Instrument repair, strip, dismantle

[wayne]

My original M speedo last week decided it wasn't going to run the Odometer and tripmeter any more. Speedo still works so it's not the cable. Trip and ODO don't turn over anymore. Some gear has shattered or slipped its mesh or ??

I've never stripped the instruments beyond the photos so before I damage something, where to from here please. What's the next step in dismantling? EDIT: keep reading, more pics showing the strip.

[hudson]

 I don't know if there are two versions of the KM/H speedo , but there are two versions of the MPH speedo. Some have the trip meter on top of the odometer. All of my early ones have the trip meter on the bottom like yours. The lower housing is differente for the two because the reset knob is farther to the left about a 1/4 of an inch for the top trip meter. And of coarse the speedo face is different. I don't know when it changed but I have seen both. Will try to get some vin. numbers to narrow it down for the history by the numbers thread. 

Brian

[wayne]

Yes, I've seen pictures of both but don't know if included the kph jobs.

Member JESS has advised I remove the black rubber gasket and all will be revealed. However, it appears glued like the proverbial to a blanket. Picking at it with sharp objects is fraught with danger as that thin blue metal top case is millimetres away. I also have the feeling that even if I did lift it, it'll come away in a thousand tiny pieces.

Might require a new gasket. Can't see it's going to come off neatly.

[wayne]

Question answered Brian, in my photo files, KPH speedo with top Trip Meter:



And a good illustration of the relative reset knob positions. Someone had to effect a mod:

[wayne]

Okay, removing the black gasket was a quandary when you don't know exactly what it is. The blue metal surround has a lip that runs around the edge and is a snug fit inside the ~ 2 mm lip of the silver steel backing tub. Best and safest way is to use a pick tool at an angle through one of the screw holes in the back. Push from behind on the metal surround (you can't see it, it looks like your pushing on the rubber gasket. Push it out and the rubber gasket comes with it. The rubber gasket is a "U" shaped channel that runs around the lip of the blue surround. Super easy.......when you know.





Once out, you can see the structure of the black rubber gasket.




Now 'round to the back and a small phillips head down the centre of the Black Plastic trip meter knob, undo a tiny phillips head. The knob will now pull off. Then undo both small phillips head either side of the where the speedo cable attaches.




The speedo will now come out:



And here's my problem. 47 years without lube but 42,000 klm is not that high in the world of motorbikes. Fingers crossed, do I still have that banged up set of M instruments? Dang! Just had a look, no longer. Should have known 10 years ago that one day, this may come in handy (that's my usual Mantra).



Many thanks to member HGH770N who sent me a spare gear (and thanks to TIMPA and Grant for searching their spares box on my behalf). It was very much appreciated.

So pleased to get this gear, 20 minute job and it'll all be back together- I should know better!!

While the gear was the same as the damaged "apple cored" gear, the worm gear on the end of the shaft that drove a jackshaft to the speedo and trip meter dials was different. MPH on the left, my KPH on the right:



As the gears and shaft appear to be machined from one piece, I had to cut the main gear away from the mph speedo, bore a 4 mm hole through the centre and then machine down the main gear on my kph shaft to an interference fit. If you ever have to do this, I recommend machining the old gear even further. Shaft diameter is 3.47 mm on my digital calipers. So somewhere slightly above that to give an interference fit to the hole you drill through the new gear. My 4mm was a tad too much taking away the bottom of the gear teeth valleys but there's enough back lash to get away with it.



I'm not a precision machinist by any stretch but it survived the power drill test freely spinning with no tight spots (thank the instrument contractor for a pretty loose design in the first place!).

Main gear from the MPH speedo now fitted to the old shaft which has the larger diameter KPH worm drive on the end. All lubed up. I used sticky lithium grease on the shaft ends and metal gears and ceramic grease on the plastic gears (the latter is sold in small inexpensive and convenient tubes at R/C model shops and made by Tamiya):

[wayne]

Member HGH770N has sent some more detail pics:

Roger's notes re the pictures:

Take care not to get any oil on the Blue face as it’s difficult to remove. That’s why I suggest removing the blue face 1st if you find something broken.





The magnetic field moves the weighted, spring loaded wheel that drives the read out pointer.




The numbers are driven by jackshafts and gears that split to drive to the trip and odometer. The axles seize up.




And I'll add my own comment. This stripped gear was my problem as well. It seems it's not uncommon. It's not a normal service item so I'd suggest anyone with an M regardless of miles, make the effort and get some lube on these gears:

[wayne]

Well, that was amusing. I took my M with the repaired speedo out today. My ODO and TRIP METER work perfectly reading in klm as they should for an AU delivered bike.

But my speedo reads in miles per hour. There is no mechanical connection between the cable drive and the speedo needle so I haven't matched the wrong gear sets. The cable spins a magnet on the end of a shaft. That's surrounded by a bell shaped thin metal housing with a fine clockwork style spring (See pics from Roger above). Magnetic drag causes the housing to be pulled so that it starts to rotate carrying the speedo needle with it.

I had to use the mph magnet as it's on a shaft with a worm gear and the one on my KPH one was too worn. There is no easy way to remove the magnet and swap shafts. I can only surmise the mph magnet is smaller or less powerful than the kph magnet so exerts less force to turn the needle (I never compared them, at a glance they looked the same). For any given speed, the needle reads lower with the mph magnet and higher for the kph magnet. Next time I have the instruments apart, I'll compare them. Not easy to swap over though.

The good news, my speedo works. I just have to remember that when the needle is pointing to 40 kph on the AU speedo face, it really means 40 mph or around 65 kph. Similarly when it points to a bit above 60 kph as printed on the face, it means mph so I'm doing 100 kph.

RE5's, never a dull moment.

[HGH 770N]

Wayne .
Maybe the KPH pointer pick up is a different distance from the magnet to the MPH pointer,or as you said the magnet is a different size or even different strength?

[wayne]

Yes, that's another real possibility Roger. Shorter or longer distance magnet to bell.

In a nutshell though, I'm very glad to be back on the road and this is working fine. I'm of that generation in Australia that straddled the Imperial to metric transition so mph are just as good!

I'll keep an eye out for a wrecked metric speedo, may turn up one day.

[hudson]

 Wayne,

 Did you happen to count teeth on the worn gear and magnet gear (KM/H ) vs the new replacment MPH gears ? I was just wondering if that ratio was the same.

The other question I have is about the cable drive gear box at the front wheel axle. My MPH boxes are one turn of the wheel  = 3 turns of the cable.
I have heard miths and rumors that there are two different ratio gear boxes, but have never been able to confirm this.

If you do the KPH to MPH conversion,  our speedo goes to 160 MPH  the 200 KPH converts to about 120 MPH ( actual 124.2 ) This is where the gear box rumor comes from that 120 MPH speedo bikes (other models of Suzuki's ) have a different drive box at the wheel than the 160 MPH speedo bikes. I see that 1976 A model RE's have 120 MPH speedo.

This would be 6 different speedometers for the RE5

MPH top trip meter
MPH bottom trip meter
KPH top trip meter
KPH bottom trip meter
A model  MPH
A model  KPH

Part of the rumor consisted of there were possibly 160 MPH A model speedometers ( Conversion bikes ? )  
Has anybody seen an A model 160 MPH speedo ?      or maybe a picture of one ?

That is so RE5 to have that many variation in a production run of only about 6300 bikes.

Brian

[wayne]

Yes indeed, the variation is astounding and I wonder if it's the same for other bikes if you delve as deeply as we have?

I didn't count the teeth. Visually looked so close I didn't bother and it was obvious the end gear was different. Initially I had the metric worm driving the imperial gear and the mesh worked so if they're different, they'd be very close.

It would make no sense to change two sets of gears on the same shaft to flick between klm and miles but we're dealing with Suzuki and RE5's! However the gearing doesn't affect the speedo reading as the speed of the magnetic drive is governed directly by the cable rpm. No gears other than front axle 'box.

I'm aware the mph/kph faces don't match, so I was mystified that what my speedo needle was pointing to on the kph face was effectively showing me mph. However, I don't know what actual speed I was doing, only that I was in a group of 8 odd riders and knew, more or less, they were following the speed limits (as well as gauging by the relative speeds of the cars on the motorway who in AU generally adhere to the limits (we're full of hidden police cars, fixed and mobile cameras).

Next ride I'll take a GPS and somewhere in my notes I'll have noted the difference between GPS and RE5 speedo in the past. I think somewhere between 5 and 8% depending on what tyres I was using. A bit of arithmetic and I'll fine tune what my speedo is actually showing.

Next time my fairing is off, I'll measure front wheel rotation vs cable on a metric bike. I do have a NOS metric set of clocks so one day I may count the gear teeth.

[hudson]

That was my lack of understandin. now that you have pointed it out I relize the magnet is direct drive on the end of the cable. Thank you


Brian

[timpa136]

Wayne,

I am interested in your GPS reading to actual, both mileage and speed readings.

It seemed some early gear boxes at the wheel were at least 8% optimistic at least as MPH here in the States.

Later gear boxes were spot on and could be actually reading a bit slow with a larger tire. Tim

[wayne]

Best thing is to give you data from past notes when I had a normal speedo:

M model high VIN ~13800 AU delivered.

With Metzeler Lasertechs, stock gearing, top gear 4000 rpm = 108 kph indicated, 103 kph GPS (27 kph per 1000 rpm indicated, 25.75 by GPS). Over reads very close to 5%.

Speedo readings:

63 indicated = 60 GPS

83 = 80

94 = 90

104 = 100

115 = 110

ODO readings with same setup:

105.7 indicated = 100 by Google maps distance (I've found Google map distances to be very accurate and this was done on a very simple route, mostly freeway, to reduce errors).

I don't have the data but I recall with period style tyres (K81s) the speedo/odo errors were closer to 8%.