Speedo Drive 1972 500 K1

[Charliecharlcomb]

As I've got my wheels apart for restoration I have a chance to refurbish my speedo drive. It looks OK tbh and I'm inclined to leave it alone. I guess the alternative is to thoroughly degrease and flush it and then repack with grease.

I've ordered a new speedo drive oil seal as recommended by Ken elsewhere (it doesn't appear in the parts list.)

https://www.ebay.co.uk/itm/224125083081

I guess my question is:

1) Should I leave it alone or clean it up?

2) What grease should I use to repack it? The current grease is very black

Any suggestions are welcomed.

[Trigger]

Easy to take apart and refurbish. As in the bottom of this page >> http://www.sohc.co.uk/index.php/topic,20419.30.html

[Charliecharlcomb]

Easy to take apart and refurbish. As in the bottom of this page >> http://www.sohc.co.uk/index.php/topic,20419.30.html

Think that's a good plan, thanks

[Toko_Jo]

Has anyone been able to identify the differences between the CB750K0/sandcast spedo drive and the later ones? And do the later ones work on a K0/sandcast. OK I know the hubs are different widths and the drive-plates are different but I don't see any significant differences in the speedo drives themselves.

[Oddjob]

If I was giving one piece of advise on doing this Charlie it would be to make sure the screwdriver you are using to remove the grub screw fits perfectly. It's made of brass ( I think) and it's very soft and it's very easy to round it off with an ill fitting screwdriver. A little heat when removing it can't hurt as well. The bung in the end is a press fit, it's knurled so don't try to spin it out, the only way I found to get it out is to use the drive gear to push it out, that can be a little daunting as the small tang for the cable is all you have to press against, it's possible though. So remove the large seal first, remove the circlip holding the drive bevel in place and the shim and the drive bevel, then remove the grub screw, press out the drive gear and you can finally remove the seal on the drive gear then.

Got 2 of mine part right now, not decided on a grease yet but leaning towards using MolyD due to it's high loading properties but feel free to use what you think is best for you.

[Charliecharlcomb]

If I was giving one piece of advise on doing this Charlie it would be to make sure the screwdriver you are using to remove the grub screw fits perfectly. It's made of brass ( I think) and it's very soft and it's very easy to round it off with an ill fitting screwdriver. A little heat when removing it can't hurt as well. The bung in the end is a press fit, it's knurled so don't try to spin it out, the only way I found to get it out is to use the drive gear to push it out, that can be a little daunting as the small tang for the cable is all you have to press against, it's possible though. So remove the large seal first, remove the circlip holding the drive bevel in place and the shim and the drive bevel, then remove the grub screw, press out the drive gear and you can finally remove the seal on the drive gear then.

Got 2 of mine part right now, not decided on a grease yet but leaning towards using MolyD due to it's high loading properties but feel free to use what you think is best for you.

Great advice and I feel properly warned. Thanks Ken!

P.s. Has anyone ever replaced the seals in the speedo drive retainer pressed steel plate 44641-341-000 and know what the replacements should be?

[Bryanj]

There are no seals on the drive plate so no idea what you are on about

[Oddjob]

There are 2 seals fitted to the speedo drive Bryan. The large one which fits against the wheel part of the drive and is clearly visible and a smaller one hiding down the cable shaft. Both seal the grease in and dirt out so to speak. Not so much an oil seal but a grease seal.

[Bryanj]

Yes i agree but not on the drive plate attached to the wheel which is what that part number relates too.
That number is also the later type which is different to the very early 750 but will also fit the early ones with the appropriate chrome cover

[Charliecharlcomb]

There are no seals on the drive plate so no idea what you are on about

It looks like the top piece is rubber mounted so I'm guessing it's not a seal, more like a cushion. See photo

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[Bryanj]

This has been brought up in a recent post bylaverdaroo i think.
We think it is some sort of damper on later drive plates, possibly to try and stop speedo needle bounce, not found on earlier plates and not officialy replaceable, i think Roo used some sort of rubberised bonding like Sicaflex but dont know if it will work

[Charliecharlcomb]

This has been brought up in a recent post bylaverdaroo i think.
We think it is some sort of damper on later drive plates, possibly to try and stop speedo needle bounce, not found on earlier plates and not officialy replaceable, i think Roo used some sort of rubberised bonding like Sicaflex but dont know if it will work

Gotcha. I was tempted to get it plated but best leave it alone as its pretty well hidden anyway. Glad to clear that up.

[Laverdaroo]

Yeah, twas I.
ifyou have a read,the muppet had cut it out with a craft knife!!
Bonded it back together with windscreen adhesive, worked perfectly. Dont lose that bit they are rarer than unicorn plop!

[Oddjob]

Sorry Bryan, missed the reference to the drive plate. Thought you were talking about the drive itself, oddly a quick search of that part number turns up a pic on the Yamiya site which shows a plate with a rubber seal around and 2 others without. Maybe as you said it was some modification that either never caught on and was dropped asap or a very rare part only fitted to a few bikes.

Never seen or heard of one before.

[Bryanj]

No worries Ken, i have done the same, i wonder if it was fitted to bikes after a certain year but without a part number mod as it was an "improvement" i must admit that i havent done much to those after about 76.
Bit like the mod from the first 750 with the turned over tabs and different chrome plate, i think there was a bulletin about that but not sure, i will have to find the book