speedo g/box repair

Has anyone devised a repair for refixing that washer type thing that fits over the 4 small pins and keeps the driven ring going round correctly. I've had several fail over the years and just can't think of a way of fixing this washer back on. Bike is 850 mk 3 , but will affect all models.

Is the mk 3 speedo g/box the same as a T160 one
thanks
sam

Remove the rivets. tap the holes in the ring for #2 screws. Screw in flat head screws.
However fixing the pot metal body back to useable is the most difficult part of the job. Many I have worked on are beyond saving. The ring does not (should not) really hold the drive gear to operate. It is held in position by engaging with the drive ring/bearing retainer in the MKIII sprocket...or hub on early bikes. If the gear rubs constantly with the ring, the body is trash or will be very shortly.

trident sam said:

Has anyone devised a repair for refixing that washer type thing that fits over the 4 small pins and keeps the driven ring going round correctly. I've had several fail over the years and just can't think of a way of fixing this washer back on. Bike is 850 mk 3 , but will affect all models.

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trident sam said:

Is the mk 3 speedo g/box the same as a T160 one

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I think it has a different "BG" number-but from memory, it is essentially the same unit-except for the size of the spindle/axle hole.

The centre hole is the critical size for model fitment. What diameter is the T160? and what drive ratio? (maybe 2:1).

Smiths Speedo Drive -NORTON
- BG5330/164. 1.25:1 5/8"
- BG5330/171. 15:12 11/16"
- BG5330/170. 15:12 5/8"
- BG5330/168. 15:12 3/4"
Ta.

I once made copper rivets but the plate is really to hold the ring gear in place until fitment i.e. it is not load bearing.

needing said:

What diameter is the T160? and what drive ratio? (maybe 2:1).

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The T160 spindle/axle is 5/8". The drive ratio is 1.25:1

needing said:

Smiths Speedo Drive -NORTON
- BG5330/164. 1.25:1 5/8"
- BG5330/171. 15:12 11/16"
- BG5330/170. 15:12 5/8"
- BG5330/168. 15:12 3/4"

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If that list (apparently copied from Burton website), is quoted in full then it's not a "Norton" list-but is for: "BSA/Norton/Triumph/Royal Enfield".

Suitable for BSA / Norton / Triumph / Royal Enfield
Part Number Ratio Hole Size
BG5330/0287 2:1 3/4"
BG5330/164 1.25:1 5/8"
BG5330/171 15:12 11/16"
BG5330/170 15:12 5/8"
BG5330/168 15:12 3/4"

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According to the T160 parts book, the drive gearbox is BG5333/164.
The Klempf website lists BG5333/164 for "T160" and BG5333/171 for "MkIII".
http://www.klempfsbritishparts.com/guag ... genumber=3

The only hangup I have with the speedo drives is the main gear wears out too fast, I now squirt slick 50 grease in every month or so and before a big ride. I read that Jin Comstock took a new one apart and heated it in Case Hardening Compound and that made it last a lot longer.
The only other hang up I had with speedo drive was the cable. I once got a cable that was made too long where it entered the speedo. I ground the end down to make it fit more correctly then found the bloody thing would not go into the drive gearbox properly., Al I needed to do originally was place some thrust washers on the end of the cable to hold it away from going into the head too far.
Dereck

Perhaps not a common thing but Ive had genuine cables that will not fit a pattern gearbox but will
fit a Smith's box just fine.
Genuine Smith's boxes have a fairly short life. Despite having a box of them in various states I've come
to see it is a pointless task now. You can just buy a pattern box and keep it lubed or buy a
electronic one and forget the hassle.

A smart phone with a GPS speedo app works fine (can also provide journey logs, maps, voice directions, etc and when removed from the bike is good for phone calls, camera, accessnorton, etc. I kept the gauge for 'historic' looks - a rego requirement.
Ta.

Thanks for the replies chaps.
Must admit the electronic ones do appeal to me, shame the price doesn't.
will have a go repairing it before I launch it at the wall :shock:
sam