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Fox FV-721 tachometer removal


DownRange762

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I need to remove the tachometer in my Fox armored car for cleaning and calibration since the needle is sticking. I've pulled the instrument panel and removed what I thought were the two retaining clips on the back of the tachometer housing but I cannot get the tach to come forward through the panel. The mounting system appear similar to that of many other 1960's and 1970's vehicles I've worked on. I've attached a photo showing the rear of the instrument panel.

 

The silver looking "can" is the tach housing and note the two silver threaded rods which have already had the nuts and retaining clips removed. While not shown in the photo, I have removed all of the screws on the back of the tach housing and they are not the cause of the mechanism not coming out of the housing.

 

I suspect the tach on a Ferret is similar, has anyone any suggestions on how to remove?

Wade's iPhone 1923[1].jpg

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This is not at all the same as the tachometer fitted to the Ferret, which has a mechanical tachometer.

 

This tachometer is an impulse type inductive pickup which measures the pulses as the ignition coil is fired. Remove the brass knurled nut and clean all the surfaces, refit ensuring the knurled nut is tight. Ensure there is 24volts at the instrument terminal in addition.

 

If that fails the fault is within the instrument. The front of the instrument has a rubber ring that fits between it and the panel and it is probable that this has "stuck" holding the panel and instrument together.

 

It goes without saying that the engine should run to measure its speed.

 

Diana

 

 

 

I need to remove the tachometer in my Fox armored car for cleaning and calibration since the needle is sticking. I've pulled the instrument panel and removed what I thought were the two retaining clips on the back of the tachometer housing but I cannot get the tach to come forward through the panel. The mounting system appear similar to that of many other 1960's and 1970's vehicles I've worked on. I've attached a photo showing the rear of the instrument panel.

 

The silver looking "can" is the tach housing and note the two silver threaded rods which have already had the nuts and retaining clips removed. While not shown in the photo, I have removed all of the screws on the back of the tach housing and they are not the cause of the mechanism not coming out of the housing.

 

I suspect the tach on a Ferret is similar, has anyone any suggestions on how to remove?

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Ok, thanks for clarifying the differences between the two vehicles regarding type of tachs, mechanical vs. electric, but what I was really after was how to dismount the electric tach from the instrument panel. I wasn't clear that I don't think the tachs are the same, I was asking if their mounting systems were the same. But perhaps not.

 

Your point about the rubber gasket between the bezel and the face of the instrument panel is helpful and I'll do some very gentle prying around the circumference of the bezel.

 

The tach tracks increasing RPM correctly, but upon deceleration/reducing RPMs, the needle sticks and requires a slight tap on the glass for it to drop to the correct position. In talking with the instrument rebuilder, they agree it isn't likely a problem with the electronics, but rather a dirty or worn mechanism so the fix shouldn't be too difficult....for them.

 

Thanks.

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Wade's iPhone 1926.jpgTach successfully removed. Picture of removed tach hopefully will post correctly. The short story is the silver "can" in the first photo is the housing for the tach and it simply was both rusted in place and held in place by an ancient decaying rubber gasket. With a little wiggling it did push through the front of the instrument panel. Now it is off to the repair shop.

Edited by DownRange762
to include photo
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