Sleeve gear bushes replacement

[muskrat]

 Bugga, that's not good.
Upon re-assembly I'd check EVERYTHING. Bent shaft, motor/gbox alignment, sprocket alignment, chain wear(tight spots). Also check the bore of the bush is true to the gear.
Best of luck. Cheers

[KiwiGF]

I've done the sleeve bushes but not got the bike running yet and this does not sound promising!

These bushes only have a job to in the lower gears don't they? In top the gear and shaft rotate together?

Astonishing they wore so quickly if so. It probably might mean no oil got the bush but how can that happen.

[Brian]

Those bushes usually do many thousands of miles before needing attention so there is something very wrong here.

Even if the material they are made of was incorrect they still shouldnt wear that quick. If you have the three radial holes in the bushes then they will get enough lubrication. What oil are you using ? Do not put grease in the box, thats the best way to kill a gearbox.

The mainshaft, does it have any burrs on it that would act as a cutter ?

Triton Thrasher suggested chain tension and I think this could be the likely culprit. After fitting the primary chain turn the whole show over several times and make sure there are no tight spots in the chain. When you have tensioned the rear chain get someone to sit on the bike and re check it, the rear chain will tighten quite a bit with weight on the bike. Correct tension of both chains is important but its better to be slightly loose rather than too tight. Once you have adjusted both chains make sure the gearbox mounting bolts are tight.

Both the shaft and sleeve gear turn at different speeds, their speeds get closer as you go up in the gears but they dont actually turn together.

[BSA500]

Ok many questions to answer. Primary chain tension fine I always tend towards a little loose for just this issue. Mainshaft is a smooth as it should be with no obvious bends or kinks. I am using 80/90 gearbox oil and the gearbox bolts were bloody tight it took quite an effort to undo the bolts when I put on the new chains. I shall order some new ones from C&D Autos and redo them again. I will have to book a day off work just to do these but they are being a**es so a day up to my elbows in a BSA isn't all bad . Perhaps the oil just didn't get into the bush due to an air lock or something ???? ???? ???? ????. Its a mystery oh I do approx 130 miles a week so its living a full life

[BSA_54A10]

Which 80/90 gearbox oil ?
Gear & diff oils designed for cars & trucks may have extreme pressure additives that attack copper alloys.
This is why BSA originally specified engine oil in the gear box
Always make sure that any oil that goes in the gear box is marked as "Syncro safe ".
When syncromesh gearboxes became the norm they had to change the additive package as syncro cones were usually bronze.

[BSA500]

It is motorcycle gear oil the same type I have used for years without any issues. C&D Autos have said they had heard from various customers about issues with the type of metals used wearing very quickly.

[wilko]

That bronze eating oil hasn't been around for years. Otherwise every manual gearbox with synchro cones would be stuffed. Another wandering myth!!

[BSA_54A10]

That bronze eating oil hasn't been around for years. Otherwise every manual gearbox with synchro cones would be stuffed. Another wandering myth!!

No it is still with us as the sulphur compounds are the best for the job.
Truck gear box and diff oils still use sulphur as their extreme pressure anti scuff additive
Some synthetic oils are also not safe for bronze or brass bushes.
Generally the oils you buy from standard auto shops will be "syncro safe" but there are lot of gearbox & diff oils out there.
I just bought a job lot os 22 part drums of manual gearbox & diff oils.
Some are specific to a particular make or even a particular model.
Ie there is an oil for ford & holden V8 diffs and another for Ford XR6 diffs and yet another for standard 6 cylinders.

I am part way through going through the spec sheets but it looks like about 1/3 would not be copper alloy safe.
So yes they are still there.

[KiwiGF]

I'm still struggling with brians post that the mainshaft and sleeve gear do not turn together but I thought the top gear ratio is 1:1 and cannot be changed, as on the service sheet on this post below

Also that this makes the BSA gearbox more efficient compared to modern japanese boxes which drive through the layshaft even in top

But even if that's right and all tops are 1:1 all it would mean is that the sleeve gears got worn out in 1st to 3rd.

Puzzled!

http://www.a7a10.net/forum/index.php?topic=296.0

[Triton Thrasher]

Both the shaft and sleeve gear turn at different speeds, their speeds get closer as you go up in the gears but they dont actually turn together.

To engage top gear, the mainshaft and the concentric output are locked together, on practically all old British bikes.

[KiwiGF]

Im not sure if you have the sleeve gear out yet but if its still a mystery why they need replacing so quickly maybe post a pic up if the worn bushes and mainshaft?

[BSA500]

Right I now have the new bushes-I know how long has this taken!!. I will try to fit them this weekend and carry out an investigation on the old ones. C&D supplied the new set, two long bushes this time,actually too long I had to cut the excess sticking out the sleeve gear. Still better than too short. I shall aim for 1 thou clearance. Wish me luck.

[Topdad]

The very best of luck, your perseverance should be rewarded , Regards BobH

[BSA500]

Just pulled the box apart and look what I found...



Looks like the bush shifted a little and blocked the oil ways

[BSA500]

Just finished the rebuild all seems ok will find out tomorrow when I go to work. Again fingers crossed