Replacing or Repairing Parts
I will refer to gauge dash as the “dash” to make it simpler and not meaning the main metal dash which is completely different ball game. there will be a different range of pics to explain the scenarios even when i hadn’t rebuilt the back of the dash. The wires were not all correct so I have to assume your dash loom is correct and working OK.
The dash is held in place by six screws, four at the top and two at the bottom. At this point note that the screws are fitted at an angle and NOT straight in or straight up.
This walk through I will split into sections, gauges, speedo, bulbs, and regulator, skip to the part you need.
Two important points:
Firstly disconnect the battery, if you still have the Ammeter in place this is a direct feed from the battery and you could short something out.
Secondly cover up the steering column, if you don’t you stand a very good change of chipping the column paint job.
Generic process for removal:
Undo the all the screws for the dash while in the main dash, I found the best way was to start at the bottom and then work to the top.
Depending how small your hands are you can either put your hand up the back of the dash to find the speedo cable bolt and undo it if you’re lucky. Or, the chances are you might not be able to undo it by hand so you will have to go with the second option – Pull the dash forward a little to leave a space and get a spanner on the nut and undo it. Pull the cable case away from the dash making sure the inner part cable comes out with it. This is the second most tricky part about this job. Pull the dash out a little more from the main dash.
Important Note: Mark up where all the wires are fitted to the gauges from the senders so you know where to replace them when you refit the dash. Remove the wires from the gauges not the dash pigtail. These wires can be seen coming in from the loom itself.
Place the dash face down and undo the screws around the outside of the case.
GENTLY lift the metal case of the back to expose the gauges.
Do NOT touch the dial needles as they are very fragile, do NOT use solvents on the dial faces or you could damage the lettering on the faces. If you have to clean them use a very soft small make up brush or modelling brush.
Move the lens out-of-the-way and gently place the dash onto a soft surface. Depending on what gauge you want to remove they are held in place by two nuts on an insulating pad. between the live feed and the resistance wire from the sender, oil, water or fuel. The Ammeter has its own separate Red & Yellow wires to make that gauge work. With the wires removed and the bulbs holders removed you can clearly see the beige insulating pad.
Undo the nuts and hold the gauge in place until you tip the dash back to expose the face of the gauges again. Now gently remove the gauge.
To replace the gauges this is an exact reverse with a very careful fitting. Take your new gauge and insert into the dash back. Turn over slightly to apply the insulating strip and very lightly finger tight the nut to the pad as you will have to move it in a bit.
With the dash face down again look at the position of your new gauge. this MUST be in the middle of the cut out slot on the back metal part of the case. No metal part of the gauge threaded posts must touch the rear of the dash. IF you do leave it like that, it will earth out and none of the gauges will work correctly. Then the voltage step down regulator will get hot and burn out with a possibility of damaging all the gauges. You must be very careful and patient at this refitting stage. With the gauge in place, tighten up both the nuts to a little nip. Do NOT overtighten as this could move the gauge and earth out again on the posts.
All three of the gauges are the same process, the ammeter has a slightly different shape but the principle is the same.
If you wish to remove the speedo there are an additional two screws at the top and bottom of the speedo cable connection point. The principle is exactly the same here, undo the back, hold in place until you can hold the front and remove it from the dash back.
To refit the speedo slide the speedo back into the case and insert the screws inside the recessed grommets and tighten up. These screws can be a little tighter than the gauge nuts.
Optional Advanced Gauge Project:
If you wish to swap the Ammeter out with a voltmeter I have done this conversion and it can be found by clicking here, or looking at How to Projects/Electrical/ Ammeter to volt meter conversion.
I will not repeat myself again on this page for that, but it involves cutting and making holes in the back of the dash case. You may well end up modifying your wire loom. But, it looks great once it’s done.
Generic process for refit of dash case:
The front lens can be replaced by simply swapping over, making sure the lens is inserted the correct way. You can even change the front of the dash at this point if you need too, or even both as I did. the old one obviously at the bottom for comparison.
Fitting the dash back in place is delicate as the indicator bulbs need to fit inside a cardboard tube to keep the light from polluting the rest of the gauges at the back. Gently lower the case down and align to the holes to the front of the dash. Starting from the centre and working out, insert the screws and tighten down evenly. Do NOT over tighten or you will hear a nice crack from the brittle dash case! I’ve done it.
To replace the bulbs you do not need to open the dash up. The bulbs are held in place by a series of holders that just push into the back of the case. Here you can see part of the loom pig tail wires still attached to the bulb holders. The live feed goes to the back of the holder and the earth is to the holder itself in the dash.
Find the blown bulb, pull the holder out from the back of the dash case by rocking it out from side to side(s). Press in the bulb in and twist out just like any other bayonet fitting bulbs. Replace the bulb and press the holder back into the case. This is a twenty-second job.
To replace the stock bulbs with the LED upgrades click here.
Instrument Voltage Regulator:
This is a critical part of the dash, if this blows there is no gauges. If you try to make a direct feed to the gauges with the 12v live feed you will obliterate the delicate gauges. You have been warned. The Oil, Water & Fuel all work form a 5v feed from the regulator and this regulator part is an expensive for what it is! From the pic above you can see the square looking box part in the top right corner, this will have a 12v feed in from the loom, the output is then reduced to 5v which then feeds the live part of the gauges from the same pig tail. The regulator has a male and female terminals and these correspond with the wire loom so you shouldn’t get it wrong. The ammeter has its own live feed and return direct from the live part of the loom. Ammeters are very old school and tend to burn out without showing too much information anyway. Hence my swap out to something more reliable and accurate like the volt meter, see above or by clicking here. There are many variations on the market for this part, OEM, Chinese made, Scott Drake or a special custom-made one like I have here with a built-in heat sync and LED to show it’s working. The quality will vary, you pay your money and take your chances with this part. I strongly advise to get a high quality replacement.
The regulator is earthed out to the back of the case. Now you can see why the alignment of the gauges is critical not to short out to the case.
Generic process for refitting back into the main dash:
There are clips on the main dash area that fit over cut outs, make sure the clips are in place and not pinged of as they can have a habit of doing when removing the dash. If you are running a voltmeter I used the switched live from the ignition and a separate earth to the chassis. Connect your wires up to the voltage regulator, and clip the wires for the gauges back in place. For my re-wire job I made a quick disconnect block, that has all the wires running into it from the loom, then the corresponding fitting has the wires to the gauges, bulbs, regulator and earth. This just plugs in and works. Most original looms will need to be plugged back into the gauges as they were removed. Refer to your notes or get a proper colour wire diagram to help you.
You should be able to rest the gauge on the column ready for the next tricky bit.
With the wires connected the worst part is to attach the speedo cable, this is a small hand job to reach behind and insert the square centre and the retaining collar nut. The speedo cable is quite inflexible so I found that by moving the cable under the dash you can angle the dash into the correct position. you will have to try what ever works for you, even hand under the dash reaching up if you can. With the speedo cable in place I would suggest checking the changes have worked before screwing everything call back in place. all is ok insert the retaining screws only to grab the first turn to allow any movement that you may need to align up[ correctly. With all the screws in place complete the tighten up and make sure not to over tighten the dash for fear of cracking the mounts, as my old dash had done.
Not a difficult job but fiddle to refit the speedo. The gauges are critical for alignment. Total time to remove, change and refit was about hour to hour and a half.