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Anyone know anything about Auto Tempo 5" speedos?

vapide

Well Known and Active Website User
Non-VOC Member
I have a broken Auto Tempo repro 5" Shadow clock I'd like to get fixed. These were a popular item back in the '80s, but Auto Tempo is no longer around, and the company that bought them out doesn't seem to know much about them.

There has always been a mystery about what the actual movement is inside. I always heard they used a later sytle, magnetic, movement, but I opened mine and it looks like it might be chrono. But there is no name or numbers anywhere on it. I'd like to identify the movement before I send it off for repairs, since several of the shops I have contacted will only work on Smiths/Jaeger.
 

Hugo Myatt

Well Known and Active Website User
VOC Member
My Auto Tempo five inch speedo has identical workings to the standard Rapide style speedo. I.E. standard Smiths Chronometric. Incidentally Smiths supplied 5 inch speedos to Sunbeam for some models (e.g. 95L) in the early thirties. These were usually mounted in a flat position. The speedo itself was rather flat with a bulge at the back to accommodate the works. PCV used a similar one on one of the pre-war racers. I forget which one.
 
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vapide

Well Known and Active Website User
Non-VOC Member
Interesting. Guess I will have to open up my Rap speedo to see if mine is to.

I got my Auto Tempo second hand, and believe the previous owner may have had to send it back for repairs, and I had it fixed once (by Auto Tempo), so I have some doubts about the quality of the workings, which as I mentioned have no markings on them at all. I can't help but wonder if someone may have been making inferior pattern copies of the Smith movement back then, which might explain why the Smiths chronos on my other bikes have been merrily running without attention for 50+ years, while this one seems hard pressed to go 2000 miles without servicing.

Oh, anyone know which way I should spin it to test it? I'm pretty sure its clockwise (as seen looking at the drive nipple from the back of of the instrument) but would like to be sure.

My Auto Tempo five inch speedo has identical workings to the standard Rapide style speedo. I.E. standard Smiths Chronometric.
 

Hugo Myatt

Well Known and Active Website User
VOC Member
No knowing the symptoms your 5" speedo is displaying the following may be of no use at all. However,the drive to my garage has a long and severe downward slope which requires me to wheel the bike down backwards over quite some distance. For some time I was plagued with an erratic speedo and frequent breakage of the cable. The culprit was the right angle gearbox on the back of the speedo. Pardon my lack of correct technical terms but there is a scroll type gear engaging with a helical cut gear. After about 20 or so turns of the cable backwards, one gear in the box would tend to drive the other one up until it seized solid against the end cap and so snapping the cable. This was a known problem with early Shadow speedo gearboxes. In 1998 I sent the gearbox to a company called Speedograph Richfield Ltd., Rolleston Drive, Arnold, Notts., NG5 7RJ. They modified the box and, touch wood, I have had no further trouble. I do not know whether this company still exists. I believe the modification involved inserting a small ball bearing between the end cap and the gear to take this upwards thrust.
 

vapide

Well Known and Active Website User
Non-VOC Member
I dissected the 3" speedo on my Rap, and it does indeed appear identical to the movement in the Auto Tempo. Neither have any markings, but only difference is in the frame, where the axles for the odometers go. The 3" clock has the axles running directly in holes in the pot metal frame, where the legs on the 5"s frame are wider and slit for bushings clamped in by a screw. This could easily have been a running change in the 30 or 30 years that separates the two instruments, and the rest of the frame is so similar as to make me think they were by the same maker. So it appears the Auto Tempo may very well have a genuine Smiths movement too (which brings up the question again, why does it break so much more often?).

Oh while the 3" was off the Rap I checked the direction of rotation, and it is counterclockwise, as seen looking at the back of the instrument.
 
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Vinthou

Website User
VOC Member
I don't like to denigrate anyone, BUT - quite a few years ago I had Joe Shaw rebuild a badly damaged 5" speedo. It required a new case, bezel and glass - bike got flung down the road. What I got back was a disaster. It had a regular chronometric movement which only allowed the cable to stick straight out the back. i.e. NO angle drive and no way to install one. Being the other side of the pond I did not persue the issue further. I eventualy got David Woods (advertises in MPH) to build one up for me , which was exactly what I wanted. I would highly recommend him.
 

Vinthou

Website User
VOC Member
Not having one to look at, as I'm on the road, I can't describe the details very well, but there is a distinct difference. What I got from Shaw had the threaded piece that the outer speedo cable sheath screws onto sticking out the back of the case, as is normal on a 3" instrument. With the 5" unit there is just a hole where the angle drive case bolts on, with the "drive" (or more accurately "driven spindle" of the angle drive) protruding into the case to mate up with the mechanism internaly.
Confused yet?
 

Hugo Myatt

Well Known and Active Website User
VOC Member
I am trusting to memory again so beware. Very early speedos - when you took the right angle gearbox off the back it exposed a gear (helical, I think) sticking out of the back of the speedo. Very late speedo's (Auto - Tempo, or whomsoever) Had a straight drive out of the back similar to the standard 3" speedo. This was used with a much chunkier right angled gearbox with a knurled locking screw that secured it to the speedo drive. I believe this chunkier gearbox was also used in early Land Rovers.
 

Paul Ennis

Well Known and Active Website User
VOC Member
Shadow clocks

The chronometric mechanism is a standard Smiths unit (the weight of the balance wheel varies for 80 120 or 150 MPH speedos), but the Shadow clock and Series D clocks have a different aluminium chassis. Instead of a threaded protrusion they have a hole into which the right angle drive unit fits.
Paul,
 

Len Matthews

Well Known and Active Website User
VOC Member
There were two designs of angle drive on the back of Shadow speedos. The first type was in brass (I think) and secured with a little clamping band that nipped up on a projection of the mechanism that protruded through the back of the case. The second type is in Marzac secured by a plate with a "U" shaped cutaway which slotted in groove in the angle drive. the plate was fastened to the instrument with two 4BA screws. This type can be dismantled for cleaning and luubricating by removing the two small internal circlips, something you need to do to avoid broken cables,
 

vapide

Well Known and Active Website User
Non-VOC Member
My understanding is that of the real 5" clocks there were the two variations you mention, where the right angle box either clamped to the nipple, or was held down by a horseshoe shaped plate screwed to the case. Both of these apparently lacked the threaded nipple to accept a cable directly, and had to be used with the appropriate angle drive.

However, it was apparently a common mod (done by Auto Tempo among others) to modify the speedo so it had the standard threaded nipple which could accept a cable directly in order to do away with the troublesome angle drive. This considerably improved reliability.

Speedos with the straight-cable mod could also be fitted with the later style Smiths BG2410 angle drive which had a round knurled nut that screwed down onto the nipple and could be used on almost any speedometer that accepted a standard cable. This is the gearbox used on most of the repros. Since having the cable come straight out of the back looked like hell, some original speedos so modified doubtlessly ended up with the newer style drive as owners tried to revert to stock appearance. And some rebuilders apparently used the later knurled-nut style boxes when repairing original 5" clocks once the original style boxes became unavailable, back in the days when riders were more concerned with function than originality.

The Smiths BG 2410/00A knurled-nut gearboxes are no longer available (though they turn up on eBay quite cheaply) but an even clunkier version is still available from Land Rover dealers.

There remains some question as to whether 5" speedos were ever supplied by the factory with knurled-nut style gearboxes. My suspicion is that they were not and that, apart from a few modified original 5" clocks, just about all the 5" clocks with the big gearbox are later replicas.

BTW someone was selling a "genuine, original, NOS Smiths 5" speedo" on ebay a couple weeks ago, which appeared indentical in every respect including the late-style gearbox to my Auto Tempo. It sold for $1550.


There were two designs of angle drive on the back of Shadow speedos. The first type was in brass (I think) and secured with a little clamping band that nipped up on a projection of the mechanism that protruded through the back of the case. The second type is in Marzac secured by a plate with a "U" shaped cutaway which slotted in groove in the angle drive. the plate was fastened to the instrument with two 4BA screws. This type can be dismantled for cleaning and luubricating by removing the two small internal circlips, something you need to do to avoid broken cables,
 
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