Smiths speedo gearbox repair

Thanks LAB, that helps.

Dave
69S

DogT said:

Mine must be the exception. The Patent number on the outside is 529397. Otherwise appears pretty much as your photo. Here you can see the 4 circular machine marks that would not be there if there was a raised rim on the retainer that was rubbed off. Who knows???

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Dave,

I just realised, :idea: the raised area that looks like a washer, which you think is the retainer.....is actually an integral part of the drive box casting!

Hmmmm. So It looks like I either didn't have the retainer or it got eaten up, or removed at some point, not by me. Can you give me a dimension on the retainer thickness? Maybe I can make one up. Does the retainer mount on those little rivets too? But I'll tell you, with my ring gear resting on that washer with no retainer and grease, I have about .04" clearance from the ring gear to the washer under the felt. I have friend with the same model, I'll try to get him to take his apart and see what he has. Interesting!!

Has anyone ever taken apart the driven gear from that tube? It all looks like it has been installed and then press fitted from the outside with those little dimples?

I got my furnace back in operation yesterday, 2 days with the wood stove and 60 deg. F in the house, the old lady was not too happy, but didn't complain. It was tough getting the repairman in with still 15" of snow on the ground and mud out the wazoo. Only $260, not too bad for 2 trips, parts and a tuneup.

Dave
69S

DogT said:

Can you give me a dimension on the retainer thickness? Maybe I can make one up.

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I can't, as I don't have a loose one to measure, because it was missing from my one too!

DogT said:

Does the retainer mount on those little rivets too?

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The retainer is the only part the rivets hold, = retainer to the casting.

DogT said:

But I'll tell you, with my ring gear resting on that washer with no retainer and grease, I have about .04" clearance from the ring gear to the washer under the felt

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.04" (0.040"? = 40 thou.?) which is the same as I measured on both my units, so no problem, unless you meant 0.004" = 4 thou., but even so, I doubt the clearance is that critical?

Checking the other complete new unit I have handy with the retainer fixed in position, there appears to be very little play between the retainer and the flange of the ring gear, just "adequate running clearance" I would think?.

I see what you mean. Yes, the clearance is 0.040" from the ring gear to the large washer with the ring gear sitting on that raised section of the housing. I punched out the rivets and nothing happened, other than the rivets came out. It almost looks like I need a new housing with the retainer. One would think that there would be something left of the retainer if it got chewed up, but maybe it just fell out the last time it was apart and never discovered. (What is this ring that I found I probably said?) Very possible. I only found small chunks of metal when I cleaned it, and that was probably the left over crap from the bearing spacer having locked up on the wheel and rubbed a hole on the inside of the housing, you can see it as the dark area in my pic. It is about .030" deep.

There is a defective gearbox available on ebay, so far for $10 but it skips on the gears and don't know if it is the ring gear or the driven gear, most likely the driven gear, which makes it pretty useless to me. I may just see if I can repair this one to some workable semblance. At least I have the ring gear out and I can make it fit on the bearing locknut better. Actually it was working fine the last time it was on the bike, although rubbing on the hub cover.

Maybe MexicoMike had this gearbox at one time and took out the retainer? Yuk, yuk.

Thanks LAB

Dave
69S

Most of the unserviceable units suffer from worn gears, so you should be able to salvage the dished washer from one of these. I may have a disassembled one in my workshop that I can send you the washer from. Send me an e-mail at: [email='chiuchowgum@hotmail.com]'chiuchowgum@hotmail.com[/email]'

Dave M,

Many thanks!! I really don't think I need any more parts for it. Looking at how it works, it appears that the ring gear is pretty much attached to the bearing lock nut on the wheel when the gearbox is installed, and if the gearbox is centralised (UK spelling) on the ring gear and the wheel bearing lock nut, what is going to happen other than it will work. I really don't even see the need for the retainer. All my parts are OK except the main housing has been worn down a bit (.030") when apparently the bearing spacer locked up and rotated, grinding a bit of metal off the inside of the housing. I can fill that with a properly made up washer. Like I said, it does work, it just appears to be missing the retainer which is not important, at least to me. I'm trying not to be too anal.

Thanks,
Dave
69S

Dave, The retaining washer is dished and may be difficult to fabricate if you opt to try this.
Trying not to be too anal is good, however we all suffer from having to be too Amal once in a while!
I will pass on your regards to Suzie Wong the next time I am in Wanchai!
Dave M

Dave M,

Do they still serve those wonderful chocolate malts at the Pheonix hotel, if it is still there?

I was real anal about the washers if you saw that thread!!!

Dave
69S

Dave, I think you are correct about the washer being somewhat redundant once the assembly is correctly fitted to the wheel, however I think it probably keeps the whole thing centered which may make it easier to fit. I have taken quite a few of these apart and nearly always have found that the ring gear is the only part that is at fault. I think the grease dries out and everything seizes up, then the pinion mills a slot in the ring gear as it is softer material. Someone should remanufacture the ring gears, I would certainly like to repair my speedo gearboxes as the repo ones I have tried have been generally of poor quality.

The Phoenix Hotel and many other landmarks of old Hong Kong are long gone, however I am still here and a ride on my 750S awaits you the next time you visit!

Dave M

Does anyone have a paint type recommendation for the speedo gearbox???

Dave
69S

Regarding the felt washer in the speedo drive, here is my solution:

Order from Grainger the following:

Felt Disc 1/4 thick 4" #2FHD1 $1.30

I first tried cutting with scissors and it looked/fit poorly.

I then used a circle cutter: http://www.amazon.com/9911-CMP-1-Compas ... d_sim_hi_2

Dimensions (from memory, please verify) were 2"ID, 2.5" OD.

Order 2 discs in case you botch one and remember to cut the OD first.

I have an original felt seal from the Norton with only 2600 original miles and cut this one for a Triumph's drive. The gasket I made looks like it could be OEM.

I am going through both of these drives, replacing the rivets with ss screws and will clean/grease the entire assembly as part of regular wheel maintenance (see speedo-drive-work-t5188.html ) Norbsa's instructions are spot on and getting those rivets out really lets you clean the internals properly, removing years of dried grease mixed with grit that inevitably works in. Finding those small ss screws with flat heads was a bit of a challenge and you may have to order them if you don't have a great local hardware store. It seems the original drives are getting very rare and the repops are mostly junk so this seems a part to really take care of if your's is in good shape.

Best regards,

Doug Beck