Transmission Speedo Gear

[lotushans]

Hi

I`am looking for a Transmission Speedo Gear with 12 toth. I think it is a 336 Transmission, but i´am not sure.
It is a Lotus Europa 1969 4 Speed. Does anybody knows from where i can get one.

Thank you

Hannes

[BDA]

If you can't find one, I can recommend going to and electronic speedo with a GPS input. Smiths makes an electronic speedo that is pretty similar to the original (there are other manufacturers as well and some customizable - e.g. http://www.speedhut.com/gauge/GR338-GPS-01/1/GPS-Speedometer-Gauge-120mph) and GPS senders are available many places. The speedo face does not look out of place next to all the other Smiths gauges and I know my my speedo is accurate. The only disadvantage is that I miss about a mile on every trip while it acquires the GPS satellites - pretty minor problem, if you ask me.

[Grumblebuns]

The 336 speedo gears have been NLA for many years. Steve Veris on the Yahoo Europa mail list has been reproducing replacement gears. Contact him directly to see if he has any left over from his previous production run or email me directly and I can provide you his email address.

Joji Tokumoto
Fallbrook, Ca

[Serge]

Not sure if these are the same, but worth checking out.

http://www.ebay.co.uk/itm/370457764929?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

http://www.ebay.co.uk/itm/370457739338?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649


Serge

[ezuskin]

GPS speedo looks really cool but seems So wrong in our non electronic cars but, then again, I still miss my Lucas starter, the sound and the mystery of whether it was really going to start the car

[BDA]

It does seem uncharacteristic to have something on a Lotus that doesn't involve any drama, but then I figured that the drama that occurred when the speedo gear in the transaxle shredded, requiring me to open the tranny up to clean it out, made up for the lack of drama with the GPS driven speedo!

[LotusJoe]

You can get the GPS Speedo customized to look pretty close.

[BDA]

I think you're talking about the Speedhut unit on which another member gave a favorable report. It is sized in inches rather than mms requiring some minor binnacle surgery and it's less expensive than the Smiths unit I got. The Smiths until I got is the same size and looks a bit more like the original. I'll post a picture later today.

[jbcollier]

There are also electronic versions of Smiths instruments that will run off a simple magnetic sensor.  That's what I'm using.  My speedo drive is still good so I'm using it to drive a Hall effect sensor.  It is also easy to put a magnet on a wheel (front or rear), driveshaft or axle and get a signal off that.

http://www.smithsinstruments.co.uk/auto.html

http://www.smithsinstruments.co.uk/GT40.html

http://www.smithsinstruments.co.uk/heritage.html

[BDA]

Yes, the electronic speedos can be driven by either a hall effect sensor or a GPS antenna (there is actually a conversion in the antenna that sends pulses to the speedo where they are counted; so the speedo doesn't know the difference). Since I didn't notice a good place to mount the hall effect sensor, my mount for the hall effect sensor was a failure. It must be very rigid to maintain a constant air gap between the sensor and the protrusions it's detecting during bumps. After I gave up on the hall effect sensor, I found a better place to mount it on my NG3. I don't know if there are similarly good places on other Renault trannies. Another problem I had, although I really didn't get that far, was that nobody could authoritatively tell the air gap between the sensor and the magnets I glued to my CV joint. The GPS antenna was a quick and simple, if more expensive, solution. The antenna was set to send a certain number of pulses per mile and I only needed to tell the speedo what that number was. It was much easier than driving a measured mile and counting the pulses and then telling the speedo that number - although, as I said, I had other problems so this really isn't that onerous.

One thing to keep in mind is that the more pulses the hall effect sends per mile, the better. In my case, the CV joint seemed to be the most reasonable thing for the hall effect sensor to count from and it had three lobes to the housing, meaning three pulses per revolution of the half shaft which ended up in the low, but acceptable range of pulses per mile. It would have been better to count more pulses per rev. The hall effect sensor can detect bolt heads or other protrusions. Magnetic protrusions are better.

In the end, I don't regret going the GPS route. It is not susceptible at all to vibrations or road hazards such as gravel though if it is mounted properly, that shouldn't be a problem. It does have some disadvantages other than price, but for me, they are minor. It takes about a mile to acquire satellites and that is extended in the case of heavy tree cover or tunnels. Trees are my only concern but not where I live. For folks going through the Chunnel, the trip will just be that much "shorter"! 

Here's a picture of mine. I had to request the half round bezel as an angle bezel was standard.

[Murramor]

Yes, the electronic speedos can be driven by either a hall effect sensor or a GPS antenna (there is actually a conversion in the antenna that sends pulses to the speedo where they are counted; so the speedo doesn't know the difference). Since I didn't notice a good place to mount the hall effect sensor, my mount for the hall effect sensor was a failure.

I have the Smiths electronic speedo and I mounted my sensor in the gearbox.  I understand that, the original poster has no speedo drive so this is irrelevant to him.  My 385 gearbox speedo drive would not work accurately with my original speedo and, in any case, I needed a speedo in Km.  Also I ruled out the GPS option because of the number of tunnels in Sydney where the GPS signal is lost.

I used the sensor as in the link below.

http://www.lotus-europa.com/manuals/misc/electrical/365_electronic_speedo.pdf

[BDA]

Great point, Murramor! Because my speedo gear shredded, I didn't think about your third option which is very handy. Before I lost my speedo gear, I was getting ready to have my speedo recalibrated. This involves counting the number of times the speedo cable turns over a measured distance (I forgot the distance). You would send your speedo with that number to a Smiths service center. They would calibrate the speedo and send it back. I don't know how much they charge, but with their labor, shipping costs, and the hassle, you would probably be getting close to the cost of an electronic speedo and sensor. For people who have changed the height of their tires or their tranny, an electronic speedo driven from the tranny is a very appealing option. In that case, it boils down to how original do you need to keep your car.

[Murramor]

I guessed a starting point for the number of revolutions and then calibrated my speedo by trial and error to match a GPS exactly at a steady 100 Kph.  It didn't take long and now I have a speedo that has a rock steady reading and that is more accurate than the original instrument.  As for appearance nobody has yet noticed the LCD odometer unless I point it out.

[BDA]

I agree. While I do not worry about originality in my car, I do want as much of a consistent look in my gauges as I can (unfortunately because of some replacements they aren't as consistent as I'd like) and I think my Smiths electronic speedo looks very much at home in my dash!