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BA kickstart quadrant stop rubber advice

Posted: Tue Mar 05, 2019 11:21 am
by Pete.Silson
I rebuilt my BA box 2 years ago and replaced the kickstart quadrant stop rubber (3338-33). I have just had the outer cover off and find that the rubber stop has completely disintegrated. I am surprised that it should fail so quickly especially since the gearbox has done less that 1000 miles since the rebuild.
Does anybody know of a better replacement for this part? The previous one was from Draganfly who now list it as no stock. I was wondering if a nylon bump stop might be more robust.

Pete

Re: BA kickstart quadrant stop rubber advice

Posted: Tue Mar 05, 2019 11:47 am
by dave.owen
peter, I've got a spare somewhere, again its a drags part as unobtainable anywhere else.

dave

Re: BA kickstart quadrant stop rubber advice

Posted: Tue Mar 05, 2019 11:55 am
by simon.holyfield
Did it have the metal ring around it, like a small Silentbloc bush?

Re: BA kickstart quadrant stop rubber advice

Posted: Tue Mar 05, 2019 1:34 pm
by Pete.Silson
Did it have the metal ring around it, like a small Silentbloc bush?

Simon, Yes it had the metal ring however, when first fitted, the one from Drags looked like it had been a smaller inside diameter and been roughly drilled out. The rubber inside the bush has now broken down to to a slimy black mush.

I've got a spare somewhere, again its a drags part as unobtainable anywhere else.dave

Dave, Thanks but I've got a one I can take out of the 39 box I have just built however my concern is that the same thing will happen with this one. I don't want to have to replace the thing every two years so I was wondering if anybody has found a suitable alternative

Pete

Re: BA kickstart quadrant stop rubber advice

Posted: Tue Mar 05, 2019 1:40 pm
by simon.holyfield
So they have specified the wrong elastomer. How about looking for a suitable bit of viton tube?

Re: BA kickstart quadrant stop rubber advice

Posted: Tue Mar 05, 2019 2:25 pm
by Pete.Silson
So they have specified the wrong elastomer. How about looking for a suitable bit of viton tube?


Simon, Is there a particular grade of Viton I should be looking for?

Re: BA kickstart quadrant stop rubber advice

Posted: Tue Mar 05, 2019 2:53 pm
by simon.holyfield
I don't think so - i think all the Viton grades I've seen are good with automotive oils & greases, but I'm sure an expert will be along in a minute.

The issue you are going to have is finding something of a suitable cross section in an appropriate Shore hardness. I'd be googling viton tubing, bushes, grommets, washers - see what you can find.

Re: BA kickstart quadrant stop rubber advice

Posted: Tue Mar 05, 2019 5:14 pm
by TonyBaxter
How about machining a new one out of some of that plastic type material that is used in place of rubber nowadays? Assuming you can find a nylon, urethane or similar that has enough 'give' to do the job.

Re: BA kickstart quadrant stop rubber advice

Posted: Tue Mar 05, 2019 5:26 pm
by Simon.Gardiner
Possibly a job for that new-fangled 3D printing.... :)

SG

Re: BA kickstart quadrant stop rubber advice

Posted: Tue Mar 05, 2019 7:59 pm
by Pete.Silson
I've ordered some nylon suspension bushes and will see if they can be fitted inside the old metal cap. I wouldn't expect the nylon to deteriorate in gearbox grease for a year or two.
bushes 1a.jpg


Possibly a job for that new-fangled 3D printing....

Does anybody have access to a 3D printer I can think of a few other useful bits and pieces that could be printed - Burman speedometer pinion worm gear is one that springs immediately to mind.

Pete