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Mainshaft sleeve gear bush (wm20)

Hello Everyone,

I'm about to replace the bushings in the mainshaft sleeve gear (bushing part # 66-3155) of my wm20. Before I started I thought I'd ask for some advice.

The bushings from Draganfly come as two parts. Am I correct in thinking I can use the new bushings to push out the old? Or is there something I'm unaware of?

All advice most gratefully received!

Allan

email (option): allanmatchless@yahoo.com

Re: Mainshaft sleeve gear bush (wm20)

i use a small grinding bit to make a groove in the old one, go in from both sides and then collapse it in on itself, then press in the new ones
Dont use the new ones to try and press out the old one you will definitely damage it
i have also used a hacksaw blade in the past as well to split the old one

Re: Mainshaft sleeve gear bush (wm20)

I press them out with my hydraulic press and can't remember using anything other than a suitable size socket. Otherwise I would have got my mate to turn up a correct size stepped tool. Ron

email (option): ronpier@talk21.com

Re: Mainshaft sleeve gear bush (wm20)

And they were all 2 pieces AFAIK
One goes in from each end so you have a bout a 1/2" gap in the middle which is supposed to retain oil to compensate for the time it takes for splash to drain down into the bush

email (option): bsansw1@tpg.com.au

Re: Mainshaft sleeve gear bush (wm20)

I remove the old bushes with a suitable shouldered drift as Ron describes...That and a hammer as I don't have a press at home...

If the bushes that are being supplied are bronze they may well need reaming to size after fitting....

One problem you may also encounter is the drilling of the lubrication holes in the inner bush..These are a small diameter and at an angle to the axis of the bush..There is a high chance therefore that the drill will snap when it breaks through, particularly if you are using a hand held pistol drill...
Another consideration is the amount of wear you have on the main shaft...Many are undersize but they can be reground to provide a clean, true surface as they are hardened all the way through. In some cases stoning is enough to remove irregularities...Undersize bushes will then be required...

Generally, for that reason, I manufacture my own bushes to suit the shaft condition but that aside the procedure I use is as follows...

First remove the old bushes..Next, using a suitable drift fit the inner bush (the one furthest from the clutch)..Now, using a suitable size drill, drill slightly into the surface of the bush using the lubrication holes in the gear as a guide..Then remove the bush and drill each of the (now) marked holes through with a larger drill...say 3/16" diameter...Refit the bush to the gear taking care to correctly align the oil holes...Then fit the outer bush to the gear and finally ream/bore both bushes to the finished size as required..

The main shaft diameter when new should be .872"-.873"...Finished bush clearance should be .0015"-.0035"...I try to aim for the lower figure..If you choose to manufacture bushes a bushing bronze such as PB1 is a suitable choice....Ian

email (option): ian@wright52.plus.com

Re: Mainshaft sleeve gear bush (wm20)

I have always prefferred LG2 to Phos bronze because it is too hard for my liking.
Replacing the bushes more often is the lesser evil of doing a bushing and a main shaft less often.
Apart from that I have a good supply of 85-5-5-5 in a few sizes and it machines a lot better than any PB .

email (option): bsansw1@tpg.com.au

Re: Mainshaft sleeve gear bush (wm20)

Gentlemen,

Thank you so much for all this valuable information - I don't know any other place I could possibly have found such expertise. I know you've saved me from making some very silly errors! I can now proceed with more confidence, and I hope more competence.

Very best wishes to you all,

Allan

email (option): allanmatchless@yahoo.com

Re: Mainshaft sleeve gear bush (wm20)

Let us know how it goes...Ian

email (option): ian@wright52.plus.com

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