[John M]

Well after getting the 78's head back together...I was getting a little bored tonight. So I decided to go after my slow reading tachometer. I had hoped that the speedometer and tachometer on our S4 Spiders had the same type of adjustment screws as seen in the Milanos. Well....the short of it....they do! Hot diggidy Dam! as we say in KY. So here comes the skinny on both!

 

[John M]

First thing you have to do is get the monopod out of the car. You can follow the recommendations of the manual to pull the knee pad, the column cover, and then the entire pod with harnesses.....or if you feel a little dangerous you can do it like I did....just take care of that clear plastic. I didn't take any pictures of this, but its pretty simple. Pop the trim ring off the front of the pod. Contorsion it out from behind the column and out of the way without scratching your gauge cluster face. Then there are just four screws in the corners to release the inner cluster from the pod shell. Once those are out, roll the cluster forward and face down and disconnect the four harnesses. Then contorsion the cluster out from behind the steering wheel. Pushing gently on the monopod shell helps in this step.

 

[John M]

Now seperate the gauge cluster into its two halves. There are four screws to remove highlighted in the picture below.

 

[John M]

So lets start with the tachometer. This type has the air bag light within. There are three screws to remove from behind on the ribbon board. Also the tachometer sits on 3 prongs that are soldered into the board. Lift at the corners to pull the tach off the prongs once the three screws are removed. Eventually the tach comes out in your hand as below.

 

[John M]

Here is picture from the back for reference when removing the tachometer. The three screw holes are highlighted as well as the solder points for the prongs. Its a good idea check these to see if you need to resolder these as I found mine somewhat loose.

 

[John M]

And here is a picture of the three prongs from within the housing once the tach is pulled. Its very important to keep these guys straight for easy reassembly. After all you may have to install and uninstall several times before you get the tach adjusted correctly.

 

[John M]

Once you get the tach out, you will find the adjustment screw on the back. Its got some hot glue on it to keep it from moving. 1.
1. Note the position of the screw.
2. Go ahead and break the screw free of the glue by turning counter clockwise.
3. Turn back and forth a few times to insure a good electrical connection and discover the range of the screw. It turns about 300 degrees total.
4. Now return screw to original position.
5. Turn screw clockwise to increase indicated rpm (a good digital multimeter with tach comes in handy to set it up right from the start).
6. Connect the tach back on to the prongs (note in the picture the female connector for the prongs in the housing)
7. Plug pod half back into its 3 wire harnesses and test to see what your reading is.
8. Repeat 5-7 until you get it right.

 

[John M]

The Speedometer is very similar but easier as better prongs. Speedo comes out like this.

 

[John M]

You remove the speedo with 4 screws noted in the picture below. Make sure to check its prongs soldering too.

 

[John M]

And here are the speedo prongs inside the cluster casing.

 

[John M]

And finally the speedo adjustment screw. I assume clockwise to increase indicated speed if its like the tachometer.

 

[John M]

Thats all there is to it. Finally a tachometer that reads! Post your questions if you have any. Make sure you find the range of the adjustment screws. They can actually go all the way around with out damaging them....or at least my tach did, but I believe its just a sliding scale in about a 300 degree range of turn from least to most aplification.

Almost forgot to say......reverse procedure to reassemble!

Best Regards,
John M

 

[toasterhunter]

Awesome John. Thanks for the tutorial.

I'm definately going to hang onto this for when I've got a running Spider's tach and speedo to fix (they were pretty **** flakey before.)

Will this probably fix a wobbily speedo as well? Mine always shows a range of speeds when running.

'course, I do always enjoy telling people that she's doin' 10 mph sitting still, and won't even start!

 

[texas_spider]

Great info! Does this apply to an '86 spider as well? Got one that reads slow (5th gear, 4k rpm shows about 45 MPH)

 

[John M]

Hey Toaster:

That sounds to me like additional troubles. Could be those prongs if your 86 has the same setup in its monopod. Not much holding the prongs into the circuit board and no support other than the casing. With that said, vibration will ultimately brake the contacts and possibly make it function intermittently. But a hot solder iron will fix that easily and quickly. Other thoughts are sending units. But the more I think about the design, I would check those prongs.

Best Regards,
John M

 

[John M]

Hey Texas:

I don't know for sure, but my bet its the same. One of you two 86 owners crack that puppy open.

Best Regards,
John M

 

[Mr. C.]

John,
That is a lot of work that you have done for the benefit of others.
Wow. As they say in New Yawk, you some kinda cool m***a.

 

[John M]

Hey Mr C:

Actually, I was just sick of my tach reading low. Thought I would snap some pics while in there as I hear this question all the time on these speedos and tachs reading low. I am glad Alfa had the foresight to install a tach/speedo with an adjustment. Otherwise we would all be out of $300 or so. Again, my frugleness shines through!

Best Regards,
John M

 

[Bazza]

Hi there

I have an 89 quad I have just aquired and I my Speedo and Tach are moving slightly(Hardly at all} when I am driving. Odometer works ok. Any clues ?

Cheers

Barry

 

[John M]

Hey Barry:

With both not working hardly at all, my first suggestion is to check the connectors to the pod. There are four mulitpin connectors inside the pod. Make sure those are all on tight and retest her. If not, I would give my try a fix. I suspect that due to vibration or corrosion these speedos and tachs come out of adjustment. There is a calibration screw to adjust both. And they were hot glued into position when calibrated. You have to disassemble the pod to get at them and calibrate. Once calibrated....glue the adjustment screws in place. That's all there is to it.

The speedo on a quad has a pulse generator like that on a series 4. You should see a three wire connector near the brake booster and O2 sensor wire connectors. If the color coding is the same...the speedo to pulse gen connector has a pink, grey, and black wire. Make sure you pull that connector and fill with dielectric grease.

If you cannot get them up via the calibration screws....then Palo Alto does rebuild these units. I don't have their contact info...but I bet someone does.

Hope this helps,

John M