57 twin speedo gearbox binds

Biscuit · Post by **Biscuit** » Wed Mar 30, 2005 11:27 am

David, on second thoughts my theory on the misplaced near side outer race is hogwash, whatever position this is at, the whole lot will shift, maintaining the geabox/spacer/adjusting ring relationship. here's some dimensions to check. Locking ring face to end of adjusting ring - .5" (actually .516")Adjusting ring face to flange of spacer (against which the gearbox seats) .2" (.2095"). If this isn't clear, let me know and I'll send off a sketch via E-Mail.

Dave Walker · Post by **Dave Walker** » Tue Apr 05, 2005 5:51 pm

Thanks - I get as follows, estimated in 32nds so +/- .025 or so

1) locking ring face to adj ring end 0.59 (less than 19/32)
2) adj ring face to upper flange face 0.15 (c 5/32)

so potentialy 1) being too great could cause the problem?
... by leaving no clearance between the driving dogs and the bottom of the slots in the adjusting ring when the securing nut is tightened. - have I got that right?

so if this is correct then the outer o/s bearing race must be protruding too far. If there was no obvious play at the wheel rim then this seems to suggest that the "spacer between bearings..8 " or the "bearing spacing collar - brake side..9" (from p66 fig 77) are the wrong size, which feels unlikely. Or that the roller cages are not tight up against the spacer - is this possible? or is there more than one type of speedo gearbox (2:1 british patent 529397)?

Would be grateful for your thoughts.

In the meantime I'm off to buy the digital caliper I've been promising myself for all these years.

Dave Walker · Post by **Dave Walker** » Thu Apr 14, 2005 11:52 pm

Still can't get to the bottom of it.

When the wheel is in place and the spindle nut is finger tight there is about 50thou side float on the wheel which is taken up as further turns are put on the spindle nut. Is this normal?

TommoT · Post by **TommoT** » Fri Apr 15, 2005 12:40 am

Looking over the posts up till now, as far as I can see, two points have either not been covered in depth or described incorrectly (bear with me as English is not my native language, I was at some stage taught the "Queens" English which has haunted me ever since!):

1. The illogical cup/seal assembly in the right hand side (is this offside?) of the spindle/bearing assembly must be assembled exactly that way, i.e. contrary to logical deduction. The "cup" of the seal cup must face away from the seal, as it acts as a spacer, not a seal cup! If not assembled this way the total length of the the bearing assembly will be too short, allowing the speedobox to be caught between bearing adjuster and the gearbox dummy spindle.

2. From experience working with my own wheel set-up (q.d. 1956) you must engage the speedo gearbox driving pegs with the driving slots in the bearing adjuster, already when lining up all the bits'n pieces. If not you will run out of available space to fit the final stepped space just inside the swinging arm. This may vary over the years so I can only vouch for 1956.

Hope you get it sorted, lets hear about your findings!

Tom M. (TM)
Denmark

Colin F · Post by **Colin F** » Fri Apr 15, 2005 9:47 am

There is this way to ensure that you never have this problem ever again, never have to buy another speedo cable and be able to change easily from miles to kilometers for continental use.[8D]

Remove the speedo gear box and cable, then fit an electronic "bicycle" speedo, this is operated by sensor and magnet on the front wheel[:D]
Be sure you get a hard wired one not the wireless version otherwise the various components in the engine flying round at high speed could mess up the reading![:0]

Seriously this can always be considered a temporary option to get your bike back on the road while investigating this problem further.[;)]

Dave Walker · Post by **Dave Walker** » Sun Apr 17, 2005 8:09 pm

Thank you Tom, your english is absolutely precise. I think I have covered both of those possibilities.

Colin - it must be Sods law - I had intended to do exactly that as the speedo was in bits in a margarine tub in my mates workshop - where it had lain for about 20 years unmolested. Then I thought blow it I'll do the job properly and get it fixed, renew components in the back wheel and here we are ...

My concern is that the problem I have may be symptomatic of something I have done wrong within the wheel and brake drum assemblies, which may prove dangerous. The accountants tale of the errors of +£500,000 and -£499.999.99 which concatenate to give a 1p discrepancy in the overall account seems apposite.

In any event the next thing I'll try is putting a spacing washer on the inside of the speedeo gearbox to see what effect that has - it should tell me something.

Dave Walker · Post by **Dave Walker** » Tue Apr 19, 2005 8:03 pm

well that's fixed it - just wish I knew why!

I've fitted a thick washer (021604 dummy spindle washer) between the outer flange of the speedo gearbox spacer (021594) and the inside of the speedo gearbox. The whole thing sits firmly together, tightens up well and the wheel rotates freely, turning the speedo drive with no apparent binding.

The washer could be a tad thinner as it just makes it hard push to slide in the rear wheel spindle spacer (021591).

But why? - guess I'll eventually find out when the back wheel siezes solid after a few hundred miles?