mixup, because the one that arrived was a no-tach dash. Still waiting for that to get all ironed out.

 

Thanks for the info, but I am fine with the index kph under miles, it is american truck, so miles should be there right? I am waiting for the captain chairs from Idaho, hope it works out, even the matching colour and fabric, I am so excited. Now I only need alu rims and all is nice and set.

 

So the wiring was in place, correct? It didn't make sense that there'd be a different wiring harness, but you never know what a manufacture is thinking.

 

Correct. The wiring was already there. But 1983 and 1984 diesels did not have a tach option, and their wiring harness was different. They also lack the threaded plug for the sensor in the IP gear housing. On 80-86 gas trucks the tach wiring is there except if you have a truck with warning lights instead of gauges.

 

That makes sense, and it explains the why of why do some 6.9's have the plug and some don't.
Good info there.

 

This also explains why these diesel tachs are so darn scarce. They were only used for two years (85 & 86) and only in manual transmission trucks (and that was optional).

Even over those two years Ford managed to produce two versions of diesel tachs. The early ones had non-integrated circuitry and an enclosed case, the newer ones had integrated circuits and an exposed circuit board. It has fewer moving parts and is the more desirable one. The paint they used for the redline zones was different, or at least faded differently. If you only saw a picture of the face you might be able to tell the older style by the yellow zone still being visible as a dirty tan whereas the newer style bleaches out worse than the red.








Haven't had enough trivia? How about the two different WTS lights found in these trucks?