HBJ8 Tach Conversion

[pkmh]

Folks, My next [possible] ajida in life...

Because my HB8 is negativily grounded, this morning, I finally went ahead cutting and crossing the white [loop] wire to the back side of the tach with hopes that the tach would function again.

I never knew the tach to work since I bought the car a year and a half ago. But according to instructions provided regarding converting the tach, it mentioned how I am to change or convert a ground wire found inside the housing or that which has a resistor.

Just curious to know if any damage is done by performing one task but not the other. No reference to possible harm was mentioned and one conversation I had with another owner, all that was needed was to reverse that one wire.

With that in mind, I only had the car running for a few seconds and then turned it off and reversed the wiring back, until I can get inside the tach housing.

Again, just curious to know if anyone has done this step. I am about to take the glass and dial apart, as the instruction sheet indicates and being careful not to bend the needle they made reference to.

A photo showing the backside of my tach, before having cut and reversed any wires, shown.

Thanks for any input offered.

Paul

 

[Keoke]

Do all the specified electrical changes or it will not work.


Removing the glass can be a chalenge and may require some kind of solvent to free the class.Just do not try to btute force remove it and be sure the black retainer ring tabs have been been bent back to free it too.

 

[pkmh]

Thanks, Keoke.

I will be sure to go slow as I'm taking all apart for I understand it is difficult to replace with exact.

 

[pkmh]

Hello again Forum,

It's been a few days, but I finally managed to successfully remove the Smith tachometer bezel, together with it's glass and seals without any real issues developing. It was necessary the lightly bend up on the bezel locking tabs as necessary to pop off rather than try to rotate the bezel, even after using PB Blaster with a Q-tip numerous times. No damage to bending back the tabs and using the blaster made popping off the bezel a lot easier. Those rubber seals were glued shut to the glass and bezel. What other trick could I have used??

Moving along, I was then able to carefully remove the mechanism after unscrewing the two surface mount screws, (not the recessed screws, as advised NOT TO), from the housing and at the same time, being careful not to cause bending or damage to the needle. I also marked off exactly the loop configuration and placement of that white wire through the raised portion found at the rear of the housing. I felt it necessary to remove in order to remove the mechanism from the housing (or am I misunderstanding something basic?).

I have posted two photos below for ease of reference and hopefully good enough to seek advice regarding completing the conversion process from a positive setup to a negative one. Right now, my tach does not work with the present negative ground setup (as purchased), and am not sure if it ever did work when the car had a positive setup. I must assume it is still capable of working.

From what I've read so far, I understand some de-soldering must be done as well as resoldering, or to suggest reversing certain electrical components is necessary to complete the conversion, but what those components are, I will have to investigate.

Or, if anyone out there has done this and can explain from the photos provided, it would be most helpful.

Thanks so much!

Paul