rebuilding the speedo drive

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bill said:
other than a rivet counters restoration why waist your time and money on this POS drive system when there is better electronic instruments.
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There is at least one report that the "better electronic instruments" won't even keep out rain. And don't forget the approx $400 cost, the incomprehensible instructions, (https://www.caigauge.com/documents//pdfs/pil017-368.pdf ) and the trouble of fitting.
How's this for a wiring diagram?:http://kullendesign.com/smithgaugewebsite/wp-content/uploads/2014/01/Smiths-A4-Wiring2.jpg
I may be dense, but my hat is off to anyone who has accomplished this.
 
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like i have stated i have no experience with the smiths repops. mine has been with the legendary GPS units and the autometer pro cycle units. the legendary is almost a plug and play with negative ground and and a single relay with positive ground if you want the hot start option. the autometer was more difficult as the instructions wanted an HD speed sensor that they stated was 12 volt. NOT it was a 5 volt and had to install a resistor on the + side of the sensor. after i figured that out the rest was simple to calibrate, all you needed was a 2 mile stretch of road. both brands have preformed great for me and the others that i know of.
 
I have torn apart my gauges and my speedo drive gear box. I've actually reversed the output of my original gear box drive and mounted it on the primary side of my front wheel to drive the speedometer. With the straighter run of the drive cable to the speedometer, the needle has no bounce whatsoever. I lube the gearbox with the jewel amber oil that Jim Comstock recommended. I also changed the wierd pyramid shaped grease fitting to a standard american style grease fitting. (what is with that weird pyramid shaped grease fitting? is that a british thing?)

Anyway, My speedo is spot on up to about 80mph, then it gets optimistic beyond that. I have a GPS mounted between my instruments that is set to show my speed, so I can see my speedometer is accurate below 80mph. I have calculated my gearing and tire size on gearcommander.com then checked it all by measurement and GPS speed verification. I don't need electronic instruments because I can view my GPS and see my real speed and verify my other 2 instruments are still reasonably accurate at a glance.
 
Mr. Rick said:
There is at least one report that the "better electronic instruments" won't even keep out rain. And don't forget the approx $400 cost, the incomprehensible instructions, (https://www.caigauge.com/documents//pdfs/pil017-368.pdf ) and the trouble of fitting.
How's this for a wiring diagram?:http://kullendesign.com/smithgaugewebsite/wp-content/uploads/2014/01/Smiths-A4-Wiring2.jpg
I may be dense, but my hat is off to anyone who has accomplished this.
Click to expand...
Incomprehensible instructions. If anyone can help me with this nightmare please post. If not I'll go back to cable stuff and keep things greased up. Why did I spend a grand on instruments with a fuzzy photocopied wiring chart of confusions ?
 
Well, in December I'll be installing the set of E-Smiths I bought for my Commando. I have to admit I just glanced at the instructions before purchasing and thought, "Sounds confusing but I'll be able to figure it out when I have the gauges, bike, and me all in the same place at the same time." Or maybe not! :)
 
Torontonian said:
Incomprehensible instructions. If anyone can help me with this nightmare please post. If not I'll go back to cable stuff and keep things greased up. Why did I spend a grand on instruments with a fuzzy photocopied wiring chart of confusions ?
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76 Canadian MK III BTW, enjoy.
 
I don't know what jewel amber oil is like, but watching these things in action turning by hand tells me that ordinary grease is not very effective, being too stiff and wiping off the bearing surfaces immediately.
I've pulled apart several units that were packed with grease and still failed. The ring gear is just too soft, but maybe sitting in a pool wd see it last longer?
 
Running Jewel Amber and it escapes out and decorates the hub. Also use it in the swing arm and it escapes there as well.
I console myself by believing it lubricates well.
 
Mr. Rick said:
I don't know what jewel amber oil is like, but watching these things in action turning by hand tells me that ordinary grease is not very effective, being too stiff and wiping off the bearing surfaces immediately.
I've pulled apart several units that were packed with grease and still failed. The ring gear is just too soft, but maybe sitting in a pool wd see it last longer?
Click to expand...


Amber is like a cross between a grease and heavy oil. I believe it is used in old type aircraft engines in the rocker boxes. I have used it in the gearbox with good results. I put a new felt seal in and don’t have a leaking problem. The down side was the product with shipping was a little expensive. I think the next time I will look at John Deere Cornhead grease (Hobot). It seems to behave the same as Amber and should be available at the local Tractor Supply.

Pete
 
Grease doesn't work for moving parts unless it's captured by seals, like a drive train U joint where you pump it full so any motion moves the grease around. In a speedo gearbox, it doesn't take long for the drive gear to throw the grease aside and cavitate. Because grease doesn't flow like an oil, it doesn't flow back to coat and recoat the gears to lower the friction between the gnashing teeth.

The amber oil is the best stuff I've found so far. I squeezed a blob out onto a rock in the sun during the summer and it stuck around for a long time just sagging and slowly running. It's got to be better than grease for the speedo drive.
 
Miy speedo drive has worked fine with standard wheel bearing grease since I overhauled it years ago. The speedo cable is lubricated by...

wait for it...

Cable lubricant! (any parts store)! :)
 
Just a thought, would cryogenic hardening the ring gear help or would that just transfer the problem to the worm (pinion) gear?

Ray
 
Scooter62 said:
Just a thought, would cryogenic hardening the ring gear help or would that just transfer the problem to the worm (pinion) gear?

Ray
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Comnoz has shown hardening of the ring gear greatly extends the life of the drive.

Slick
 
thanks for replies - I'll try do a fix on the original smiths drive at some point but switch out for an emgo unit meantime - and make sure to lube it properly ! Whats the UK recommendation for drive lube ? - never heard of "jewel amber oil". Those retro styled digital speedos are not for me - much of the appeal of these bikes is their simplicity and being able to understand how they work - "less is more" sort of thing.
That said - looking to switch my analogue boyer for a tri spark soon . .
 
After reading this thread I thought I’d drag my drive out of a box (waiting to be fitted on final build) and check its ring gear. It turns smoothly and looking through the cable hole, it appears to be flat across the edge. Good news. It’s now soaking in kero to dissolve any lubricant.
I have a veteran motorcycle that runs a fluid grease in the gearbox (grease consistency when cold but fluid as it warms up). Has anyone tried this in a speedo drive, it seems like it is just what is needed.
 
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