swapped from 1.6 cluster to 1.8 cluster, tach problems

[im2bad4ya]

I swapped my 92 RS cluster for a GS cluster, since my fuel gauge needle was broken and temp gauge was non-op and am soon going to do a BP swap. So now I have both of these gauges working but the tachometer is not reading properly. It works though, when I rev, it runs up, when idle it stays where it should, but it seems to be miscalibrated. the car redlines at 6.4K but the tach reads somewhere around 4K. Could this be a bad tachometer? If it is, could I swap the old one into this new cluster? Anyone see this before?

BTW, since I've had the car, I never had the speedometer working cause the cable is broken, so that's a non-issue for now until after I do the BP swap.

[Nd4SpdSe]

1.8 cluster from a V6? I can't see it working 100%. I know for aftermarket tachometers, there's a switch on them for 4cyl, v6 and V8's. Now, you'd thing that firing off of say Cyl1 on any motor, that it wouldn't matter how many cylinders the motor had cause going back to firing #1 would be a completely cycle anyway, but I guess not

I don't know of anyone whose done the swap between GS andRS clusters to say if it'll work or not, but from what I've seen in aftermarket gauges, I want to say it won't work correctly.

[cWs306]

Wouldnt it be off because of the different transmissions and everything? your best bet for a new cluster is a junk yard and or ebay for the oh so famous indigo blue/white set that most of us have. haha

[im2bad4ya]

well these gauges were pulled off a MTX which is fine because my car is also MTX. I also read in the Electronics FAQ that all gauges are swappable (save for the cable driven speedo). I was under the impression that a meter is a meter across all platforms, and the difference might not be with the gauge, but maybe in the ECU reading the gauge. but to ND4SpdSe's point, if what he is saying is accurate, I could simply swap my old RS tach into the new gauge, unless the signal reading the tach is built or hardwired into the cluster or the ECU. Anyone else have any input? If not, my next step is to see who might wanna swap gauges, or I''d sell the one's I have first and buy RS gauges after.

[Nd4SpdSe]

The tach doesn't get affected by the trans, it's driven off the coil of the motor anyway.

I also read in the Electronics FAQ that all gauges are swappable (save for the cable driven speedo). I was under the impression that a meter is a meter across all platforms.

That I wasn't aware of. Hopefully I'm wrong.

[MrMazda92]

was this ever resolved?

[Ryan]

This wouldn't be hard to sort out. Print out the copies of the B6 cluster pinout and the GS cluster pinout and match it up. The VSS readings should be the same, the sensors have the same number of teeth, as far as I know.

[MrMazda92]

Well if it's of any issue, I have a few clusters laying around...

[im2bad4ya]

Since the swap I've been using my RS gauge with the wimpy 6.5K redline. It's fine, since it's practical, I know the true redline of the car........but still, I didn't wanna settle for this. So this is what I found out.


The tachometer gauge itself screws on to a circuit board that controls it. As far as you're concerned, the tachometer just reads the signal off the circuit board. So in essence, both tachs are the same, mechanically speaking, and the difference is in the circuit board.

This is the GS tach circuit board:










Both boards are the same with a few exceptions. After swapping the GS tach to the RS circuit board, SUCCESS! It functions properly. So there you have it, no more having to slip on GS indiglow gauges on to RS tachs to get the redline right.

So there are two ways to go about this. You can buy the GS tach and put it on the RS circuit board or if you wanna go the cheaper route and you're good with a soldering iron, just replace the components and you should have the same thing. I took the liberty of making a chart of the differences. I used a multimeter just to make sure the resistors were correct. You can see the notes for resistor R6, but I guess it doesn't make a difference since they're both the same on both circuit boards. All you gotta do is change R7, C3, C7, D1 & D2. Unfortunately I could't figure out the specs on the diodes, just the letters printed on them. If anyone can tell me more and figure out the values, I'd be more than happy to update the chart. You can buy these components at Radio Shack, mouser.com, digikey.com, etc. Also if anyone wants to double check my list, please do so, I want to make sure it's absolutely correct before it becomes the law of the land.

[ethand]

A much simpler option, I would think, is what I did when I broke my fuel/temp gauges. I simply swapped the fuel/temp gauge from the new unit into the old one. Then it worked perfectly. Haha...
There were no issues with things not reading properly, or anything like that. I just took the face off both sets of gauges, unscrewed the 6 screws to the fuel gauge from the back of the unit, and swapped it straight over. I put the old cluster (with the new fuel/temp gauge) into the car. boom. sorted
I figured that swapping the fuel/temp gauge was much simpler than a rev counter, etc., because the rev counter has all the wiring & other crap for the odometer behind it, as well as the speedo gauge.