Is it possible......?
Discussion
Yes but it is not cheap. The 520Se has had an electronic speedo for years as the cable version kept sticking at around 70. I used a SPA digital unit but it isn't a straightforward replacement.
The Griff/Chim/Cerbera intelligent speedo sensor I do can be used on a Wedge and will drive the speedo directly, The speedo will need to be re callibrated as the ratios etc are all wrong.
Overall cost would be around £200+ so it might be easier to get a new cable and the original speedo unit overhauled as it will be a lot cheaper.
The Griff/Chim/Cerbera intelligent speedo sensor I do can be used on a Wedge and will drive the speedo directly, The speedo will need to be re callibrated as the ratios etc are all wrong.
Overall cost would be around £200+ so it might be easier to get a new cable and the original speedo unit overhauled as it will be a lot cheaper.
What about a very simple and inexpensive GPS based speedo?
First one I found on google:
http://www.expansys.com/d.aspx?i=162308
First one I found on google:
http://www.expansys.com/d.aspx?i=162308
Edited by L33 on Thursday 1st January 17:55
shpub said:
Yes but it is not cheap. The 520Se has had an electronic speedo for years as the cable version kept sticking at around 70. I used a SPA digital unit but it isn't a straightforward replacement.
The Griff/Chim/Cerbera intelligent speedo sensor I do can be used on a Wedge and will drive the speedo directly, The speedo will need to be re callibrated as the ratios etc are all wrong.
Overall cost would be around £200+ so it might be easier to get a new cable and the original speedo unit overhauled as it will be a lot cheaper.
Is it easy to replace the speedo drive gear too?The Griff/Chim/Cerbera intelligent speedo sensor I do can be used on a Wedge and will drive the speedo directly, The speedo will need to be re callibrated as the ratios etc are all wrong.
Overall cost would be around £200+ so it might be easier to get a new cable and the original speedo unit overhauled as it will be a lot cheaper.
GV said:
shpub said:
Yes but it is not cheap. The 520Se has had an electronic speedo for years as the cable version kept sticking at around 70. I used a SPA digital unit but it isn't a straightforward replacement.
The Griff/Chim/Cerbera intelligent speedo sensor I do can be used on a Wedge and will drive the speedo directly, The speedo will need to be re callibrated as the ratios etc are all wrong.
Overall cost would be around £200+ so it might be easier to get a new cable and the original speedo unit overhauled as it will be a lot cheaper.
Is it easy to replace the speedo drive gear too?The Griff/Chim/Cerbera intelligent speedo sensor I do can be used on a Wedge and will drive the speedo directly, The speedo will need to be re callibrated as the ratios etc are all wrong.
Overall cost would be around £200+ so it might be easier to get a new cable and the original speedo unit overhauled as it will be a lot cheaper.
grahamw48 said:
Interesting topic.
I had a new cable fitted last summer, and charged for by the 'specialist' only to be told later that the gearbox end where the drive gear exits is knacked, and basically unfixable.
I use my satnav, but a working speedo would be nice.
Yeah I got told the same thing - was told the gearbox had to come out etc etc. I've been looking at the Griff/Chimp forums here they have a sensor located on the propshaft which is picked up electronically and fed tothe speedo accordingly. The S Series have them too apparently. It must be a do-able mod surely at the expense of a Griff/Chimp speedo...I had a new cable fitted last summer, and charged for by the 'specialist' only to be told later that the gearbox end where the drive gear exits is knacked, and basically unfixable.
I use my satnav, but a working speedo would be nice.
The early cars use a built in sensor in the LT77 gearbox. There are a lot of different sensors giving different calibration options. The later Griff/Chimaera sensors are either based on a pickup wheel built into the diff or use a slotted wheel bolted onto the propshaft. Each method have their own specific speedo which is calibrated differently depending on which system is used.
The diff pickup method is a non starter as the Wedge diff doesn't have them although some of the later Jag diffs have a built in sensor.
You can replicate the propshaft method but why bother when it is easier to fit the sensor to take readings off the front wheel studs. In any case, the speedo will need to be recalibrated because the wheel sizes/diff ratios etc are different.
The other problem with the Griff Chimp setup is that the sensor is notoriously unreliable. It has to be within a few thou of the plate otherwise it doesn't work and if the alignment goes out, the sensor wheel will take out the sensor. This is why I developed the intelligent version which works with a gap of around 1-2mm.
The cable can be replaced without removing the gearbox although the exhaust will probably need to be dropped.
The diff pickup method is a non starter as the Wedge diff doesn't have them although some of the later Jag diffs have a built in sensor.
You can replicate the propshaft method but why bother when it is easier to fit the sensor to take readings off the front wheel studs. In any case, the speedo will need to be recalibrated because the wheel sizes/diff ratios etc are different.
The other problem with the Griff Chimp setup is that the sensor is notoriously unreliable. It has to be within a few thou of the plate otherwise it doesn't work and if the alignment goes out, the sensor wheel will take out the sensor. This is why I developed the intelligent version which works with a gap of around 1-2mm.
The cable can be replaced without removing the gearbox although the exhaust will probably need to be dropped.
grahamw48 said:
Interesting topic.
I had a new cable fitted last summer, and charged for by the 'specialist' only to be told later that the gearbox end where the drive gear exits is knacked, and basically unfixable.
I use my satnav, but a working speedo would be nice.
The drive gear can be pulled out and replaced, no need to remove gearbox. I've never heard of the internal drive worm stripping. The drive gears come in different colours depending on reduction ratio. What's the chances your 'specialist' decided he needed yours for another car and switched it for a duff/wrong one...? [/cynicalb'stard]I had a new cable fitted last summer, and charged for by the 'specialist' only to be told later that the gearbox end where the drive gear exits is knacked, and basically unfixable.
I use my satnav, but a working speedo would be nice.
Back to topic: some Range Rovers had an electronic speedo driven by a sensor on the end of a standard drive cable. Same sensor is used by the ECU on hotwire cars. You could use that to get pulses on a wedge, then all you need is a suitably-calibrated speedo head. Griff/Chim?
I'm only familiar with the drive gear on Fords (little nylon cogwheel), which I have replaced myself in the past. - Had to get a different one as I'd done an engine transplant. My local garage mechanic said that the drive output was knacked, so maybe I'll have a look for myself, but I think he meant the actual gearbox casing around it. 
grahamw48 said:
I'm only familiar with the drive gear on Fords (little nylon cogwheel), which I have replaced myself in the past. - Had to get a different one as I'd done an engine transplant. My local garage mechanic said that the drive output was knacked, so maybe I'll have a look for myself, but I think he meant the actual gearbox casing around it.
Hard to see how unless you'd been doing a Dukes of Hazard style leap and landed on it. There's quite a bit of alloy around the speedo drive. Essentially the drive gear plugs in to the gearbox and is held there by the Will Of Allah (or is it an O ring) while the cable is pulled down tight by a fork around the end flange (similar to the distributor clamp if you like). Apart from a stripped thread for the clamp bolt I can't visualise what might be wrong if the gear itself isn't nadgered.
d. 
The gear is a lose fit on the main shaft and can move back and forward. First job is to remove the geared drive unit. One bolt and check its engagement with the cog inside the box and that the cog is to the rear of the hole left when the drive gear is removed. if it is forward any friction in the cable will force it out of engagement. if in the wrong place it can be slid back with carful use of a prob (screwdriver) if all else fails it can be replaced with the gear box in situe by removing the rear drive flange and seal not easy but possible.
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