Converting Speedometer to Electric Drive

[Craig]

My ITI odometer gears stripped out and I can't find any way of repairing it. I would like to keep the bike somewhat saleable, which means replacing with a bike speedo won't cut it. The plan is to use VDO 80mm Speedo and Tach. The instruments should fit in the gauge cluster without too much persuasion. The trick will be to interface a hall effect drive to the bike. The first attempt will be a GM Hall effect drive available from many places. In this case eBay $20 shipped.

 

The first problem is to adapt the threads. The GM sender is a female 7/8-18" thread, which is very unusual. Luckily I have a lathe and a modicum of machining skill, so I will machine an adapter. The bigger problem will be fitting the sender and associated wiring beneath the throttle linkage. There is very little room as this picture shows:

 

When the throttle is wide open the fitting only clears the top of the sender by 1mm or so. Once I have the adapter machined I will cut down the skirt around the connector pins and solder leads directly. This will allow me to increase the clearance by 10mm which should be plenty. I will put a weather pack connector closer to the meter to allow for disconnection later.

 

This has been done on a different model of Guzzi, and was documented here. Luckily for him his speedo drive was further aft and only interfered with non-moving parts.

[pasotibbs]

My ITI odometer gears stripped out and I can't find any way of repairing it. I would like to keep the bike somewhat saleable, which means replacing with a bike speedo won't cut it. The plan is to use VDO 80mm Speedo and Tach. The instruments should fit in the gauge cluster without too much persuasion. The trick will be to interface a hall effect drive to the bike. The first attempt will be a GM Hall effect drive available from many places. In this case eBay $20 shipped.

 

The first problem is to adapt the threads. The GM sender is a female 7/8-18" thread, which is very unusual. Luckily I have a lathe and a modicum of machining skill, so I will machine an adapter. The bigger problem will be fitting the sender and associated wiring beneath the throttle linkage. There is very little room as this picture shows:

 

When the throttle is wide open the fitting only clears the top of the sender by 1mm or so. Once I have the adapter machined I will cut down the skirt around the connector pins and solder leads directly. This will allow me to increase the clearance by 10mm which should be plenty. I will put a weather pack connector closer to the meter to allow for disconnection later.

 

This has been done on a different model of Guzzi, and was documented here. Luckily for him his speedo drive was further aft and only interfered with non-moving parts.

I think somebody here got around this problem by having a short drive cable made so that the sender could be positioned out of harms way,but your way could be better.

[Craig]

I think somebody here got around this problem by having a short drive cable made so that the sender could be positioned out of harms way,but your way could be better.

 

I found a right angle drive on eBay that should obviate the need for heroics with the electrical side. It has the same 7/8-18 threads as the GM sende so I still need to machine an adapter.

 

Plan B is to modify the speedo cable to drive the new sender.

[guzzi323]

Well if plan B fails you can do what I did as your plan C. I used an Autometer speedometer but this hall sensor would probably work for your VDO gauge as well.

This is from an older thread on speedo replacement here..http://www.v11lemans.com/forums/index.php?showtopic=16879

 

I put a white faced Autometer speedo on my Scura and use an industrial hall sensor to run it.

The Autometer speedo is not designed for 'outdoor' use and it does get moisture in it. So far this hasn't been a problem beyong the face fogging up.

If I recall correctly the housing even had a little drain hole in it.

It's a white faced with (non fading, I might add) flourescent needle with a chrome bezel. It's a resonably close match for the original

I used the sensor number GS100502 on this page to drive it.

http://www.cherrycor...gs1005_1009.htm

 

If you read through the little bit of technical info on that page it mentions using a pull up resistor which I didn't do initially and I got a bit of electrical noise that made it occaisionally behave more like a tach than a speedo.

Once I installed the pull up resistor it's been great.

 

I drilled a hole in the rear brake hanger and positioned the sensor to read the heads of the disc mounting bolts. It's only 6 pulses per revolution but it works at anything over 5 mph.

 

Good luck.

johnk

[Craig]

Well if plan B fails you can do what I did as your plan C. I used an Autometer speedometer but this hall sensor would probably work for your VDO gauge as well.

This is from an older thread on speedo replacement here..http://www.v11lemans.com/forums/index.php?showtopic=16879

 

 

Plan C is to fit a speed sensor to the wheels, I just want the extra resolution at low speeds you get by coming off the transmission.

[Craig]

 

I found a right angle drive on eBay that should obviate the need for heroics with the electrical side. It has the same 7/8-18 threads as the GM sender so I still need to machine an adapter.

 

Plan B is to modify the speedo cable to drive the new sender.

 

I am back from vacation and started in yesterday. Right now I am on Plan A and a half. The right angle drive was about two millimeters two tall to clear the throttle connecting rod. And even if it cleared the sensor wouldn't clear the seat removal lock barrel.

 

So I am modifying the top of the GM sensor to allow the electrical connections to bend over and clear the throttle connecting rod. After I cut the quick connector skirt off the sensor, I soldered wires to the terminals and covered them with heat shrink and liquid electrical insulation for added isolation. Once I have the sensor completely screwed down I will gently bend the terminals over toward the center of the bike (I am not sure how the sensor will be clocked once it is completely tightened).

 

 

Here is the start of the wiring harness. I will be using the old speedo and tach illumination terminals to provide switched power, and run another line direct from the battery (fused of course) to provide hot power to the clocks in the new instruments. This is probably a good time to add headlight relays "while I'm here" (the four words that signal the initial descent into project hell)...

 

[Craig]

It's done. The install took a bit longer than it should have due to some learning experiences. First, the finished product:

The gauges look OEM, and work better. The two buttons below the meters control the modes for the LCD displays. The speedo has ODO, Trip ODO, Voltage, and a Clock. The Tach has total hours, trip hours, voltage and clock.

The only drawback is that the plastic housing will not fit over the rear of the gauges. I wasn't able to find adequate gauges in the diameter the originals came in. The metal plate that holds the instruments was exactly the correct size to hold the larger gauges without the rubber insulators use with the ITI meter.

 

My next project will be to splash a fiberglass cover to hide the guts.

 

If you go down this road, here is the first critical lesson. The GM sending unit has a small flange at the base of the input spindle. If you don't have adequate space it will seize and snap the input shaft:

 

This took a while to figure out since I checked all the circuitry before I installed the sender unit on the trans. The ultimate solution involved machining a slightly different adapter that had adequate clearance at the top.

 

The second lesson is that the sending units are fairly sensitive to solder heat. I tried to solder leads and destroyed one sender (that's my theory for now, I was a bit ham-handed when I solder the ground lead on).

 

The accuracy is great and I have very good speed resolution at low speeds. The tach has a bit too much damping, but I can live with it.

 

The proper calibration pulse count for the speedometer is 35449 counts per mile, which is very close to what I predicted based on measuring the turns of the speedo cable over 1/100 mile as recommended by Palo Alto Speedometer. 22.1 turns X 16 pulse/rev *100 = 35360

 

The GM sending unit easily drives the positive input to the speedo and the signal line to the ITI tach drives the VDO Tach set for 2 pulses per rev.

[Distilled Waters Run Deep]

New to this, looks likely I'll fit an Acewell single pod I'm having trouble inserting images & links to their site, sorry...

They make an electronic speedo cable adaptor for Guzzis...

I've seen on previous posts that the Cali fuel sensor is a simple on/off affair, does anyone know of a better replacement or if it will be feasible to fit the acewell sensor?

[Craig]

New to this, looks likely I'll fit an Acewell single pod

 

 

I'm having trouble inserting images & links to their site, sorry...

They make an electronic speedo cable adaptor for Guzzis...

I've seen on previous posts that the Cali fuel sensor is a simple on/off affair, does anyone know of a better replacement or if it will be feasible to fit the acewell sensor?

 

That looks like a nice piece of kit. Acewell is hard to get in the US so I didn't look into them much. You might want to ask this question in the Technical section. I doubt anyone who isn't interested in the VDO gauge set up will see it here

[Distilled Waters Run Deep]

Cheers Craig -I gather they do overseas shipping at reasonable cost. I'll copy to the tech section, as you suggest.

 

BW Phil

[rex007can]

I just finished installing the Koso RX1N, works well.

I intend to install a micro relay/opto coupler /ssr to get the fuel gauge working properly, shouldn't be too difficult. I have 5 long months of winter to get it done...

 

[gstallons]

Looks pretty good. How 'bout a closer shot?

[rex007can]

I used the mounts from the old/broken dials, removed the spacer and screwed them directly into the tree. I figured the rubbers would work well.

Then I used flat bars to attach the koso bracket to the rubbers.

Works pretty well. I plan on replacing the screws and washers with something nicer, but the position is perfect.

[Orange Guzzi]

Plan D. I used the VDO. Used a Sigma bike speedo pickup. Ran wire from speedo to rear brake rotor area and mounted to the brake caliper. Used 4 magnets from Home Depot mounted with jb weld into the rear brake rotor. Equally space. Cheap, easy and fast fix.

[felix42o]

Craig,

Those guages look nice in there.

With regards to the hall effect sensor, I found this one which looks to be lower profile.

 

 

What type of adapter did you need to fit the oddball GM female threads onto the Guzzi male side?

 

-Brian