Author Topic: Speedometer driveshaft  (Read 240 times)

Offline JHG1958

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Speedometer driveshaft
« on: 13.11. 2019 16:52 »
Does anyone know how to remove the speedometer driveshaft from the gearbox outer casing?  I am having the cases vapour blasted and need to remove everything.

John

Online JulianS

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Re: Speedometer driveshaft
« Reply #1 on: 13.11. 2019 18:36 »
My method is to remove the nut (if the type which takes one) remove the retaining screw in the outer cover, attach an old speedo cable to the thread and clamp cable in a vice then gently tap the cover off the speedo bush using a hide or rubber mallet.


Offline JHG1958

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Re: Speedometer driveshaft
« Reply #2 on: 13.11. 2019 18:44 »
Fantastic advice and quick too.  Mine was a little less willing to come out.  The advice gave me confidence to put a ring spanner behind the nut and screw the nut back on.  See photo.  I applied some heat and screwed the nut down.  In fact I ended up with four ring spanner’s before the sod was loose enough to pull out.

This will let me take my gearbox casings with the engine casings to get vapour blasted tomorrow.  My engine and gearbox rebuild is gaining momentum.

On stripping I found the interior of the gearbox covered in a waxy grease almost a varnish. All the components were reluctant to move.  Has anyone else found this? 

Any gems of advice for the rebuild?

Offline Whipstrut

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Re: Speedometer driveshaft
« Reply #3 on: 13.11. 2019 18:59 »
My gearbox also was coated throughout, and frozen solid. A month of soaking with my favorite penetrating oil freed it up most of the way, but of course it's now in bits. Worked on lots of gearboxes in my time and never seen this happen before.

Online chaterlea25

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Re: Speedometer driveshaft
« Reply #4 on: 13.11. 2019 20:10 »
Hi JHG,
Either blank off the oil relief passage to the cam trough at both ends and the tiny hole mid ways along where it oils the cam gears or make plans to drill out the blanking plugs to clean the oilway afterwards
Blasting media has wrecked more engines than most other seemingly good ideas  *warn* *warn* *problem* *problem* *problem*

John
1961 Super Rocket
1963 RGS (ongoing)

Offline Gerry

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Re: Speedometer driveshaft
« Reply #5 on: 14.11. 2019 00:24 »
Yep that was the same problem I had.....didn't realize there was media in the vapor blast. Put every thing together and buggered the bottom end!! Also tightened the big end bolts and then slackened them off to fit the split pins, luckily a friend who has a wealth of BSA experience noticed the side play in the rods (before it blew up) and re did the bottom end for me at extra big bucks...groan. Cheers Gerry

Offline Swarfcut

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Re: Speedometer driveshaft
« Reply #6 on: 14.11. 2019 08:23 »
'58,  While the drive gear and carrier are removed, check how the small top hat spindle support bush is looking. If worn enough to need replacement, a nut and bolt plus spacer draw bolt arrangement and the good old hot air gun on the casting trick will get it out without drama. Try not to use any violence on that thin web of the casting.

Swarfy.

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Re: Speedometer driveshaft
« Reply #7 on: 14.11. 2019 09:09 »
G'day JHG
I believe soda blasting is better. The "soda" is just bi-carb and disolves easily.
Cheers
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Offline JHG1958

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Re: Speedometer driveshaft
« Reply #8 on: 14.11. 2019 11:02 »
I do realise the problems with vapour blasting. I am taking the advice from the guy rebuilding my engine. He knows what he is doing and probably forgot more than I ever knew about bikes.

He will clean the engine after the reborn and vapour blasting.  I am ding the gearbox and primary drive.

One trick that I found is to use electrical contact cleaner aerosol.  It dissolves most oil and blows out the dirt.  Then it evaporates. Goo for the final clean.

John

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Re: Speedometer driveshaft
« Reply #9 on: 14.11. 2019 13:16 »
chaterlea25 is on the money here, I had mine done and used syringes to pump petrol through the camshaft feed holes etc then compressed air. when I drilled out the plug above the prv that seals the horizontal drilling to timing gears and camshaft I still got a small amount of medium out from there hiding away until the oil flow wants to drag it out *eek*