Sleeve gear bushes replacement

[BSA500]

I used a dremel drill nice and small and fast .

[KiwiGF]

I drilled the holes in the bushes first the same size as was there already, they are quite a lot larger than the casing holes so you can get them misaligned a bit and not block flow.

[KiwiGF]

I know this is an old post but I fitted Draganfly sleeve gear bushes and they were toast after 600 miles. For some reason they seem to have glued themselves to the mainshaft and melted and turned inside the sleeve gear, lots of brass filings in the box etc

I'm just wondering what to do next! I've ordered more bushes from Draganfly today and all I can think of is to Ream them to a bigger clearance this next time, and use bearing retainer to ensure they do not turn inside the sleeve gear.

Any thoughts? Is it possible these thin bushes are not strong enough to get a permanant interference fit ?

[BSA500]

I gad that same issue with them turning and blocking the oil holes. I thought at the time they pressed in with ease and the replacemnet ones required more pressure to press in. Like you I thought I had made them too tight,now I'm not so sure

[KiwiGF]

Hi bsa500 so the bushes that were a tighter fit..were they solid brass or steel backed and have they lasted this time for you?

[BSA500]

Solid brass and so far they seem to holding up ok. I still have vibration I am leaning towards other gearbox issues either bent mainshaft or bearing replacement. I got a dial gauge for crimble so when I am next playing with the clutch I will check the shaft for run out.

[KiwiGF]

THanks 500, I'm away for a while now and will get onto the job of replacing them once I get the new bushes from draganfly.

I wonder if BSA "glued" these bushes into the sleeve gear? I'm going to this time anyway!

[chaterlea25]

Hi Kiwi, BSA500 and All,
"Brass" is not a term to use when talking about gearbox bushes, brass wouldnt last kissing time!!!
The original bushes were/are steel backed with a bronze lining
This would make the bush "stable" in size after pressing in and not contract like a solid bronze bush will do after installation,
Fairly recently I had trouble with a solid bronze bush which tightened after a mile or two, even though it all turned nicely on assembly
Since then I have sourced a set of NOS steel backed bushes, waiting until I get time to install them

Reasons why bushes fail after short milages must have to do with , material incorrect, chain tension incorrect or
incorrect fitment/ bent shafts etc
I really dont believe the oil holes have much to do with it, !!!!! other makes and models survive away without any

HTH
John

[BSA_54A10]

THanks 500, I'm away for a while now and will get onto the job of replacing them once I get the new bushes from draganfly.

I wonder if BSA "glued" these bushes into the sleeve gear? I'm going to this time anyway!

No the bush is shrunk fitted to the steel backing then reamed out to size.


The material to use is 85:5:5:5 leaded gunmetal.
I would have no worries fitting a plain gunmetal bush with .002" to .004" interfearence fit

[KiwiGF]

hi chaterlea, do you know where i can get steel backed sleeve gear bushes?

ref other post i meant maybe bsa "glued" and  also have an interfence fit....sorry i should made this clear... as to me the bushes do seem very thin, to maintain the pressure over time, and also I had a strange experience which got me doubting my sanity when I was fitting the bushes that just failed...i fitted them into the sleeve gear and the mainshaft fitted  just right with no reaming required  - which was as i expected given they had  a few tho clearance before pressing into the sleeve gear and the sleeve gear did not compress them THAT much.......but a couple of days later they had  "shrunk " and required reaming for the mainshaft to fit through them...i suppose with hindsight i should have realised something was amiss.

Im wondering if i will find the same happens with the new solid bronze bushes when they arrive from draganfly, but I'll only fit the non steel backed bushes a second time if i cannot find any steel backed bushes instead.

[chaterlea25]

Hi Kiwi
PM sent

John