speedometer and tach gauge removal

[Rok]

can anyone tell me how to remove the speedo and the tachometer... have everything out and rebuilt as far left as the cigar lighter and im hung up

thx
rok

[Rolf-Dieter ✝︎]

Rok,

Go here and have a read ---> http://www.sl113.org/wiki/Electrical/RevCounter

[garymand]

Hi Rok,  This is a bear,  and you can't drop the steering wheel until you get the gauges out and dropping the wheel is only important for r&r of the ignition switch.  I just did this twice on my 250.  You have to get on your back with feet up, see where the speedo cable is and disconnectit.  hope that the last guy didn't over tighten the cable.  There are pull-out lights and a gasket around the guage.  PA speedo has cheap replacement gaskets.  One of the suppliers has all three at a good price.  To get to the Tach, you need to pull the guage cluster next by reaching thru the speedo hole and then reach thru the cluster hole to get the tach out. 

Now you might want to consider pulling the radio, clock & glovebox so you can refinish your wood. And pull uyou dash covers if they need refurbishing.  For me, it ws bight the bullet time: my ignition switch broke loose from its metal housing and my dash cover needed replacement.

[Garry]

And be very careful when pulling the centre cluster out that you dont damage the capillary tubes attached to the gauges.

Garry

[garymand]

Good point.  I much prefer to unscrew the guage if you are planning on doing much in the dashboard.  Its a good time to replace all the light bulbs too.  The oil pressure is removed with a wrench, the temp guage with 2 little screws.  That is the one not to kink.

[pj]

Reading about how difficult all this work is behind the dash, I wonder if any creative shop genius has come up with a permanent solution. Heck, we can squeeze a big V8 under the hood, we can put in limited slip differentials, give the car cruise control or EFI, and on and on with all the lovely upgrades. What about some kind of hinge or outer flange on the dash that could be opened easily to permit access to the gauges and other critical gear behind there? I guess modern cars don't care about this sort of innovation because, even if something minor happens, you just toss out the whole thing and replace the module. But for us, we know we are going to need access behind the dash over and over again through the years, so why not make it accessible somehow?

[stickandrudderman]

The easiest way to do this is to remove the chrome vent/grill next to the A post, remove the three screws that hold the duct behind it in place and then you can reach in to remove tach/cluster/speedo.
The whole lot can be done in half and hour with no contortionism required, especially if you remove the steering wheel first.
The only difficult part is in getting the chrome grill off without breaking the studs.

[ja17]

Never tried it that way Stick, I'll will give it a try next time!

The sequence I follow is:
*Remove steering wheel (center pad, then 22mm nut, then wheel, notice and make note of the indexing mark on the end of the steering column))
*Remove dash pad lower left (three screws).
* Unplug the wire harnesses and remove bracket holding wiring harness plugs under dash and move it aside (two screws)
*Reach up into dash and dis-connect small round duct tube going to dash vent and move out of way (just pops off remove one end only)
*Unfasten tachometer cable (round knurled collar around cable )
*Unfasten tach bracket knurled thumb nut holding tack in place ( try using wearing some thin leather driving gloves if the nut is very tight)
*Remove the RPM Gauge from the front of the dash (notice the brown wire with the ring terminal was attached to the tach mounting stud)
  (don't forget to re-attach this wire during re-assembly)
*Simply pull the light bulb sockets with wires out of the gauge.
*Next move to the center cluster (be gentile with the capillary tube attached to the back of the temp gauge.
*Unfasten the 10mm fitting holding the oil line to the oil pressure gauge. ( do not start engine with line dis-connected or oil shower will begin)
*Remove the knurled nuts holding the center cluster in place.
*Center cluster can be move far enough out of the dash to move onto speedometer with capillary tube still connected.
**If you wish to remove the center cluster all-together, the back part of the center cluster can be removed by also unfastening the small knurled nuts and the small slotted  screws on the back of the cluster. The back section can now be lifted off.  The engine temperature gauge can now be removed by unfastening its two mounting screws. Leave the temperature gauge attached to its capillary tube and leave it at the dash.  You can tie a plastic bag around it to protect the fragile needle if yo like. Again be gentile with the capillary tube.The center cluster can now be removed from the car. Take this opportunity to check the lighting rheostat and all the bulbs.
*Next remove the knurled collar around the speedometer cable
*Remove the knurled thumb screw holding the speedometer and  bracket in place (notice the brown wire with ring terminal also fastened underneath)
*Remove the speedometer.
*Simply pull the light bulb sockets with wires out of the gauge.

re-assemble in reverse order

Some tips... don't forget the brown ground wire under the small knurled thumb screws ! Ask questions as needed.
 

[jan lauwers]

I have just placed a new temp gauge and what I have read here about clock removal has been of GREAT help. I have taken the opportunity of cleaning the clocks and I have replaced the light bulbs. In an attempt to do something back for all the help that I have found here, I'd like to share my experiences, hoping that it is useful to somebody one day.

As we all know, the tachometer is the most difficult, since it is the first one to come out and the last one to go back in, so that one can only access it with one hand behind the dash, not from the front. My right hand still hurts!. Here is what I found:

1/ The brown mass cable on the tach can also be fixed with 2 little nuts and an O connection on the same axle. This gives the benefit that it can be fixed from the front, before the clock goes back in, so that you don't have to struggle with the knurled nut AND the earth cable all between 2 fingers of your hand squeezed behind the dash. If you do it this way, make sure that the mass cable is fixed as deep as possible on the threaded axle, (close to the back of the instrument). If not, it may prevent the bracket from bowing deep enough to be fixed firmly against the back of the dash plate.

2/ I replaced the knurled nut by a wing nut. This has the benefit of being somewhat easier to hold and to turn between 2 fingers when you are struggling to fix it on the axle on the back of the tach. 

3/ I had a short circuit when I had fixed it for the first time, causing fuse 7 to pop. The shortcut was caused by the + of one light bulb touching the bracket which is -. Make sure that bracket is turned just that little bit anti clockwise so that it does not touch the + poole of the bulb(s). As a precaution I put insulation tape around the bracket on the area that comes close to the bulb(s).

I hope this is somewhat helpful to others. Nevertheless, this will always be the kind of job on our beloved cars that is hard to do without a decent amount of swearing. 

Have fun!

Jan, from Geel in Belgium.

280 SL from 1969
 

 
   

[ctaylor738]

I thought i would add to this that several times I have painstakingly positioned the bracket on the back of the tach, put the ground wire on the threaded rod, carefully positioned the knurled nut, and DROPPED IT.  There is no rhyme nor reason where it will end up, except that it will NOT fall to the floor where you can simply pick it up.  Occasionally I got lucky and could find it with my fingers or fish it with a magnet.  Most of the time I had to take the tach out and a couple of times I had to remove the light switch to find it.

So yesterday I was installing a rebuilt tach in a 250SL.  Before I put the nut on, I tied a 12" piece of dental floss around it with a slip knot and then put a piece of masking tape around it.  I positioned the nut, and dropped it.  I then extracted my hand, used the string to recover the nut.  Second time was the charm.