Are these tachometers interchangeable???
 

I have an '86 560SL - two piece clock/tach gauge of course, and I'm wondering if these tachs are interchangeable with other models? I have found several clock/tach gauges on W124's and W126's at my local pull-a-part...

I know the instrument clusters are different, but can I swap out just the tach mechanism?

ryan

I think a W116 is the same as the R107.

Problem is the circuit board will be a different shape, and this will have an effect on just about every aspect of the instrument panel from connectors to lights.

Jim

Let me be a little clearer - sorry. All I need is the tach mechanism, I'm just planning on swapping out the guts. I've been looking at ones listed on ebay and am wondering if all of the 7000 rpm's are basically the same?? Mine redlines at 6000 and many of the W124 and W126's do the same, and it looks like the W126 mount the same to the back plate.

ryan

OK, I replaced just the tach "guts" from a pull-a-part W126, or maybe a 190E (I pulled 2 and don't know for sure which is which now). They were both 7000 rpm and were stamped with 004, which is the same as mine from my 560SL. The circuit board was shaped a little differently, but all the components looked the same. I removed just the tach mechanism and installed it on my 560SL plate with my original clock. Fired up the car and the needle shows the car idling right, but when I punch the gas, the needle only goes to about 1300 rpm, or so.

So, it works at idle but won't work on acceleration - any ideas? I was very careful with the needle this time and didn't push it on too hard - either you can't interchange these because some signal, or the tach itself is different; OR whenever you pull the needle off, it is hard to get it back without maybe bending something inside the mechanism??? Anyone had this problem before?

I don't know, although the needle moved smoothly and returned to 0 before I put everything back together.

ryan

It sounds like you installed a tach from a 6 cylinder. Your car is an 8 cylinder, correct?

Yes, mine is an 8 cyl - I guess that might make a difference???

yep, you probably have a 6 cylinder tach on your hands. Take look on the back of the tach, it will say, 6 cyl or 8cyl.

Man! I thought I checked on that, but clearly I didn't look close enough!

Anyone have a spare clock/tach laying around?
For an 8 cyl?

Will any 8 cylinder one interchange? What are some options here as far as models go?

ryan

yes, a 8 cyl tach will work.

What did the tach come off of at the yard? A w126 or a W201?

I know one came off of a 190E (W201), but I'm not sure about the other - it was either a W126 or a W124. I just didn't pay enough attention - I was in a hurry!

The two that I got look exactly the same though - their circuit boards are shaped the same, while my old one is a different shape.

As long has 8cyl on the back of the tach then the tach motor will fit in yours. The backs will look different but the tach motor itself will work.

None of these have anything stamped on the back like that...

I need to find a web page that lists mercedes model information...

I think they are basically the same, but different voltages or resistance or something that distinguishes them between 4, 6 or 8 cylinder. I had put a little sunpro tach on my van to see what RPM's it could do, and it had a switch to apply it to a 4,6 or 8 cylinder car.